1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/cache.h> 3 #include <linux/sched.h> 4 #include <linux/slab.h> 5 #include <linux/pid_namespace.h> 6 #include "internal.h" 7 8 /* 9 * /proc/thread_self: 10 */ 11 static const char *proc_thread_self_get_link(struct dentry *dentry, 12 struct inode *inode, 13 struct delayed_call *done) 14 { 15 struct pid_namespace *ns = proc_pid_ns(inode->i_sb); 16 pid_t tgid = task_tgid_nr_ns(current, ns); 17 pid_t pid = task_pid_nr_ns(current, ns); 18 char *name; 19 20 if (!pid) 21 return ERR_PTR(-ENOENT); 22 name = kmalloc(10 + 6 + 10 + 1, dentry ? GFP_KERNEL : GFP_ATOMIC); 23 if (unlikely(!name)) 24 return dentry ? ERR_PTR(-ENOMEM) : ERR_PTR(-ECHILD); 25 sprintf(name, "%u/task/%u", tgid, pid); 26 set_delayed_call(done, kfree_link, name); 27 return name; 28 } 29 30 static const struct inode_operations proc_thread_self_inode_operations = { 31 .get_link = proc_thread_self_get_link, 32 }; 33 34 unsigned thread_self_inum __ro_after_init; 35 36 int proc_setup_thread_self(struct super_block *s) 37 { 38 struct dentry *thread_self; 39 int ret = -ENOMEM; 40 41 thread_self = d_alloc_name(s->s_root, "thread-self"); 42 if (thread_self) { 43 struct inode *inode = new_inode(s); 44 if (inode) { 45 inode->i_ino = thread_self_inum; 46 simple_inode_init_ts(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_thread_self_inode_operations; 51 d_make_persistent(thread_self, inode); 52 ret = 0; 53 } 54 dput(thread_self); 55 } 56 57 if (ret) 58 pr_err("proc_fill_super: can't allocate /proc/thread-self\n"); 59 return ret; 60 } 61 62 void __init proc_thread_self_init(void) 63 { 64 proc_alloc_inum(&thread_self_inum); 65 } 66