Line data    Source code

       1             : // SPDX-License-Identifier: GPL-2.0
       2             : #include <linux/cache.h>
       3             : #include <linux/sched.h>
       4             : #include <linux/slab.h>
       5             : #include <linux/pid_namespace.h>
       6             : #include "internal.h"
       7             : 
       8             : /*
       9             :  * /proc/self:
      10             :  */
      11         810 : static const char *proc_self_get_link(struct dentry *dentry,
      12             :                                       struct inode *inode,
      13             :                                       struct delayed_call *done)
      14             : {
      15         810 :         struct pid_namespace *ns = proc_pid_ns(inode->i_sb);
      16         810 :         pid_t tgid = task_tgid_nr_ns(current, ns);
      17         813 :         char *name;
      18             : 
      19         813 :         if (!tgid)
      20         814 :                 return ERR_PTR(-ENOENT);
      21             :         /* max length of unsigned int in decimal + NULL term */
      22         813 :         name = kmalloc(10 + 1, dentry ? GFP_KERNEL : GFP_ATOMIC);
      23         814 :         if (unlikely(!name))
      24           0 :                 return dentry ? ERR_PTR(-ENOMEM) : ERR_PTR(-ECHILD);
      25         814 :         sprintf(name, "%u", tgid);
      26         814 :         set_delayed_call(done, kfree_link, name);
      27         814 :         return name;
      28             : }
      29             : 
      30             : static const struct inode_operations proc_self_inode_operations = {
      31             :         .get_link       = proc_self_get_link,
      32             : };
      33             : 
      34             : static unsigned self_inum __ro_after_init;
      35             : 
      36           2 : int proc_setup_self(struct super_block *s)
      37             : {
      38           2 :         struct inode *root_inode = d_inode(s->s_root);
      39           2 :         struct proc_fs_info *fs_info = proc_sb_info(s);
      40           2 :         struct dentry *self;
      41           2 :         int ret = -ENOMEM;
      42             : 
      43           2 :         inode_lock(root_inode);
      44           2 :         self = d_alloc_name(s->s_root, "self");
      45           2 :         if (self) {
      46           2 :                 struct inode *inode = new_inode(s);
      47           2 :                 if (inode) {
      48           2 :                         inode->i_ino = self_inum;
      49           2 :                         inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
      50           2 :                         inode->i_mode = S_IFLNK | S_IRWXUGO;
      51           2 :                         inode->i_uid = GLOBAL_ROOT_UID;
      52           2 :                         inode->i_gid = GLOBAL_ROOT_GID;
      53           2 :                         inode->i_op = &proc_self_inode_operations;
      54           2 :                         d_add(self, inode);
      55           2 :                         ret = 0;
      56             :                 } else {
      57           0 :                         dput(self);
      58             :                 }
      59             :         }
      60           2 :         inode_unlock(root_inode);
      61             : 
      62           2 :         if (ret)
      63           0 :                 pr_err("proc_fill_super: can't allocate /proc/self\n");
      64             :         else
      65           2 :                 fs_info->proc_self = self;
      66             : 
      67           2 :         return ret;
      68             : }
      69             : 
      70           1 : void __init proc_self_init(void)
      71             : {
      72           1 :         proc_alloc_inum(&self_inum);
      73           1 : }