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 #ifdef CONFIG_NET_NS
  20         &netns_operations,
  21 #endif
  22 };
  23
  24 static const struct file_operations ns_file_operations = {
  25         .llseek         = no_llseek,
  26 };
  27
  28 static struct dentry *proc_ns_instantiate(struct inode *dir,
  29         struct dentry *dentry, struct task_struct *task, const void *ptr)
  30 {
  31         const struct proc_ns_operations *ns_ops = ptr;
  32         struct inode *inode;
  33         struct proc_inode *ei;
  34         struct dentry *error = ERR_PTR(-ENOENT);
  35
  36         inode = proc_pid_make_inode(dir->i_sb, task);
  37         if (!inode)
  38                 goto out;
  39
  40         ei = PROC_I(inode);
  41         inode->i_mode = S_IFREG|S_IRUSR;
  42         inode->i_fop  = &ns_file_operations;
  43         ei->ns_ops    = ns_ops;
  44         ei->ns        = ns_ops->get(task);
  45         if (!ei->ns)
  46                 goto out_iput;
  47
  48         dentry->d_op = &pid_dentry_operations;
  49         d_add(dentry, inode);
  50         /* Close the race of the process dying before we return the dentry */
  51         if (pid_revalidate(dentry, NULL))
  52                 error = NULL;
  53 out:
  54         return error;
  55 out_iput:
  56         iput(inode);
  57         goto out;
  58 }
  59
  60 static int proc_ns_fill_cache(struct file *filp, void *dirent,
  61         filldir_t filldir, struct task_struct *task,
  62         const struct proc_ns_operations *ops)
  63 {
  64         return proc_fill_cache(filp, dirent, filldir,
  65                                 ops->name, strlen(ops->name),
  66                                 proc_ns_instantiate, task, ops);
  67 }
  68
  69 static int proc_ns_dir_readdir(struct file *filp, void *dirent,
  70                                 filldir_t filldir)
  71 {
  72         int i;
  73         struct dentry *dentry = filp->f_path.dentry;
  74         struct inode *inode = dentry->d_inode;
  75         struct task_struct *task = get_proc_task(inode);
  76         const struct proc_ns_operations **entry, **last;
  77         ino_t ino;
  78         int ret;
  79
  80         ret = -ENOENT;
  81         if (!task)
  82                 goto out_no_task;
  83
  84         ret = -EPERM;
  85         if (!ptrace_may_access(task, PTRACE_MODE_READ))
  86                 goto out;
  87
  88         ret = 0;
  89         i = filp->f_pos;
  90         switch (i) {
  91         case 0:
  92                 ino = inode->i_ino;
  93                 if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
  94                         goto out;
  95                 i++;
  96                 filp->f_pos++;
  97                 /* fall through */
  98         case 1:
  99                 ino = parent_ino(dentry);
 100                 if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
 101                         goto out;
 102                 i++;
 103                 filp->f_pos++;
 104                 /* fall through */
 105         default:
 106                 i -= 2;
 107                 if (i >= ARRAY_SIZE(ns_entries)) {
 108                         ret = 1;
 109                         goto out;
 110                 }
 111                 entry = ns_entries + i;
 112                 last = &ns_entries[ARRAY_SIZE(ns_entries) - 1];
 113                 while (entry <= last) {
 114                         if (proc_ns_fill_cache(filp, dirent, filldir,
 115                                                 task, *entry) < 0)
 116                                 goto out;
 117                         filp->f_pos++;
 118                         entry++;
 119                 }
 120         }
 121
 122         ret = 1;
 123 out:
 124         put_task_struct(task);
 125 out_no_task:
 126         return ret;
 127 }
 128
 129 const struct file_operations proc_ns_dir_operations = {
 130         .read           = generic_read_dir,
 131         .readdir        = proc_ns_dir_readdir,
 132 };
 133
 134 static struct dentry *proc_ns_dir_lookup(struct inode *dir,
 135                                 struct dentry *dentry, struct nameidata *nd)
 136 {
 137         struct dentry *error;
 138         struct task_struct *task = get_proc_task(dir);
 139         const struct proc_ns_operations **entry, **last;
 140         unsigned int len = dentry->d_name.len;
 141
 142         error = ERR_PTR(-ENOENT);
 143
 144         if (!task)
 145                 goto out_no_task;
 146
 147         error = ERR_PTR(-EPERM);
 148         if (!ptrace_may_access(task, PTRACE_MODE_READ))
 149                 goto out;
 150
 151         last = &ns_entries[ARRAY_SIZE(ns_entries) - 1];
 152         for (entry = ns_entries; entry <= last; entry++) {
 153                 if (strlen((*entry)->name) != len)
 154                         continue;
 155                 if (!memcmp(dentry->d_name.name, (*entry)->name, len))
 156                         break;
 157         }
 158         if (entry > last)
 159                 goto out;
 160
 161         error = proc_ns_instantiate(dir, dentry, task, *entry);
 162 out:
 163         put_task_struct(task);
 164 out_no_task:
 165         return error;
 166 }
 167
 168 const struct inode_operations proc_ns_dir_inode_operations = {
 169         .lookup         = proc_ns_dir_lookup,
 170         .getattr        = pid_getattr,
 171         .setattr        = proc_setattr,
 172 };
 173
 174 struct file *proc_ns_fget(int fd)
 175 {
 176         struct file *file;
 177
 178         file = fget(fd);
 179         if (!file)
 180                 return ERR_PTR(-EBADF);
 181
 182         if (file->f_op != &ns_file_operations)
 183                 goto out_invalid;
 184
 185         return file;
 186
 187 out_invalid:
 188         fput(file);
 189         return ERR_PTR(-EINVAL);
 190 }
 191