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![Linus Torvalds](/assets/img/avatar_default.png)
Pull user namespace changes from Eric Biederman: "While small this set of changes is very significant with respect to containers in general and user namespaces in particular. The user space interface is now complete. This set of changes adds support for unprivileged users to create user namespaces and as a user namespace root to create other namespaces. The tyranny of supporting suid root preventing unprivileged users from using cool new kernel features is broken. This set of changes completes the work on setns, adding support for the pid, user, mount namespaces. This set of changes includes a bunch of basic pid namespace cleanups/simplifications. Of particular significance is the rework of the pid namespace cleanup so it no longer requires sending out tendrils into all kinds of unexpected cleanup paths for operation. At least one case of broken error handling is fixed by this cleanup. The files under /proc/<pid>/ns/ have been converted from regular files to magic symlinks which prevents incorrect caching by the VFS, ensuring the files always refer to the namespace the process is currently using and ensuring that the ptrace_mayaccess permission checks are always applied. The files under /proc/<pid>/ns/ have been given stable inode numbers so it is now possible to see if different processes share the same namespaces. Through the David Miller's net tree are changes to relax many of the permission checks in the networking stack to allowing the user namespace root to usefully use the networking stack. Similar changes for the mount namespace and the pid namespace are coming through my tree. Two small changes to add user namespace support were commited here adn in David Miller's -net tree so that I could complete the work on the /proc/<pid>/ns/ files in this tree. Work remains to make it safe to build user namespaces and 9p, afs, ceph, cifs, coda, gfs2, ncpfs, nfs, nfsd, ocfs2, and xfs so the Kconfig guard remains in place preventing that user namespaces from being built when any of those filesystems are enabled. Future design work remains to allow root users outside of the initial user namespace to mount more than just /proc and /sys." * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (38 commits) proc: Usable inode numbers for the namespace file descriptors. proc: Fix the namespace inode permission checks. proc: Generalize proc inode allocation userns: Allow unprivilged mounts of proc and sysfs userns: For /proc/self/{uid,gid}_map derive the lower userns from the struct file procfs: Print task uids and gids in the userns that opened the proc file userns: Implement unshare of the user namespace userns: Implent proc namespace operations userns: Kill task_user_ns userns: Make create_new_namespaces take a user_ns parameter userns: Allow unprivileged use of setns. userns: Allow unprivileged users to create new namespaces userns: Allow setting a userns mapping to your current uid. userns: Allow chown and setgid preservation userns: Allow unprivileged users to create user namespaces. userns: Ignore suid and sgid on binaries if the uid or gid can not be mapped userns: fix return value on mntns_install() failure vfs: Allow unprivileged manipulation of the mount namespace. vfs: Only support slave subtrees across different user namespaces vfs: Add a user namespace reference from struct mnt_namespace ...
376 lines
11 KiB
C
376 lines
11 KiB
C
/* Credentials management - see Documentation/security/credentials.txt
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*
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* Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public Licence
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* as published by the Free Software Foundation; either version
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* 2 of the Licence, or (at your option) any later version.
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*/
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#ifndef _LINUX_CRED_H
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#define _LINUX_CRED_H
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#include <linux/capability.h>
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#include <linux/init.h>
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#include <linux/key.h>
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#include <linux/selinux.h>
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#include <linux/atomic.h>
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#include <linux/uidgid.h>
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struct user_struct;
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struct cred;
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struct inode;
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/*
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* COW Supplementary groups list
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*/
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#define NGROUPS_SMALL 32
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#define NGROUPS_PER_BLOCK ((unsigned int)(PAGE_SIZE / sizeof(kgid_t)))
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struct group_info {
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atomic_t usage;
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int ngroups;
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int nblocks;
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kgid_t small_block[NGROUPS_SMALL];
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kgid_t *blocks[0];
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};
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/**
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* get_group_info - Get a reference to a group info structure
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* @group_info: The group info to reference
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*
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* This gets a reference to a set of supplementary groups.
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*
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* If the caller is accessing a task's credentials, they must hold the RCU read
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* lock when reading.
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*/
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static inline struct group_info *get_group_info(struct group_info *gi)
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{
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atomic_inc(&gi->usage);
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return gi;
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}
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/**
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* put_group_info - Release a reference to a group info structure
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* @group_info: The group info to release
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*/
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#define put_group_info(group_info) \
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do { \
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if (atomic_dec_and_test(&(group_info)->usage)) \
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groups_free(group_info); \
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} while (0)
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extern struct group_info *groups_alloc(int);
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extern struct group_info init_groups;
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extern void groups_free(struct group_info *);
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extern int set_current_groups(struct group_info *);
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extern int set_groups(struct cred *, struct group_info *);
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extern int groups_search(const struct group_info *, kgid_t);
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/* access the groups "array" with this macro */
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#define GROUP_AT(gi, i) \
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((gi)->blocks[(i) / NGROUPS_PER_BLOCK][(i) % NGROUPS_PER_BLOCK])
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extern int in_group_p(kgid_t);
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extern int in_egroup_p(kgid_t);
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/*
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* The security context of a task
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*
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* The parts of the context break down into two categories:
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*
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* (1) The objective context of a task. These parts are used when some other
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* task is attempting to affect this one.
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*
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* (2) The subjective context. These details are used when the task is acting
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* upon another object, be that a file, a task, a key or whatever.
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*
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* Note that some members of this structure belong to both categories - the
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* LSM security pointer for instance.
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*
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* A task has two security pointers. task->real_cred points to the objective
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* context that defines that task's actual details. The objective part of this
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* context is used whenever that task is acted upon.
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*
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* task->cred points to the subjective context that defines the details of how
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* that task is going to act upon another object. This may be overridden
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* temporarily to point to another security context, but normally points to the
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* same context as task->real_cred.
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*/
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struct cred {
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atomic_t usage;
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#ifdef CONFIG_DEBUG_CREDENTIALS
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atomic_t subscribers; /* number of processes subscribed */
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void *put_addr;
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unsigned magic;
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#define CRED_MAGIC 0x43736564
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#define CRED_MAGIC_DEAD 0x44656144
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#endif
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kuid_t uid; /* real UID of the task */
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kgid_t gid; /* real GID of the task */
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kuid_t suid; /* saved UID of the task */
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kgid_t sgid; /* saved GID of the task */
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kuid_t euid; /* effective UID of the task */
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kgid_t egid; /* effective GID of the task */
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kuid_t fsuid; /* UID for VFS ops */
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kgid_t fsgid; /* GID for VFS ops */
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unsigned securebits; /* SUID-less security management */
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kernel_cap_t cap_inheritable; /* caps our children can inherit */
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kernel_cap_t cap_permitted; /* caps we're permitted */
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kernel_cap_t cap_effective; /* caps we can actually use */
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kernel_cap_t cap_bset; /* capability bounding set */
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#ifdef CONFIG_KEYS
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unsigned char jit_keyring; /* default keyring to attach requested
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* keys to */
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struct key __rcu *session_keyring; /* keyring inherited over fork */
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struct key *process_keyring; /* keyring private to this process */
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struct key *thread_keyring; /* keyring private to this thread */
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struct key *request_key_auth; /* assumed request_key authority */
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struct thread_group_cred *tgcred; /* thread-group shared credentials */
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#endif
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#ifdef CONFIG_SECURITY
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void *security; /* subjective LSM security */
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#endif
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struct user_struct *user; /* real user ID subscription */
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struct user_namespace *user_ns; /* user_ns the caps and keyrings are relative to. */
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struct group_info *group_info; /* supplementary groups for euid/fsgid */
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struct rcu_head rcu; /* RCU deletion hook */
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};
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extern void __put_cred(struct cred *);
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extern void exit_creds(struct task_struct *);
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extern int copy_creds(struct task_struct *, unsigned long);
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extern const struct cred *get_task_cred(struct task_struct *);
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extern struct cred *cred_alloc_blank(void);
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extern struct cred *prepare_creds(void);
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extern struct cred *prepare_exec_creds(void);
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extern int commit_creds(struct cred *);
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extern void abort_creds(struct cred *);
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extern const struct cred *override_creds(const struct cred *);
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extern void revert_creds(const struct cred *);
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extern struct cred *prepare_kernel_cred(struct task_struct *);
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extern int change_create_files_as(struct cred *, struct inode *);
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extern int set_security_override(struct cred *, u32);
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extern int set_security_override_from_ctx(struct cred *, const char *);
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extern int set_create_files_as(struct cred *, struct inode *);
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extern void __init cred_init(void);
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/*
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* check for validity of credentials
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*/
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#ifdef CONFIG_DEBUG_CREDENTIALS
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extern void __invalid_creds(const struct cred *, const char *, unsigned);
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extern void __validate_process_creds(struct task_struct *,
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const char *, unsigned);
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extern bool creds_are_invalid(const struct cred *cred);
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static inline void __validate_creds(const struct cred *cred,
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const char *file, unsigned line)
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{
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if (unlikely(creds_are_invalid(cred)))
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__invalid_creds(cred, file, line);
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}
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#define validate_creds(cred) \
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do { \
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__validate_creds((cred), __FILE__, __LINE__); \
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} while(0)
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#define validate_process_creds() \
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do { \
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__validate_process_creds(current, __FILE__, __LINE__); \
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} while(0)
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extern void validate_creds_for_do_exit(struct task_struct *);
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#else
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static inline void validate_creds(const struct cred *cred)
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{
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}
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static inline void validate_creds_for_do_exit(struct task_struct *tsk)
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{
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}
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static inline void validate_process_creds(void)
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{
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}
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#endif
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/**
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* get_new_cred - Get a reference on a new set of credentials
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* @cred: The new credentials to reference
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*
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* Get a reference on the specified set of new credentials. The caller must
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* release the reference.
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*/
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static inline struct cred *get_new_cred(struct cred *cred)
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{
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atomic_inc(&cred->usage);
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return cred;
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}
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/**
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* get_cred - Get a reference on a set of credentials
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* @cred: The credentials to reference
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*
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* Get a reference on the specified set of credentials. The caller must
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* release the reference.
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*
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* This is used to deal with a committed set of credentials. Although the
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* pointer is const, this will temporarily discard the const and increment the
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* usage count. The purpose of this is to attempt to catch at compile time the
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* accidental alteration of a set of credentials that should be considered
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* immutable.
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*/
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static inline const struct cred *get_cred(const struct cred *cred)
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{
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struct cred *nonconst_cred = (struct cred *) cred;
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validate_creds(cred);
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return get_new_cred(nonconst_cred);
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}
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/**
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* put_cred - Release a reference to a set of credentials
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* @cred: The credentials to release
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*
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* Release a reference to a set of credentials, deleting them when the last ref
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* is released.
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*
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* This takes a const pointer to a set of credentials because the credentials
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* on task_struct are attached by const pointers to prevent accidental
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* alteration of otherwise immutable credential sets.
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*/
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static inline void put_cred(const struct cred *_cred)
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{
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struct cred *cred = (struct cred *) _cred;
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validate_creds(cred);
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if (atomic_dec_and_test(&(cred)->usage))
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__put_cred(cred);
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}
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/**
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* current_cred - Access the current task's subjective credentials
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*
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* Access the subjective credentials of the current task. RCU-safe,
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* since nobody else can modify it.
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*/
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#define current_cred() \
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rcu_dereference_protected(current->cred, 1)
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/**
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* __task_cred - Access a task's objective credentials
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* @task: The task to query
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*
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* Access the objective credentials of a task. The caller must hold the RCU
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* readlock.
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*
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* The result of this function should not be passed directly to get_cred();
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* rather get_task_cred() should be used instead.
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*/
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#define __task_cred(task) \
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rcu_dereference((task)->real_cred)
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/**
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* get_current_cred - Get the current task's subjective credentials
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*
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* Get the subjective credentials of the current task, pinning them so that
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* they can't go away. Accessing the current task's credentials directly is
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* not permitted.
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*/
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#define get_current_cred() \
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(get_cred(current_cred()))
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/**
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* get_current_user - Get the current task's user_struct
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*
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* Get the user record of the current task, pinning it so that it can't go
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* away.
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*/
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#define get_current_user() \
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({ \
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struct user_struct *__u; \
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const struct cred *__cred; \
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__cred = current_cred(); \
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__u = get_uid(__cred->user); \
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__u; \
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})
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/**
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* get_current_groups - Get the current task's supplementary group list
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*
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* Get the supplementary group list of the current task, pinning it so that it
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* can't go away.
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*/
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#define get_current_groups() \
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({ \
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struct group_info *__groups; \
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const struct cred *__cred; \
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__cred = current_cred(); \
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__groups = get_group_info(__cred->group_info); \
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__groups; \
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})
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#define task_cred_xxx(task, xxx) \
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({ \
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__typeof__(((struct cred *)NULL)->xxx) ___val; \
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rcu_read_lock(); \
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___val = __task_cred((task))->xxx; \
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rcu_read_unlock(); \
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___val; \
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})
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#define task_uid(task) (task_cred_xxx((task), uid))
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#define task_euid(task) (task_cred_xxx((task), euid))
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#define current_cred_xxx(xxx) \
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({ \
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current_cred()->xxx; \
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})
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#define current_uid() (current_cred_xxx(uid))
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#define current_gid() (current_cred_xxx(gid))
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#define current_euid() (current_cred_xxx(euid))
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#define current_egid() (current_cred_xxx(egid))
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#define current_suid() (current_cred_xxx(suid))
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#define current_sgid() (current_cred_xxx(sgid))
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#define current_fsuid() (current_cred_xxx(fsuid))
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#define current_fsgid() (current_cred_xxx(fsgid))
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#define current_cap() (current_cred_xxx(cap_effective))
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#define current_user() (current_cred_xxx(user))
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#define current_security() (current_cred_xxx(security))
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extern struct user_namespace init_user_ns;
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#ifdef CONFIG_USER_NS
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#define current_user_ns() (current_cred_xxx(user_ns))
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#else
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#define current_user_ns() (&init_user_ns)
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#endif
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#define current_uid_gid(_uid, _gid) \
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do { \
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const struct cred *__cred; \
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__cred = current_cred(); \
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*(_uid) = __cred->uid; \
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*(_gid) = __cred->gid; \
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} while(0)
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#define current_euid_egid(_euid, _egid) \
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do { \
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const struct cred *__cred; \
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__cred = current_cred(); \
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*(_euid) = __cred->euid; \
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*(_egid) = __cred->egid; \
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} while(0)
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#define current_fsuid_fsgid(_fsuid, _fsgid) \
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do { \
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const struct cred *__cred; \
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__cred = current_cred(); \
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*(_fsuid) = __cred->fsuid; \
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*(_fsgid) = __cred->fsgid; \
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} while(0)
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#endif /* _LINUX_CRED_H */
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