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/thread_self: |
10 | */ |
11 | static const char *proc_thread_self_get_link(struct dentry *dentry, |
12 | struct inode *inode, |
13 | struct delayed_call *done) |
14 | { |
15 | struct pid_namespace *ns = proc_pid_ns(sb: inode->i_sb); |
16 | pid_t tgid = task_tgid_nr_ns(current, ns); |
17 | pid_t pid = task_pid_nr_ns(current, ns); |
18 | char *name; |
19 | |
20 | if (!pid) |
21 | return ERR_PTR(error: -ENOENT); |
22 | name = kmalloc(size: 10 + 6 + 10 + 1, flags: dentry ? GFP_KERNEL : GFP_ATOMIC); |
23 | if (unlikely(!name)) |
24 | return dentry ? ERR_PTR(error: -ENOMEM) : ERR_PTR(error: -ECHILD); |
25 | sprintf(buf: name, fmt: "%u/task/%u" , tgid, pid); |
26 | set_delayed_call(call: done, fn: kfree_link, arg: name); |
27 | return name; |
28 | } |
29 | |
30 | static const struct inode_operations proc_thread_self_inode_operations = { |
31 | .get_link = proc_thread_self_get_link, |
32 | }; |
33 | |
34 | static unsigned thread_self_inum __ro_after_init; |
35 | |
36 | int proc_setup_thread_self(struct super_block *s) |
37 | { |
38 | struct inode *root_inode = d_inode(dentry: s->s_root); |
39 | struct proc_fs_info *fs_info = proc_sb_info(sb: s); |
40 | struct dentry *thread_self; |
41 | int ret = -ENOMEM; |
42 | |
43 | inode_lock(inode: root_inode); |
44 | thread_self = d_alloc_name(s->s_root, "thread-self" ); |
45 | if (thread_self) { |
46 | struct inode *inode = new_inode(sb: s); |
47 | if (inode) { |
48 | inode->i_ino = thread_self_inum; |
49 | simple_inode_init_ts(inode); |
50 | inode->i_mode = S_IFLNK | S_IRWXUGO; |
51 | inode->i_uid = GLOBAL_ROOT_UID; |
52 | inode->i_gid = GLOBAL_ROOT_GID; |
53 | inode->i_op = &proc_thread_self_inode_operations; |
54 | d_add(thread_self, inode); |
55 | ret = 0; |
56 | } else { |
57 | dput(thread_self); |
58 | } |
59 | } |
60 | inode_unlock(root_inode); |
61 | |
62 | if (ret) |
63 | pr_err("proc_fill_super: can't allocate /proc/thread-self\n" ); |
64 | else |
65 | fs_info->proc_thread_self = thread_self; |
66 | |
67 | return ret; |
68 | } |
69 | |
70 | void __init proc_thread_self_init(void) |
71 | { |
72 | proc_alloc_inum(pino: &thread_self_inum); |
73 | } |
74 | |