blob: b6a8d3529fea9714fb25d063e9505b198201e7ab [file] [log] [blame]
Eric W. Biedermane656d8a2010-07-10 14:52:49 -07001#include <linux/sched.h>
David Howells0d01ff22013-04-11 23:51:01 +01002#include <linux/slab.h>
Al Viro021ada72013-03-29 19:27:05 -04003#include <linux/pid_namespace.h>
4#include "internal.h"
Eric W. Biedermane656d8a2010-07-10 14:52:49 -07005
6/*
7 * /proc/self:
8 */
9static int proc_self_readlink(struct dentry *dentry, char __user *buffer,
10 int buflen)
11{
12 struct pid_namespace *ns = dentry->d_sb->s_fs_info;
13 pid_t tgid = task_tgid_nr_ns(current, ns);
14 char tmp[PROC_NUMBUF];
15 if (!tgid)
16 return -ENOENT;
17 sprintf(tmp, "%d", tgid);
Al Viro5d826c82014-03-14 13:42:45 -040018 return readlink_copy(buffer, buflen, tmp);
Eric W. Biedermane656d8a2010-07-10 14:52:49 -070019}
20
Al Viro6b255392015-11-17 10:20:54 -050021static const char *proc_self_get_link(struct dentry *dentry,
Al Virofceef392015-12-29 15:58:39 -050022 struct inode *inode,
23 struct delayed_call *done)
Eric W. Biedermane656d8a2010-07-10 14:52:49 -070024{
Al Viro6b255392015-11-17 10:20:54 -050025 struct pid_namespace *ns = inode->i_sb->s_fs_info;
Eric W. Biedermane656d8a2010-07-10 14:52:49 -070026 pid_t tgid = task_tgid_nr_ns(current, ns);
Al Viro680baac2015-05-02 13:32:22 -040027 char *name;
28
29 if (!tgid)
30 return ERR_PTR(-ENOENT);
31 /* 11 for max length of signed int in decimal + NULL term */
Al Viro1a384ea2015-11-17 10:58:42 -050032 name = kmalloc(12, dentry ? GFP_KERNEL : GFP_ATOMIC);
33 if (unlikely(!name))
34 return dentry ? ERR_PTR(-ENOMEM) : ERR_PTR(-ECHILD);
Al Viro680baac2015-05-02 13:32:22 -040035 sprintf(name, "%d", tgid);
Al Virofceef392015-12-29 15:58:39 -050036 set_delayed_call(done, kfree_link, name);
37 return name;
Eric W. Biedermane656d8a2010-07-10 14:52:49 -070038}
39
Eric W. Biedermane656d8a2010-07-10 14:52:49 -070040static const struct inode_operations proc_self_inode_operations = {
41 .readlink = proc_self_readlink,
Al Viro6b255392015-11-17 10:20:54 -050042 .get_link = proc_self_get_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
Al Viro59551022016-01-22 15:40:57 -050053 inode_lock(root_inode);
Al Viro021ada72013-03-29 19:27:05 -040054 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 }
Al Viro59551022016-01-22 15:40:57 -050072 inode_unlock(root_inode);
Al Viro021ada72013-03-29 19:27:05 -040073 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}