mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-06 01:36:41 +07:00
e52e713ec3
* 'docs-move' of git://git.kernel.org/pub/scm/linux/kernel/git/rdunlap/linux-docs: Create Documentation/security/, move LSM-, credentials-, and keys-related files from Documentation/ to Documentation/security/, add Documentation/security/00-INDEX, and update all occurrences of Documentation/<moved_file> to Documentation/security/<moved_file>.
862 lines
22 KiB
C
862 lines
22 KiB
C
/* Task credentials management - see Documentation/security/credentials.txt
|
|
*
|
|
* Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
|
|
* Written by David Howells (dhowells@redhat.com)
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public Licence
|
|
* as published by the Free Software Foundation; either version
|
|
* 2 of the Licence, or (at your option) any later version.
|
|
*/
|
|
#include <linux/module.h>
|
|
#include <linux/cred.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/sched.h>
|
|
#include <linux/key.h>
|
|
#include <linux/keyctl.h>
|
|
#include <linux/init_task.h>
|
|
#include <linux/security.h>
|
|
#include <linux/cn_proc.h>
|
|
|
|
#if 0
|
|
#define kdebug(FMT, ...) \
|
|
printk("[%-5.5s%5u] "FMT"\n", current->comm, current->pid ,##__VA_ARGS__)
|
|
#else
|
|
#define kdebug(FMT, ...) \
|
|
no_printk("[%-5.5s%5u] "FMT"\n", current->comm, current->pid ,##__VA_ARGS__)
|
|
#endif
|
|
|
|
static struct kmem_cache *cred_jar;
|
|
|
|
/*
|
|
* The common credentials for the initial task's thread group
|
|
*/
|
|
#ifdef CONFIG_KEYS
|
|
static struct thread_group_cred init_tgcred = {
|
|
.usage = ATOMIC_INIT(2),
|
|
.tgid = 0,
|
|
.lock = __SPIN_LOCK_UNLOCKED(init_cred.tgcred.lock),
|
|
};
|
|
#endif
|
|
|
|
/*
|
|
* The initial credentials for the initial task
|
|
*/
|
|
struct cred init_cred = {
|
|
.usage = ATOMIC_INIT(4),
|
|
#ifdef CONFIG_DEBUG_CREDENTIALS
|
|
.subscribers = ATOMIC_INIT(2),
|
|
.magic = CRED_MAGIC,
|
|
#endif
|
|
.securebits = SECUREBITS_DEFAULT,
|
|
.cap_inheritable = CAP_EMPTY_SET,
|
|
.cap_permitted = CAP_FULL_SET,
|
|
.cap_effective = CAP_FULL_SET,
|
|
.cap_bset = CAP_FULL_SET,
|
|
.user = INIT_USER,
|
|
.user_ns = &init_user_ns,
|
|
.group_info = &init_groups,
|
|
#ifdef CONFIG_KEYS
|
|
.tgcred = &init_tgcred,
|
|
#endif
|
|
};
|
|
|
|
static inline void set_cred_subscribers(struct cred *cred, int n)
|
|
{
|
|
#ifdef CONFIG_DEBUG_CREDENTIALS
|
|
atomic_set(&cred->subscribers, n);
|
|
#endif
|
|
}
|
|
|
|
static inline int read_cred_subscribers(const struct cred *cred)
|
|
{
|
|
#ifdef CONFIG_DEBUG_CREDENTIALS
|
|
return atomic_read(&cred->subscribers);
|
|
#else
|
|
return 0;
|
|
#endif
|
|
}
|
|
|
|
static inline void alter_cred_subscribers(const struct cred *_cred, int n)
|
|
{
|
|
#ifdef CONFIG_DEBUG_CREDENTIALS
|
|
struct cred *cred = (struct cred *) _cred;
|
|
|
|
atomic_add(n, &cred->subscribers);
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* Dispose of the shared task group credentials
|
|
*/
|
|
#ifdef CONFIG_KEYS
|
|
static void release_tgcred_rcu(struct rcu_head *rcu)
|
|
{
|
|
struct thread_group_cred *tgcred =
|
|
container_of(rcu, struct thread_group_cred, rcu);
|
|
|
|
BUG_ON(atomic_read(&tgcred->usage) != 0);
|
|
|
|
key_put(tgcred->session_keyring);
|
|
key_put(tgcred->process_keyring);
|
|
kfree(tgcred);
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Release a set of thread group credentials.
|
|
*/
|
|
static void release_tgcred(struct cred *cred)
|
|
{
|
|
#ifdef CONFIG_KEYS
|
|
struct thread_group_cred *tgcred = cred->tgcred;
|
|
|
|
if (atomic_dec_and_test(&tgcred->usage))
|
|
call_rcu(&tgcred->rcu, release_tgcred_rcu);
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* The RCU callback to actually dispose of a set of credentials
|
|
*/
|
|
static void put_cred_rcu(struct rcu_head *rcu)
|
|
{
|
|
struct cred *cred = container_of(rcu, struct cred, rcu);
|
|
|
|
kdebug("put_cred_rcu(%p)", cred);
|
|
|
|
#ifdef CONFIG_DEBUG_CREDENTIALS
|
|
if (cred->magic != CRED_MAGIC_DEAD ||
|
|
atomic_read(&cred->usage) != 0 ||
|
|
read_cred_subscribers(cred) != 0)
|
|
panic("CRED: put_cred_rcu() sees %p with"
|
|
" mag %x, put %p, usage %d, subscr %d\n",
|
|
cred, cred->magic, cred->put_addr,
|
|
atomic_read(&cred->usage),
|
|
read_cred_subscribers(cred));
|
|
#else
|
|
if (atomic_read(&cred->usage) != 0)
|
|
panic("CRED: put_cred_rcu() sees %p with usage %d\n",
|
|
cred, atomic_read(&cred->usage));
|
|
#endif
|
|
|
|
security_cred_free(cred);
|
|
key_put(cred->thread_keyring);
|
|
key_put(cred->request_key_auth);
|
|
release_tgcred(cred);
|
|
if (cred->group_info)
|
|
put_group_info(cred->group_info);
|
|
free_uid(cred->user);
|
|
kmem_cache_free(cred_jar, cred);
|
|
}
|
|
|
|
/**
|
|
* __put_cred - Destroy a set of credentials
|
|
* @cred: The record to release
|
|
*
|
|
* Destroy a set of credentials on which no references remain.
|
|
*/
|
|
void __put_cred(struct cred *cred)
|
|
{
|
|
kdebug("__put_cred(%p{%d,%d})", cred,
|
|
atomic_read(&cred->usage),
|
|
read_cred_subscribers(cred));
|
|
|
|
BUG_ON(atomic_read(&cred->usage) != 0);
|
|
#ifdef CONFIG_DEBUG_CREDENTIALS
|
|
BUG_ON(read_cred_subscribers(cred) != 0);
|
|
cred->magic = CRED_MAGIC_DEAD;
|
|
cred->put_addr = __builtin_return_address(0);
|
|
#endif
|
|
BUG_ON(cred == current->cred);
|
|
BUG_ON(cred == current->real_cred);
|
|
|
|
call_rcu(&cred->rcu, put_cred_rcu);
|
|
}
|
|
EXPORT_SYMBOL(__put_cred);
|
|
|
|
/*
|
|
* Clean up a task's credentials when it exits
|
|
*/
|
|
void exit_creds(struct task_struct *tsk)
|
|
{
|
|
struct cred *cred;
|
|
|
|
kdebug("exit_creds(%u,%p,%p,{%d,%d})", tsk->pid, tsk->real_cred, tsk->cred,
|
|
atomic_read(&tsk->cred->usage),
|
|
read_cred_subscribers(tsk->cred));
|
|
|
|
cred = (struct cred *) tsk->real_cred;
|
|
tsk->real_cred = NULL;
|
|
validate_creds(cred);
|
|
alter_cred_subscribers(cred, -1);
|
|
put_cred(cred);
|
|
|
|
cred = (struct cred *) tsk->cred;
|
|
tsk->cred = NULL;
|
|
validate_creds(cred);
|
|
alter_cred_subscribers(cred, -1);
|
|
put_cred(cred);
|
|
|
|
cred = (struct cred *) tsk->replacement_session_keyring;
|
|
if (cred) {
|
|
tsk->replacement_session_keyring = NULL;
|
|
validate_creds(cred);
|
|
put_cred(cred);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* get_task_cred - Get another task's objective credentials
|
|
* @task: The task to query
|
|
*
|
|
* Get the objective credentials of a task, pinning them so that they can't go
|
|
* away. Accessing a task's credentials directly is not permitted.
|
|
*
|
|
* The caller must also make sure task doesn't get deleted, either by holding a
|
|
* ref on task or by holding tasklist_lock to prevent it from being unlinked.
|
|
*/
|
|
const struct cred *get_task_cred(struct task_struct *task)
|
|
{
|
|
const struct cred *cred;
|
|
|
|
rcu_read_lock();
|
|
|
|
do {
|
|
cred = __task_cred((task));
|
|
BUG_ON(!cred);
|
|
} while (!atomic_inc_not_zero(&((struct cred *)cred)->usage));
|
|
|
|
rcu_read_unlock();
|
|
return cred;
|
|
}
|
|
|
|
/*
|
|
* Allocate blank credentials, such that the credentials can be filled in at a
|
|
* later date without risk of ENOMEM.
|
|
*/
|
|
struct cred *cred_alloc_blank(void)
|
|
{
|
|
struct cred *new;
|
|
|
|
new = kmem_cache_zalloc(cred_jar, GFP_KERNEL);
|
|
if (!new)
|
|
return NULL;
|
|
|
|
#ifdef CONFIG_KEYS
|
|
new->tgcred = kzalloc(sizeof(*new->tgcred), GFP_KERNEL);
|
|
if (!new->tgcred) {
|
|
kmem_cache_free(cred_jar, new);
|
|
return NULL;
|
|
}
|
|
atomic_set(&new->tgcred->usage, 1);
|
|
#endif
|
|
|
|
atomic_set(&new->usage, 1);
|
|
#ifdef CONFIG_DEBUG_CREDENTIALS
|
|
new->magic = CRED_MAGIC;
|
|
#endif
|
|
|
|
if (security_cred_alloc_blank(new, GFP_KERNEL) < 0)
|
|
goto error;
|
|
|
|
return new;
|
|
|
|
error:
|
|
abort_creds(new);
|
|
return NULL;
|
|
}
|
|
|
|
/**
|
|
* prepare_creds - Prepare a new set of credentials for modification
|
|
*
|
|
* Prepare a new set of task credentials for modification. A task's creds
|
|
* shouldn't generally be modified directly, therefore this function is used to
|
|
* prepare a new copy, which the caller then modifies and then commits by
|
|
* calling commit_creds().
|
|
*
|
|
* Preparation involves making a copy of the objective creds for modification.
|
|
*
|
|
* Returns a pointer to the new creds-to-be if successful, NULL otherwise.
|
|
*
|
|
* Call commit_creds() or abort_creds() to clean up.
|
|
*/
|
|
struct cred *prepare_creds(void)
|
|
{
|
|
struct task_struct *task = current;
|
|
const struct cred *old;
|
|
struct cred *new;
|
|
|
|
validate_process_creds();
|
|
|
|
new = kmem_cache_alloc(cred_jar, GFP_KERNEL);
|
|
if (!new)
|
|
return NULL;
|
|
|
|
kdebug("prepare_creds() alloc %p", new);
|
|
|
|
old = task->cred;
|
|
memcpy(new, old, sizeof(struct cred));
|
|
|
|
atomic_set(&new->usage, 1);
|
|
set_cred_subscribers(new, 0);
|
|
get_group_info(new->group_info);
|
|
get_uid(new->user);
|
|
|
|
#ifdef CONFIG_KEYS
|
|
key_get(new->thread_keyring);
|
|
key_get(new->request_key_auth);
|
|
atomic_inc(&new->tgcred->usage);
|
|
#endif
|
|
|
|
#ifdef CONFIG_SECURITY
|
|
new->security = NULL;
|
|
#endif
|
|
|
|
if (security_prepare_creds(new, old, GFP_KERNEL) < 0)
|
|
goto error;
|
|
validate_creds(new);
|
|
return new;
|
|
|
|
error:
|
|
abort_creds(new);
|
|
return NULL;
|
|
}
|
|
EXPORT_SYMBOL(prepare_creds);
|
|
|
|
/*
|
|
* Prepare credentials for current to perform an execve()
|
|
* - The caller must hold ->cred_guard_mutex
|
|
*/
|
|
struct cred *prepare_exec_creds(void)
|
|
{
|
|
struct thread_group_cred *tgcred = NULL;
|
|
struct cred *new;
|
|
|
|
#ifdef CONFIG_KEYS
|
|
tgcred = kmalloc(sizeof(*tgcred), GFP_KERNEL);
|
|
if (!tgcred)
|
|
return NULL;
|
|
#endif
|
|
|
|
new = prepare_creds();
|
|
if (!new) {
|
|
kfree(tgcred);
|
|
return new;
|
|
}
|
|
|
|
#ifdef CONFIG_KEYS
|
|
/* newly exec'd tasks don't get a thread keyring */
|
|
key_put(new->thread_keyring);
|
|
new->thread_keyring = NULL;
|
|
|
|
/* create a new per-thread-group creds for all this set of threads to
|
|
* share */
|
|
memcpy(tgcred, new->tgcred, sizeof(struct thread_group_cred));
|
|
|
|
atomic_set(&tgcred->usage, 1);
|
|
spin_lock_init(&tgcred->lock);
|
|
|
|
/* inherit the session keyring; new process keyring */
|
|
key_get(tgcred->session_keyring);
|
|
tgcred->process_keyring = NULL;
|
|
|
|
release_tgcred(new);
|
|
new->tgcred = tgcred;
|
|
#endif
|
|
|
|
return new;
|
|
}
|
|
|
|
/*
|
|
* Copy credentials for the new process created by fork()
|
|
*
|
|
* We share if we can, but under some circumstances we have to generate a new
|
|
* set.
|
|
*
|
|
* The new process gets the current process's subjective credentials as its
|
|
* objective and subjective credentials
|
|
*/
|
|
int copy_creds(struct task_struct *p, unsigned long clone_flags)
|
|
{
|
|
#ifdef CONFIG_KEYS
|
|
struct thread_group_cred *tgcred;
|
|
#endif
|
|
struct cred *new;
|
|
int ret;
|
|
|
|
if (
|
|
#ifdef CONFIG_KEYS
|
|
!p->cred->thread_keyring &&
|
|
#endif
|
|
clone_flags & CLONE_THREAD
|
|
) {
|
|
p->real_cred = get_cred(p->cred);
|
|
get_cred(p->cred);
|
|
alter_cred_subscribers(p->cred, 2);
|
|
kdebug("share_creds(%p{%d,%d})",
|
|
p->cred, atomic_read(&p->cred->usage),
|
|
read_cred_subscribers(p->cred));
|
|
atomic_inc(&p->cred->user->processes);
|
|
return 0;
|
|
}
|
|
|
|
new = prepare_creds();
|
|
if (!new)
|
|
return -ENOMEM;
|
|
|
|
if (clone_flags & CLONE_NEWUSER) {
|
|
ret = create_user_ns(new);
|
|
if (ret < 0)
|
|
goto error_put;
|
|
}
|
|
|
|
/* cache user_ns in cred. Doesn't need a refcount because it will
|
|
* stay pinned by cred->user
|
|
*/
|
|
new->user_ns = new->user->user_ns;
|
|
|
|
#ifdef CONFIG_KEYS
|
|
/* new threads get their own thread keyrings if their parent already
|
|
* had one */
|
|
if (new->thread_keyring) {
|
|
key_put(new->thread_keyring);
|
|
new->thread_keyring = NULL;
|
|
if (clone_flags & CLONE_THREAD)
|
|
install_thread_keyring_to_cred(new);
|
|
}
|
|
|
|
/* we share the process and session keyrings between all the threads in
|
|
* a process - this is slightly icky as we violate COW credentials a
|
|
* bit */
|
|
if (!(clone_flags & CLONE_THREAD)) {
|
|
tgcred = kmalloc(sizeof(*tgcred), GFP_KERNEL);
|
|
if (!tgcred) {
|
|
ret = -ENOMEM;
|
|
goto error_put;
|
|
}
|
|
atomic_set(&tgcred->usage, 1);
|
|
spin_lock_init(&tgcred->lock);
|
|
tgcred->process_keyring = NULL;
|
|
tgcred->session_keyring = key_get(new->tgcred->session_keyring);
|
|
|
|
release_tgcred(new);
|
|
new->tgcred = tgcred;
|
|
}
|
|
#endif
|
|
|
|
atomic_inc(&new->user->processes);
|
|
p->cred = p->real_cred = get_cred(new);
|
|
alter_cred_subscribers(new, 2);
|
|
validate_creds(new);
|
|
return 0;
|
|
|
|
error_put:
|
|
put_cred(new);
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* commit_creds - Install new credentials upon the current task
|
|
* @new: The credentials to be assigned
|
|
*
|
|
* Install a new set of credentials to the current task, using RCU to replace
|
|
* the old set. Both the objective and the subjective credentials pointers are
|
|
* updated. This function may not be called if the subjective credentials are
|
|
* in an overridden state.
|
|
*
|
|
* This function eats the caller's reference to the new credentials.
|
|
*
|
|
* Always returns 0 thus allowing this function to be tail-called at the end
|
|
* of, say, sys_setgid().
|
|
*/
|
|
int commit_creds(struct cred *new)
|
|
{
|
|
struct task_struct *task = current;
|
|
const struct cred *old = task->real_cred;
|
|
|
|
kdebug("commit_creds(%p{%d,%d})", new,
|
|
atomic_read(&new->usage),
|
|
read_cred_subscribers(new));
|
|
|
|
BUG_ON(task->cred != old);
|
|
#ifdef CONFIG_DEBUG_CREDENTIALS
|
|
BUG_ON(read_cred_subscribers(old) < 2);
|
|
validate_creds(old);
|
|
validate_creds(new);
|
|
#endif
|
|
BUG_ON(atomic_read(&new->usage) < 1);
|
|
|
|
get_cred(new); /* we will require a ref for the subj creds too */
|
|
|
|
/* dumpability changes */
|
|
if (old->euid != new->euid ||
|
|
old->egid != new->egid ||
|
|
old->fsuid != new->fsuid ||
|
|
old->fsgid != new->fsgid ||
|
|
!cap_issubset(new->cap_permitted, old->cap_permitted)) {
|
|
if (task->mm)
|
|
set_dumpable(task->mm, suid_dumpable);
|
|
task->pdeath_signal = 0;
|
|
smp_wmb();
|
|
}
|
|
|
|
/* alter the thread keyring */
|
|
if (new->fsuid != old->fsuid)
|
|
key_fsuid_changed(task);
|
|
if (new->fsgid != old->fsgid)
|
|
key_fsgid_changed(task);
|
|
|
|
/* do it
|
|
* - What if a process setreuid()'s and this brings the
|
|
* new uid over his NPROC rlimit? We can check this now
|
|
* cheaply with the new uid cache, so if it matters
|
|
* we should be checking for it. -DaveM
|
|
*/
|
|
alter_cred_subscribers(new, 2);
|
|
if (new->user != old->user)
|
|
atomic_inc(&new->user->processes);
|
|
rcu_assign_pointer(task->real_cred, new);
|
|
rcu_assign_pointer(task->cred, new);
|
|
if (new->user != old->user)
|
|
atomic_dec(&old->user->processes);
|
|
alter_cred_subscribers(old, -2);
|
|
|
|
/* send notifications */
|
|
if (new->uid != old->uid ||
|
|
new->euid != old->euid ||
|
|
new->suid != old->suid ||
|
|
new->fsuid != old->fsuid)
|
|
proc_id_connector(task, PROC_EVENT_UID);
|
|
|
|
if (new->gid != old->gid ||
|
|
new->egid != old->egid ||
|
|
new->sgid != old->sgid ||
|
|
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);
|
|
get_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);
|
|
|
|
/*
|
|
* 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, 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.
|
|
*
|
|
* Does not take, and does not return holding current->cred_replace_mutex.
|
|
*/
|
|
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;
|
|
atomic_set(&new->usage, 1);
|
|
set_cred_subscribers(new, 0);
|
|
get_uid(new->user);
|
|
get_group_info(new->group_info);
|
|
|
|
#ifdef CONFIG_KEYS
|
|
atomic_inc(&init_tgcred.usage);
|
|
new->tgcred = &init_tgcred;
|
|
new->request_key_auth = NULL;
|
|
new->thread_keyring = 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) < 0)
|
|
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)
|
|
{
|
|
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;
|
|
#ifdef CONFIG_SECURITY_SELINUX
|
|
/*
|
|
* cred->security == NULL if security_cred_alloc_blank() or
|
|
* security_prepare_creds() returned an error.
|
|
*/
|
|
if (selinux_is_enabled() && cred->security) {
|
|
if ((unsigned long) cred->security < PAGE_SIZE)
|
|
return true;
|
|
if ((*(u32 *)cred->security & 0xffffff00) ==
|
|
(POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8))
|
|
return true;
|
|
}
|
|
#endif
|
|
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",
|
|
cred->uid, cred->euid, cred->suid, cred->fsuid);
|
|
printk(KERN_ERR "CRED: ->*gid = { %d,%d,%d,%d }\n",
|
|
cred->gid, cred->egid, cred->sgid, 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 */
|