1e656d8a6SEric W. Biederman #include <linux/sched.h> 20d01ff25SDavid Howells #include <linux/slab.h> 3021ada7dSAl Viro #include <linux/pid_namespace.h> 4021ada7dSAl Viro #include "internal.h" 5e656d8a6SEric W. Biederman 6e656d8a6SEric W. Biederman /* 7e656d8a6SEric W. Biederman * /proc/self: 8e656d8a6SEric W. Biederman */ 9e656d8a6SEric W. Biederman static int proc_self_readlink(struct dentry *dentry, char __user *buffer, 10e656d8a6SEric W. Biederman int buflen) 11e656d8a6SEric W. Biederman { 12e656d8a6SEric W. Biederman struct pid_namespace *ns = dentry->d_sb->s_fs_info; 13e656d8a6SEric W. Biederman pid_t tgid = task_tgid_nr_ns(current, ns); 14e656d8a6SEric W. Biederman char tmp[PROC_NUMBUF]; 15e656d8a6SEric W. Biederman if (!tgid) 16e656d8a6SEric W. Biederman return -ENOENT; 17e656d8a6SEric W. Biederman sprintf(tmp, "%d", tgid); 185d826c84SAl Viro return readlink_copy(buffer, buflen, tmp); 19e656d8a6SEric W. Biederman } 20e656d8a6SEric W. Biederman 216b255391SAl Viro static const char *proc_self_get_link(struct dentry *dentry, 22fceef393SAl Viro struct inode *inode, 23fceef393SAl Viro struct delayed_call *done) 24e656d8a6SEric W. Biederman { 256b255391SAl Viro struct pid_namespace *ns = inode->i_sb->s_fs_info; 26e656d8a6SEric W. Biederman pid_t tgid = task_tgid_nr_ns(current, ns); 27680baacbSAl Viro char *name; 28680baacbSAl Viro 29680baacbSAl Viro if (!tgid) 30680baacbSAl Viro return ERR_PTR(-ENOENT); 31e656d8a6SEric W. Biederman /* 11 for max length of signed int in decimal + NULL term */ 321a384eaaSAl Viro name = kmalloc(12, dentry ? GFP_KERNEL : GFP_ATOMIC); 331a384eaaSAl Viro if (unlikely(!name)) 341a384eaaSAl Viro return dentry ? ERR_PTR(-ENOMEM) : ERR_PTR(-ECHILD); 35e656d8a6SEric W. Biederman sprintf(name, "%d", tgid); 36fceef393SAl Viro set_delayed_call(done, kfree_link, name); 37fceef393SAl Viro return name; 38e656d8a6SEric W. Biederman } 39e656d8a6SEric W. Biederman 40e656d8a6SEric W. Biederman static const struct inode_operations proc_self_inode_operations = { 41e656d8a6SEric W. Biederman .readlink = proc_self_readlink, 426b255391SAl Viro .get_link = proc_self_get_link, 43e656d8a6SEric W. Biederman }; 44e656d8a6SEric W. Biederman 45021ada7dSAl Viro static unsigned self_inum; 46021ada7dSAl Viro 47021ada7dSAl Viro int proc_setup_self(struct super_block *s) 48021ada7dSAl Viro { 492b0143b5SDavid Howells struct inode *root_inode = d_inode(s->s_root); 50021ada7dSAl Viro struct pid_namespace *ns = s->s_fs_info; 51021ada7dSAl Viro struct dentry *self; 52021ada7dSAl Viro 535955102cSAl Viro inode_lock(root_inode); 54021ada7dSAl Viro self = d_alloc_name(s->s_root, "self"); 55021ada7dSAl Viro if (self) { 56021ada7dSAl Viro struct inode *inode = new_inode_pseudo(s); 57021ada7dSAl Viro if (inode) { 58021ada7dSAl Viro inode->i_ino = self_inum; 59078cd827SDeepa Dinamani inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); 60021ada7dSAl Viro inode->i_mode = S_IFLNK | S_IRWXUGO; 61021ada7dSAl Viro inode->i_uid = GLOBAL_ROOT_UID; 62021ada7dSAl Viro inode->i_gid = GLOBAL_ROOT_GID; 63021ada7dSAl Viro inode->i_op = &proc_self_inode_operations; 64021ada7dSAl Viro d_add(self, inode); 65021ada7dSAl Viro } else { 66021ada7dSAl Viro dput(self); 67021ada7dSAl Viro self = ERR_PTR(-ENOMEM); 68021ada7dSAl Viro } 69021ada7dSAl Viro } else { 70021ada7dSAl Viro self = ERR_PTR(-ENOMEM); 71021ada7dSAl Viro } 725955102cSAl Viro inode_unlock(root_inode); 73021ada7dSAl Viro if (IS_ERR(self)) { 74021ada7dSAl Viro pr_err("proc_fill_super: can't allocate /proc/self\n"); 75021ada7dSAl Viro return PTR_ERR(self); 76021ada7dSAl Viro } 77021ada7dSAl Viro ns->proc_self = self; 78021ada7dSAl Viro return 0; 79021ada7dSAl Viro } 80021ada7dSAl Viro 81e656d8a6SEric W. Biederman void __init proc_self_init(void) 82e656d8a6SEric W. Biederman { 83021ada7dSAl Viro proc_alloc_inum(&self_inum); 84e656d8a6SEric W. Biederman } 85