fs/proc/namespaces.c

   1 #include <linux/proc_fs.h>
   2 #include <linux/nsproxy.h>
   3 #include <linux/sched.h>
   4 #include <linux/ptrace.h>
   5 #include <linux/fs_struct.h>
   6 #include <linux/mount.h>
   7 #include <linux/path.h>
   8 #include <linux/namei.h>
   9 #include <linux/file.h>
  10 #include <linux/utsname.h>
  11 #include <net/net_namespace.h>
  12 #include <linux/mnt_namespace.h>
  13 #include <linux/ipc_namespace.h>
  14 #include <linux/pid_namespace.h>
  15 #include "internal.h"
  16
  17
  18 static const struct proc_ns_operations *ns_entries[] = {
  19 };
  20
  21 static const struct file_operations ns_file_operations = {
  22         .llseek         = no_llseek,
  23 };
  24
  25 static struct dentry *proc_ns_instantiate(struct inode *dir,
  26         struct dentry *dentry, struct task_struct *task, const void *ptr)
  27 {
  28         const struct proc_ns_operations *ns_ops = ptr;
  29         struct inode *inode;
  30         struct proc_inode *ei;
  31         struct dentry *error = ERR_PTR(-ENOENT);
  32
  33         inode = proc_pid_make_inode(dir->i_sb, task);
  34         if (!inode)
  35                 goto out;
  36
  37         ei = PROC_I(inode);
  38         inode->i_mode = S_IFREG|S_IRUSR;
  39         inode->i_fop  = &ns_file_operations;
  40         ei->ns_ops    = ns_ops;
  41         ei->ns        = ns_ops->get(task);
  42         if (!ei->ns)
  43                 goto out_iput;
  44
  45         dentry->d_op = &pid_dentry_operations;
  46         d_add(dentry, inode);
  47         /* Close the race of the process dying before we return the dentry */
  48         if (pid_revalidate(dentry, NULL))
  49                 error = NULL;
  50 out:
  51         return error;
  52 out_iput:
  53         iput(inode);
  54         goto out;
  55 }
  56
  57 static int proc_ns_fill_cache(struct file *filp, void *dirent,
  58         filldir_t filldir, struct task_struct *task,
  59         const struct proc_ns_operations *ops)
  60 {
  61         return proc_fill_cache(filp, dirent, filldir,
  62                                 ops->name, strlen(ops->name),
  63                                 proc_ns_instantiate, task, ops);
  64 }
  65
  66 static int proc_ns_dir_readdir(struct file *filp, void *dirent,
  67                                 filldir_t filldir)
  68 {
  69         int i;
  70         struct dentry *dentry = filp->f_path.dentry;
  71         struct inode *inode = dentry->d_inode;
  72         struct task_struct *task = get_proc_task(inode);
  73         const struct proc_ns_operations **entry, **last;
  74         ino_t ino;
  75         int ret;
  76
  77         ret = -ENOENT;
  78         if (!task)
  79                 goto out_no_task;
  80
  81         ret = -EPERM;
  82         if (!ptrace_may_access(task, PTRACE_MODE_READ))
  83                 goto out;
  84
  85         ret = 0;
  86         i = filp->f_pos;
  87         switch (i) {
  88         case 0:
  89                 ino = inode->i_ino;
  90                 if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
  91                         goto out;
  92                 i++;
  93                 filp->f_pos++;
  94                 /* fall through */
  95         case 1:
  96                 ino = parent_ino(dentry);
  97                 if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
  98                         goto out;
  99                 i++;
 100                 filp->f_pos++;
 101                 /* fall through */
 102         default:
 103                 i -= 2;
 104                 if (i >= ARRAY_SIZE(ns_entries)) {
 105                         ret = 1;
 106                         goto out;
 107                 }
 108                 entry = ns_entries + i;
 109                 last = &ns_entries[ARRAY_SIZE(ns_entries) - 1];
 110                 while (entry <= last) {
 111                         if (proc_ns_fill_cache(filp, dirent, filldir,
 112                                                 task, *entry) < 0)
 113                                 goto out;
 114                         filp->f_pos++;
 115                         entry++;
 116                 }
 117         }
 118
 119         ret = 1;
 120 out:
 121         put_task_struct(task);
 122 out_no_task:
 123         return ret;
 124 }
 125
 126 const struct file_operations proc_ns_dir_operations = {
 127         .read           = generic_read_dir,
 128         .readdir        = proc_ns_dir_readdir,
 129 };
 130
 131 static struct dentry *proc_ns_dir_lookup(struct inode *dir,
 132                                 struct dentry *dentry, struct nameidata *nd)
 133 {
 134         struct dentry *error;
 135         struct task_struct *task = get_proc_task(dir);
 136         const struct proc_ns_operations **entry, **last;
 137         unsigned int len = dentry->d_name.len;
 138
 139         error = ERR_PTR(-ENOENT);
 140
 141         if (!task)
 142                 goto out_no_task;
 143
 144         error = ERR_PTR(-EPERM);
 145         if (!ptrace_may_access(task, PTRACE_MODE_READ))
 146                 goto out;
 147
 148         last = &ns_entries[ARRAY_SIZE(ns_entries) - 1];
 149         for (entry = ns_entries; entry <= last; entry++) {
 150                 if (strlen((*entry)->name) != len)
 151                         continue;
 152                 if (!memcmp(dentry->d_name.name, (*entry)->name, len))
 153                         break;
 154         }
 155         if (entry > last)
 156                 goto out;
 157
 158         error = proc_ns_instantiate(dir, dentry, task, *entry);
 159 out:
 160         put_task_struct(task);
 161 out_no_task:
 162         return error;
 163 }
 164
 165 const struct inode_operations proc_ns_dir_inode_operations = {
 166         .lookup         = proc_ns_dir_lookup,
 167         .getattr        = pid_getattr,
 168         .setattr        = proc_setattr,
 169 };
 170
 171 struct file *proc_ns_fget(int fd)
 172 {
 173         struct file *file;
 174
 175         file = fget(fd);
 176         if (!file)
 177                 return ERR_PTR(-EBADF);
 178
 179         if (file->f_op != &ns_file_operations)
 180                 goto out_invalid;
 181
 182         return file;
 183
 184 out_invalid:
 185         fput(file);
 186         return ERR_PTR(-EINVAL);
 187 }
 188