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