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/namei.h>
3#include <linux/slab.h>
4#include <linux/pid_namespace.h>
5#include "internal.h"
6
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);
19 return vfs_readlink(dentry,buffer,buflen,tmp);
20}
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
39static void proc_self_put_link(struct dentry *dentry, struct nameidata *nd,
40 void *cookie)
41{
42 char *s = nd_get_link(nd);
43 if (!IS_ERR(s))
44 kfree(s);
45}
46
47static const struct inode_operations proc_self_inode_operations = {
48 .readlink = proc_self_readlink,
49 .follow_link = proc_self_follow_link,
50 .put_link = proc_self_put_link,
51};
52
53static unsigned self_inum;
54
55int proc_setup_self(struct super_block *s)
56{
57 struct inode *root_inode = s->s_root->d_inode;
58 struct pid_namespace *ns = s->s_fs_info;
59 struct dentry *self;
60
61 mutex_lock(&root_inode->i_mutex);
62 self = d_alloc_name(s->s_root, "self");
63 if (self) {
64 struct inode *inode = new_inode_pseudo(s);
65 if (inode) {
66 inode->i_ino = self_inum;
67 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
68 inode->i_mode = S_IFLNK | S_IRWXUGO;
69 inode->i_uid = GLOBAL_ROOT_UID;
70 inode->i_gid = GLOBAL_ROOT_GID;
71 inode->i_op = &proc_self_inode_operations;
72 d_add(self, inode);
73 } else {
74 dput(self);
75 self = ERR_PTR(-ENOMEM);
76 }
77 } else {
78 self = ERR_PTR(-ENOMEM);
79 }
80 mutex_unlock(&root_inode->i_mutex);
81 if (IS_ERR(self)) {
82 pr_err("proc_fill_super: can't allocate /proc/self\n");
83 return PTR_ERR(self);
84 }
85 ns->proc_self = self;
86 return 0;
87}
88
89void __init proc_self_init(void)
90{
91 proc_alloc_inum(&self_inum);
92}