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![Linus Torvalds](/assets/img/avatar_default.png)
Pull user namespace rlimit handling update from Eric Biederman: "This is the work mainly by Alexey Gladkov to limit rlimits to the rlimits of the user that created a user namespace, and to allow users to have stricter limits on the resources created within a user namespace." * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: cred: add missing return error code when set_cred_ucounts() failed ucounts: Silence warning in dec_rlimit_ucounts ucounts: Set ucount_max to the largest positive value the type can hold kselftests: Add test to check for rlimit changes in different user namespaces Reimplement RLIMIT_MEMLOCK on top of ucounts Reimplement RLIMIT_SIGPENDING on top of ucounts Reimplement RLIMIT_MSGQUEUE on top of ucounts Reimplement RLIMIT_NPROC on top of ucounts Use atomic_t for ucounts reference counting Add a reference to ucounts for each cred Increase size of ucounts to atomic_long_t
934 lines
24 KiB
C
934 lines
24 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* Task credentials management - see Documentation/security/credentials.rst
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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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#include <linux/export.h>
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#include <linux/cred.h>
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#include <linux/slab.h>
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#include <linux/sched.h>
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#include <linux/sched/coredump.h>
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#include <linux/key.h>
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#include <linux/keyctl.h>
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#include <linux/init_task.h>
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#include <linux/security.h>
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#include <linux/binfmts.h>
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#include <linux/cn_proc.h>
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#include <linux/uidgid.h>
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#if 0
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#define kdebug(FMT, ...) \
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printk("[%-5.5s%5u] " FMT "\n", \
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current->comm, current->pid, ##__VA_ARGS__)
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#else
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#define kdebug(FMT, ...) \
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do { \
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if (0) \
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no_printk("[%-5.5s%5u] " FMT "\n", \
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current->comm, current->pid, ##__VA_ARGS__); \
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} while (0)
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#endif
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static struct kmem_cache *cred_jar;
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/* init to 2 - one for init_task, one to ensure it is never freed */
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static struct group_info init_groups = { .usage = ATOMIC_INIT(2) };
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/*
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* The initial credentials for the initial task
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*/
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struct cred init_cred = {
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.usage = ATOMIC_INIT(4),
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#ifdef CONFIG_DEBUG_CREDENTIALS
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.subscribers = ATOMIC_INIT(2),
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.magic = CRED_MAGIC,
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#endif
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.uid = GLOBAL_ROOT_UID,
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.gid = GLOBAL_ROOT_GID,
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.suid = GLOBAL_ROOT_UID,
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.sgid = GLOBAL_ROOT_GID,
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.euid = GLOBAL_ROOT_UID,
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.egid = GLOBAL_ROOT_GID,
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.fsuid = GLOBAL_ROOT_UID,
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.fsgid = GLOBAL_ROOT_GID,
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.securebits = SECUREBITS_DEFAULT,
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.cap_inheritable = CAP_EMPTY_SET,
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.cap_permitted = CAP_FULL_SET,
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.cap_effective = CAP_FULL_SET,
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.cap_bset = CAP_FULL_SET,
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.user = INIT_USER,
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.user_ns = &init_user_ns,
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.group_info = &init_groups,
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.ucounts = &init_ucounts,
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};
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static inline void set_cred_subscribers(struct cred *cred, int n)
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{
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#ifdef CONFIG_DEBUG_CREDENTIALS
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atomic_set(&cred->subscribers, n);
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#endif
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}
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static inline int read_cred_subscribers(const struct cred *cred)
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{
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#ifdef CONFIG_DEBUG_CREDENTIALS
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return atomic_read(&cred->subscribers);
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#else
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return 0;
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#endif
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}
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static inline void alter_cred_subscribers(const struct cred *_cred, int n)
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{
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#ifdef CONFIG_DEBUG_CREDENTIALS
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struct cred *cred = (struct cred *) _cred;
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atomic_add(n, &cred->subscribers);
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#endif
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}
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/*
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* The RCU callback to actually dispose of a set of credentials
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*/
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static void put_cred_rcu(struct rcu_head *rcu)
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{
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struct cred *cred = container_of(rcu, struct cred, rcu);
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kdebug("put_cred_rcu(%p)", cred);
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#ifdef CONFIG_DEBUG_CREDENTIALS
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if (cred->magic != CRED_MAGIC_DEAD ||
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atomic_read(&cred->usage) != 0 ||
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read_cred_subscribers(cred) != 0)
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panic("CRED: put_cred_rcu() sees %p with"
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" mag %x, put %p, usage %d, subscr %d\n",
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cred, cred->magic, cred->put_addr,
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atomic_read(&cred->usage),
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read_cred_subscribers(cred));
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#else
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if (atomic_read(&cred->usage) != 0)
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panic("CRED: put_cred_rcu() sees %p with usage %d\n",
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cred, atomic_read(&cred->usage));
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#endif
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security_cred_free(cred);
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key_put(cred->session_keyring);
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key_put(cred->process_keyring);
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key_put(cred->thread_keyring);
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key_put(cred->request_key_auth);
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if (cred->group_info)
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put_group_info(cred->group_info);
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free_uid(cred->user);
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if (cred->ucounts)
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put_ucounts(cred->ucounts);
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put_user_ns(cred->user_ns);
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kmem_cache_free(cred_jar, cred);
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}
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/**
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* __put_cred - Destroy a set of credentials
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* @cred: The record to release
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*
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* Destroy a set of credentials on which no references remain.
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*/
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void __put_cred(struct cred *cred)
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{
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kdebug("__put_cred(%p{%d,%d})", cred,
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atomic_read(&cred->usage),
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read_cred_subscribers(cred));
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BUG_ON(atomic_read(&cred->usage) != 0);
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#ifdef CONFIG_DEBUG_CREDENTIALS
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BUG_ON(read_cred_subscribers(cred) != 0);
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cred->magic = CRED_MAGIC_DEAD;
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cred->put_addr = __builtin_return_address(0);
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#endif
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BUG_ON(cred == current->cred);
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BUG_ON(cred == current->real_cred);
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if (cred->non_rcu)
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put_cred_rcu(&cred->rcu);
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else
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call_rcu(&cred->rcu, put_cred_rcu);
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}
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EXPORT_SYMBOL(__put_cred);
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/*
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* Clean up a task's credentials when it exits
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*/
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void exit_creds(struct task_struct *tsk)
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{
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struct cred *cred;
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kdebug("exit_creds(%u,%p,%p,{%d,%d})", tsk->pid, tsk->real_cred, tsk->cred,
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atomic_read(&tsk->cred->usage),
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read_cred_subscribers(tsk->cred));
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cred = (struct cred *) tsk->real_cred;
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tsk->real_cred = NULL;
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validate_creds(cred);
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alter_cred_subscribers(cred, -1);
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put_cred(cred);
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cred = (struct cred *) tsk->cred;
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tsk->cred = NULL;
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validate_creds(cred);
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alter_cred_subscribers(cred, -1);
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put_cred(cred);
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#ifdef CONFIG_KEYS_REQUEST_CACHE
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key_put(tsk->cached_requested_key);
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tsk->cached_requested_key = NULL;
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#endif
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}
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/**
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* get_task_cred - Get another task's objective credentials
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* @task: The task to query
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*
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* Get the objective credentials of a task, pinning them so that they can't go
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* away. Accessing a task's credentials directly is not permitted.
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*
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* The caller must also make sure task doesn't get deleted, either by holding a
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* ref on task or by holding tasklist_lock to prevent it from being unlinked.
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*/
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const struct cred *get_task_cred(struct task_struct *task)
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{
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const struct cred *cred;
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rcu_read_lock();
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do {
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cred = __task_cred((task));
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BUG_ON(!cred);
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} while (!get_cred_rcu(cred));
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rcu_read_unlock();
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return cred;
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}
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EXPORT_SYMBOL(get_task_cred);
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/*
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* Allocate blank credentials, such that the credentials can be filled in at a
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* later date without risk of ENOMEM.
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*/
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struct cred *cred_alloc_blank(void)
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{
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struct cred *new;
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new = kmem_cache_zalloc(cred_jar, GFP_KERNEL);
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if (!new)
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return NULL;
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atomic_set(&new->usage, 1);
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#ifdef CONFIG_DEBUG_CREDENTIALS
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new->magic = CRED_MAGIC;
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#endif
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new->ucounts = get_ucounts(&init_ucounts);
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if (security_cred_alloc_blank(new, GFP_KERNEL_ACCOUNT) < 0)
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goto error;
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return new;
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error:
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abort_creds(new);
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return NULL;
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}
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/**
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* prepare_creds - Prepare a new set of credentials for modification
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*
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* Prepare a new set of task credentials for modification. A task's creds
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* shouldn't generally be modified directly, therefore this function is used to
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* prepare a new copy, which the caller then modifies and then commits by
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* calling commit_creds().
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*
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* Preparation involves making a copy of the objective creds for modification.
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*
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* Returns a pointer to the new creds-to-be if successful, NULL otherwise.
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*
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* Call commit_creds() or abort_creds() to clean up.
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*/
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struct cred *prepare_creds(void)
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{
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struct task_struct *task = current;
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const struct cred *old;
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struct cred *new;
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validate_process_creds();
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new = kmem_cache_alloc(cred_jar, GFP_KERNEL);
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if (!new)
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return NULL;
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kdebug("prepare_creds() alloc %p", new);
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old = task->cred;
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memcpy(new, old, sizeof(struct cred));
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new->non_rcu = 0;
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atomic_set(&new->usage, 1);
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set_cred_subscribers(new, 0);
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get_group_info(new->group_info);
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get_uid(new->user);
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get_user_ns(new->user_ns);
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#ifdef CONFIG_KEYS
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key_get(new->session_keyring);
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key_get(new->process_keyring);
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key_get(new->thread_keyring);
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key_get(new->request_key_auth);
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#endif
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#ifdef CONFIG_SECURITY
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new->security = NULL;
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#endif
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if (security_prepare_creds(new, old, GFP_KERNEL_ACCOUNT) < 0)
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goto error;
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new->ucounts = get_ucounts(new->ucounts);
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if (!new->ucounts)
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goto error;
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validate_creds(new);
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return new;
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error:
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abort_creds(new);
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return NULL;
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}
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EXPORT_SYMBOL(prepare_creds);
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/*
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* Prepare credentials for current to perform an execve()
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* - The caller must hold ->cred_guard_mutex
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*/
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struct cred *prepare_exec_creds(void)
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{
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struct cred *new;
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new = prepare_creds();
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if (!new)
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return new;
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#ifdef CONFIG_KEYS
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/* newly exec'd tasks don't get a thread keyring */
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key_put(new->thread_keyring);
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new->thread_keyring = NULL;
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/* inherit the session keyring; new process keyring */
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key_put(new->process_keyring);
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new->process_keyring = NULL;
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#endif
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new->suid = new->fsuid = new->euid;
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new->sgid = new->fsgid = new->egid;
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return new;
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}
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/*
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* Copy credentials for the new process created by fork()
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*
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* We share if we can, but under some circumstances we have to generate a new
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* set.
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*
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* The new process gets the current process's subjective credentials as its
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* objective and subjective credentials
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*/
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int copy_creds(struct task_struct *p, unsigned long clone_flags)
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{
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struct cred *new;
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int ret;
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#ifdef CONFIG_KEYS_REQUEST_CACHE
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p->cached_requested_key = NULL;
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#endif
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if (
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#ifdef CONFIG_KEYS
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!p->cred->thread_keyring &&
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#endif
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clone_flags & CLONE_THREAD
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) {
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p->real_cred = get_cred(p->cred);
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get_cred(p->cred);
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alter_cred_subscribers(p->cred, 2);
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kdebug("share_creds(%p{%d,%d})",
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p->cred, atomic_read(&p->cred->usage),
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read_cred_subscribers(p->cred));
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inc_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
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return 0;
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}
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new = prepare_creds();
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if (!new)
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return -ENOMEM;
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if (clone_flags & CLONE_NEWUSER) {
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ret = create_user_ns(new);
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if (ret < 0)
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goto error_put;
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ret = set_cred_ucounts(new);
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if (ret < 0)
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goto error_put;
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}
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#ifdef CONFIG_KEYS
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/* new threads get their own thread keyrings if their parent already
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* had one */
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if (new->thread_keyring) {
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key_put(new->thread_keyring);
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new->thread_keyring = NULL;
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if (clone_flags & CLONE_THREAD)
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install_thread_keyring_to_cred(new);
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}
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/* The process keyring is only shared between the threads in a process;
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* anything outside of those threads doesn't inherit.
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*/
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if (!(clone_flags & CLONE_THREAD)) {
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key_put(new->process_keyring);
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new->process_keyring = NULL;
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}
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#endif
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p->cred = p->real_cred = get_cred(new);
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inc_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
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alter_cred_subscribers(new, 2);
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validate_creds(new);
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return 0;
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error_put:
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put_cred(new);
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return ret;
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}
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static bool cred_cap_issubset(const struct cred *set, const struct cred *subset)
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{
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const struct user_namespace *set_ns = set->user_ns;
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const struct user_namespace *subset_ns = subset->user_ns;
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/* If the two credentials are in the same user namespace see if
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* the capabilities of subset are a subset of set.
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*/
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if (set_ns == subset_ns)
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return cap_issubset(subset->cap_permitted, set->cap_permitted);
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/* The credentials are in a different user namespaces
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* therefore one is a subset of the other only if a set is an
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* ancestor of subset and set->euid is owner of subset or one
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* of subsets ancestors.
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*/
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for (;subset_ns != &init_user_ns; subset_ns = subset_ns->parent) {
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if ((set_ns == subset_ns->parent) &&
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uid_eq(subset_ns->owner, set->euid))
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return true;
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}
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return false;
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}
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/**
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* commit_creds - Install new credentials upon the current task
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* @new: The credentials to be assigned
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*
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* Install a new set of credentials to the current task, using RCU to replace
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* the old set. Both the objective and the subjective credentials pointers are
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* updated. This function may not be called if the subjective credentials are
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* in an overridden state.
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*
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* This function eats the caller's reference to the new credentials.
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*
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* Always returns 0 thus allowing this function to be tail-called at the end
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* of, say, sys_setgid().
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*/
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int commit_creds(struct cred *new)
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{
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struct task_struct *task = current;
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const struct cred *old = task->real_cred;
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kdebug("commit_creds(%p{%d,%d})", new,
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atomic_read(&new->usage),
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read_cred_subscribers(new));
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BUG_ON(task->cred != old);
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#ifdef CONFIG_DEBUG_CREDENTIALS
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BUG_ON(read_cred_subscribers(old) < 2);
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validate_creds(old);
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validate_creds(new);
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#endif
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BUG_ON(atomic_read(&new->usage) < 1);
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get_cred(new); /* we will require a ref for the subj creds too */
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|
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/* dumpability changes */
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if (!uid_eq(old->euid, new->euid) ||
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!gid_eq(old->egid, new->egid) ||
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!uid_eq(old->fsuid, new->fsuid) ||
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!gid_eq(old->fsgid, new->fsgid) ||
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!cred_cap_issubset(old, new)) {
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if (task->mm)
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set_dumpable(task->mm, suid_dumpable);
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task->pdeath_signal = 0;
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/*
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* If a task drops privileges and becomes nondumpable,
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* the dumpability change must become visible before
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* the credential change; otherwise, a __ptrace_may_access()
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* racing with this change may be able to attach to a task it
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* shouldn't be able to attach to (as if the task had dropped
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* privileges without becoming nondumpable).
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* Pairs with a read barrier in __ptrace_may_access().
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*/
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smp_wmb();
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}
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|
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/* alter the thread keyring */
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if (!uid_eq(new->fsuid, old->fsuid))
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key_fsuid_changed(new);
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if (!gid_eq(new->fsgid, old->fsgid))
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key_fsgid_changed(new);
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|
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/* do it
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* RLIMIT_NPROC limits on user->processes have already been checked
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* in set_user().
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*/
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alter_cred_subscribers(new, 2);
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if (new->user != old->user || new->user_ns != old->user_ns)
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inc_rlimit_ucounts(new->ucounts, UCOUNT_RLIMIT_NPROC, 1);
|
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rcu_assign_pointer(task->real_cred, new);
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rcu_assign_pointer(task->cred, new);
|
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if (new->user != old->user)
|
|
dec_rlimit_ucounts(old->ucounts, UCOUNT_RLIMIT_NPROC, 1);
|
|
alter_cred_subscribers(old, -2);
|
|
|
|
/* send notifications */
|
|
if (!uid_eq(new->uid, old->uid) ||
|
|
!uid_eq(new->euid, old->euid) ||
|
|
!uid_eq(new->suid, old->suid) ||
|
|
!uid_eq(new->fsuid, old->fsuid))
|
|
proc_id_connector(task, PROC_EVENT_UID);
|
|
|
|
if (!gid_eq(new->gid, old->gid) ||
|
|
!gid_eq(new->egid, old->egid) ||
|
|
!gid_eq(new->sgid, old->sgid) ||
|
|
!gid_eq(new->fsgid, old->fsgid))
|
|
proc_id_connector(task, PROC_EVENT_GID);
|
|
|
|
/* release the old obj and subj refs both */
|
|
put_cred(old);
|
|
put_cred(old);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(commit_creds);
|
|
|
|
/**
|
|
* abort_creds - Discard a set of credentials and unlock the current task
|
|
* @new: The credentials that were going to be applied
|
|
*
|
|
* Discard a set of credentials that were under construction and unlock the
|
|
* current task.
|
|
*/
|
|
void abort_creds(struct cred *new)
|
|
{
|
|
kdebug("abort_creds(%p{%d,%d})", new,
|
|
atomic_read(&new->usage),
|
|
read_cred_subscribers(new));
|
|
|
|
#ifdef CONFIG_DEBUG_CREDENTIALS
|
|
BUG_ON(read_cred_subscribers(new) != 0);
|
|
#endif
|
|
BUG_ON(atomic_read(&new->usage) < 1);
|
|
put_cred(new);
|
|
}
|
|
EXPORT_SYMBOL(abort_creds);
|
|
|
|
/**
|
|
* override_creds - Override the current process's subjective credentials
|
|
* @new: The credentials to be assigned
|
|
*
|
|
* Install a set of temporary override subjective credentials on the current
|
|
* process, returning the old set for later reversion.
|
|
*/
|
|
const struct cred *override_creds(const struct cred *new)
|
|
{
|
|
const struct cred *old = current->cred;
|
|
|
|
kdebug("override_creds(%p{%d,%d})", new,
|
|
atomic_read(&new->usage),
|
|
read_cred_subscribers(new));
|
|
|
|
validate_creds(old);
|
|
validate_creds(new);
|
|
|
|
/*
|
|
* NOTE! This uses 'get_new_cred()' rather than 'get_cred()'.
|
|
*
|
|
* That means that we do not clear the 'non_rcu' flag, since
|
|
* we are only installing the cred into the thread-synchronous
|
|
* '->cred' pointer, not the '->real_cred' pointer that is
|
|
* visible to other threads under RCU.
|
|
*
|
|
* Also note that we did validate_creds() manually, not depending
|
|
* on the validation in 'get_cred()'.
|
|
*/
|
|
get_new_cred((struct cred *)new);
|
|
alter_cred_subscribers(new, 1);
|
|
rcu_assign_pointer(current->cred, new);
|
|
alter_cred_subscribers(old, -1);
|
|
|
|
kdebug("override_creds() = %p{%d,%d}", old,
|
|
atomic_read(&old->usage),
|
|
read_cred_subscribers(old));
|
|
return old;
|
|
}
|
|
EXPORT_SYMBOL(override_creds);
|
|
|
|
/**
|
|
* revert_creds - Revert a temporary subjective credentials override
|
|
* @old: The credentials to be restored
|
|
*
|
|
* Revert a temporary set of override subjective credentials to an old set,
|
|
* discarding the override set.
|
|
*/
|
|
void revert_creds(const struct cred *old)
|
|
{
|
|
const struct cred *override = current->cred;
|
|
|
|
kdebug("revert_creds(%p{%d,%d})", old,
|
|
atomic_read(&old->usage),
|
|
read_cred_subscribers(old));
|
|
|
|
validate_creds(old);
|
|
validate_creds(override);
|
|
alter_cred_subscribers(old, 1);
|
|
rcu_assign_pointer(current->cred, old);
|
|
alter_cred_subscribers(override, -1);
|
|
put_cred(override);
|
|
}
|
|
EXPORT_SYMBOL(revert_creds);
|
|
|
|
/**
|
|
* cred_fscmp - Compare two credentials with respect to filesystem access.
|
|
* @a: The first credential
|
|
* @b: The second credential
|
|
*
|
|
* cred_cmp() will return zero if both credentials have the same
|
|
* fsuid, fsgid, and supplementary groups. That is, if they will both
|
|
* provide the same access to files based on mode/uid/gid.
|
|
* If the credentials are different, then either -1 or 1 will
|
|
* be returned depending on whether @a comes before or after @b
|
|
* respectively in an arbitrary, but stable, ordering of credentials.
|
|
*
|
|
* Return: -1, 0, or 1 depending on comparison
|
|
*/
|
|
int cred_fscmp(const struct cred *a, const struct cred *b)
|
|
{
|
|
struct group_info *ga, *gb;
|
|
int g;
|
|
|
|
if (a == b)
|
|
return 0;
|
|
if (uid_lt(a->fsuid, b->fsuid))
|
|
return -1;
|
|
if (uid_gt(a->fsuid, b->fsuid))
|
|
return 1;
|
|
|
|
if (gid_lt(a->fsgid, b->fsgid))
|
|
return -1;
|
|
if (gid_gt(a->fsgid, b->fsgid))
|
|
return 1;
|
|
|
|
ga = a->group_info;
|
|
gb = b->group_info;
|
|
if (ga == gb)
|
|
return 0;
|
|
if (ga == NULL)
|
|
return -1;
|
|
if (gb == NULL)
|
|
return 1;
|
|
if (ga->ngroups < gb->ngroups)
|
|
return -1;
|
|
if (ga->ngroups > gb->ngroups)
|
|
return 1;
|
|
|
|
for (g = 0; g < ga->ngroups; g++) {
|
|
if (gid_lt(ga->gid[g], gb->gid[g]))
|
|
return -1;
|
|
if (gid_gt(ga->gid[g], gb->gid[g]))
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(cred_fscmp);
|
|
|
|
int set_cred_ucounts(struct cred *new)
|
|
{
|
|
struct task_struct *task = current;
|
|
const struct cred *old = task->real_cred;
|
|
struct ucounts *old_ucounts = new->ucounts;
|
|
|
|
if (new->user == old->user && new->user_ns == old->user_ns)
|
|
return 0;
|
|
|
|
/*
|
|
* This optimization is needed because alloc_ucounts() uses locks
|
|
* for table lookups.
|
|
*/
|
|
if (old_ucounts && old_ucounts->ns == new->user_ns && uid_eq(old_ucounts->uid, new->euid))
|
|
return 0;
|
|
|
|
if (!(new->ucounts = alloc_ucounts(new->user_ns, new->euid)))
|
|
return -EAGAIN;
|
|
|
|
if (old_ucounts)
|
|
put_ucounts(old_ucounts);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* initialise the credentials stuff
|
|
*/
|
|
void __init cred_init(void)
|
|
{
|
|
/* allocate a slab in which we can store credentials */
|
|
cred_jar = kmem_cache_create("cred_jar", sizeof(struct cred), 0,
|
|
SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, NULL);
|
|
}
|
|
|
|
/**
|
|
* prepare_kernel_cred - Prepare a set of credentials for a kernel service
|
|
* @daemon: A userspace daemon to be used as a reference
|
|
*
|
|
* Prepare a set of credentials for a kernel service. This can then be used to
|
|
* override a task's own credentials so that work can be done on behalf of that
|
|
* task that requires a different subjective context.
|
|
*
|
|
* @daemon is used to provide a base for the security record, but can be NULL.
|
|
* If @daemon is supplied, then the security data will be derived from that;
|
|
* otherwise they'll be set to 0 and no groups, full capabilities and no keys.
|
|
*
|
|
* The caller may change these controls afterwards if desired.
|
|
*
|
|
* Returns the new credentials or NULL if out of memory.
|
|
*/
|
|
struct cred *prepare_kernel_cred(struct task_struct *daemon)
|
|
{
|
|
const struct cred *old;
|
|
struct cred *new;
|
|
|
|
new = kmem_cache_alloc(cred_jar, GFP_KERNEL);
|
|
if (!new)
|
|
return NULL;
|
|
|
|
kdebug("prepare_kernel_cred() alloc %p", new);
|
|
|
|
if (daemon)
|
|
old = get_task_cred(daemon);
|
|
else
|
|
old = get_cred(&init_cred);
|
|
|
|
validate_creds(old);
|
|
|
|
*new = *old;
|
|
new->non_rcu = 0;
|
|
atomic_set(&new->usage, 1);
|
|
set_cred_subscribers(new, 0);
|
|
get_uid(new->user);
|
|
get_user_ns(new->user_ns);
|
|
get_group_info(new->group_info);
|
|
|
|
#ifdef CONFIG_KEYS
|
|
new->session_keyring = NULL;
|
|
new->process_keyring = NULL;
|
|
new->thread_keyring = NULL;
|
|
new->request_key_auth = NULL;
|
|
new->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING;
|
|
#endif
|
|
|
|
#ifdef CONFIG_SECURITY
|
|
new->security = NULL;
|
|
#endif
|
|
if (security_prepare_creds(new, old, GFP_KERNEL_ACCOUNT) < 0)
|
|
goto error;
|
|
|
|
new->ucounts = get_ucounts(new->ucounts);
|
|
if (!new->ucounts)
|
|
goto error;
|
|
|
|
put_cred(old);
|
|
validate_creds(new);
|
|
return new;
|
|
|
|
error:
|
|
put_cred(new);
|
|
put_cred(old);
|
|
return NULL;
|
|
}
|
|
EXPORT_SYMBOL(prepare_kernel_cred);
|
|
|
|
/**
|
|
* set_security_override - Set the security ID in a set of credentials
|
|
* @new: The credentials to alter
|
|
* @secid: The LSM security ID to set
|
|
*
|
|
* Set the LSM security ID in a set of credentials so that the subjective
|
|
* security is overridden when an alternative set of credentials is used.
|
|
*/
|
|
int set_security_override(struct cred *new, u32 secid)
|
|
{
|
|
return security_kernel_act_as(new, secid);
|
|
}
|
|
EXPORT_SYMBOL(set_security_override);
|
|
|
|
/**
|
|
* set_security_override_from_ctx - Set the security ID in a set of credentials
|
|
* @new: The credentials to alter
|
|
* @secctx: The LSM security context to generate the security ID from.
|
|
*
|
|
* Set the LSM security ID in a set of credentials so that the subjective
|
|
* security is overridden when an alternative set of credentials is used. The
|
|
* security ID is specified in string form as a security context to be
|
|
* interpreted by the LSM.
|
|
*/
|
|
int set_security_override_from_ctx(struct cred *new, const char *secctx)
|
|
{
|
|
u32 secid;
|
|
int ret;
|
|
|
|
ret = security_secctx_to_secid(secctx, strlen(secctx), &secid);
|
|
if (ret < 0)
|
|
return ret;
|
|
|
|
return set_security_override(new, secid);
|
|
}
|
|
EXPORT_SYMBOL(set_security_override_from_ctx);
|
|
|
|
/**
|
|
* set_create_files_as - Set the LSM file create context in a set of credentials
|
|
* @new: The credentials to alter
|
|
* @inode: The inode to take the context from
|
|
*
|
|
* Change the LSM file creation context in a set of credentials to be the same
|
|
* as the object context of the specified inode, so that the new inodes have
|
|
* the same MAC context as that inode.
|
|
*/
|
|
int set_create_files_as(struct cred *new, struct inode *inode)
|
|
{
|
|
if (!uid_valid(inode->i_uid) || !gid_valid(inode->i_gid))
|
|
return -EINVAL;
|
|
new->fsuid = inode->i_uid;
|
|
new->fsgid = inode->i_gid;
|
|
return security_kernel_create_files_as(new, inode);
|
|
}
|
|
EXPORT_SYMBOL(set_create_files_as);
|
|
|
|
#ifdef CONFIG_DEBUG_CREDENTIALS
|
|
|
|
bool creds_are_invalid(const struct cred *cred)
|
|
{
|
|
if (cred->magic != CRED_MAGIC)
|
|
return true;
|
|
return false;
|
|
}
|
|
EXPORT_SYMBOL(creds_are_invalid);
|
|
|
|
/*
|
|
* dump invalid credentials
|
|
*/
|
|
static void dump_invalid_creds(const struct cred *cred, const char *label,
|
|
const struct task_struct *tsk)
|
|
{
|
|
printk(KERN_ERR "CRED: %s credentials: %p %s%s%s\n",
|
|
label, cred,
|
|
cred == &init_cred ? "[init]" : "",
|
|
cred == tsk->real_cred ? "[real]" : "",
|
|
cred == tsk->cred ? "[eff]" : "");
|
|
printk(KERN_ERR "CRED: ->magic=%x, put_addr=%p\n",
|
|
cred->magic, cred->put_addr);
|
|
printk(KERN_ERR "CRED: ->usage=%d, subscr=%d\n",
|
|
atomic_read(&cred->usage),
|
|
read_cred_subscribers(cred));
|
|
printk(KERN_ERR "CRED: ->*uid = { %d,%d,%d,%d }\n",
|
|
from_kuid_munged(&init_user_ns, cred->uid),
|
|
from_kuid_munged(&init_user_ns, cred->euid),
|
|
from_kuid_munged(&init_user_ns, cred->suid),
|
|
from_kuid_munged(&init_user_ns, cred->fsuid));
|
|
printk(KERN_ERR "CRED: ->*gid = { %d,%d,%d,%d }\n",
|
|
from_kgid_munged(&init_user_ns, cred->gid),
|
|
from_kgid_munged(&init_user_ns, cred->egid),
|
|
from_kgid_munged(&init_user_ns, cred->sgid),
|
|
from_kgid_munged(&init_user_ns, cred->fsgid));
|
|
#ifdef CONFIG_SECURITY
|
|
printk(KERN_ERR "CRED: ->security is %p\n", cred->security);
|
|
if ((unsigned long) cred->security >= PAGE_SIZE &&
|
|
(((unsigned long) cred->security & 0xffffff00) !=
|
|
(POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8)))
|
|
printk(KERN_ERR "CRED: ->security {%x, %x}\n",
|
|
((u32*)cred->security)[0],
|
|
((u32*)cred->security)[1]);
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* report use of invalid credentials
|
|
*/
|
|
void __invalid_creds(const struct cred *cred, const char *file, unsigned line)
|
|
{
|
|
printk(KERN_ERR "CRED: Invalid credentials\n");
|
|
printk(KERN_ERR "CRED: At %s:%u\n", file, line);
|
|
dump_invalid_creds(cred, "Specified", current);
|
|
BUG();
|
|
}
|
|
EXPORT_SYMBOL(__invalid_creds);
|
|
|
|
/*
|
|
* check the credentials on a process
|
|
*/
|
|
void __validate_process_creds(struct task_struct *tsk,
|
|
const char *file, unsigned line)
|
|
{
|
|
if (tsk->cred == tsk->real_cred) {
|
|
if (unlikely(read_cred_subscribers(tsk->cred) < 2 ||
|
|
creds_are_invalid(tsk->cred)))
|
|
goto invalid_creds;
|
|
} else {
|
|
if (unlikely(read_cred_subscribers(tsk->real_cred) < 1 ||
|
|
read_cred_subscribers(tsk->cred) < 1 ||
|
|
creds_are_invalid(tsk->real_cred) ||
|
|
creds_are_invalid(tsk->cred)))
|
|
goto invalid_creds;
|
|
}
|
|
return;
|
|
|
|
invalid_creds:
|
|
printk(KERN_ERR "CRED: Invalid process credentials\n");
|
|
printk(KERN_ERR "CRED: At %s:%u\n", file, line);
|
|
|
|
dump_invalid_creds(tsk->real_cred, "Real", tsk);
|
|
if (tsk->cred != tsk->real_cred)
|
|
dump_invalid_creds(tsk->cred, "Effective", tsk);
|
|
else
|
|
printk(KERN_ERR "CRED: Effective creds == Real creds\n");
|
|
BUG();
|
|
}
|
|
EXPORT_SYMBOL(__validate_process_creds);
|
|
|
|
/*
|
|
* check creds for do_exit()
|
|
*/
|
|
void validate_creds_for_do_exit(struct task_struct *tsk)
|
|
{
|
|
kdebug("validate_creds_for_do_exit(%p,%p{%d,%d})",
|
|
tsk->real_cred, tsk->cred,
|
|
atomic_read(&tsk->cred->usage),
|
|
read_cred_subscribers(tsk->cred));
|
|
|
|
__validate_process_creds(tsk, __FILE__, __LINE__);
|
|
}
|
|
|
|
#endif /* CONFIG_DEBUG_CREDENTIALS */
|