| #include <linux/sched.h> |
| #include <linux/slab.h> |
| #include <linux/pid_namespace.h> |
| #include "internal.h" |
| |
| /* |
| * /proc/self: |
| */ |
| static int proc_self_readlink(struct dentry *dentry, char __user *buffer, |
| int buflen) |
| { |
| struct pid_namespace *ns = dentry->d_sb->s_fs_info; |
| pid_t tgid = task_tgid_nr_ns(current, ns); |
| char tmp[PROC_NUMBUF]; |
| if (!tgid) |
| return -ENOENT; |
| sprintf(tmp, "%d", tgid); |
| return readlink_copy(buffer, buflen, tmp); |
| } |
| |
| static const char *proc_self_follow_link(struct dentry *dentry, void **cookie, struct nameidata *nd) |
| { |
| struct pid_namespace *ns = dentry->d_sb->s_fs_info; |
| pid_t tgid = task_tgid_nr_ns(current, ns); |
| char *name; |
| |
| if (!tgid) |
| return ERR_PTR(-ENOENT); |
| /* 11 for max length of signed int in decimal + NULL term */ |
| name = kmalloc(12, GFP_KERNEL); |
| if (!name) |
| return ERR_PTR(-ENOMEM); |
| sprintf(name, "%d", tgid); |
| return *cookie = name; |
| } |
| |
| static const struct inode_operations proc_self_inode_operations = { |
| .readlink = proc_self_readlink, |
| .follow_link = proc_self_follow_link, |
| .put_link = kfree_put_link, |
| }; |
| |
| static unsigned self_inum; |
| |
| int proc_setup_self(struct super_block *s) |
| { |
| struct inode *root_inode = d_inode(s->s_root); |
| struct pid_namespace *ns = s->s_fs_info; |
| struct dentry *self; |
| |
| mutex_lock(&root_inode->i_mutex); |
| self = d_alloc_name(s->s_root, "self"); |
| if (self) { |
| struct inode *inode = new_inode_pseudo(s); |
| if (inode) { |
| inode->i_ino = self_inum; |
| inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; |
| inode->i_mode = S_IFLNK | S_IRWXUGO; |
| inode->i_uid = GLOBAL_ROOT_UID; |
| inode->i_gid = GLOBAL_ROOT_GID; |
| inode->i_op = &proc_self_inode_operations; |
| d_add(self, inode); |
| } else { |
| dput(self); |
| self = ERR_PTR(-ENOMEM); |
| } |
| } else { |
| self = ERR_PTR(-ENOMEM); |
| } |
| mutex_unlock(&root_inode->i_mutex); |
| if (IS_ERR(self)) { |
| pr_err("proc_fill_super: can't allocate /proc/self\n"); |
| return PTR_ERR(self); |
| } |
| ns->proc_self = self; |
| return 0; |
| } |
| |
| void __init proc_self_init(void) |
| { |
| proc_alloc_inum(&self_inum); |
| } |