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 struct dentry *proc_ns_instantiate(struct inode *dir,
  35         struct dentry *dentry, struct task_struct *task, const void *ptr)
  36 {
  37         const struct proc_ns_operations *ns_ops = ptr;
  38         struct inode *inode;
  39         struct proc_inode *ei;
  40         struct dentry *error = ERR_PTR(-ENOENT);
  41         void *ns;
  42
  43         inode = proc_pid_make_inode(dir->i_sb, task);
  44         if (!inode)
  45                 goto out;
  46
  47         ns = ns_ops->get(task);
  48         if (!ns)
  49                 goto out_iput;
  50
  51         ei = PROC_I(inode);
  52         inode->i_mode = S_IFREG|S_IRUSR;
  53         inode->i_fop  = &ns_file_operations;
  54         ei->ns_ops    = ns_ops;
  55         ei->ns        = ns;
  56
  57         d_set_d_op(dentry, &pid_dentry_operations);
  58         d_add(dentry, inode);
  59         /* Close the race of the process dying before we return the dentry */
  60         if (pid_revalidate(dentry, NULL))
  61                 error = NULL;
  62 out:
  63         return error;
  64 out_iput:
  65         iput(inode);
  66         goto out;
  67 }
  68
  69 static int proc_ns_fill_cache(struct file *filp, void *dirent,
  70         filldir_t filldir, struct task_struct *task,
  71         const struct proc_ns_operations *ops)
  72 {
  73         return proc_fill_cache(filp, dirent, filldir,
  74                                 ops->name, strlen(ops->name),
  75                                 proc_ns_instantiate, task, ops);
  76 }
  77
  78 static int proc_ns_dir_readdir(struct file *filp, void *dirent,
  79                                 filldir_t filldir)
  80 {
  81         int i;
  82         struct dentry *dentry = filp->f_path.dentry;
  83         struct inode *inode = dentry->d_inode;
  84         struct task_struct *task = get_proc_task(inode);
  85         const struct proc_ns_operations **entry, **last;
  86         ino_t ino;
  87         int ret;
  88
  89         ret = -ENOENT;
  90         if (!task)
  91                 goto out_no_task;
  92
  93         ret = -EPERM;
  94         if (!ptrace_may_access(task, PTRACE_MODE_READ))
  95                 goto out;
  96
  97         ret = 0;
  98         i = filp->f_pos;
  99         switch (i) {
 100         case 0:
 101                 ino = inode->i_ino;
 102                 if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
 103                         goto out;
 104                 i++;
 105                 filp->f_pos++;
 106                 /* fall through */
 107         case 1:
 108                 ino = parent_ino(dentry);
 109                 if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
 110                         goto out;
 111                 i++;
 112                 filp->f_pos++;
 113                 /* fall through */
 114         default:
 115                 i -= 2;
 116                 if (i >= ARRAY_SIZE(ns_entries)) {
 117                         ret = 1;
 118                         goto out;
 119                 }
 120                 entry = ns_entries + i;
 121                 last = &ns_entries[ARRAY_SIZE(ns_entries) - 1];
 122                 while (entry <= last) {
 123                         if (proc_ns_fill_cache(filp, dirent, filldir,
 124                                                 task, *entry) < 0)
 125                                 goto out;
 126                         filp->f_pos++;
 127                         entry++;
 128                 }
 129         }
 130
 131         ret = 1;
 132 out:
 133         put_task_struct(task);
 134 out_no_task:
 135         return ret;
 136 }
 137
 138 const struct file_operations proc_ns_dir_operations = {
 139         .read           = generic_read_dir,
 140         .readdir        = proc_ns_dir_readdir,
 141 };
 142
 143 static struct dentry *proc_ns_dir_lookup(struct inode *dir,
 144                                 struct dentry *dentry, struct nameidata *nd)
 145 {
 146         struct dentry *error;
 147         struct task_struct *task = get_proc_task(dir);
 148         const struct proc_ns_operations **entry, **last;
 149         unsigned int len = dentry->d_name.len;
 150
 151         error = ERR_PTR(-ENOENT);
 152
 153         if (!task)
 154                 goto out_no_task;
 155
 156         error = ERR_PTR(-EPERM);
 157         if (!ptrace_may_access(task, PTRACE_MODE_READ))
 158                 goto out;
 159
 160         last = &ns_entries[ARRAY_SIZE(ns_entries) - 1];
 161         for (entry = ns_entries; entry <= last; entry++) {
 162                 if (strlen((*entry)->name) != len)
 163                         continue;
 164                 if (!memcmp(dentry->d_name.name, (*entry)->name, len))
 165                         break;
 166         }
 167         error = ERR_PTR(-ENOENT);
 168         if (entry > last)
 169                 goto out;
 170
 171         error = proc_ns_instantiate(dir, dentry, task, *entry);
 172 out:
 173         put_task_struct(task);
 174 out_no_task:
 175         return error;
 176 }
 177
 178 const struct inode_operations proc_ns_dir_inode_operations = {
 179         .lookup         = proc_ns_dir_lookup,
 180         .getattr        = pid_getattr,
 181         .setattr        = proc_setattr,
 182 };
 183
 184 struct file *proc_ns_fget(int fd)
 185 {
 186         struct file *file;
 187
 188         file = fget(fd);
 189         if (!file)
 190                 return ERR_PTR(-EBADF);
 191
 192         if (file->f_op != &ns_file_operations)
 193                 goto out_invalid;
 194
 195         return file;
 196
 197 out_invalid:
 198         fput(file);
 199         return ERR_PTR(-EINVAL);
 200 }
 201