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 = PROC_I(inode)->ns.ns_ops;
  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         void *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
  79         inode = iget_locked(sb, ns_ops->inum(ns));
  80         if (!inode) {
  81                 dput(dentry);
  82                 ns_ops->put(ns);
  83                 return ERR_PTR(-ENOMEM);
  84         }
  85
  86         ei = PROC_I(inode);
  87         if (inode->i_state & I_NEW) {
  88                 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
  89                 inode->i_op = &ns_inode_operations;
  90                 inode->i_mode = S_IFREG | S_IRUGO;
  91                 inode->i_fop = &ns_file_operations;
  92                 ei->ns.ns_ops = ns_ops;
  93                 ei->ns.ns = ns;
  94                 unlock_new_inode(inode);
  95         } else {
  96                 ns_ops->put(ns);
  97         }
  98
  99         d_set_d_op(dentry, &ns_dentry_operations);
 100         result = d_instantiate_unique(dentry, inode);
 101         if (result) {
 102                 dput(dentry);
 103                 dentry = result;
 104         }
 105
 106         return dentry;
 107 }
 108
 109 static void *proc_ns_follow_link(struct dentry *dentry, struct nameidata *nd)
 110 {
 111         struct inode *inode = dentry->d_inode;
 112         struct super_block *sb = inode->i_sb;
 113         struct proc_inode *ei = PROC_I(inode);
 114         struct task_struct *task;
 115         struct path ns_path;
 116         void *error = ERR_PTR(-EACCES);
 117
 118         task = get_proc_task(inode);
 119         if (!task)
 120                 goto out;
 121
 122         if (!ptrace_may_access(task, PTRACE_MODE_READ))
 123                 goto out_put_task;
 124
 125         ns_path.dentry = proc_ns_get_dentry(sb, task, ei->ns.ns_ops);
 126         if (IS_ERR(ns_path.dentry)) {
 127                 error = ERR_CAST(ns_path.dentry);
 128                 goto out_put_task;
 129         }
 130
 131         ns_path.mnt = mntget(nd->path.mnt);
 132         nd_jump_link(nd, &ns_path);
 133         error = NULL;
 134
 135 out_put_task:
 136         put_task_struct(task);
 137 out:
 138         return error;
 139 }
 140
 141 static int proc_ns_readlink(struct dentry *dentry, char __user *buffer, int buflen)
 142 {
 143         struct inode *inode = dentry->d_inode;
 144         struct proc_inode *ei = PROC_I(inode);
 145         const struct proc_ns_operations *ns_ops = ei->ns.ns_ops;
 146         struct task_struct *task;
 147         void *ns;
 148         char name[50];
 149         int len = -EACCES;
 150
 151         task = get_proc_task(inode);
 152         if (!task)
 153                 goto out;
 154
 155         if (!ptrace_may_access(task, PTRACE_MODE_READ))
 156                 goto out_put_task;
 157
 158         len = -ENOENT;
 159         ns = ns_ops->get(task);
 160         if (!ns)
 161                 goto out_put_task;
 162
 163         snprintf(name, sizeof(name), "%s:[%u]", ns_ops->name, ns_ops->inum(ns));
 164         len = strlen(name);
 165
 166         if (len > buflen)
 167                 len = buflen;
 168         if (copy_to_user(buffer, name, len))
 169                 len = -EFAULT;
 170
 171         ns_ops->put(ns);
 172 out_put_task:
 173         put_task_struct(task);
 174 out:
 175         return len;
 176 }
 177
 178 static const struct inode_operations proc_ns_link_inode_operations = {
 179         .readlink       = proc_ns_readlink,
 180         .follow_link    = proc_ns_follow_link,
 181         .setattr        = proc_setattr,
 182 };
 183
 184 static int proc_ns_instantiate(struct inode *dir,
 185         struct dentry *dentry, struct task_struct *task, const void *ptr)
 186 {
 187         const struct proc_ns_operations *ns_ops = ptr;
 188         struct inode *inode;
 189         struct proc_inode *ei;
 190
 191         inode = proc_pid_make_inode(dir->i_sb, task);
 192         if (!inode)
 193                 goto out;
 194
 195         ei = PROC_I(inode);
 196         inode->i_mode = S_IFLNK|S_IRWXUGO;
 197         inode->i_op = &proc_ns_link_inode_operations;
 198         ei->ns.ns_ops = ns_ops;
 199
 200         d_set_d_op(dentry, &pid_dentry_operations);
 201         d_add(dentry, inode);
 202         /* Close the race of the process dying before we return the dentry */
 203         if (pid_revalidate(dentry, 0))
 204                 return 0;
 205 out:
 206         return -ENOENT;
 207 }
 208
 209 static int proc_ns_dir_readdir(struct file *file, struct dir_context *ctx)
 210 {
 211         struct task_struct *task = get_proc_task(file_inode(file));
 212         const struct proc_ns_operations **entry, **last;
 213
 214         if (!task)
 215                 return -ENOENT;
 216
 217         if (!dir_emit_dots(file, ctx))
 218                 goto out;
 219         if (ctx->pos >= 2 + ARRAY_SIZE(ns_entries))
 220                 goto out;
 221         entry = ns_entries + (ctx->pos - 2);
 222         last = &ns_entries[ARRAY_SIZE(ns_entries) - 1];
 223         while (entry <= last) {
 224                 const struct proc_ns_operations *ops = *entry;
 225                 if (!proc_fill_cache(file, ctx, ops->name, strlen(ops->name),
 226                                      proc_ns_instantiate, task, ops))
 227                         break;
 228                 ctx->pos++;
 229                 entry++;
 230         }
 231 out:
 232         put_task_struct(task);
 233         return 0;
 234 }
 235
 236 const struct file_operations proc_ns_dir_operations = {
 237         .read           = generic_read_dir,
 238         .iterate        = proc_ns_dir_readdir,
 239 };
 240
 241 static struct dentry *proc_ns_dir_lookup(struct inode *dir,
 242                                 struct dentry *dentry, unsigned int flags)
 243 {
 244         int error;
 245         struct task_struct *task = get_proc_task(dir);
 246         const struct proc_ns_operations **entry, **last;
 247         unsigned int len = dentry->d_name.len;
 248
 249         error = -ENOENT;
 250
 251         if (!task)
 252                 goto out_no_task;
 253
 254         last = &ns_entries[ARRAY_SIZE(ns_entries)];
 255         for (entry = ns_entries; entry < last; entry++) {
 256                 if (strlen((*entry)->name) != len)
 257                         continue;
 258                 if (!memcmp(dentry->d_name.name, (*entry)->name, len))
 259                         break;
 260         }
 261         if (entry == last)
 262                 goto out;
 263
 264         error = proc_ns_instantiate(dir, dentry, task, *entry);
 265 out:
 266         put_task_struct(task);
 267 out_no_task:
 268         return ERR_PTR(error);
 269 }
 270
 271 const struct inode_operations proc_ns_dir_inode_operations = {
 272         .lookup         = proc_ns_dir_lookup,
 273         .getattr        = pid_getattr,
 274         .setattr        = proc_setattr,
 275 };
 276
 277 struct file *proc_ns_fget(int fd)
 278 {
 279         struct file *file;
 280
 281         file = fget(fd);
 282         if (!file)
 283                 return ERR_PTR(-EBADF);
 284
 285         if (file->f_op != &ns_file_operations)
 286                 goto out_invalid;
 287
 288         return file;
 289
 290 out_invalid:
 291         fput(file);
 292         return ERR_PTR(-EINVAL);
 293 }
 294
 295 struct proc_ns *get_proc_ns(struct inode *inode)
 296 {
 297         return &PROC_I(inode)->ns;
 298 }
 299
 300 bool proc_ns_inode(struct inode *inode)
 301 {
 302         return inode->i_fop == &ns_file_operations;
 303 }