1 #include <linux/sched.h> 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 22 static const char *proc_thread_self_follow_link(struct dentry *dentry, void **cookie) 23 { 24 struct pid_namespace *ns = dentry->d_sb->s_fs_info; 25 pid_t tgid = task_tgid_nr_ns(current, ns); 26 pid_t pid = task_pid_nr_ns(current, ns); 27 char *name; 28 29 if (!pid) 30 return ERR_PTR(-ENOENT); 31 name = kmalloc(PROC_NUMBUF + 6 + PROC_NUMBUF, GFP_KERNEL); 32 if (!name) 33 return ERR_PTR(-ENOMEM); 34 sprintf(name, "%d/task/%d", tgid, pid); 35 return *cookie = name; 36 } 37 38 static const struct inode_operations proc_thread_self_inode_operations = { 39 .readlink = proc_thread_self_readlink, 40 .follow_link = proc_thread_self_follow_link, 41 .put_link = kfree_put_link, 42 }; 43 44 static unsigned thread_self_inum; 45 46 int proc_setup_thread_self(struct super_block *s) 47 { 48 struct inode *root_inode = d_inode(s->s_root); 49 struct pid_namespace *ns = s->s_fs_info; 50 struct dentry *thread_self; 51 52 mutex_lock(&root_inode->i_mutex); 53 thread_self = d_alloc_name(s->s_root, "thread-self"); 54 if (thread_self) { 55 struct inode *inode = new_inode_pseudo(s); 56 if (inode) { 57 inode->i_ino = thread_self_inum; 58 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 59 inode->i_mode = S_IFLNK | S_IRWXUGO; 60 inode->i_uid = GLOBAL_ROOT_UID; 61 inode->i_gid = GLOBAL_ROOT_GID; 62 inode->i_op = &proc_thread_self_inode_operations; 63 d_add(thread_self, inode); 64 } else { 65 dput(thread_self); 66 thread_self = ERR_PTR(-ENOMEM); 67 } 68 } else { 69 thread_self = ERR_PTR(-ENOMEM); 70 } 71 mutex_unlock(&root_inode->i_mutex); 72 if (IS_ERR(thread_self)) { 73 pr_err("proc_fill_super: can't allocate /proc/thread_self\n"); 74 return PTR_ERR(thread_self); 75 } 76 ns->proc_thread_self = thread_self; 77 return 0; 78 } 79 80 void __init proc_thread_self_init(void) 81 { 82 proc_alloc_inum(&thread_self_inum); 83 } 84