Merge tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost

[deliverable/linux.git] / security / smack / smackfs.c

/*
 * Copyright (C) 2007 Casey Schaufler <casey@schaufler-ca.com>
 *
 *      This program is free software; you can redistribute it and/or modify
 *      it under the terms of the GNU General Public License as published by
 *      the Free Software Foundation, version 2.
 *
 * Authors:
 *      Casey Schaufler <casey@schaufler-ca.com>
 *      Ahmed S. Darwish <darwish.07@gmail.com>
 *
 * Special thanks to the authors of selinuxfs.
 *
 *      Karl MacMillan <kmacmillan@tresys.com>
 *      James Morris <jmorris@redhat.com>
 *
 */

#include <linux/kernel.h>
#include <linux/vmalloc.h>
#include <linux/security.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <net/net_namespace.h>
#include <net/cipso_ipv4.h>
#include <linux/seq_file.h>
#include <linux/ctype.h>
#include <linux/audit.h>
#include <linux/magic.h>
#include "smack.h"

/*
 * smackfs pseudo filesystem.
 */

enum smk_inos {
        SMK_ROOT_INO    = 2,
        SMK_LOAD        = 3,    /* load policy */
        SMK_CIPSO       = 4,    /* load label -> CIPSO mapping */
        SMK_DOI         = 5,    /* CIPSO DOI */
        SMK_DIRECT      = 6,    /* CIPSO level indicating direct label */
        SMK_AMBIENT     = 7,    /* internet ambient label */
        SMK_NETLBLADDR  = 8,    /* single label hosts */
        SMK_ONLYCAP     = 9,    /* the only "capable" label */
        SMK_LOGGING     = 10,   /* logging */
        SMK_LOAD_SELF   = 11,   /* task specific rules */
        SMK_ACCESSES    = 12,   /* access policy */
        SMK_MAPPED      = 13,   /* CIPSO level indicating mapped label */
        SMK_LOAD2       = 14,   /* load policy with long labels */
        SMK_LOAD_SELF2  = 15,   /* load task specific rules with long labels */
        SMK_ACCESS2     = 16,   /* make an access check with long labels */
        SMK_CIPSO2      = 17,   /* load long label -> CIPSO mapping */
        SMK_REVOKE_SUBJ = 18,   /* set rules with subject label to '-' */
        SMK_CHANGE_RULE = 19,   /* change or add rules (long labels) */
        SMK_SYSLOG      = 20,   /* change syslog label) */
        SMK_PTRACE      = 21,   /* set ptrace rule */
#ifdef CONFIG_SECURITY_SMACK_BRINGUP
        SMK_UNCONFINED  = 22,   /* define an unconfined label */
#endif
};

/*
 * List locks
 */
static DEFINE_MUTEX(smack_cipso_lock);
static DEFINE_MUTEX(smack_ambient_lock);
static DEFINE_MUTEX(smk_netlbladdr_lock);

/*
 * This is the "ambient" label for network traffic.
 * If it isn't somehow marked, use this.
 * It can be reset via smackfs/ambient
 */
struct smack_known *smack_net_ambient;

/*
 * This is the level in a CIPSO header that indicates a
 * smack label is contained directly in the category set.
 * It can be reset via smackfs/direct
 */
int smack_cipso_direct = SMACK_CIPSO_DIRECT_DEFAULT;

/*
 * This is the level in a CIPSO header that indicates a
 * secid is contained directly in the category set.
 * It can be reset via smackfs/mapped
 */
int smack_cipso_mapped = SMACK_CIPSO_MAPPED_DEFAULT;

#ifdef CONFIG_SECURITY_SMACK_BRINGUP
/*
 * Allow one label to be unconfined. This is for
 * debugging and application bring-up purposes only.
 * It is bad and wrong, but everyone seems to expect
 * to have it.
 */
struct smack_known *smack_unconfined;
#endif

/*
 * If this value is set restrict syslog use to the label specified.
 * It can be reset via smackfs/syslog
 */
struct smack_known *smack_syslog_label;

/*
 * Ptrace current rule
 * SMACK_PTRACE_DEFAULT    regular smack ptrace rules (/proc based)
 * SMACK_PTRACE_EXACT      labels must match, but can be overriden with
 *                         CAP_SYS_PTRACE
 * SMACK_PTRACE_DRACONIAN  lables must match, CAP_SYS_PTRACE has no effect
 */
int smack_ptrace_rule = SMACK_PTRACE_DEFAULT;

/*
 * Certain IP addresses may be designated as single label hosts.
 * Packets are sent there unlabeled, but only from tasks that
 * can write to the specified label.
 */

LIST_HEAD(smk_netlbladdr_list);

/*
 * Rule lists are maintained for each label.
 * This master list is just for reading /smack/load and /smack/load2.
 */
struct smack_master_list {
        struct list_head        list;
        struct smack_rule       *smk_rule;
};

LIST_HEAD(smack_rule_list);

struct smack_parsed_rule {
        struct smack_known      *smk_subject;
        struct smack_known      *smk_object;
        int                     smk_access1;
        int                     smk_access2;
};

static int smk_cipso_doi_value = SMACK_CIPSO_DOI_DEFAULT;

struct smack_known smack_cipso_option = {
        .smk_known      = SMACK_CIPSO_OPTION,
        .smk_secid      = 0,
};

/*
 * Values for parsing cipso rules
 * SMK_DIGITLEN: Length of a digit field in a rule.
 * SMK_CIPSOMIN: Minimum possible cipso rule length.
 * SMK_CIPSOMAX: Maximum possible cipso rule length.
 */
#define SMK_DIGITLEN 4
#define SMK_CIPSOMIN (SMK_LABELLEN + 2 * SMK_DIGITLEN)
#define SMK_CIPSOMAX (SMK_CIPSOMIN + SMACK_CIPSO_MAXCATNUM * SMK_DIGITLEN)

/*
 * Values for parsing MAC rules
 * SMK_ACCESS: Maximum possible combination of access permissions
 * SMK_ACCESSLEN: Maximum length for a rule access field
 * SMK_LOADLEN: Smack rule length
 */
#define SMK_OACCESS     "rwxa"
#define SMK_ACCESS      "rwxatl"
#define SMK_OACCESSLEN  (sizeof(SMK_OACCESS) - 1)
#define SMK_ACCESSLEN   (sizeof(SMK_ACCESS) - 1)
#define SMK_OLOADLEN    (SMK_LABELLEN + SMK_LABELLEN + SMK_OACCESSLEN)
#define SMK_LOADLEN     (SMK_LABELLEN + SMK_LABELLEN + SMK_ACCESSLEN)

/*
 * Stricly for CIPSO level manipulation.
 * Set the category bit number in a smack label sized buffer.
 */
static inline void smack_catset_bit(unsigned int cat, char *catsetp)
{
        if (cat == 0 || cat > (SMK_CIPSOLEN * 8))
                return;

        catsetp[(cat - 1) / 8] |= 0x80 >> ((cat - 1) % 8);
}

/**
 * smk_netlabel_audit_set - fill a netlbl_audit struct
 * @nap: structure to fill
 */
static void smk_netlabel_audit_set(struct netlbl_audit *nap)
{
        struct smack_known *skp = smk_of_current();

        nap->loginuid = audit_get_loginuid(current);
        nap->sessionid = audit_get_sessionid(current);
        nap->secid = skp->smk_secid;
}

/*
 * Value for parsing single label host rules
 * "1.2.3.4 X"
 */
#define SMK_NETLBLADDRMIN       9

/**
 * smk_set_access - add a rule to the rule list or replace an old rule
 * @srp: the rule to add or replace
 * @rule_list: the list of rules
 * @rule_lock: the rule list lock
 * @global: if non-zero, indicates a global rule
 *
 * Looks through the current subject/object/access list for
 * the subject/object pair and replaces the access that was
 * there. If the pair isn't found add it with the specified
 * access.
 *
 * Returns 0 if nothing goes wrong or -ENOMEM if it fails
 * during the allocation of the new pair to add.
 */
static int smk_set_access(struct smack_parsed_rule *srp,
                                struct list_head *rule_list,
                                struct mutex *rule_lock, int global)
{
        struct smack_rule *sp;
        struct smack_master_list *smlp;
        int found = 0;
        int rc = 0;

        mutex_lock(rule_lock);

        /*
         * Because the object label is less likely to match
         * than the subject label check it first
         */
        list_for_each_entry_rcu(sp, rule_list, list) {
                if (sp->smk_object == srp->smk_object &&
                    sp->smk_subject == srp->smk_subject) {
                        found = 1;
                        sp->smk_access |= srp->smk_access1;
                        sp->smk_access &= ~srp->smk_access2;
                        break;
                }
        }

        if (found == 0) {
                sp = kzalloc(sizeof(*sp), GFP_KERNEL);
                if (sp == NULL) {
                        rc = -ENOMEM;
                        goto out;
                }

                sp->smk_subject = srp->smk_subject;
                sp->smk_object = srp->smk_object;
                sp->smk_access = srp->smk_access1 & ~srp->smk_access2;

                list_add_rcu(&sp->list, rule_list);
                /*
                 * If this is a global as opposed to self and a new rule
                 * it needs to get added for reporting.
                 */
                if (global) {
                        smlp = kzalloc(sizeof(*smlp), GFP_KERNEL);
                        if (smlp != NULL) {
                                smlp->smk_rule = sp;
                                list_add_rcu(&smlp->list, &smack_rule_list);
                        } else
                                rc = -ENOMEM;
                }
        }

out:
        mutex_unlock(rule_lock);
        return rc;
}

/**
 * smk_perm_from_str - parse smack accesses from a text string
 * @string: a text string that contains a Smack accesses code
 *
 * Returns an integer with respective bits set for specified accesses.
 */
static int smk_perm_from_str(const char *string)
{
        int perm = 0;
        const char *cp;

        for (cp = string; ; cp++)
                switch (*cp) {
                case '-':
                        break;
                case 'r':
                case 'R':
                        perm |= MAY_READ;
                        break;
                case 'w':
                case 'W':
                        perm |= MAY_WRITE;
                        break;
                case 'x':
                case 'X':
                        perm |= MAY_EXEC;
                        break;
                case 'a':
                case 'A':
                        perm |= MAY_APPEND;
                        break;
                case 't':
                case 'T':
                        perm |= MAY_TRANSMUTE;
                        break;
                case 'l':
                case 'L':
                        perm |= MAY_LOCK;
                        break;
                case 'b':
                case 'B':
                        perm |= MAY_BRINGUP;
                        break;
                default:
                        return perm;
                }
}

/**
 * smk_fill_rule - Fill Smack rule from strings
 * @subject: subject label string
 * @object: object label string
 * @access1: access string
 * @access2: string with permissions to be removed
 * @rule: Smack rule
 * @import: if non-zero, import labels
 * @len: label length limit
 *
 * Returns 0 on success, appropriate error code on failure.
 */
static int smk_fill_rule(const char *subject, const char *object,
                                const char *access1, const char *access2,
                                struct smack_parsed_rule *rule, int import,
                                int len)
{
        const char *cp;
        struct smack_known *skp;

        if (import) {
                rule->smk_subject = smk_import_entry(subject, len);
                if (IS_ERR(rule->smk_subject))
                        return PTR_ERR(rule->smk_subject);

                rule->smk_object = smk_import_entry(object, len);
                if (IS_ERR(rule->smk_object))
                        return PTR_ERR(rule->smk_object);
        } else {
                cp = smk_parse_smack(subject, len);
                if (IS_ERR(cp))
                        return PTR_ERR(cp);
                skp = smk_find_entry(cp);
                kfree(cp);
                if (skp == NULL)
                        return -ENOENT;
                rule->smk_subject = skp;

                cp = smk_parse_smack(object, len);
                if (IS_ERR(cp))
                        return PTR_ERR(cp);
                skp = smk_find_entry(cp);
                kfree(cp);
                if (skp == NULL)
                        return -ENOENT;
                rule->smk_object = skp;
        }

        rule->smk_access1 = smk_perm_from_str(access1);
        if (access2)
                rule->smk_access2 = smk_perm_from_str(access2);
        else
                rule->smk_access2 = ~rule->smk_access1;

        return 0;
}

/**
 * smk_parse_rule - parse Smack rule from load string
 * @data: string to be parsed whose size is SMK_LOADLEN
 * @rule: Smack rule
 * @import: if non-zero, import labels
 *
 * Returns 0 on success, -1 on errors.
 */
static int smk_parse_rule(const char *data, struct smack_parsed_rule *rule,
                                int import)
{
        int rc;

        rc = smk_fill_rule(data, data + SMK_LABELLEN,
                           data + SMK_LABELLEN + SMK_LABELLEN, NULL, rule,
                           import, SMK_LABELLEN);
        return rc;
}

/**
 * smk_parse_long_rule - parse Smack rule from rule string
 * @data: string to be parsed, null terminated
 * @rule: Will be filled with Smack parsed rule
 * @import: if non-zero, import labels
 * @tokens: numer of substrings expected in data
 *
 * Returns number of processed bytes on success, -ERRNO on failure.
 */
static ssize_t smk_parse_long_rule(char *data, struct smack_parsed_rule *rule,
                                int import, int tokens)
{
        ssize_t cnt = 0;
        char *tok[4];
        int rc;
        int i;

        /*
         * Parsing the rule in-place, filling all white-spaces with '\0'
         */
        for (i = 0; i < tokens; ++i) {
                while (isspace(data[cnt]))
                        data[cnt++] = '\0';

                if (data[cnt] == '\0')
                        /* Unexpected end of data */
                        return -EINVAL;

                tok[i] = data + cnt;

                while (data[cnt] && !isspace(data[cnt]))
                        ++cnt;
        }
        while (isspace(data[cnt]))
                data[cnt++] = '\0';

        while (i < 4)
                tok[i++] = NULL;

        rc = smk_fill_rule(tok[0], tok[1], tok[2], tok[3], rule, import, 0);
        return rc == 0 ? cnt : rc;
}

#define SMK_FIXED24_FMT 0       /* Fixed 24byte label format */
#define SMK_LONG_FMT    1       /* Variable long label format */
#define SMK_CHANGE_FMT  2       /* Rule modification format */
/**
 * smk_write_rules_list - write() for any /smack rule file
 * @file: file pointer, not actually used
 * @buf: where to get the data from
 * @count: bytes sent
 * @ppos: where to start - must be 0
 * @rule_list: the list of rules to write to
 * @rule_lock: lock for the rule list
 * @format: /smack/load or /smack/load2 or /smack/change-rule format.
 *
 * Get one smack access rule from above.
 * The format for SMK_LONG_FMT is:
 *      "subject<whitespace>object<whitespace>access[<whitespace>...]"
 * The format for SMK_FIXED24_FMT is exactly:
 *      "subject                 object                  rwxat"
 * The format for SMK_CHANGE_FMT is:
 *      "subject<whitespace>object<whitespace>
 *       acc_enable<whitespace>acc_disable[<whitespace>...]"
 */
static ssize_t smk_write_rules_list(struct file *file, const char __user *buf,
                                        size_t count, loff_t *ppos,
                                        struct list_head *rule_list,
                                        struct mutex *rule_lock, int format)
{
        struct smack_parsed_rule rule;
        char *data;
        int rc;
        int trunc = 0;
        int tokens;
        ssize_t cnt = 0;

        /*
         * No partial writes.
         * Enough data must be present.
         */
        if (*ppos != 0)
                return -EINVAL;

        if (format == SMK_FIXED24_FMT) {
                /*
                 * Minor hack for backward compatibility
                 */
                if (count < SMK_OLOADLEN || count > SMK_LOADLEN)
                        return -EINVAL;
        } else {
                if (count >= PAGE_SIZE) {
                        count = PAGE_SIZE - 1;
                        trunc = 1;
                }
        }

        data = kmalloc(count + 1, GFP_KERNEL);
        if (data == NULL)
                return -ENOMEM;

        if (copy_from_user(data, buf, count) != 0) {
                rc = -EFAULT;
                goto out;
        }

        /*
         * In case of parsing only part of user buf,
         * avoid having partial rule at the data buffer
         */
        if (trunc) {
                while (count > 0 && (data[count - 1] != '\n'))
                        --count;
                if (count == 0) {
                        rc = -EINVAL;
                        goto out;
                }
        }

        data[count] = '\0';
        tokens = (format == SMK_CHANGE_FMT ? 4 : 3);
        while (cnt < count) {
                if (format == SMK_FIXED24_FMT) {
                        rc = smk_parse_rule(data, &rule, 1);
                        if (rc < 0)
                                goto out;
                        cnt = count;
                } else {
                        rc = smk_parse_long_rule(data + cnt, &rule, 1, tokens);
                        if (rc < 0)
                                goto out;
                        if (rc == 0) {
                                rc = -EINVAL;
                                goto out;
                        }
                        cnt += rc;
                }

                if (rule_list == NULL)
                        rc = smk_set_access(&rule, &rule.smk_subject->smk_rules,
                                &rule.smk_subject->smk_rules_lock, 1);
                else
                        rc = smk_set_access(&rule, rule_list, rule_lock, 0);

                if (rc)
                        goto out;
        }

        rc = cnt;
out:
        kfree(data);
        return rc;
}

/*
 * Core logic for smackfs seq list operations.
 */

static void *smk_seq_start(struct seq_file *s, loff_t *pos,
                                struct list_head *head)
{
        struct list_head *list;
        int i = *pos;

        rcu_read_lock();
        for (list = rcu_dereference(list_next_rcu(head));
                list != head;
                list = rcu_dereference(list_next_rcu(list))) {
                if (i-- == 0)
                        return list;
        }

        return NULL;
}

static void *smk_seq_next(struct seq_file *s, void *v, loff_t *pos,
                                struct list_head *head)
{
        struct list_head *list = v;

        ++*pos;
        list = rcu_dereference(list_next_rcu(list));

        return (list == head) ? NULL : list;
}

static void smk_seq_stop(struct seq_file *s, void *v)
{
        rcu_read_unlock();
}

static void smk_rule_show(struct seq_file *s, struct smack_rule *srp, int max)
{
        /*
         * Don't show any rules with label names too long for
         * interface file (/smack/load or /smack/load2)
         * because you should expect to be able to write
         * anything you read back.
         */
        if (strlen(srp->smk_subject->smk_known) >= max ||
            strlen(srp->smk_object->smk_known) >= max)
                return;

        if (srp->smk_access == 0)
                return;

        seq_printf(s, "%s %s",
                   srp->smk_subject->smk_known,
                   srp->smk_object->smk_known);

        seq_putc(s, ' ');

        if (srp->smk_access & MAY_READ)
                seq_putc(s, 'r');
        if (srp->smk_access & MAY_WRITE)
                seq_putc(s, 'w');
        if (srp->smk_access & MAY_EXEC)
                seq_putc(s, 'x');
        if (srp->smk_access & MAY_APPEND)
                seq_putc(s, 'a');
        if (srp->smk_access & MAY_TRANSMUTE)
                seq_putc(s, 't');
        if (srp->smk_access & MAY_LOCK)
                seq_putc(s, 'l');
        if (srp->smk_access & MAY_BRINGUP)
                seq_putc(s, 'b');

        seq_putc(s, '\n');
}

/*
 * Seq_file read operations for /smack/load
 */

static void *load2_seq_start(struct seq_file *s, loff_t *pos)
{
        return smk_seq_start(s, pos, &smack_rule_list);
}

static void *load2_seq_next(struct seq_file *s, void *v, loff_t *pos)
{
        return smk_seq_next(s, v, pos, &smack_rule_list);
}

static int load_seq_show(struct seq_file *s, void *v)
{
        struct list_head *list = v;
        struct smack_master_list *smlp =
                list_entry_rcu(list, struct smack_master_list, list);

        smk_rule_show(s, smlp->smk_rule, SMK_LABELLEN);

        return 0;
}

static const struct seq_operations load_seq_ops = {
        .start = load2_seq_start,
        .next  = load2_seq_next,
        .show  = load_seq_show,
        .stop  = smk_seq_stop,
};

/**
 * smk_open_load - open() for /smack/load
 * @inode: inode structure representing file
 * @file: "load" file pointer
 *
 * For reading, use load_seq_* seq_file reading operations.
 */
static int smk_open_load(struct inode *inode, struct file *file)
{
        return seq_open(file, &load_seq_ops);
}

/**
 * smk_write_load - write() for /smack/load
 * @file: file pointer, not actually used
 * @buf: where to get the data from
 * @count: bytes sent
 * @ppos: where to start - must be 0
 *
 */
static ssize_t smk_write_load(struct file *file, const char __user *buf,
                              size_t count, loff_t *ppos)
{
        /*
         * Must have privilege.
         * No partial writes.
         * Enough data must be present.
         */
        if (!smack_privileged(CAP_MAC_ADMIN))
                return -EPERM;

        return smk_write_rules_list(file, buf, count, ppos, NULL, NULL,
                                    SMK_FIXED24_FMT);
}

static const struct file_operations smk_load_ops = {
        .open           = smk_open_load,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .write          = smk_write_load,
        .release        = seq_release,
};

/**
 * smk_cipso_doi - initialize the CIPSO domain
 */
static void smk_cipso_doi(void)
{
        int rc;
        struct cipso_v4_doi *doip;
        struct netlbl_audit nai;

        smk_netlabel_audit_set(&nai);

        rc = netlbl_cfg_map_del(NULL, PF_INET, NULL, NULL, &nai);
        if (rc != 0)
                printk(KERN_WARNING "%s:%d remove rc = %d\n",
                       __func__, __LINE__, rc);

        doip = kmalloc(sizeof(struct cipso_v4_doi), GFP_KERNEL);
        if (doip == NULL)
                panic("smack:  Failed to initialize cipso DOI.\n");
        doip->map.std = NULL;
        doip->doi = smk_cipso_doi_value;
        doip->type = CIPSO_V4_MAP_PASS;
        doip->tags[0] = CIPSO_V4_TAG_RBITMAP;
        for (rc = 1; rc < CIPSO_V4_TAG_MAXCNT; rc++)
                doip->tags[rc] = CIPSO_V4_TAG_INVALID;

        rc = netlbl_cfg_cipsov4_add(doip, &nai);
        if (rc != 0) {
                printk(KERN_WARNING "%s:%d cipso add rc = %d\n",
                       __func__, __LINE__, rc);
                kfree(doip);
                return;
        }
        rc = netlbl_cfg_cipsov4_map_add(doip->doi, NULL, NULL, NULL, &nai);
        if (rc != 0) {
                printk(KERN_WARNING "%s:%d map add rc = %d\n",
                       __func__, __LINE__, rc);
                kfree(doip);
                return;
        }
}

/**
 * smk_unlbl_ambient - initialize the unlabeled domain
 * @oldambient: previous domain string
 */
static void smk_unlbl_ambient(char *oldambient)
{
        int rc;
        struct netlbl_audit nai;

        smk_netlabel_audit_set(&nai);

        if (oldambient != NULL) {
                rc = netlbl_cfg_map_del(oldambient, PF_INET, NULL, NULL, &nai);
                if (rc != 0)
                        printk(KERN_WARNING "%s:%d remove rc = %d\n",
                               __func__, __LINE__, rc);
        }
        if (smack_net_ambient == NULL)
                smack_net_ambient = &smack_known_floor;

        rc = netlbl_cfg_unlbl_map_add(smack_net_ambient->smk_known, PF_INET,
                                      NULL, NULL, &nai);
        if (rc != 0)
                printk(KERN_WARNING "%s:%d add rc = %d\n",
                       __func__, __LINE__, rc);
}

/*
 * Seq_file read operations for /smack/cipso
 */

static void *cipso_seq_start(struct seq_file *s, loff_t *pos)
{
        return smk_seq_start(s, pos, &smack_known_list);
}

static void *cipso_seq_next(struct seq_file *s, void *v, loff_t *pos)
{
        return smk_seq_next(s, v, pos, &smack_known_list);
}

/*
 * Print cipso labels in format:
 * label level[/cat[,cat]]
 */
static int cipso_seq_show(struct seq_file *s, void *v)
{
        struct list_head  *list = v;
        struct smack_known *skp =
                list_entry_rcu(list, struct smack_known, list);
        struct netlbl_lsm_catmap *cmp = skp->smk_netlabel.attr.mls.cat;
        char sep = '/';
        int i;

        /*
         * Don't show a label that could not have been set using
         * /smack/cipso. This is in support of the notion that
         * anything read from /smack/cipso ought to be writeable
         * to /smack/cipso.
         *
         * /smack/cipso2 should be used instead.
         */
        if (strlen(skp->smk_known) >= SMK_LABELLEN)
                return 0;

        seq_printf(s, "%s %3d", skp->smk_known, skp->smk_netlabel.attr.mls.lvl);

        for (i = netlbl_catmap_walk(cmp, 0); i >= 0;
             i = netlbl_catmap_walk(cmp, i + 1)) {
                seq_printf(s, "%c%d", sep, i);
                sep = ',';
        }

        seq_putc(s, '\n');

        return 0;
}

static const struct seq_operations cipso_seq_ops = {
        .start = cipso_seq_start,
        .next  = cipso_seq_next,
        .show  = cipso_seq_show,
        .stop  = smk_seq_stop,
};

/**
 * smk_open_cipso - open() for /smack/cipso
 * @inode: inode structure representing file
 * @file: "cipso" file pointer
 *
 * Connect our cipso_seq_* operations with /smack/cipso
 * file_operations
 */
static int smk_open_cipso(struct inode *inode, struct file *file)
{
        return seq_open(file, &cipso_seq_ops);
}

/**
 * smk_set_cipso - do the work for write() for cipso and cipso2
 * @file: file pointer, not actually used
 * @buf: where to get the data from
 * @count: bytes sent
 * @ppos: where to start
 * @format: /smack/cipso or /smack/cipso2
 *
 * Accepts only one cipso rule per write call.
 * Returns number of bytes written or error code, as appropriate
 */
static ssize_t smk_set_cipso(struct file *file, const char __user *buf,
                                size_t count, loff_t *ppos, int format)
{
        struct smack_known *skp;
        struct netlbl_lsm_secattr ncats;
        char mapcatset[SMK_CIPSOLEN];
        int maplevel;
        unsigned int cat;
        int catlen;
        ssize_t rc = -EINVAL;
        char *data = NULL;
        char *rule;
        int ret;
        int i;

        /*
         * Must have privilege.
         * No partial writes.
         * Enough data must be present.
         */
        if (!smack_privileged(CAP_MAC_ADMIN))
                return -EPERM;
        if (*ppos != 0)
                return -EINVAL;
        if (format == SMK_FIXED24_FMT &&
            (count < SMK_CIPSOMIN || count > SMK_CIPSOMAX))
                return -EINVAL;

        data = kzalloc(count + 1, GFP_KERNEL);
        if (data == NULL)
                return -ENOMEM;

        if (copy_from_user(data, buf, count) != 0) {
                rc = -EFAULT;
                goto unlockedout;
        }

        data[count] = '\0';
        rule = data;
        /*
         * Only allow one writer at a time. Writes should be
         * quite rare and small in any case.
         */
        mutex_lock(&smack_cipso_lock);

        skp = smk_import_entry(rule, 0);
        if (IS_ERR(skp)) {
                rc = PTR_ERR(skp);
                goto out;
        }

        if (format == SMK_FIXED24_FMT)
                rule += SMK_LABELLEN;
        else
                rule += strlen(skp->smk_known) + 1;

        ret = sscanf(rule, "%d", &maplevel);
        if (ret != 1 || maplevel > SMACK_CIPSO_MAXLEVEL)
                goto out;

        rule += SMK_DIGITLEN;
        ret = sscanf(rule, "%d", &catlen);
        if (ret != 1 || catlen > SMACK_CIPSO_MAXCATNUM)
                goto out;

        if (format == SMK_FIXED24_FMT &&
            count != (SMK_CIPSOMIN + catlen * SMK_DIGITLEN))
                goto out;

        memset(mapcatset, 0, sizeof(mapcatset));

        for (i = 0; i < catlen; i++) {
                rule += SMK_DIGITLEN;
                ret = sscanf(rule, "%u", &cat);
                if (ret != 1 || cat > SMACK_CIPSO_MAXCATNUM)
                        goto out;

                smack_catset_bit(cat, mapcatset);
        }

        rc = smk_netlbl_mls(maplevel, mapcatset, &ncats, SMK_CIPSOLEN);
        if (rc >= 0) {
                netlbl_catmap_free(skp->smk_netlabel.attr.mls.cat);
                skp->smk_netlabel.attr.mls.cat = ncats.attr.mls.cat;
                skp->smk_netlabel.attr.mls.lvl = ncats.attr.mls.lvl;
                rc = count;
        }

out:
        mutex_unlock(&smack_cipso_lock);
unlockedout:
        kfree(data);
        return rc;
}

/**
 * smk_write_cipso - write() for /smack/cipso
 * @file: file pointer, not actually used
 * @buf: where to get the data from
 * @count: bytes sent
 * @ppos: where to start
 *
 * Accepts only one cipso rule per write call.
 * Returns number of bytes written or error code, as appropriate
 */
static ssize_t smk_write_cipso(struct file *file, const char __user *buf,
                               size_t count, loff_t *ppos)
{
        return smk_set_cipso(file, buf, count, ppos, SMK_FIXED24_FMT);
}

static const struct file_operations smk_cipso_ops = {
        .open           = smk_open_cipso,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .write          = smk_write_cipso,
        .release        = seq_release,
};

/*
 * Seq_file read operations for /smack/cipso2
 */

/*
 * Print cipso labels in format:
 * label level[/cat[,cat]]
 */
static int cipso2_seq_show(struct seq_file *s, void *v)
{
        struct list_head  *list = v;
        struct smack_known *skp =
                list_entry_rcu(list, struct smack_known, list);
        struct netlbl_lsm_catmap *cmp = skp->smk_netlabel.attr.mls.cat;
        char sep = '/';
        int i;

        seq_printf(s, "%s %3d", skp->smk_known, skp->smk_netlabel.attr.mls.lvl);

        for (i = netlbl_catmap_walk(cmp, 0); i >= 0;
             i = netlbl_catmap_walk(cmp, i + 1)) {
                seq_printf(s, "%c%d", sep, i);
                sep = ',';
        }

        seq_putc(s, '\n');

        return 0;
}

static const struct seq_operations cipso2_seq_ops = {
        .start = cipso_seq_start,
        .next  = cipso_seq_next,
        .show  = cipso2_seq_show,
        .stop  = smk_seq_stop,
};

/**
 * smk_open_cipso2 - open() for /smack/cipso2
 * @inode: inode structure representing file
 * @file: "cipso2" file pointer
 *
 * Connect our cipso_seq_* operations with /smack/cipso2
 * file_operations
 */
static int smk_open_cipso2(struct inode *inode, struct file *file)
{
        return seq_open(file, &cipso2_seq_ops);
}

/**
 * smk_write_cipso2 - write() for /smack/cipso2
 * @file: file pointer, not actually used
 * @buf: where to get the data from
 * @count: bytes sent
 * @ppos: where to start
 *
 * Accepts only one cipso rule per write call.
 * Returns number of bytes written or error code, as appropriate
 */
static ssize_t smk_write_cipso2(struct file *file, const char __user *buf,
                              size_t count, loff_t *ppos)
{
        return smk_set_cipso(file, buf, count, ppos, SMK_LONG_FMT);
}

static const struct file_operations smk_cipso2_ops = {
        .open           = smk_open_cipso2,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .write          = smk_write_cipso2,
        .release        = seq_release,
};

/*
 * Seq_file read operations for /smack/netlabel
 */

static void *netlbladdr_seq_start(struct seq_file *s, loff_t *pos)
{
        return smk_seq_start(s, pos, &smk_netlbladdr_list);
}

static void *netlbladdr_seq_next(struct seq_file *s, void *v, loff_t *pos)
{
        return smk_seq_next(s, v, pos, &smk_netlbladdr_list);
}
#define BEBITS  (sizeof(__be32) * 8)

/*
 * Print host/label pairs
 */
static int netlbladdr_seq_show(struct seq_file *s, void *v)
{
        struct list_head *list = v;
        struct smk_netlbladdr *skp =
                        list_entry_rcu(list, struct smk_netlbladdr, list);
        unsigned char *hp = (char *) &skp->smk_host.sin_addr.s_addr;
        int maskn;
        u32 temp_mask = be32_to_cpu(skp->smk_mask.s_addr);

        for (maskn = 0; temp_mask; temp_mask <<= 1, maskn++);

        seq_printf(s, "%u.%u.%u.%u/%d %s\n",
                hp[0], hp[1], hp[2], hp[3], maskn, skp->smk_label->smk_known);

        return 0;
}

static const struct seq_operations netlbladdr_seq_ops = {
        .start = netlbladdr_seq_start,
        .next  = netlbladdr_seq_next,
        .show  = netlbladdr_seq_show,
        .stop  = smk_seq_stop,
};

/**
 * smk_open_netlbladdr - open() for /smack/netlabel
 * @inode: inode structure representing file
 * @file: "netlabel" file pointer
 *
 * Connect our netlbladdr_seq_* operations with /smack/netlabel
 * file_operations
 */
static int smk_open_netlbladdr(struct inode *inode, struct file *file)
{
        return seq_open(file, &netlbladdr_seq_ops);
}

/**
 * smk_netlbladdr_insert
 * @new : netlabel to insert
 *
 * This helper insert netlabel in the smack_netlbladdrs list
 * sorted by netmask length (longest to smallest)
 * locked by &smk_netlbladdr_lock in smk_write_netlbladdr
 *
 */
static void smk_netlbladdr_insert(struct smk_netlbladdr *new)
{
        struct smk_netlbladdr *m, *m_next;

        if (list_empty(&smk_netlbladdr_list)) {
                list_add_rcu(&new->list, &smk_netlbladdr_list);
                return;
        }

        m = list_entry_rcu(smk_netlbladdr_list.next,
                           struct smk_netlbladdr, list);

        /* the comparison '>' is a bit hacky, but works */
        if (new->smk_mask.s_addr > m->smk_mask.s_addr) {
                list_add_rcu(&new->list, &smk_netlbladdr_list);
                return;
        }

        list_for_each_entry_rcu(m, &smk_netlbladdr_list, list) {
                if (list_is_last(&m->list, &smk_netlbladdr_list)) {
                        list_add_rcu(&new->list, &m->list);
                        return;
                }
                m_next = list_entry_rcu(m->list.next,
                                        struct smk_netlbladdr, list);
                if (new->smk_mask.s_addr > m_next->smk_mask.s_addr) {
                        list_add_rcu(&new->list, &m->list);
                        return;
                }
        }
}


/**
 * smk_write_netlbladdr - write() for /smack/netlabel
 * @file: file pointer, not actually used
 * @buf: where to get the data from
 * @count: bytes sent
 * @ppos: where to start
 *
 * Accepts only one netlbladdr per write call.
 * Returns number of bytes written or error code, as appropriate
 */
static ssize_t smk_write_netlbladdr(struct file *file, const char __user *buf,
                                size_t count, loff_t *ppos)
{
        struct smk_netlbladdr *snp;
        struct sockaddr_in newname;
        char *smack;
        struct smack_known *skp;
        char *data;
        char *host = (char *)&newname.sin_addr.s_addr;
        int rc;
        struct netlbl_audit audit_info;
        struct in_addr mask;
        unsigned int m;
        int found;
        u32 mask_bits = (1<<31);
        __be32 nsa;
        u32 temp_mask;

        /*
         * Must have privilege.
         * No partial writes.
         * Enough data must be present.
         * "<addr/mask, as a.b.c.d/e><space><label>"
         * "<addr, as a.b.c.d><space><label>"
         */
        if (!smack_privileged(CAP_MAC_ADMIN))
                return -EPERM;
        if (*ppos != 0)
                return -EINVAL;
        if (count < SMK_NETLBLADDRMIN)
                return -EINVAL;

        data = kzalloc(count + 1, GFP_KERNEL);
        if (data == NULL)
                return -ENOMEM;

        if (copy_from_user(data, buf, count) != 0) {
                rc = -EFAULT;
                goto free_data_out;
        }

        smack = kzalloc(count + 1, GFP_KERNEL);
        if (smack == NULL) {
                rc = -ENOMEM;
                goto free_data_out;
        }

        data[count] = '\0';

        rc = sscanf(data, "%hhd.%hhd.%hhd.%hhd/%u %s",
                &host[0], &host[1], &host[2], &host[3], &m, smack);
        if (rc != 6) {
                rc = sscanf(data, "%hhd.%hhd.%hhd.%hhd %s",
                        &host[0], &host[1], &host[2], &host[3], smack);
                if (rc != 5) {
                        rc = -EINVAL;
                        goto free_out;
                }
                m = BEBITS;
        }
        if (m > BEBITS) {
                rc = -EINVAL;
                goto free_out;
        }

        /*
         * If smack begins with '-', it is an option, don't import it
         */
        if (smack[0] != '-') {
                skp = smk_import_entry(smack, 0);
                if (IS_ERR(skp)) {
                        rc = PTR_ERR(skp);
                        goto free_out;
                }
        } else {
                /* check known options */
                if (strcmp(smack, smack_cipso_option.smk_known) == 0)
                        skp = &smack_cipso_option;
                else {
                        rc = -EINVAL;
                        goto free_out;
                }
        }

        for (temp_mask = 0; m > 0; m--) {
                temp_mask |= mask_bits;
                mask_bits >>= 1;
        }
        mask.s_addr = cpu_to_be32(temp_mask);

        newname.sin_addr.s_addr &= mask.s_addr;
        /*
         * Only allow one writer at a time. Writes should be
         * quite rare and small in any case.
         */
        mutex_lock(&smk_netlbladdr_lock);

        nsa = newname.sin_addr.s_addr;
        /* try to find if the prefix is already in the list */
        found = 0;
        list_for_each_entry_rcu(snp, &smk_netlbladdr_list, list) {
                if (snp->smk_host.sin_addr.s_addr == nsa &&
                    snp->smk_mask.s_addr == mask.s_addr) {
                        found = 1;
                        break;
                }
        }
        smk_netlabel_audit_set(&audit_info);

        if (found == 0) {
                snp = kzalloc(sizeof(*snp), GFP_KERNEL);
                if (snp == NULL)
                        rc = -ENOMEM;
                else {
                        rc = 0;
                        snp->smk_host.sin_addr.s_addr = newname.sin_addr.s_addr;
                        snp->smk_mask.s_addr = mask.s_addr;
                        snp->smk_label = skp;
                        smk_netlbladdr_insert(snp);
                }
        } else {
                /* we delete the unlabeled entry, only if the previous label
                 * wasn't the special CIPSO option */
                if (snp->smk_label != &smack_cipso_option)
                        rc = netlbl_cfg_unlbl_static_del(&init_net, NULL,
                                        &snp->smk_host.sin_addr, &snp->smk_mask,
                                        PF_INET, &audit_info);
                else
                        rc = 0;
                snp->smk_label = skp;
        }

        /*
         * Now tell netlabel about the single label nature of
         * this host so that incoming packets get labeled.
         * but only if we didn't get the special CIPSO option
         */
        if (rc == 0 && skp != &smack_cipso_option)
                rc = netlbl_cfg_unlbl_static_add(&init_net, NULL,
                        &snp->smk_host.sin_addr, &snp->smk_mask, PF_INET,
                        snp->smk_label->smk_secid, &audit_info);

        if (rc == 0)
                rc = count;

        mutex_unlock(&smk_netlbladdr_lock);

free_out:
        kfree(smack);
free_data_out:
        kfree(data);

        return rc;
}

static const struct file_operations smk_netlbladdr_ops = {
        .open           = smk_open_netlbladdr,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .write          = smk_write_netlbladdr,
        .release        = seq_release,
};

/**
 * smk_read_doi - read() for /smack/doi
 * @filp: file pointer, not actually used
 * @buf: where to put the result
 * @count: maximum to send along
 * @ppos: where to start
 *
 * Returns number of bytes read or error code, as appropriate
 */
static ssize_t smk_read_doi(struct file *filp, char __user *buf,
                            size_t count, loff_t *ppos)
{
        char temp[80];
        ssize_t rc;

        if (*ppos != 0)
                return 0;

        sprintf(temp, "%d", smk_cipso_doi_value);
        rc = simple_read_from_buffer(buf, count, ppos, temp, strlen(temp));

        return rc;
}

/**
 * smk_write_doi - write() for /smack/doi
 * @file: file pointer, not actually used
 * @buf: where to get the data from
 * @count: bytes sent
 * @ppos: where to start
 *
 * Returns number of bytes written or error code, as appropriate
 */
static ssize_t smk_write_doi(struct file *file, const char __user *buf,
                             size_t count, loff_t *ppos)
{
        char temp[80];
        int i;

        if (!smack_privileged(CAP_MAC_ADMIN))
                return -EPERM;

        if (count >= sizeof(temp) || count == 0)
                return -EINVAL;

        if (copy_from_user(temp, buf, count) != 0)
                return -EFAULT;

        temp[count] = '\0';

        if (sscanf(temp, "%d", &i) != 1)
                return -EINVAL;

        smk_cipso_doi_value = i;

        smk_cipso_doi();

        return count;
}

static const struct file_operations smk_doi_ops = {
        .read           = smk_read_doi,
        .write          = smk_write_doi,
        .llseek         = default_llseek,
};

/**
 * smk_read_direct - read() for /smack/direct
 * @filp: file pointer, not actually used
 * @buf: where to put the result
 * @count: maximum to send along
 * @ppos: where to start
 *
 * Returns number of bytes read or error code, as appropriate
 */
static ssize_t smk_read_direct(struct file *filp, char __user *buf,
                               size_t count, loff_t *ppos)
{
        char temp[80];
        ssize_t rc;

        if (*ppos != 0)
                return 0;

        sprintf(temp, "%d", smack_cipso_direct);
        rc = simple_read_from_buffer(buf, count, ppos, temp, strlen(temp));

        return rc;
}

/**
 * smk_write_direct - write() for /smack/direct
 * @file: file pointer, not actually used
 * @buf: where to get the data from
 * @count: bytes sent
 * @ppos: where to start
 *
 * Returns number of bytes written or error code, as appropriate
 */
static ssize_t smk_write_direct(struct file *file, const char __user *buf,
                                size_t count, loff_t *ppos)
{
        struct smack_known *skp;
        char temp[80];
        int i;

        if (!smack_privileged(CAP_MAC_ADMIN))
                return -EPERM;

        if (count >= sizeof(temp) || count == 0)
                return -EINVAL;

        if (copy_from_user(temp, buf, count) != 0)
                return -EFAULT;

        temp[count] = '\0';

        if (sscanf(temp, "%d", &i) != 1)
                return -EINVAL;

        /*
         * Don't do anything if the value hasn't actually changed.
         * If it is changing reset the level on entries that were
         * set up to be direct when they were created.
         */
        if (smack_cipso_direct != i) {
                mutex_lock(&smack_known_lock);
                list_for_each_entry_rcu(skp, &smack_known_list, list)
                        if (skp->smk_netlabel.attr.mls.lvl ==
                            smack_cipso_direct)
                                skp->smk_netlabel.attr.mls.lvl = i;
                smack_cipso_direct = i;
                mutex_unlock(&smack_known_lock);
        }

        return count;
}

static const struct file_operations smk_direct_ops = {
        .read           = smk_read_direct,
        .write          = smk_write_direct,
        .llseek         = default_llseek,
};

/**
 * smk_read_mapped - read() for /smack/mapped
 * @filp: file pointer, not actually used
 * @buf: where to put the result
 * @count: maximum to send along
 * @ppos: where to start
 *
 * Returns number of bytes read or error code, as appropriate
 */
static ssize_t smk_read_mapped(struct file *filp, char __user *buf,
                               size_t count, loff_t *ppos)
{
        char temp[80];
        ssize_t rc;

        if (*ppos != 0)
                return 0;

        sprintf(temp, "%d", smack_cipso_mapped);
        rc = simple_read_from_buffer(buf, count, ppos, temp, strlen(temp));

        return rc;
}

/**
 * smk_write_mapped - write() for /smack/mapped
 * @file: file pointer, not actually used
 * @buf: where to get the data from
 * @count: bytes sent
 * @ppos: where to start
 *
 * Returns number of bytes written or error code, as appropriate
 */
static ssize_t smk_write_mapped(struct file *file, const char __user *buf,
                                size_t count, loff_t *ppos)
{
        struct smack_known *skp;
        char temp[80];
        int i;

        if (!smack_privileged(CAP_MAC_ADMIN))
                return -EPERM;

        if (count >= sizeof(temp) || count == 0)
                return -EINVAL;

        if (copy_from_user(temp, buf, count) != 0)
                return -EFAULT;

        temp[count] = '\0';

        if (sscanf(temp, "%d", &i) != 1)
                return -EINVAL;

        /*
         * Don't do anything if the value hasn't actually changed.
         * If it is changing reset the level on entries that were
         * set up to be mapped when they were created.
         */
        if (smack_cipso_mapped != i) {
                mutex_lock(&smack_known_lock);
                list_for_each_entry_rcu(skp, &smack_known_list, list)
                        if (skp->smk_netlabel.attr.mls.lvl ==
                            smack_cipso_mapped)
                                skp->smk_netlabel.attr.mls.lvl = i;
                smack_cipso_mapped = i;
                mutex_unlock(&smack_known_lock);
        }

        return count;
}

static const struct file_operations smk_mapped_ops = {
        .read           = smk_read_mapped,
        .write          = smk_write_mapped,
        .llseek         = default_llseek,
};

/**
 * smk_read_ambient - read() for /smack/ambient
 * @filp: file pointer, not actually used
 * @buf: where to put the result
 * @cn: maximum to send along
 * @ppos: where to start
 *
 * Returns number of bytes read or error code, as appropriate
 */
static ssize_t smk_read_ambient(struct file *filp, char __user *buf,
                                size_t cn, loff_t *ppos)
{
        ssize_t rc;
        int asize;

        if (*ppos != 0)
                return 0;
        /*
         * Being careful to avoid a problem in the case where
         * smack_net_ambient gets changed in midstream.
         */
        mutex_lock(&smack_ambient_lock);

        asize = strlen(smack_net_ambient->smk_known) + 1;

        if (cn >= asize)
                rc = simple_read_from_buffer(buf, cn, ppos,
                                             smack_net_ambient->smk_known,
                                             asize);
        else
                rc = -EINVAL;

        mutex_unlock(&smack_ambient_lock);

        return rc;
}

/**
 * smk_write_ambient - write() for /smack/ambient
 * @file: file pointer, not actually used
 * @buf: where to get the data from
 * @count: bytes sent
 * @ppos: where to start
 *
 * Returns number of bytes written or error code, as appropriate
 */
static ssize_t smk_write_ambient(struct file *file, const char __user *buf,
                                 size_t count, loff_t *ppos)
{
        struct smack_known *skp;
        char *oldambient;
        char *data;
        int rc = count;

        if (!smack_privileged(CAP_MAC_ADMIN))
                return -EPERM;

        data = kzalloc(count + 1, GFP_KERNEL);
        if (data == NULL)
                return -ENOMEM;

        if (copy_from_user(data, buf, count) != 0) {
                rc = -EFAULT;
                goto out;
        }

        skp = smk_import_entry(data, count);
        if (IS_ERR(skp)) {
                rc = PTR_ERR(skp);
                goto out;
        }

        mutex_lock(&smack_ambient_lock);

        oldambient = smack_net_ambient->smk_known;
        smack_net_ambient = skp;
        smk_unlbl_ambient(oldambient);

        mutex_unlock(&smack_ambient_lock);

out:
        kfree(data);
        return rc;
}

static const struct file_operations smk_ambient_ops = {
        .read           = smk_read_ambient,
        .write          = smk_write_ambient,
        .llseek         = default_llseek,
};

/*
 * Seq_file operations for /smack/onlycap
 */
static void *onlycap_seq_start(struct seq_file *s, loff_t *pos)
{
        return smk_seq_start(s, pos, &smack_onlycap_list);
}

static void *onlycap_seq_next(struct seq_file *s, void *v, loff_t *pos)
{
        return smk_seq_next(s, v, pos, &smack_onlycap_list);
}

static int onlycap_seq_show(struct seq_file *s, void *v)
{
        struct list_head *list = v;
        struct smack_onlycap *sop =
                list_entry_rcu(list, struct smack_onlycap, list);

        seq_puts(s, sop->smk_label->smk_known);
        seq_putc(s, ' ');

        return 0;
}

static const struct seq_operations onlycap_seq_ops = {
        .start = onlycap_seq_start,
        .next  = onlycap_seq_next,
        .show  = onlycap_seq_show,
        .stop  = smk_seq_stop,
};

static int smk_open_onlycap(struct inode *inode, struct file *file)
{
        return seq_open(file, &onlycap_seq_ops);
}

/**
 * smk_list_swap_rcu - swap public list with a private one in RCU-safe way
 * The caller must hold appropriate mutex to prevent concurrent modifications
 * to the public list.
 * Private list is assumed to be not accessible to other threads yet.
 *
 * @public: public list
 * @private: private list
 */
static void smk_list_swap_rcu(struct list_head *public,
                              struct list_head *private)
{
        struct list_head *first, *last;

        if (list_empty(public)) {
                list_splice_init_rcu(private, public, synchronize_rcu);
        } else {
                /* Remember public list before replacing it */
                first = public->next;
                last = public->prev;

                /* Publish private list in place of public in RCU-safe way */
                private->prev->next = public;
                private->next->prev = public;
                rcu_assign_pointer(public->next, private->next);
                public->prev = private->prev;

                synchronize_rcu();

                /* When all readers are done with the old public list,
                 * attach it in place of private */
                private->next = first;
                private->prev = last;
                first->prev = private;
                last->next = private;
        }
}

/**
 * smk_write_onlycap - write() for smackfs/onlycap
 * @file: file pointer, not actually used
 * @buf: where to get the data from
 * @count: bytes sent
 * @ppos: where to start
 *
 * Returns number of bytes written or error code, as appropriate
 */
static ssize_t smk_write_onlycap(struct file *file, const char __user *buf,
                                 size_t count, loff_t *ppos)
{
        char *data;
        char *data_parse;
        char *tok;
        struct smack_known *skp;
        struct smack_onlycap *sop;
        struct smack_onlycap *sop2;
        LIST_HEAD(list_tmp);
        int rc = count;

        if (!smack_privileged(CAP_MAC_ADMIN))
                return -EPERM;

        data = kzalloc(count + 1, GFP_KERNEL);
        if (data == NULL)
                return -ENOMEM;

        if (copy_from_user(data, buf, count) != 0) {
                kfree(data);
                return -EFAULT;
        }

        data_parse = data;
        while ((tok = strsep(&data_parse, " ")) != NULL) {
                if (!*tok)
                        continue;

                skp = smk_import_entry(tok, 0);
                if (IS_ERR(skp)) {
                        rc = PTR_ERR(skp);
                        break;
                }

                sop = kzalloc(sizeof(*sop), GFP_KERNEL);
                if (sop == NULL) {
                        rc = -ENOMEM;
                        break;
                }

                sop->smk_label = skp;
                list_add_rcu(&sop->list, &list_tmp);
        }
        kfree(data);

        /*
         * Clear the smack_onlycap on invalid label errors. This means
         * that we can pass a null string to unset the onlycap value.
         *
         * Importing will also reject a label beginning with '-',
         * so "-usecapabilities" will also work.
         *
         * But do so only on invalid label, not on system errors.
         * The invalid label must be first to count as clearing attempt.
         */
        if (rc == -EINVAL && list_empty(&list_tmp))
                rc = count;

        if (rc >= 0) {
                mutex_lock(&smack_onlycap_lock);
                smk_list_swap_rcu(&smack_onlycap_list, &list_tmp);
                mutex_unlock(&smack_onlycap_lock);
        }

        list_for_each_entry_safe(sop, sop2, &list_tmp, list)
                kfree(sop);

        return rc;
}

static const struct file_operations smk_onlycap_ops = {
        .open           = smk_open_onlycap,
        .read           = seq_read,
        .write          = smk_write_onlycap,
        .llseek         = seq_lseek,
        .release        = seq_release,
};

#ifdef CONFIG_SECURITY_SMACK_BRINGUP
/**
 * smk_read_unconfined - read() for smackfs/unconfined
 * @filp: file pointer, not actually used
 * @buf: where to put the result
 * @cn: maximum to send along
 * @ppos: where to start
 *
 * Returns number of bytes read or error code, as appropriate
 */
static ssize_t smk_read_unconfined(struct file *filp, char __user *buf,
                                        size_t cn, loff_t *ppos)
{
        char *smack = "";
        ssize_t rc = -EINVAL;
        int asize;

        if (*ppos != 0)
                return 0;

        if (smack_unconfined != NULL)
                smack = smack_unconfined->smk_known;

        asize = strlen(smack) + 1;

        if (cn >= asize)
                rc = simple_read_from_buffer(buf, cn, ppos, smack, asize);

        return rc;
}

/**
 * smk_write_unconfined - write() for smackfs/unconfined
 * @file: file pointer, not actually used
 * @buf: where to get the data from
 * @count: bytes sent
 * @ppos: where to start
 *
 * Returns number of bytes written or error code, as appropriate
 */
static ssize_t smk_write_unconfined(struct file *file, const char __user *buf,
                                        size_t count, loff_t *ppos)
{
        char *data;
        struct smack_known *skp;
        int rc = count;

        if (!smack_privileged(CAP_MAC_ADMIN))
                return -EPERM;

        data = kzalloc(count + 1, GFP_KERNEL);
        if (data == NULL)
                return -ENOMEM;

        if (copy_from_user(data, buf, count) != 0) {
                rc = -EFAULT;
                goto freeout;
        }

        /*
         * Clear the smack_unconfined on invalid label errors. This means
         * that we can pass a null string to unset the unconfined value.
         *
         * Importing will also reject a label beginning with '-',
         * so "-confine" will also work.
         *
         * But do so only on invalid label, not on system errors.
         */
        skp = smk_import_entry(data, count);
        if (PTR_ERR(skp) == -EINVAL)
                skp = NULL;
        else if (IS_ERR(skp)) {
                rc = PTR_ERR(skp);
                goto freeout;
        }

        smack_unconfined = skp;

freeout:
        kfree(data);
        return rc;
}

static const struct file_operations smk_unconfined_ops = {
        .read           = smk_read_unconfined,
        .write          = smk_write_unconfined,
        .llseek         = default_llseek,
};
#endif /* CONFIG_SECURITY_SMACK_BRINGUP */

/**
 * smk_read_logging - read() for /smack/logging
 * @filp: file pointer, not actually used
 * @buf: where to put the result
 * @cn: maximum to send along
 * @ppos: where to start
 *
 * Returns number of bytes read or error code, as appropriate
 */
static ssize_t smk_read_logging(struct file *filp, char __user *buf,
                                size_t count, loff_t *ppos)
{
        char temp[32];
        ssize_t rc;

        if (*ppos != 0)
                return 0;

        sprintf(temp, "%d\n", log_policy);
        rc = simple_read_from_buffer(buf, count, ppos, temp, strlen(temp));
        return rc;
}

/**
 * smk_write_logging - write() for /smack/logging
 * @file: file pointer, not actually used
 * @buf: where to get the data from
 * @count: bytes sent
 * @ppos: where to start
 *
 * Returns number of bytes written or error code, as appropriate
 */
static ssize_t smk_write_logging(struct file *file, const char __user *buf,
                                size_t count, loff_t *ppos)
{
        char temp[32];
        int i;

        if (!smack_privileged(CAP_MAC_ADMIN))
                return -EPERM;

        if (count >= sizeof(temp) || count == 0)
                return -EINVAL;

        if (copy_from_user(temp, buf, count) != 0)
                return -EFAULT;

        temp[count] = '\0';

        if (sscanf(temp, "%d", &i) != 1)
                return -EINVAL;
        if (i < 0 || i > 3)
                return -EINVAL;
        log_policy = i;
        return count;
}



static const struct file_operations smk_logging_ops = {
        .read           = smk_read_logging,
        .write          = smk_write_logging,
        .llseek         = default_llseek,
};

/*
 * Seq_file read operations for /smack/load-self
 */

static void *load_self_seq_start(struct seq_file *s, loff_t *pos)
{
        struct task_smack *tsp = current_security();

        return smk_seq_start(s, pos, &tsp->smk_rules);
}

static void *load_self_seq_next(struct seq_file *s, void *v, loff_t *pos)
{
        struct task_smack *tsp = current_security();

        return smk_seq_next(s, v, pos, &tsp->smk_rules);
}

static int load_self_seq_show(struct seq_file *s, void *v)
{
        struct list_head *list = v;
        struct smack_rule *srp =
                list_entry_rcu(list, struct smack_rule, list);

        smk_rule_show(s, srp, SMK_LABELLEN);

        return 0;
}

static const struct seq_operations load_self_seq_ops = {
        .start = load_self_seq_start,
        .next  = load_self_seq_next,
        .show  = load_self_seq_show,
        .stop  = smk_seq_stop,
};


/**
 * smk_open_load_self - open() for /smack/load-self2
 * @inode: inode structure representing file
 * @file: "load" file pointer
 *
 * For reading, use load_seq_* seq_file reading operations.
 */
static int smk_open_load_self(struct inode *inode, struct file *file)
{
        return seq_open(file, &load_self_seq_ops);
}

/**
 * smk_write_load_self - write() for /smack/load-self
 * @file: file pointer, not actually used
 * @buf: where to get the data from
 * @count: bytes sent
 * @ppos: where to start - must be 0
 *
 */
static ssize_t smk_write_load_self(struct file *file, const char __user *buf,
                              size_t count, loff_t *ppos)
{
        struct task_smack *tsp = current_security();

        return smk_write_rules_list(file, buf, count, ppos, &tsp->smk_rules,
                                    &tsp->smk_rules_lock, SMK_FIXED24_FMT);
}

static const struct file_operations smk_load_self_ops = {
        .open           = smk_open_load_self,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .write          = smk_write_load_self,
        .release        = seq_release,
};

/**
 * smk_user_access - handle access check transaction
 * @file: file pointer
 * @buf: data from user space
 * @count: bytes sent
 * @ppos: where to start - must be 0
 */
static ssize_t smk_user_access(struct file *file, const char __user *buf,
                                size_t count, loff_t *ppos, int format)
{
        struct smack_parsed_rule rule;
        char *data;
        int res;

        data = simple_transaction_get(file, buf, count);
        if (IS_ERR(data))
                return PTR_ERR(data);

        if (format == SMK_FIXED24_FMT) {
                if (count < SMK_LOADLEN)
                        return -EINVAL;
                res = smk_parse_rule(data, &rule, 0);
        } else {
                /*
                 * simple_transaction_get() returns null-terminated data
                 */
                res = smk_parse_long_rule(data, &rule, 0, 3);
        }

        if (res >= 0)
                res = smk_access(rule.smk_subject, rule.smk_object,
                                 rule.smk_access1, NULL);
        else if (res != -ENOENT)
                return res;

        /*
         * smk_access() can return a value > 0 in the "bringup" case.
         */
        data[0] = res >= 0 ? '1' : '0';
        data[1] = '\0';

        simple_transaction_set(file, 2);

        if (format == SMK_FIXED24_FMT)
                return SMK_LOADLEN;
        return count;
}

/**
 * smk_write_access - handle access check transaction
 * @file: file pointer
 * @buf: data from user space
 * @count: bytes sent
 * @ppos: where to start - must be 0
 */
static ssize_t smk_write_access(struct file *file, const char __user *buf,
                                size_t count, loff_t *ppos)
{
        return smk_user_access(file, buf, count, ppos, SMK_FIXED24_FMT);
}

static const struct file_operations smk_access_ops = {
        .write          = smk_write_access,
        .read           = simple_transaction_read,
        .release        = simple_transaction_release,
        .llseek         = generic_file_llseek,
};


/*
 * Seq_file read operations for /smack/load2
 */

static int load2_seq_show(struct seq_file *s, void *v)
{
        struct list_head *list = v;
        struct smack_master_list *smlp =
                list_entry_rcu(list, struct smack_master_list, list);

        smk_rule_show(s, smlp->smk_rule, SMK_LONGLABEL);

        return 0;
}

static const struct seq_operations load2_seq_ops = {
        .start = load2_seq_start,
        .next  = load2_seq_next,
        .show  = load2_seq_show,
        .stop  = smk_seq_stop,
};

/**
 * smk_open_load2 - open() for /smack/load2
 * @inode: inode structure representing file
 * @file: "load2" file pointer
 *
 * For reading, use load2_seq_* seq_file reading operations.
 */
static int smk_open_load2(struct inode *inode, struct file *file)
{
        return seq_open(file, &load2_seq_ops);
}

/**
 * smk_write_load2 - write() for /smack/load2
 * @file: file pointer, not actually used
 * @buf: where to get the data from
 * @count: bytes sent
 * @ppos: where to start - must be 0
 *
 */
static ssize_t smk_write_load2(struct file *file, const char __user *buf,
                                size_t count, loff_t *ppos)
{
        /*
         * Must have privilege.
         */
        if (!smack_privileged(CAP_MAC_ADMIN))
                return -EPERM;

        return smk_write_rules_list(file, buf, count, ppos, NULL, NULL,
                                    SMK_LONG_FMT);
}

static const struct file_operations smk_load2_ops = {
        .open           = smk_open_load2,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .write          = smk_write_load2,
        .release        = seq_release,
};

/*
 * Seq_file read operations for /smack/load-self2
 */

static void *load_self2_seq_start(struct seq_file *s, loff_t *pos)
{
        struct task_smack *tsp = current_security();

        return smk_seq_start(s, pos, &tsp->smk_rules);
}

static void *load_self2_seq_next(struct seq_file *s, void *v, loff_t *pos)
{
        struct task_smack *tsp = current_security();

        return smk_seq_next(s, v, pos, &tsp->smk_rules);
}

static int load_self2_seq_show(struct seq_file *s, void *v)
{
        struct list_head *list = v;
        struct smack_rule *srp =
                list_entry_rcu(list, struct smack_rule, list);

        smk_rule_show(s, srp, SMK_LONGLABEL);

        return 0;
}

static const struct seq_operations load_self2_seq_ops = {
        .start = load_self2_seq_start,
        .next  = load_self2_seq_next,
        .show  = load_self2_seq_show,
        .stop  = smk_seq_stop,
};

/**
 * smk_open_load_self2 - open() for /smack/load-self2
 * @inode: inode structure representing file
 * @file: "load" file pointer
 *
 * For reading, use load_seq_* seq_file reading operations.
 */
static int smk_open_load_self2(struct inode *inode, struct file *file)
{
        return seq_open(file, &load_self2_seq_ops);
}

/**
 * smk_write_load_self2 - write() for /smack/load-self2
 * @file: file pointer, not actually used
 * @buf: where to get the data from
 * @count: bytes sent
 * @ppos: where to start - must be 0
 *
 */
static ssize_t smk_write_load_self2(struct file *file, const char __user *buf,
                              size_t count, loff_t *ppos)
{
        struct task_smack *tsp = current_security();

        return smk_write_rules_list(file, buf, count, ppos, &tsp->smk_rules,
                                    &tsp->smk_rules_lock, SMK_LONG_FMT);
}

static const struct file_operations smk_load_self2_ops = {
        .open           = smk_open_load_self2,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .write          = smk_write_load_self2,
        .release        = seq_release,
};

/**
 * smk_write_access2 - handle access check transaction
 * @file: file pointer
 * @buf: data from user space
 * @count: bytes sent
 * @ppos: where to start - must be 0
 */
static ssize_t smk_write_access2(struct file *file, const char __user *buf,
                                        size_t count, loff_t *ppos)
{
        return smk_user_access(file, buf, count, ppos, SMK_LONG_FMT);
}

static const struct file_operations smk_access2_ops = {
        .write          = smk_write_access2,
        .read           = simple_transaction_read,
        .release        = simple_transaction_release,
        .llseek         = generic_file_llseek,
};

/**
 * smk_write_revoke_subj - write() for /smack/revoke-subject
 * @file: file pointer
 * @buf: data from user space
 * @count: bytes sent
 * @ppos: where to start - must be 0
 */
static ssize_t smk_write_revoke_subj(struct file *file, const char __user *buf,
                                size_t count, loff_t *ppos)
{
        char *data;
        const char *cp;
        struct smack_known *skp;
        struct smack_rule *sp;
        struct list_head *rule_list;
        struct mutex *rule_lock;
        int rc = count;

        if (*ppos != 0)
                return -EINVAL;

        if (!smack_privileged(CAP_MAC_ADMIN))
                return -EPERM;

        if (count == 0 || count > SMK_LONGLABEL)
                return -EINVAL;

        data = kzalloc(count, GFP_KERNEL);
        if (data == NULL)
                return -ENOMEM;

        if (copy_from_user(data, buf, count) != 0) {
                rc = -EFAULT;
                goto out_data;
        }

        cp = smk_parse_smack(data, count);
        if (IS_ERR(cp)) {
                rc = PTR_ERR(cp);
                goto out_data;
        }

        skp = smk_find_entry(cp);
        if (skp == NULL)
                goto out_cp;

        rule_list = &skp->smk_rules;
        rule_lock = &skp->smk_rules_lock;

        mutex_lock(rule_lock);

        list_for_each_entry_rcu(sp, rule_list, list)
                sp->smk_access = 0;

        mutex_unlock(rule_lock);

out_cp:
        kfree(cp);
out_data:
        kfree(data);

        return rc;
}

static const struct file_operations smk_revoke_subj_ops = {
        .write          = smk_write_revoke_subj,
        .read           = simple_transaction_read,
        .release        = simple_transaction_release,
        .llseek         = generic_file_llseek,
};

/**
 * smk_init_sysfs - initialize /sys/fs/smackfs
 *
 */
static int smk_init_sysfs(void)
{
        int err;
        err = sysfs_create_mount_point(fs_kobj, "smackfs");
        if (err)
                return err;
        return 0;
}

/**
 * smk_write_change_rule - write() for /smack/change-rule
 * @file: file pointer
 * @buf: data from user space
 * @count: bytes sent
 * @ppos: where to start - must be 0
 */
static ssize_t smk_write_change_rule(struct file *file, const char __user *buf,
                                size_t count, loff_t *ppos)
{
        /*
         * Must have privilege.
         */
        if (!smack_privileged(CAP_MAC_ADMIN))
                return -EPERM;

        return smk_write_rules_list(file, buf, count, ppos, NULL, NULL,
                                    SMK_CHANGE_FMT);
}

static const struct file_operations smk_change_rule_ops = {
        .write          = smk_write_change_rule,
        .read           = simple_transaction_read,
        .release        = simple_transaction_release,
        .llseek         = generic_file_llseek,
};

/**
 * smk_read_syslog - read() for smackfs/syslog
 * @filp: file pointer, not actually used
 * @buf: where to put the result
 * @cn: maximum to send along
 * @ppos: where to start
 *
 * Returns number of bytes read or error code, as appropriate
 */
static ssize_t smk_read_syslog(struct file *filp, char __user *buf,
                                size_t cn, loff_t *ppos)
{
        struct smack_known *skp;
        ssize_t rc = -EINVAL;
        int asize;

        if (*ppos != 0)
                return 0;

        if (smack_syslog_label == NULL)
                skp = &smack_known_star;
        else
                skp = smack_syslog_label;

        asize = strlen(skp->smk_known) + 1;

        if (cn >= asize)
                rc = simple_read_from_buffer(buf, cn, ppos, skp->smk_known,
                                                asize);

        return rc;
}

/**
 * smk_write_syslog - write() for smackfs/syslog
 * @file: file pointer, not actually used
 * @buf: where to get the data from
 * @count: bytes sent
 * @ppos: where to start
 *
 * Returns number of bytes written or error code, as appropriate
 */
static ssize_t smk_write_syslog(struct file *file, const char __user *buf,
                                size_t count, loff_t *ppos)
{
        char *data;
        struct smack_known *skp;
        int rc = count;

        if (!smack_privileged(CAP_MAC_ADMIN))
                return -EPERM;

        data = kzalloc(count + 1, GFP_KERNEL);
        if (data == NULL)
                return -ENOMEM;

        if (copy_from_user(data, buf, count) != 0)
                rc = -EFAULT;
        else {
                skp = smk_import_entry(data, count);
                if (IS_ERR(skp))
                        rc = PTR_ERR(skp);
                else
                        smack_syslog_label = skp;
        }

        kfree(data);
        return rc;
}

static const struct file_operations smk_syslog_ops = {
        .read           = smk_read_syslog,
        .write          = smk_write_syslog,
        .llseek         = default_llseek,
};


/**
 * smk_read_ptrace - read() for /smack/ptrace
 * @filp: file pointer, not actually used
 * @buf: where to put the result
 * @count: maximum to send along
 * @ppos: where to start
 *
 * Returns number of bytes read or error code, as appropriate
 */
static ssize_t smk_read_ptrace(struct file *filp, char __user *buf,
                               size_t count, loff_t *ppos)
{
        char temp[32];
        ssize_t rc;

        if (*ppos != 0)
                return 0;

        sprintf(temp, "%d\n", smack_ptrace_rule);
        rc = simple_read_from_buffer(buf, count, ppos, temp, strlen(temp));
        return rc;
}

/**
 * smk_write_ptrace - write() for /smack/ptrace
 * @file: file pointer
 * @buf: data from user space
 * @count: bytes sent
 * @ppos: where to start - must be 0
 */
static ssize_t smk_write_ptrace(struct file *file, const char __user *buf,
                                size_t count, loff_t *ppos)
{
        char temp[32];
        int i;

        if (!smack_privileged(CAP_MAC_ADMIN))
                return -EPERM;

        if (*ppos != 0 || count >= sizeof(temp) || count == 0)
                return -EINVAL;

        if (copy_from_user(temp, buf, count) != 0)
                return -EFAULT;

        temp[count] = '\0';

        if (sscanf(temp, "%d", &i) != 1)
                return -EINVAL;
        if (i < SMACK_PTRACE_DEFAULT || i > SMACK_PTRACE_MAX)
                return -EINVAL;
        smack_ptrace_rule = i;

        return count;
}

static const struct file_operations smk_ptrace_ops = {
        .write          = smk_write_ptrace,
        .read           = smk_read_ptrace,
        .llseek         = default_llseek,
};

/**
 * smk_fill_super - fill the smackfs superblock
 * @sb: the empty superblock
 * @data: unused
 * @silent: unused
 *
 * Fill in the well known entries for the smack filesystem
 *
 * Returns 0 on success, an error code on failure
 */
static int smk_fill_super(struct super_block *sb, void *data, int silent)
{
        int rc;
        struct inode *root_inode;

        static struct tree_descr smack_files[] = {
                [SMK_LOAD] = {
                        "load", &smk_load_ops, S_IRUGO|S_IWUSR},
                [SMK_CIPSO] = {
                        "cipso", &smk_cipso_ops, S_IRUGO|S_IWUSR},
                [SMK_DOI] = {
                        "doi", &smk_doi_ops, S_IRUGO|S_IWUSR},
                [SMK_DIRECT] = {
                        "direct", &smk_direct_ops, S_IRUGO|S_IWUSR},
                [SMK_AMBIENT] = {
                        "ambient", &smk_ambient_ops, S_IRUGO|S_IWUSR},
                [SMK_NETLBLADDR] = {
                        "netlabel", &smk_netlbladdr_ops, S_IRUGO|S_IWUSR},
                [SMK_ONLYCAP] = {
                        "onlycap", &smk_onlycap_ops, S_IRUGO|S_IWUSR},
                [SMK_LOGGING] = {
                        "logging", &smk_logging_ops, S_IRUGO|S_IWUSR},
                [SMK_LOAD_SELF] = {
                        "load-self", &smk_load_self_ops, S_IRUGO|S_IWUGO},
                [SMK_ACCESSES] = {
                        "access", &smk_access_ops, S_IRUGO|S_IWUGO},
                [SMK_MAPPED] = {
                        "mapped", &smk_mapped_ops, S_IRUGO|S_IWUSR},
                [SMK_LOAD2] = {
                        "load2", &smk_load2_ops, S_IRUGO|S_IWUSR},
                [SMK_LOAD_SELF2] = {
                        "load-self2", &smk_load_self2_ops, S_IRUGO|S_IWUGO},
                [SMK_ACCESS2] = {
                        "access2", &smk_access2_ops, S_IRUGO|S_IWUGO},
                [SMK_CIPSO2] = {
                        "cipso2", &smk_cipso2_ops, S_IRUGO|S_IWUSR},
                [SMK_REVOKE_SUBJ] = {
                        "revoke-subject", &smk_revoke_subj_ops,
                        S_IRUGO|S_IWUSR},
                [SMK_CHANGE_RULE] = {
                        "change-rule", &smk_change_rule_ops, S_IRUGO|S_IWUSR},
                [SMK_SYSLOG] = {
                        "syslog", &smk_syslog_ops, S_IRUGO|S_IWUSR},
                [SMK_PTRACE] = {
                        "ptrace", &smk_ptrace_ops, S_IRUGO|S_IWUSR},
#ifdef CONFIG_SECURITY_SMACK_BRINGUP
                [SMK_UNCONFINED] = {
                        "unconfined", &smk_unconfined_ops, S_IRUGO|S_IWUSR},
#endif
                /* last one */
                        {""}
        };

        rc = simple_fill_super(sb, SMACK_MAGIC, smack_files);
        if (rc != 0) {
                printk(KERN_ERR "%s failed %d while creating inodes\n",
                        __func__, rc);
                return rc;
        }

        root_inode = d_inode(sb->s_root);

        return 0;
}

/**
 * smk_mount - get the smackfs superblock
 * @fs_type: passed along without comment
 * @flags: passed along without comment
 * @dev_name: passed along without comment
 * @data: passed along without comment
 *
 * Just passes everything along.
 *
 * Returns what the lower level code does.
 */
static struct dentry *smk_mount(struct file_system_type *fs_type,
                      int flags, const char *dev_name, void *data)
{
        return mount_single(fs_type, flags, data, smk_fill_super);
}

static struct file_system_type smk_fs_type = {
        .name           = "smackfs",
        .mount          = smk_mount,
        .kill_sb        = kill_litter_super,
};

static struct vfsmount *smackfs_mount;

static int __init smk_preset_netlabel(struct smack_known *skp)
{
        skp->smk_netlabel.domain = skp->smk_known;
        skp->smk_netlabel.flags =
                NETLBL_SECATTR_DOMAIN | NETLBL_SECATTR_MLS_LVL;
        return smk_netlbl_mls(smack_cipso_direct, skp->smk_known,
                                &skp->smk_netlabel, strlen(skp->smk_known));
}

/**
 * init_smk_fs - get the smackfs superblock
 *
 * register the smackfs
 *
 * Do not register smackfs if Smack wasn't enabled
 * on boot. We can not put this method normally under the
 * smack_init() code path since the security subsystem get
 * initialized before the vfs caches.
 *
 * Returns true if we were not chosen on boot or if
 * we were chosen and filesystem registration succeeded.
 */
static int __init init_smk_fs(void)
{
        int err;
        int rc;

        if (!security_module_enable("smack"))
                return 0;

        err = smk_init_sysfs();
        if (err)
                printk(KERN_ERR "smackfs: sysfs mountpoint problem.\n");

        err = register_filesystem(&smk_fs_type);
        if (!err) {
                smackfs_mount = kern_mount(&smk_fs_type);
                if (IS_ERR(smackfs_mount)) {
                        printk(KERN_ERR "smackfs:  could not mount!\n");
                        err = PTR_ERR(smackfs_mount);
                        smackfs_mount = NULL;
                }
        }

        smk_cipso_doi();
        smk_unlbl_ambient(NULL);

        rc = smk_preset_netlabel(&smack_known_floor);
        if (err == 0 && rc < 0)
                err = rc;
        rc = smk_preset_netlabel(&smack_known_hat);
        if (err == 0 && rc < 0)
                err = rc;
        rc = smk_preset_netlabel(&smack_known_huh);
        if (err == 0 && rc < 0)
                err = rc;
        rc = smk_preset_netlabel(&smack_known_invalid);
        if (err == 0 && rc < 0)
                err = rc;
        rc = smk_preset_netlabel(&smack_known_star);
        if (err == 0 && rc < 0)
                err = rc;
        rc = smk_preset_netlabel(&smack_known_web);
        if (err == 0 && rc < 0)
                err = rc;

        return err;
}

__initcall(init_smk_fs);