blob: 6195b4a7c3b17f8c7feb09542e7e435b2cd59356 [file] [log] [blame]
Eric W. Biedermane656d8a2010-07-10 14:52:49 -07001#include <linux/sched.h>
2#include <linux/namei.h>
David Howells0d01ff22013-04-11 23:51:01 +01003#include <linux/slab.h>
Al Viro021ada72013-03-29 19:27:05 -04004#include <linux/pid_namespace.h>
5#include "internal.h"
Eric W. Biedermane656d8a2010-07-10 14:52:49 -07006
7/*
8 * /proc/self:
9 */
10static int proc_self_readlink(struct dentry *dentry, char __user *buffer,
11 int buflen)
12{
13 struct pid_namespace *ns = dentry->d_sb->s_fs_info;
14 pid_t tgid = task_tgid_nr_ns(current, ns);
15 char tmp[PROC_NUMBUF];
16 if (!tgid)
17 return -ENOENT;
18 sprintf(tmp, "%d", tgid);
Al Viro5d826c82014-03-14 13:42:45 -040019 return readlink_copy(buffer, buflen, tmp);
Eric W. Biedermane656d8a2010-07-10 14:52:49 -070020}
21
22static void *proc_self_follow_link(struct dentry *dentry, struct nameidata *nd)
23{
24 struct pid_namespace *ns = dentry->d_sb->s_fs_info;
25 pid_t tgid = task_tgid_nr_ns(current, ns);
26 char *name = ERR_PTR(-ENOENT);
27 if (tgid) {
28 /* 11 for max length of signed int in decimal + NULL term */
29 name = kmalloc(12, GFP_KERNEL);
30 if (!name)
31 name = ERR_PTR(-ENOMEM);
32 else
33 sprintf(name, "%d", tgid);
34 }
35 nd_set_link(nd, name);
36 return NULL;
37}
38
Eric W. Biedermane656d8a2010-07-10 14:52:49 -070039static const struct inode_operations proc_self_inode_operations = {
40 .readlink = proc_self_readlink,
41 .follow_link = proc_self_follow_link,
Al Viro87dc8002013-09-16 10:30:04 -040042 .put_link = kfree_put_link,
Eric W. Biedermane656d8a2010-07-10 14:52:49 -070043};
44
Al Viro021ada72013-03-29 19:27:05 -040045static unsigned self_inum;
46
47int proc_setup_self(struct super_block *s)
48{
David Howells2b0143b2015-03-17 22:25:59 +000049 struct inode *root_inode = d_inode(s->s_root);
Al Viro021ada72013-03-29 19:27:05 -040050 struct pid_namespace *ns = s->s_fs_info;
51 struct dentry *self;
52
53 mutex_lock(&root_inode->i_mutex);
54 self = d_alloc_name(s->s_root, "self");
55 if (self) {
56 struct inode *inode = new_inode_pseudo(s);
57 if (inode) {
58 inode->i_ino = self_inum;
59 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
60 inode->i_mode = S_IFLNK | S_IRWXUGO;
61 inode->i_uid = GLOBAL_ROOT_UID;
62 inode->i_gid = GLOBAL_ROOT_GID;
63 inode->i_op = &proc_self_inode_operations;
64 d_add(self, inode);
65 } else {
66 dput(self);
67 self = ERR_PTR(-ENOMEM);
68 }
69 } else {
70 self = ERR_PTR(-ENOMEM);
71 }
72 mutex_unlock(&root_inode->i_mutex);
73 if (IS_ERR(self)) {
74 pr_err("proc_fill_super: can't allocate /proc/self\n");
75 return PTR_ERR(self);
76 }
77 ns->proc_self = self;
78 return 0;
79}
80
Eric W. Biedermane656d8a2010-07-10 14:52:49 -070081void __init proc_self_init(void)
82{
Al Viro021ada72013-03-29 19:27:05 -040083 proc_alloc_inum(&self_inum);
Eric W. Biedermane656d8a2010-07-10 14:52:49 -070084}