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/ipc_namespace.h>
  13 #include <linux/pid_namespace.h>
  14 #include "internal.h"
  15
  16
  17 static const struct proc_ns_operations *ns_entries[] = {
  18 #ifdef CONFIG_NET_NS
  19         &netns_operations,
  20 #endif
  21 #ifdef CONFIG_UTS_NS
  22         &utsns_operations,
  23 #endif
  24 #ifdef CONFIG_IPC_NS
  25         &ipcns_operations,
  26 #endif
  27 };
  28
  29 static const struct file_operations ns_file_operations = {
  30         .llseek         = no_llseek,
  31 };
  32
  33 static struct dentry *proc_ns_instantiate(struct inode *dir,
  34         struct dentry *dentry, struct task_struct *task, const void *ptr)
  35 {
  36         const struct proc_ns_operations *ns_ops = ptr;
  37         struct inode *inode;
  38         struct proc_inode *ei;
  39         struct dentry *error = ERR_PTR(-ENOENT);
  40         void *ns;
  41
  42         inode = proc_pid_make_inode(dir->i_sb, task);
  43         if (!inode)
  44                 goto out;
  45
  46         ns = ns_ops->get(task);
  47         if (!ns)
  48                 goto out_iput;
  49
  50         ei = PROC_I(inode);
  51         inode->i_mode = S_IFREG|S_IRUSR;
  52         inode->i_fop  = &ns_file_operations;
  53         ei->ns_ops    = ns_ops;
  54         ei->ns        = ns;
  55
  56         d_set_d_op(dentry, &pid_dentry_operations);
  57         d_add(dentry, inode);
  58         /* Close the race of the process dying before we return the dentry */
  59         if (pid_revalidate(dentry, 0))
  60                 error = NULL;
  61 out:
  62         return error;
  63 out_iput:
  64         iput(inode);
  65         goto out;
  66 }
  67
  68 static int proc_ns_fill_cache(struct file *filp, void *dirent,
  69         filldir_t filldir, struct task_struct *task,
  70         const struct proc_ns_operations *ops)
  71 {
  72         return proc_fill_cache(filp, dirent, filldir,
  73                                 ops->name, strlen(ops->name),
  74                                 proc_ns_instantiate, task, ops);
  75 }
  76
  77 static int proc_ns_dir_readdir(struct file *filp, void *dirent,
  78                                 filldir_t filldir)
  79 {
  80         int i;
  81         struct dentry *dentry = filp->f_path.dentry;
  82         struct inode *inode = dentry->d_inode;
  83         struct task_struct *task = get_proc_task(inode);
  84         const struct proc_ns_operations **entry, **last;
  85         ino_t ino;
  86         int ret;
  87
  88         ret = -ENOENT;
  89         if (!task)
  90                 goto out_no_task;
  91
  92         ret = -EPERM;
  93         if (!ptrace_may_access(task, PTRACE_MODE_READ))
  94                 goto out;
  95
  96         ret = 0;
  97         i = filp->f_pos;
  98         switch (i) {
  99         case 0:
 100                 ino = inode->i_ino;
 101                 if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
 102                         goto out;
 103                 i++;
 104                 filp->f_pos++;
 105                 /* fall through */
 106         case 1:
 107                 ino = parent_ino(dentry);
 108                 if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
 109                         goto out;
 110                 i++;
 111                 filp->f_pos++;
 112                 /* fall through */
 113         default:
 114                 i -= 2;
 115                 if (i >= ARRAY_SIZE(ns_entries)) {
 116                         ret = 1;
 117                         goto out;
 118                 }
 119                 entry = ns_entries + i;
 120                 last = &ns_entries[ARRAY_SIZE(ns_entries) - 1];
 121                 while (entry <= last) {
 122                         if (proc_ns_fill_cache(filp, dirent, filldir,
 123                                                 task, *entry) < 0)
 124                                 goto out;
 125                         filp->f_pos++;
 126                         entry++;
 127                 }
 128         }
 129
 130         ret = 1;
 131 out:
 132         put_task_struct(task);
 133 out_no_task:
 134         return ret;
 135 }
 136
 137 const struct file_operations proc_ns_dir_operations = {
 138         .read           = generic_read_dir,
 139         .readdir        = proc_ns_dir_readdir,
 140 };
 141
 142 static struct dentry *proc_ns_dir_lookup(struct inode *dir,
 143                                 struct dentry *dentry, unsigned int flags)
 144 {
 145         struct dentry *error;
 146         struct task_struct *task = get_proc_task(dir);
 147         const struct proc_ns_operations **entry, **last;
 148         unsigned int len = dentry->d_name.len;
 149
 150         error = ERR_PTR(-ENOENT);
 151
 152         if (!task)
 153                 goto out_no_task;
 154
 155         error = ERR_PTR(-EPERM);
 156         if (!ptrace_may_access(task, PTRACE_MODE_READ))
 157                 goto out;
 158
 159         last = &ns_entries[ARRAY_SIZE(ns_entries)];
 160         for (entry = ns_entries; entry < last; entry++) {
 161                 if (strlen((*entry)->name) != len)
 162                         continue;
 163                 if (!memcmp(dentry->d_name.name, (*entry)->name, len))
 164                         break;
 165         }
 166         error = ERR_PTR(-ENOENT);
 167         if (entry == last)
 168                 goto out;
 169
 170         error = proc_ns_instantiate(dir, dentry, task, *entry);
 171 out:
 172         put_task_struct(task);
 173 out_no_task:
 174         return error;
 175 }
 176
 177 const struct inode_operations proc_ns_dir_inode_operations = {
 178         .lookup         = proc_ns_dir_lookup,
 179         .getattr        = pid_getattr,
 180         .setattr        = proc_setattr,
 181 };
 182
 183 struct file *proc_ns_fget(int fd)
 184 {
 185         struct file *file;
 186
 187         file = fget(fd);
 188         if (!file)
 189                 return ERR_PTR(-EBADF);
 190
 191         if (file->f_op != &ns_file_operations)
 192                 goto out_invalid;
 193
 194         return file;
 195
 196 out_invalid:
 197         fput(file);
 198         return ERR_PTR(-EINVAL);
 199 }
 200