| 1 | /* |
| 2 | * Module for modifying the secmark field of the skb, for use by |
| 3 | * security subsystems. |
| 4 | * |
| 5 | * Based on the nfmark match by: |
| 6 | * (C) 1999-2001 Marc Boucher <marc@mbsi.ca> |
| 7 | * |
| 8 | * (C) 2006,2008 Red Hat, Inc., James Morris <jmorris@redhat.com> |
| 9 | * |
| 10 | * This program is free software; you can redistribute it and/or modify |
| 11 | * it under the terms of the GNU General Public License version 2 as |
| 12 | * published by the Free Software Foundation. |
| 13 | * |
| 14 | */ |
| 15 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| 16 | #include <linux/module.h> |
| 17 | #include <linux/security.h> |
| 18 | #include <linux/skbuff.h> |
| 19 | #include <linux/netfilter/x_tables.h> |
| 20 | #include <linux/netfilter/xt_SECMARK.h> |
| 21 | |
| 22 | MODULE_LICENSE("GPL"); |
| 23 | MODULE_AUTHOR("James Morris <jmorris@redhat.com>"); |
| 24 | MODULE_DESCRIPTION("Xtables: packet security mark modification"); |
| 25 | MODULE_ALIAS("ipt_SECMARK"); |
| 26 | MODULE_ALIAS("ip6t_SECMARK"); |
| 27 | |
| 28 | #define PFX "SECMARK: " |
| 29 | |
| 30 | static u8 mode; |
| 31 | |
| 32 | static unsigned int |
| 33 | secmark_tg(struct sk_buff *skb, const struct xt_action_param *par) |
| 34 | { |
| 35 | u32 secmark = 0; |
| 36 | const struct xt_secmark_target_info *info = par->targinfo; |
| 37 | |
| 38 | BUG_ON(info->mode != mode); |
| 39 | |
| 40 | switch (mode) { |
| 41 | case SECMARK_MODE_SEL: |
| 42 | secmark = info->secid; |
| 43 | break; |
| 44 | default: |
| 45 | BUG(); |
| 46 | } |
| 47 | |
| 48 | skb->secmark = secmark; |
| 49 | return XT_CONTINUE; |
| 50 | } |
| 51 | |
| 52 | static int checkentry_lsm(struct xt_secmark_target_info *info) |
| 53 | { |
| 54 | int err; |
| 55 | |
| 56 | info->secctx[SECMARK_SECCTX_MAX - 1] = '\0'; |
| 57 | info->secid = 0; |
| 58 | |
| 59 | err = security_secctx_to_secid(info->secctx, strlen(info->secctx), |
| 60 | &info->secid); |
| 61 | if (err) { |
| 62 | if (err == -EINVAL) |
| 63 | pr_info("invalid security context \'%s\'\n", info->secctx); |
| 64 | return err; |
| 65 | } |
| 66 | |
| 67 | if (!info->secid) { |
| 68 | pr_info("unable to map security context \'%s\'\n", info->secctx); |
| 69 | return -ENOENT; |
| 70 | } |
| 71 | |
| 72 | err = security_secmark_relabel_packet(info->secid); |
| 73 | if (err) { |
| 74 | pr_info("unable to obtain relabeling permission\n"); |
| 75 | return err; |
| 76 | } |
| 77 | |
| 78 | security_secmark_refcount_inc(); |
| 79 | return 0; |
| 80 | } |
| 81 | |
| 82 | static int secmark_tg_check(const struct xt_tgchk_param *par) |
| 83 | { |
| 84 | struct xt_secmark_target_info *info = par->targinfo; |
| 85 | int err; |
| 86 | |
| 87 | if (strcmp(par->table, "mangle") != 0 && |
| 88 | strcmp(par->table, "security") != 0) { |
| 89 | pr_info("target only valid in the \'mangle\' " |
| 90 | "or \'security\' tables, not \'%s\'.\n", par->table); |
| 91 | return -EINVAL; |
| 92 | } |
| 93 | |
| 94 | if (mode && mode != info->mode) { |
| 95 | pr_info("mode already set to %hu cannot mix with " |
| 96 | "rules for mode %hu\n", mode, info->mode); |
| 97 | return -EINVAL; |
| 98 | } |
| 99 | |
| 100 | switch (info->mode) { |
| 101 | case SECMARK_MODE_SEL: |
| 102 | break; |
| 103 | default: |
| 104 | pr_info("invalid mode: %hu\n", info->mode); |
| 105 | return -EINVAL; |
| 106 | } |
| 107 | |
| 108 | err = checkentry_lsm(info); |
| 109 | if (err) |
| 110 | return err; |
| 111 | |
| 112 | if (!mode) |
| 113 | mode = info->mode; |
| 114 | return 0; |
| 115 | } |
| 116 | |
| 117 | static void secmark_tg_destroy(const struct xt_tgdtor_param *par) |
| 118 | { |
| 119 | switch (mode) { |
| 120 | case SECMARK_MODE_SEL: |
| 121 | security_secmark_refcount_dec(); |
| 122 | } |
| 123 | } |
| 124 | |
| 125 | static struct xt_target secmark_tg_reg __read_mostly = { |
| 126 | .name = "SECMARK", |
| 127 | .revision = 0, |
| 128 | .family = NFPROTO_UNSPEC, |
| 129 | .checkentry = secmark_tg_check, |
| 130 | .destroy = secmark_tg_destroy, |
| 131 | .target = secmark_tg, |
| 132 | .targetsize = sizeof(struct xt_secmark_target_info), |
| 133 | .me = THIS_MODULE, |
| 134 | }; |
| 135 | |
| 136 | static int __init secmark_tg_init(void) |
| 137 | { |
| 138 | return xt_register_target(&secmark_tg_reg); |
| 139 | } |
| 140 | |
| 141 | static void __exit secmark_tg_exit(void) |
| 142 | { |
| 143 | xt_unregister_target(&secmark_tg_reg); |
| 144 | } |
| 145 | |
| 146 | module_init(secmark_tg_init); |
| 147 | module_exit(secmark_tg_exit); |