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_get_link(struct dentry *dentry, 23 struct inode *inode, void **cookie) 24 { 25 struct pid_namespace *ns = inode->i_sb->s_fs_info; 26 pid_t tgid = task_tgid_nr_ns(current, ns); 27 pid_t pid = task_pid_nr_ns(current, ns); 28 char *name; 29 30 if (!dentry) 31 return ERR_PTR(-ECHILD); 32 if (!pid) 33 return ERR_PTR(-ENOENT); 34 name = kmalloc(PROC_NUMBUF + 6 + PROC_NUMBUF, GFP_KERNEL); 35 if (!name) 36 return ERR_PTR(-ENOMEM); 37 sprintf(name, "%d/task/%d", tgid, pid); 38 return *cookie = name; 39 } 40 41 static const struct inode_operations proc_thread_self_inode_operations = { 42 .readlink = proc_thread_self_readlink, 43 .get_link = proc_thread_self_get_link, 44 .put_link = kfree_put_link, 45 }; 46 47 static unsigned thread_self_inum; 48 49 int proc_setup_thread_self(struct super_block *s) 50 { 51 struct inode *root_inode = d_inode(s->s_root); 52 struct pid_namespace *ns = s->s_fs_info; 53 struct dentry *thread_self; 54 55 mutex_lock(&root_inode->i_mutex); 56 thread_self = d_alloc_name(s->s_root, "thread-self"); 57 if (thread_self) { 58 struct inode *inode = new_inode_pseudo(s); 59 if (inode) { 60 inode->i_ino = thread_self_inum; 61 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 62 inode->i_mode = S_IFLNK | S_IRWXUGO; 63 inode->i_uid = GLOBAL_ROOT_UID; 64 inode->i_gid = GLOBAL_ROOT_GID; 65 inode->i_op = &proc_thread_self_inode_operations; 66 d_add(thread_self, inode); 67 } else { 68 dput(thread_self); 69 thread_self = ERR_PTR(-ENOMEM); 70 } 71 } else { 72 thread_self = ERR_PTR(-ENOMEM); 73 } 74 mutex_unlock(&root_inode->i_mutex); 75 if (IS_ERR(thread_self)) { 76 pr_err("proc_fill_super: can't allocate /proc/thread_self\n"); 77 return PTR_ERR(thread_self); 78 } 79 ns->proc_thread_self = thread_self; 80 return 0; 81 } 82 83 void __init proc_thread_self_init(void) 84 { 85 proc_alloc_inum(&thread_self_inum); 86 } 87