1 #include <linux/sched.h>
2 #include <linux/slab.h>
3 #include <linux/pid_namespace.h>
9 static int proc_self_readlink(struct dentry *dentry, char __user *buffer,
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];
17 sprintf(tmp, "%d", tgid);
18 return readlink_copy(buffer, buflen, tmp);
21 static const char *proc_self_follow_link(struct dentry *dentry, void **cookie)
23 struct pid_namespace *ns = dentry->d_sb->s_fs_info;
24 pid_t tgid = task_tgid_nr_ns(current, ns);
28 return ERR_PTR(-ENOENT);
29 /* 11 for max length of signed int in decimal + NULL term */
30 name = kmalloc(12, GFP_KERNEL);
32 return ERR_PTR(-ENOMEM);
33 sprintf(name, "%d", tgid);
34 return *cookie = name;
37 static const struct inode_operations proc_self_inode_operations = {
38 .readlink = proc_self_readlink,
39 .follow_link = proc_self_follow_link,
40 .put_link = kfree_put_link,
43 static unsigned self_inum;
45 int proc_setup_self(struct super_block *s)
47 struct inode *root_inode = d_inode(s->s_root);
48 struct pid_namespace *ns = s->s_fs_info;
51 mutex_lock(&root_inode->i_mutex);
52 self = d_alloc_name(s->s_root, "self");
54 struct inode *inode = new_inode_pseudo(s);
56 inode->i_ino = self_inum;
57 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
58 inode->i_mode = S_IFLNK | S_IRWXUGO;
59 inode->i_uid = GLOBAL_ROOT_UID;
60 inode->i_gid = GLOBAL_ROOT_GID;
61 inode->i_op = &proc_self_inode_operations;
65 self = ERR_PTR(-ENOMEM);
68 self = ERR_PTR(-ENOMEM);
70 mutex_unlock(&root_inode->i_mutex);
72 pr_err("proc_fill_super: can't allocate /proc/self\n");
79 void __init proc_self_init(void)
81 proc_alloc_inum(&self_inum);