Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1#include <linux/sched.h>
2#include <linux/slab.h>
3#include <linux/pid_namespace.h>
4#include "internal.h"
5
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);
18 return readlink_copy(buffer, buflen, tmp);
19}
20
21static const char *proc_self_get_link(struct dentry *dentry,
22 struct inode *inode,
23 struct delayed_call *done)
24{
25 struct pid_namespace *ns = inode->i_sb->s_fs_info;
26 pid_t tgid = task_tgid_nr_ns(current, ns);
27 char *name;
28
29 if (!tgid)
30 return ERR_PTR(-ENOENT);
31 /* 11 for max length of signed int in decimal + NULL term */
32 name = kmalloc(12, dentry ? GFP_KERNEL : GFP_ATOMIC);
33 if (unlikely(!name))
34 return dentry ? ERR_PTR(-ENOMEM) : ERR_PTR(-ECHILD);
35 sprintf(name, "%d", tgid);
36 set_delayed_call(done, kfree_link, name);
37 return name;
38}
39
40static const struct inode_operations proc_self_inode_operations = {
41 .readlink = proc_self_readlink,
42 .get_link = proc_self_get_link,
43};
44
45static unsigned self_inum;
46
47int proc_setup_self(struct super_block *s)
48{
49 struct inode *root_inode = d_inode(s->s_root);
50 struct pid_namespace *ns = s->s_fs_info;
51 struct dentry *self;
52
53 inode_lock(root_inode);
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(inode);
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 inode_unlock(root_inode);
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
81void __init proc_self_init(void)
82{
83 proc_alloc_inum(&self_inum);
84}