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, 226b255391SAl Viro struct inode *inode, void **cookie) 23e656d8a6SEric W. Biederman { 246b255391SAl Viro struct pid_namespace *ns = inode->i_sb->s_fs_info; 25e656d8a6SEric W. Biederman pid_t tgid = task_tgid_nr_ns(current, ns); 26680baacbSAl Viro char *name; 27680baacbSAl Viro 28680baacbSAl Viro if (!tgid) 29680baacbSAl Viro return ERR_PTR(-ENOENT); 30e656d8a6SEric W. Biederman /* 11 for max length of signed int in decimal + NULL term */ 311a384eaaSAl Viro name = kmalloc(12, dentry ? GFP_KERNEL : GFP_ATOMIC); 321a384eaaSAl Viro if (unlikely(!name)) 331a384eaaSAl Viro return dentry ? ERR_PTR(-ENOMEM) : ERR_PTR(-ECHILD); 34e656d8a6SEric W. Biederman sprintf(name, "%d", tgid); 35680baacbSAl Viro return *cookie = name; 36e656d8a6SEric W. Biederman } 37e656d8a6SEric W. Biederman 38e656d8a6SEric W. Biederman static const struct inode_operations proc_self_inode_operations = { 39e656d8a6SEric W. Biederman .readlink = proc_self_readlink, 406b255391SAl Viro .get_link = proc_self_get_link, 4187dc800bSAl Viro .put_link = kfree_put_link, 42e656d8a6SEric W. Biederman }; 43e656d8a6SEric W. Biederman 44021ada7dSAl Viro static unsigned self_inum; 45021ada7dSAl Viro 46021ada7dSAl Viro int proc_setup_self(struct super_block *s) 47021ada7dSAl Viro { 482b0143b5SDavid Howells struct inode *root_inode = d_inode(s->s_root); 49021ada7dSAl Viro struct pid_namespace *ns = s->s_fs_info; 50021ada7dSAl Viro struct dentry *self; 51021ada7dSAl Viro 52021ada7dSAl Viro mutex_lock(&root_inode->i_mutex); 53021ada7dSAl Viro self = d_alloc_name(s->s_root, "self"); 54021ada7dSAl Viro if (self) { 55021ada7dSAl Viro struct inode *inode = new_inode_pseudo(s); 56021ada7dSAl Viro if (inode) { 57021ada7dSAl Viro inode->i_ino = self_inum; 58021ada7dSAl Viro inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 59021ada7dSAl Viro inode->i_mode = S_IFLNK | S_IRWXUGO; 60021ada7dSAl Viro inode->i_uid = GLOBAL_ROOT_UID; 61021ada7dSAl Viro inode->i_gid = GLOBAL_ROOT_GID; 62021ada7dSAl Viro inode->i_op = &proc_self_inode_operations; 63021ada7dSAl Viro d_add(self, inode); 64021ada7dSAl Viro } else { 65021ada7dSAl Viro dput(self); 66021ada7dSAl Viro self = ERR_PTR(-ENOMEM); 67021ada7dSAl Viro } 68021ada7dSAl Viro } else { 69021ada7dSAl Viro self = ERR_PTR(-ENOMEM); 70021ada7dSAl Viro } 71021ada7dSAl Viro mutex_unlock(&root_inode->i_mutex); 72021ada7dSAl Viro if (IS_ERR(self)) { 73021ada7dSAl Viro pr_err("proc_fill_super: can't allocate /proc/self\n"); 74021ada7dSAl Viro return PTR_ERR(self); 75021ada7dSAl Viro } 76021ada7dSAl Viro ns->proc_self = self; 77021ada7dSAl Viro return 0; 78021ada7dSAl Viro } 79021ada7dSAl Viro 80e656d8a6SEric W. Biederman void __init proc_self_init(void) 81e656d8a6SEric W. Biederman { 82021ada7dSAl Viro proc_alloc_inum(&self_inum); 83e656d8a6SEric W. Biederman } 84