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