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 <linux/user_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 #ifdef CONFIG_UTS_NS
  23         &utsns_operations,
  24 #endif
  25 #ifdef CONFIG_IPC_NS
  26         &ipcns_operations,
  27 #endif
  28 #ifdef CONFIG_PID_NS
  29         &pidns_operations,
  30 #endif
  31 #ifdef CONFIG_USER_NS
  32         &userns_operations,
  33 #endif
  34         &mntns_operations,
  35 };
  36
  37 static const struct file_operations ns_file_operations = {
  38         .llseek         = no_llseek,
  39 };
  40
  41 static const struct inode_operations ns_inode_operations = {
  42         .setattr        = proc_setattr,
  43 };
  44
  45 static char *ns_dname(struct dentry *dentry, char *buffer, int buflen)
  46 {
  47         struct inode *inode = dentry->d_inode;
  48         const struct proc_ns_operations *ns_ops = dentry->d_fsdata;
  49
  50         return dynamic_dname(dentry, buffer, buflen, "%s:[%lu]",
  51                 ns_ops->name, inode->i_ino);
  52 }
  53
  54 const struct dentry_operations ns_dentry_operations =
  55 {
  56         .d_delete       = always_delete_dentry,
  57         .d_dname        = ns_dname,
  58 };
  59
  60 static struct dentry *proc_ns_get_dentry(struct super_block *sb,
  61         struct task_struct *task, const struct proc_ns_operations *ns_ops)
  62 {
  63         struct dentry *dentry, *result;
  64         struct inode *inode;
  65         struct proc_inode *ei;
  66         struct qstr qname = { .name = "", };
  67         struct ns_common *ns;
  68
  69         ns = ns_ops->get(task);
  70         if (!ns)
  71                 return ERR_PTR(-ENOENT);
  72
  73         dentry = d_alloc_pseudo(sb, &qname);
  74         if (!dentry) {
  75                 ns_ops->put(ns);
  76                 return ERR_PTR(-ENOMEM);
  77         }
  78         dentry->d_fsdata = (void *)ns_ops;
  79
  80         inode = iget_locked(sb, ns->inum);
  81         if (!inode) {
  82                 dput(dentry);
  83                 ns_ops->put(ns);
  84                 return ERR_PTR(-ENOMEM);
  85         }
  86
  87         ei = PROC_I(inode);
  88         if (inode->i_state & I_NEW) {
  89                 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
  90                 inode->i_op = &ns_inode_operations;
  91                 inode->i_mode = S_IFREG | S_IRUGO;
  92                 inode->i_fop = &ns_file_operations;
  93                 ei->ns.ns_ops = ns_ops;
  94                 ei->ns.ns = ns;
  95                 unlock_new_inode(inode);
  96         } else {
  97                 ns_ops->put(ns);
  98         }
  99
 100         d_set_d_op(dentry, &ns_dentry_operations);
 101         result = d_instantiate_unique(dentry, inode);
 102         if (result) {
 103                 dput(dentry);
 104                 dentry = result;
 105         }
 106
 107         return dentry;
 108 }
 109
 110 static void *proc_ns_follow_link(struct dentry *dentry, struct nameidata *nd)
 111 {
 112         struct inode *inode = dentry->d_inode;
 113         struct super_block *sb = inode->i_sb;
 114         struct proc_inode *ei = PROC_I(inode);
 115         struct task_struct *task;
 116         struct path ns_path;
 117         void *error = ERR_PTR(-EACCES);
 118
 119         task = get_proc_task(inode);
 120         if (!task)
 121                 goto out;
 122
 123         if (!ptrace_may_access(task, PTRACE_MODE_READ))
 124                 goto out_put_task;
 125
 126         ns_path.dentry = proc_ns_get_dentry(sb, task, ei->ns.ns_ops);
 127         if (IS_ERR(ns_path.dentry)) {
 128                 error = ERR_CAST(ns_path.dentry);
 129                 goto out_put_task;
 130         }
 131
 132         ns_path.mnt = mntget(nd->path.mnt);
 133         nd_jump_link(nd, &ns_path);
 134         error = NULL;
 135
 136 out_put_task:
 137         put_task_struct(task);
 138 out:
 139         return error;
 140 }
 141
 142 static int proc_ns_readlink(struct dentry *dentry, char __user *buffer, int buflen)
 143 {
 144         struct inode *inode = dentry->d_inode;
 145         struct proc_inode *ei = PROC_I(inode);
 146         const struct proc_ns_operations *ns_ops = ei->ns.ns_ops;
 147         struct task_struct *task;
 148         struct ns_common *ns;
 149         char name[50];
 150         int res = -EACCES;
 151
 152         task = get_proc_task(inode);
 153         if (!task)
 154                 goto out;
 155
 156         if (!ptrace_may_access(task, PTRACE_MODE_READ))
 157                 goto out_put_task;
 158
 159         res = -ENOENT;
 160         ns = ns_ops->get(task);
 161         if (!ns)
 162                 goto out_put_task;
 163
 164         snprintf(name, sizeof(name), "%s:[%u]", ns_ops->name, ns->inum);
 165         res = readlink_copy(buffer, buflen, name);
 166         ns_ops->put(ns);
 167 out_put_task:
 168         put_task_struct(task);
 169 out:
 170         return res;
 171 }
 172
 173 static const struct inode_operations proc_ns_link_inode_operations = {
 174         .readlink       = proc_ns_readlink,
 175         .follow_link    = proc_ns_follow_link,
 176         .setattr        = proc_setattr,
 177 };
 178
 179 static int proc_ns_instantiate(struct inode *dir,
 180         struct dentry *dentry, struct task_struct *task, const void *ptr)
 181 {
 182         const struct proc_ns_operations *ns_ops = ptr;
 183         struct inode *inode;
 184         struct proc_inode *ei;
 185
 186         inode = proc_pid_make_inode(dir->i_sb, task);
 187         if (!inode)
 188                 goto out;
 189
 190         ei = PROC_I(inode);
 191         inode->i_mode = S_IFLNK|S_IRWXUGO;
 192         inode->i_op = &proc_ns_link_inode_operations;
 193         ei->ns.ns_ops = ns_ops;
 194
 195         d_set_d_op(dentry, &pid_dentry_operations);
 196         d_add(dentry, inode);
 197         /* Close the race of the process dying before we return the dentry */
 198         if (pid_revalidate(dentry, 0))
 199                 return 0;
 200 out:
 201         return -ENOENT;
 202 }
 203
 204 static int proc_ns_dir_readdir(struct file *file, struct dir_context *ctx)
 205 {
 206         struct task_struct *task = get_proc_task(file_inode(file));
 207         const struct proc_ns_operations **entry, **last;
 208
 209         if (!task)
 210                 return -ENOENT;
 211
 212         if (!dir_emit_dots(file, ctx))
 213                 goto out;
 214         if (ctx->pos >= 2 + ARRAY_SIZE(ns_entries))
 215                 goto out;
 216         entry = ns_entries + (ctx->pos - 2);
 217         last = &ns_entries[ARRAY_SIZE(ns_entries) - 1];
 218         while (entry <= last) {
 219                 const struct proc_ns_operations *ops = *entry;
 220                 if (!proc_fill_cache(file, ctx, ops->name, strlen(ops->name),
 221                                      proc_ns_instantiate, task, ops))
 222                         break;
 223                 ctx->pos++;
 224                 entry++;
 225         }
 226 out:
 227         put_task_struct(task);
 228         return 0;
 229 }
 230
 231 const struct file_operations proc_ns_dir_operations = {
 232         .read           = generic_read_dir,
 233         .iterate        = proc_ns_dir_readdir,
 234 };
 235
 236 static struct dentry *proc_ns_dir_lookup(struct inode *dir,
 237                                 struct dentry *dentry, unsigned int flags)
 238 {
 239         int error;
 240         struct task_struct *task = get_proc_task(dir);
 241         const struct proc_ns_operations **entry, **last;
 242         unsigned int len = dentry->d_name.len;
 243
 244         error = -ENOENT;
 245
 246         if (!task)
 247                 goto out_no_task;
 248
 249         last = &ns_entries[ARRAY_SIZE(ns_entries)];
 250         for (entry = ns_entries; entry < last; entry++) {
 251                 if (strlen((*entry)->name) != len)
 252                         continue;
 253                 if (!memcmp(dentry->d_name.name, (*entry)->name, len))
 254                         break;
 255         }
 256         if (entry == last)
 257                 goto out;
 258
 259         error = proc_ns_instantiate(dir, dentry, task, *entry);
 260 out:
 261         put_task_struct(task);
 262 out_no_task:
 263         return ERR_PTR(error);
 264 }
 265
 266 const struct inode_operations proc_ns_dir_inode_operations = {
 267         .lookup         = proc_ns_dir_lookup,
 268         .getattr        = pid_getattr,
 269         .setattr        = proc_setattr,
 270 };
 271
 272 struct file *proc_ns_fget(int fd)
 273 {
 274         struct file *file;
 275
 276         file = fget(fd);
 277         if (!file)
 278                 return ERR_PTR(-EBADF);
 279
 280         if (file->f_op != &ns_file_operations)
 281                 goto out_invalid;
 282
 283         return file;
 284
 285 out_invalid:
 286         fput(file);
 287         return ERR_PTR(-EINVAL);
 288 }
 289
 290 struct ns_common *get_proc_ns(struct inode *inode)
 291 {
 292         return PROC_I(inode)->ns.ns;
 293 }
 294
 295 bool proc_ns_inode(struct inode *inode)
 296 {
 297         return inode->i_fop == &ns_file_operations;
 298 }