Eric W. Biederman | 0097875 | 2014-07-31 03:10:50 -0700 | [diff] [blame] | 1 | #include <linux/sched.h> |
Eric W. Biederman | 0097875 | 2014-07-31 03:10:50 -0700 | [diff] [blame] | 2 | #include <linux/slab.h> |
| 3 | #include <linux/pid_namespace.h> |
| 4 | #include "internal.h" |
| 5 | |
| 6 | /* |
| 7 | * /proc/thread_self: |
| 8 | */ |
| 9 | static int proc_thread_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 | pid_t pid = task_pid_nr_ns(current, ns); |
| 15 | char tmp[PROC_NUMBUF + 6 + PROC_NUMBUF]; |
| 16 | if (!pid) |
| 17 | return -ENOENT; |
| 18 | sprintf(tmp, "%d/task/%d", tgid, pid); |
| 19 | return readlink_copy(buffer, buflen, tmp); |
| 20 | } |
| 21 | |
Al Viro | 6b25539 | 2015-11-17 10:20:54 -0500 | [diff] [blame] | 22 | static const char *proc_thread_self_get_link(struct dentry *dentry, |
| 23 | struct inode *inode, void **cookie) |
Eric W. Biederman | 0097875 | 2014-07-31 03:10:50 -0700 | [diff] [blame] | 24 | { |
Al Viro | 6b25539 | 2015-11-17 10:20:54 -0500 | [diff] [blame] | 25 | struct pid_namespace *ns = inode->i_sb->s_fs_info; |
Eric W. Biederman | 0097875 | 2014-07-31 03:10:50 -0700 | [diff] [blame] | 26 | pid_t tgid = task_tgid_nr_ns(current, ns); |
| 27 | pid_t pid = task_pid_nr_ns(current, ns); |
Al Viro | 680baac | 2015-05-02 13:32:22 -0400 | [diff] [blame] | 28 | char *name; |
| 29 | |
| 30 | if (!pid) |
| 31 | return ERR_PTR(-ENOENT); |
Al Viro | 1a384ea | 2015-11-17 10:58:42 -0500 | [diff] [blame] | 32 | name = kmalloc(PROC_NUMBUF + 6 + PROC_NUMBUF, |
| 33 | dentry ? GFP_KERNEL : GFP_ATOMIC); |
| 34 | if (unlikely(!name)) |
| 35 | return dentry ? ERR_PTR(-ENOMEM) : ERR_PTR(-ECHILD); |
Al Viro | 680baac | 2015-05-02 13:32:22 -0400 | [diff] [blame] | 36 | sprintf(name, "%d/task/%d", tgid, pid); |
| 37 | return *cookie = name; |
Eric W. Biederman | 0097875 | 2014-07-31 03:10:50 -0700 | [diff] [blame] | 38 | } |
| 39 | |
| 40 | static const struct inode_operations proc_thread_self_inode_operations = { |
| 41 | .readlink = proc_thread_self_readlink, |
Al Viro | 6b25539 | 2015-11-17 10:20:54 -0500 | [diff] [blame] | 42 | .get_link = proc_thread_self_get_link, |
Eric W. Biederman | 0097875 | 2014-07-31 03:10:50 -0700 | [diff] [blame] | 43 | .put_link = kfree_put_link, |
| 44 | }; |
| 45 | |
| 46 | static unsigned thread_self_inum; |
| 47 | |
| 48 | int proc_setup_thread_self(struct super_block *s) |
| 49 | { |
David Howells | 2b0143b | 2015-03-17 22:25:59 +0000 | [diff] [blame] | 50 | struct inode *root_inode = d_inode(s->s_root); |
Eric W. Biederman | 0097875 | 2014-07-31 03:10:50 -0700 | [diff] [blame] | 51 | struct pid_namespace *ns = s->s_fs_info; |
| 52 | struct dentry *thread_self; |
| 53 | |
| 54 | mutex_lock(&root_inode->i_mutex); |
| 55 | thread_self = d_alloc_name(s->s_root, "thread-self"); |
| 56 | if (thread_self) { |
| 57 | struct inode *inode = new_inode_pseudo(s); |
| 58 | if (inode) { |
| 59 | inode->i_ino = thread_self_inum; |
| 60 | inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; |
| 61 | inode->i_mode = S_IFLNK | S_IRWXUGO; |
| 62 | inode->i_uid = GLOBAL_ROOT_UID; |
| 63 | inode->i_gid = GLOBAL_ROOT_GID; |
| 64 | inode->i_op = &proc_thread_self_inode_operations; |
| 65 | d_add(thread_self, inode); |
| 66 | } else { |
| 67 | dput(thread_self); |
| 68 | thread_self = ERR_PTR(-ENOMEM); |
| 69 | } |
| 70 | } else { |
| 71 | thread_self = ERR_PTR(-ENOMEM); |
| 72 | } |
| 73 | mutex_unlock(&root_inode->i_mutex); |
| 74 | if (IS_ERR(thread_self)) { |
| 75 | pr_err("proc_fill_super: can't allocate /proc/thread_self\n"); |
| 76 | return PTR_ERR(thread_self); |
| 77 | } |
| 78 | ns->proc_thread_self = thread_self; |
| 79 | return 0; |
| 80 | } |
| 81 | |
| 82 | void __init proc_thread_self_init(void) |
| 83 | { |
| 84 | proc_alloc_inum(&thread_self_inum); |
| 85 | } |