blob: 947b0f4fd0a194057334762bafeff3548c276568 [file] [log] [blame]
Eric W. Biederman00978752014-07-31 03:10:50 -07001#include <linux/sched.h>
Eric W. Biederman00978752014-07-31 03:10:50 -07002#include <linux/slab.h>
3#include <linux/pid_namespace.h>
4#include "internal.h"
5
6/*
7 * /proc/thread_self:
8 */
9static int proc_thread_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 pid_t pid = task_pid_nr_ns(current, ns);
15 char tmp[PROC_NUMBUF + 6 + PROC_NUMBUF];
16 if (!pid)
17 return -ENOENT;
18 sprintf(tmp, "%d/task/%d", tgid, pid);
19 return readlink_copy(buffer, buflen, tmp);
20}
21
Al Viro6e771372015-05-02 13:37:52 -040022static const char *proc_thread_self_follow_link(struct dentry *dentry, void **cookie)
Eric W. Biederman00978752014-07-31 03:10:50 -070023{
24 struct pid_namespace *ns = dentry->d_sb->s_fs_info;
25 pid_t tgid = task_tgid_nr_ns(current, ns);
26 pid_t pid = task_pid_nr_ns(current, ns);
Al Viro680baac2015-05-02 13:32:22 -040027 char *name;
28
29 if (!pid)
30 return ERR_PTR(-ENOENT);
31 name = kmalloc(PROC_NUMBUF + 6 + PROC_NUMBUF, GFP_KERNEL);
32 if (!name)
33 return ERR_PTR(-ENOMEM);
34 sprintf(name, "%d/task/%d", tgid, pid);
35 return *cookie = name;
Eric W. Biederman00978752014-07-31 03:10:50 -070036}
37
38static const struct inode_operations proc_thread_self_inode_operations = {
39 .readlink = proc_thread_self_readlink,
40 .follow_link = proc_thread_self_follow_link,
41 .put_link = kfree_put_link,
42};
43
44static unsigned thread_self_inum;
45
46int proc_setup_thread_self(struct super_block *s)
47{
David Howells2b0143b2015-03-17 22:25:59 +000048 struct inode *root_inode = d_inode(s->s_root);
Eric W. Biederman00978752014-07-31 03:10:50 -070049 struct pid_namespace *ns = s->s_fs_info;
50 struct dentry *thread_self;
51
52 mutex_lock(&root_inode->i_mutex);
53 thread_self = d_alloc_name(s->s_root, "thread-self");
54 if (thread_self) {
55 struct inode *inode = new_inode_pseudo(s);
56 if (inode) {
57 inode->i_ino = thread_self_inum;
58 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
59 inode->i_mode = S_IFLNK | S_IRWXUGO;
60 inode->i_uid = GLOBAL_ROOT_UID;
61 inode->i_gid = GLOBAL_ROOT_GID;
62 inode->i_op = &proc_thread_self_inode_operations;
63 d_add(thread_self, inode);
64 } else {
65 dput(thread_self);
66 thread_self = ERR_PTR(-ENOMEM);
67 }
68 } else {
69 thread_self = ERR_PTR(-ENOMEM);
70 }
71 mutex_unlock(&root_inode->i_mutex);
72 if (IS_ERR(thread_self)) {
73 pr_err("proc_fill_super: can't allocate /proc/thread_self\n");
74 return PTR_ERR(thread_self);
75 }
76 ns->proc_thread_self = thread_self;
77 return 0;
78}
79
80void __init proc_thread_self_init(void)
81{
82 proc_alloc_inum(&thread_self_inum);
83}