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 #ifdef CONFIG_UTS_NS
  23         &utsns_operations,
  24 #endif
  25 #ifdef CONFIG_IPC_NS
  26         &ipcns_operations,
  27 #endif
  28 };
  29
  30 static const struct file_operations ns_file_operations = {
  31         .llseek         = no_llseek,
  32 };
  33
  34 static const struct inode_operations ns_inode_operations = {
  35         .setattr        = proc_setattr,
  36 };
  37
  38 static int ns_delete_dentry(const struct dentry *dentry)
  39 {
  40         /* Don't cache namespace dentries when not in use */
  41         return 1;
  42 }
  43
  44 static char *ns_dname(struct dentry *dentry, char *buffer, int buflen)
  45 {
  46         struct inode *inode = dentry->d_inode;
  47         const struct proc_ns_operations *ns_ops = PROC_I(inode)->ns_ops;
  48
  49         return dynamic_dname(dentry, buffer, buflen, "%s:[%lu]",
  50                 ns_ops->name, inode->i_ino);
  51 }
  52
  53 static const struct dentry_operations ns_dentry_operations =
  54 {
  55         .d_delete       = ns_delete_dentry,
  56         .d_dname        = ns_dname,
  57 };
  58
  59 static struct dentry *proc_ns_get_dentry(struct super_block *sb,
  60         struct task_struct *task, const struct proc_ns_operations *ns_ops)
  61 {
  62         struct dentry *dentry;
  63         struct inode *inode;
  64         struct proc_inode *ei;
  65         struct qstr qname = { .name = "", };
  66         void *ns;
  67
  68         ns = ns_ops->get(task);
  69         if (!ns)
  70                 return ERR_PTR(-ENOENT);
  71
  72         dentry = d_alloc_pseudo(sb, &qname);
  73         if (!dentry) {
  74                 ns_ops->put(ns);
  75                 return ERR_PTR(-ENOMEM);
  76         }
  77
  78         inode = new_inode(sb);
  79         if (!inode) {
  80                 dput(dentry);
  81                 ns_ops->put(ns);
  82                 return ERR_PTR(-ENOMEM);
  83         }
  84
  85         ei = PROC_I(inode);
  86         inode->i_ino = get_next_ino();
  87         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
  88         inode->i_op = &ns_inode_operations;
  89         inode->i_mode = S_IFREG|S_IRUSR;
  90         inode->i_fop = &ns_file_operations;
  91         ei->ns_ops = ns_ops;
  92         ei->ns = ns;
  93
  94         d_set_d_op(dentry, &ns_dentry_operations);
  95         d_instantiate(dentry, inode);
  96
  97         return dentry;
  98 }
  99
 100 static void *proc_ns_follow_link(struct dentry *dentry, struct nameidata *nd)
 101 {
 102         struct inode *inode = dentry->d_inode;
 103         struct super_block *sb = inode->i_sb;
 104         struct proc_inode *ei = PROC_I(inode);
 105         struct task_struct *task;
 106         struct dentry *ns_dentry;
 107         void *error = ERR_PTR(-EACCES);
 108
 109         task = get_proc_task(inode);
 110         if (!task)
 111                 goto out;
 112
 113         if (!ptrace_may_access(task, PTRACE_MODE_READ))
 114                 goto out_put_task;
 115
 116         ns_dentry = proc_ns_get_dentry(sb, task, ei->ns_ops);
 117         if (IS_ERR(ns_dentry)) {
 118                 error = ERR_CAST(ns_dentry);
 119                 goto out_put_task;
 120         }
 121
 122         dput(nd->path.dentry);
 123         nd->path.dentry = ns_dentry;
 124         error = NULL;
 125
 126 out_put_task:
 127         put_task_struct(task);
 128 out:
 129         return error;
 130 }
 131
 132 static int proc_ns_readlink(struct dentry *dentry, char __user *buffer, int buflen)
 133 {
 134         struct inode *inode = dentry->d_inode;
 135         struct proc_inode *ei = PROC_I(inode);
 136         const struct proc_ns_operations *ns_ops = ei->ns_ops;
 137         struct task_struct *task;
 138         char name[50];
 139         int len = -EACCES;
 140
 141         task = get_proc_task(inode);
 142         if (!task)
 143                 goto out;
 144
 145         if (!ptrace_may_access(task, PTRACE_MODE_READ))
 146                 goto out_put_task;
 147
 148         snprintf(name, sizeof(name), "%s", ns_ops->name);
 149         len = strlen(name);
 150
 151         if (len > buflen)
 152                 len = buflen;
 153         if (copy_to_user(buffer, ns_ops->name, len))
 154                 len = -EFAULT;
 155
 156 out_put_task:
 157         put_task_struct(task);
 158 out:
 159         return len;
 160 }
 161
 162 static const struct inode_operations proc_ns_link_inode_operations = {
 163         .readlink       = proc_ns_readlink,
 164         .follow_link    = proc_ns_follow_link,
 165         .setattr        = proc_setattr,
 166 };
 167
 168 static struct dentry *proc_ns_instantiate(struct inode *dir,
 169         struct dentry *dentry, struct task_struct *task, const void *ptr)
 170 {
 171         const struct proc_ns_operations *ns_ops = ptr;
 172         struct inode *inode;
 173         struct proc_inode *ei;
 174         struct dentry *error = ERR_PTR(-ENOENT);
 175
 176         inode = proc_pid_make_inode(dir->i_sb, task);
 177         if (!inode)
 178                 goto out;
 179
 180         ei = PROC_I(inode);
 181         inode->i_mode = S_IFLNK|S_IRWXUGO;
 182         inode->i_op = &proc_ns_link_inode_operations;
 183         ei->ns_ops = ns_ops;
 184
 185         d_set_d_op(dentry, &pid_dentry_operations);
 186         d_add(dentry, inode);
 187         /* Close the race of the process dying before we return the dentry */
 188         if (pid_revalidate(dentry, NULL))
 189                 error = NULL;
 190 out:
 191         return error;
 192 }
 193
 194 static int proc_ns_fill_cache(struct file *filp, void *dirent,
 195         filldir_t filldir, struct task_struct *task,
 196         const struct proc_ns_operations *ops)
 197 {
 198         return proc_fill_cache(filp, dirent, filldir,
 199                                 ops->name, strlen(ops->name),
 200                                 proc_ns_instantiate, task, ops);
 201 }
 202
 203 static int proc_ns_dir_readdir(struct file *filp, void *dirent,
 204                                 filldir_t filldir)
 205 {
 206         int i;
 207         struct dentry *dentry = filp->f_path.dentry;
 208         struct inode *inode = dentry->d_inode;
 209         struct task_struct *task = get_proc_task(inode);
 210         const struct proc_ns_operations **entry, **last;
 211         ino_t ino;
 212         int ret;
 213
 214         ret = -ENOENT;
 215         if (!task)
 216                 goto out_no_task;
 217
 218         ret = 0;
 219         i = filp->f_pos;
 220         switch (i) {
 221         case 0:
 222                 ino = inode->i_ino;
 223                 if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
 224                         goto out;
 225                 i++;
 226                 filp->f_pos++;
 227                 /* fall through */
 228         case 1:
 229                 ino = parent_ino(dentry);
 230                 if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
 231                         goto out;
 232                 i++;
 233                 filp->f_pos++;
 234                 /* fall through */
 235         default:
 236                 i -= 2;
 237                 if (i >= ARRAY_SIZE(ns_entries)) {
 238                         ret = 1;
 239                         goto out;
 240                 }
 241                 entry = ns_entries + i;
 242                 last = &ns_entries[ARRAY_SIZE(ns_entries) - 1];
 243                 while (entry <= last) {
 244                         if (proc_ns_fill_cache(filp, dirent, filldir,
 245                                                 task, *entry) < 0)
 246                                 goto out;
 247                         filp->f_pos++;
 248                         entry++;
 249                 }
 250         }
 251
 252         ret = 1;
 253 out:
 254         put_task_struct(task);
 255 out_no_task:
 256         return ret;
 257 }
 258
 259 const struct file_operations proc_ns_dir_operations = {
 260         .read           = generic_read_dir,
 261         .readdir        = proc_ns_dir_readdir,
 262 };
 263
 264 static struct dentry *proc_ns_dir_lookup(struct inode *dir,
 265                                 struct dentry *dentry, struct nameidata *nd)
 266 {
 267         struct dentry *error;
 268         struct task_struct *task = get_proc_task(dir);
 269         const struct proc_ns_operations **entry, **last;
 270         unsigned int len = dentry->d_name.len;
 271
 272         error = ERR_PTR(-ENOENT);
 273
 274         if (!task)
 275                 goto out_no_task;
 276
 277         last = &ns_entries[ARRAY_SIZE(ns_entries) - 1];
 278         for (entry = ns_entries; entry <= last; entry++) {
 279                 if (strlen((*entry)->name) != len)
 280                         continue;
 281                 if (!memcmp(dentry->d_name.name, (*entry)->name, len))
 282                         break;
 283         }
 284         if (entry > last)
 285                 goto out;
 286
 287         error = proc_ns_instantiate(dir, dentry, task, *entry);
 288 out:
 289         put_task_struct(task);
 290 out_no_task:
 291         return error;
 292 }
 293
 294 const struct inode_operations proc_ns_dir_inode_operations = {
 295         .lookup         = proc_ns_dir_lookup,
 296         .getattr        = pid_getattr,
 297         .setattr        = proc_setattr,
 298 };
 299
 300 struct file *proc_ns_fget(int fd)
 301 {
 302         struct file *file;
 303
 304         file = fget(fd);
 305         if (!file)
 306                 return ERR_PTR(-EBADF);
 307
 308         if (file->f_op != &ns_file_operations)
 309                 goto out_invalid;
 310
 311         return file;
 312
 313 out_invalid:
 314         fput(file);
 315         return ERR_PTR(-EINVAL);
 316 }
 317