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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 | */ | |
9 | static const char *proc_self_get_link(struct dentry *dentry, | |
10 | struct inode *inode, | |
11 | struct delayed_call *done) | |
12 | { | |
13 | struct pid_namespace *ns = inode->i_sb->s_fs_info; | |
14 | pid_t tgid = task_tgid_nr_ns(current, ns); | |
15 | char *name; | |
16 | ||
17 | if (!tgid) | |
18 | return ERR_PTR(-ENOENT); | |
19 | /* 11 for max length of signed int in decimal + NULL term */ | |
20 | name = kmalloc(12, dentry ? GFP_KERNEL : GFP_ATOMIC); | |
21 | if (unlikely(!name)) | |
22 | return dentry ? ERR_PTR(-ENOMEM) : ERR_PTR(-ECHILD); | |
23 | sprintf(name, "%d", tgid); | |
24 | set_delayed_call(done, kfree_link, name); | |
25 | return name; | |
26 | } | |
27 | ||
28 | static const struct inode_operations proc_self_inode_operations = { | |
29 | .get_link = proc_self_get_link, | |
30 | }; | |
31 | ||
32 | static unsigned self_inum; | |
33 | ||
34 | int proc_setup_self(struct super_block *s) | |
35 | { | |
36 | struct inode *root_inode = d_inode(s->s_root); | |
37 | struct pid_namespace *ns = s->s_fs_info; | |
38 | struct dentry *self; | |
39 | ||
40 | inode_lock(root_inode); | |
41 | self = d_alloc_name(s->s_root, "self"); | |
42 | if (self) { | |
43 | struct inode *inode = new_inode_pseudo(s); | |
44 | if (inode) { | |
45 | inode->i_ino = self_inum; | |
46 | inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); | |
47 | inode->i_mode = S_IFLNK | S_IRWXUGO; | |
48 | inode->i_uid = GLOBAL_ROOT_UID; | |
49 | inode->i_gid = GLOBAL_ROOT_GID; | |
50 | inode->i_op = &proc_self_inode_operations; | |
51 | d_add(self, inode); | |
52 | } else { | |
53 | dput(self); | |
54 | self = ERR_PTR(-ENOMEM); | |
55 | } | |
56 | } else { | |
57 | self = ERR_PTR(-ENOMEM); | |
58 | } | |
59 | inode_unlock(root_inode); | |
60 | if (IS_ERR(self)) { | |
61 | pr_err("proc_fill_super: can't allocate /proc/self\n"); | |
62 | return PTR_ERR(self); | |
63 | } | |
64 | ns->proc_self = self; | |
65 | return 0; | |
66 | } | |
67 | ||
68 | void __init proc_self_init(void) | |
69 | { | |
70 | proc_alloc_inum(&self_inum); | |
71 | } |