1b2441318SGreg Kroah-Hartman // SPDX-License-Identifier: GPL-2.0 2efb1a57dSAlexey Dobriyan #include <linux/cache.h> 3e656d8a6SEric W. Biederman #include <linux/sched.h> 40d01ff25SDavid Howells #include <linux/slab.h> 5021ada7dSAl Viro #include <linux/pid_namespace.h> 6021ada7dSAl Viro #include "internal.h" 7e656d8a6SEric W. Biederman 8e656d8a6SEric W. Biederman /* 9e656d8a6SEric W. Biederman * /proc/self: 10e656d8a6SEric W. Biederman */ 116b255391SAl Viro static const char *proc_self_get_link(struct dentry *dentry, 12fceef393SAl Viro struct inode *inode, 13fceef393SAl Viro struct delayed_call *done) 14e656d8a6SEric W. Biederman { 159d78edeaSAlexey Gladkov struct pid_namespace *ns = proc_pid_ns(inode->i_sb); 16e656d8a6SEric W. Biederman pid_t tgid = task_tgid_nr_ns(current, ns); 17680baacbSAl Viro char *name; 18680baacbSAl Viro 19680baacbSAl Viro if (!tgid) 20680baacbSAl Viro return ERR_PTR(-ENOENT); 21e3912ac3SAlexey Dobriyan /* max length of unsigned int in decimal + NULL term */ 22e3912ac3SAlexey Dobriyan name = kmalloc(10 + 1, dentry ? GFP_KERNEL : GFP_ATOMIC); 231a384eaaSAl Viro if (unlikely(!name)) 241a384eaaSAl Viro return dentry ? ERR_PTR(-ENOMEM) : ERR_PTR(-ECHILD); 25e3912ac3SAlexey Dobriyan sprintf(name, "%u", tgid); 26fceef393SAl Viro set_delayed_call(done, kfree_link, name); 27fceef393SAl Viro return name; 28e656d8a6SEric W. Biederman } 29e656d8a6SEric W. Biederman 30e656d8a6SEric W. Biederman static const struct inode_operations proc_self_inode_operations = { 316b255391SAl Viro .get_link = proc_self_get_link, 32e656d8a6SEric W. Biederman }; 33e656d8a6SEric W. Biederman 34efb1a57dSAlexey Dobriyan static unsigned self_inum __ro_after_init; 35021ada7dSAl Viro 36021ada7dSAl Viro int proc_setup_self(struct super_block *s) 37021ada7dSAl Viro { 382b0143b5SDavid Howells struct inode *root_inode = d_inode(s->s_root); 39fa10fed3SAlexey Gladkov struct proc_fs_info *fs_info = proc_sb_info(s); 40021ada7dSAl Viro struct dentry *self; 41756ca74cSChengguang Xu int ret = -ENOMEM; 42021ada7dSAl Viro 435955102cSAl Viro inode_lock(root_inode); 44021ada7dSAl Viro self = d_alloc_name(s->s_root, "self"); 45021ada7dSAl Viro if (self) { 46021ada7dSAl Viro struct inode *inode = new_inode_pseudo(s); 47021ada7dSAl Viro if (inode) { 48021ada7dSAl Viro inode->i_ino = self_inum; 49078cd827SDeepa Dinamani inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); 50021ada7dSAl Viro inode->i_mode = S_IFLNK | S_IRWXUGO; 51021ada7dSAl Viro inode->i_uid = GLOBAL_ROOT_UID; 52021ada7dSAl Viro inode->i_gid = GLOBAL_ROOT_GID; 53021ada7dSAl Viro inode->i_op = &proc_self_inode_operations; 54021ada7dSAl Viro d_add(self, inode); 55756ca74cSChengguang Xu ret = 0; 56021ada7dSAl Viro } else { 57021ada7dSAl Viro dput(self); 58021ada7dSAl Viro } 59021ada7dSAl Viro } 605955102cSAl Viro inode_unlock(root_inode); 61756ca74cSChengguang Xu 62756ca74cSChengguang Xu if (ret) 63021ada7dSAl Viro pr_err("proc_fill_super: can't allocate /proc/self\n"); 64756ca74cSChengguang Xu else 65fa10fed3SAlexey Gladkov fs_info->proc_self = self; 66756ca74cSChengguang Xu 67756ca74cSChengguang Xu return ret; 68021ada7dSAl Viro } 69021ada7dSAl Viro 70e656d8a6SEric W. Biederman void __init proc_self_init(void) 71e656d8a6SEric W. Biederman { 72021ada7dSAl Viro proc_alloc_inum(&self_inum); 73e656d8a6SEric W. Biederman } 74