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linux-2.6/security/tomoyo/gc.c

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/*
* security/tomoyo/gc.c
*
* Implementation of the Domain-Based Mandatory Access Control.
*
* Copyright (C) 2005-2010 NTT DATA CORPORATION
*
*/
#include "common.h"
#include <linux/kthread.h>
include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo <tj@kernel.org> Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-24 08:04:11 +00:00
#include <linux/slab.h>
struct tomoyo_gc {
struct list_head list;
enum tomoyo_policy_id type;
struct list_head *element;
};
static LIST_HEAD(tomoyo_gc_queue);
static DEFINE_MUTEX(tomoyo_gc_mutex);
/**
* tomoyo_add_to_gc - Add an entry to to be deleted list.
*
* @type: One of values in "enum tomoyo_policy_id".
* @element: Pointer to "struct list_head".
*
* Returns true on success, false otherwise.
*
* Caller holds tomoyo_policy_lock mutex.
*
* Adding an entry needs kmalloc(). Thus, if we try to add thousands of
* entries at once, it will take too long time. Thus, do not add more than 128
* entries per a scan. But to be able to handle worst case where all entries
* are in-use, we accept one more entry per a scan.
*
* If we use singly linked list using "struct list_head"->prev (which is
* LIST_POISON2), we can avoid kmalloc().
*/
static bool tomoyo_add_to_gc(const int type, struct list_head *element)
{
struct tomoyo_gc *entry = kzalloc(sizeof(*entry), GFP_ATOMIC);
if (!entry)
return false;
entry->type = type;
entry->element = element;
list_add(&entry->list, &tomoyo_gc_queue);
list_del_rcu(element);
return true;
}
/**
* tomoyo_del_transition_control - Delete members in "struct tomoyo_transition_control".
*
* @element: Pointer to "struct list_head".
*
* Returns nothing.
*/
static void tomoyo_del_transition_control(struct list_head *element)
{
struct tomoyo_transition_control *ptr =
container_of(element, typeof(*ptr), head.list);
tomoyo_put_name(ptr->domainname);
tomoyo_put_name(ptr->program);
}
/**
* tomoyo_del_aggregator - Delete members in "struct tomoyo_aggregator".
*
* @element: Pointer to "struct list_head".
*
* Returns nothing.
*/
static void tomoyo_del_aggregator(struct list_head *element)
{
struct tomoyo_aggregator *ptr =
container_of(element, typeof(*ptr), head.list);
tomoyo_put_name(ptr->original_name);
tomoyo_put_name(ptr->aggregated_name);
}
/**
* tomoyo_del_manager - Delete members in "struct tomoyo_manager".
*
* @element: Pointer to "struct list_head".
*
* Returns nothing.
*/
static void tomoyo_del_manager(struct list_head *element)
{
struct tomoyo_manager *ptr =
container_of(element, typeof(*ptr), head.list);
tomoyo_put_name(ptr->manager);
}
/**
* tomoyo_del_acl - Delete members in "struct tomoyo_acl_info".
*
* @element: Pointer to "struct list_head".
*
* Returns nothing.
*/
static void tomoyo_del_acl(struct list_head *element)
{
struct tomoyo_acl_info *acl =
container_of(element, typeof(*acl), list);
switch (acl->type) {
case TOMOYO_TYPE_PATH_ACL:
{
struct tomoyo_path_acl *entry
= container_of(acl, typeof(*entry), head);
tomoyo_put_name_union(&entry->name);
}
break;
case TOMOYO_TYPE_PATH2_ACL:
{
struct tomoyo_path2_acl *entry
= container_of(acl, typeof(*entry), head);
tomoyo_put_name_union(&entry->name1);
tomoyo_put_name_union(&entry->name2);
}
break;
case TOMOYO_TYPE_PATH_NUMBER_ACL:
{
struct tomoyo_path_number_acl *entry
= container_of(acl, typeof(*entry), head);
tomoyo_put_name_union(&entry->name);
tomoyo_put_number_union(&entry->number);
}
break;
case TOMOYO_TYPE_MKDEV_ACL:
{
struct tomoyo_mkdev_acl *entry
= container_of(acl, typeof(*entry), head);
tomoyo_put_name_union(&entry->name);
tomoyo_put_number_union(&entry->mode);
tomoyo_put_number_union(&entry->major);
tomoyo_put_number_union(&entry->minor);
}
break;
case TOMOYO_TYPE_MOUNT_ACL:
{
struct tomoyo_mount_acl *entry
= container_of(acl, typeof(*entry), head);
tomoyo_put_name_union(&entry->dev_name);
tomoyo_put_name_union(&entry->dir_name);
tomoyo_put_name_union(&entry->fs_type);
tomoyo_put_number_union(&entry->flags);
}
break;
}
}
static bool tomoyo_del_domain(struct list_head *element)
{
struct tomoyo_domain_info *domain =
container_of(element, typeof(*domain), list);
struct tomoyo_acl_info *acl;
struct tomoyo_acl_info *tmp;
/*
* Since we don't protect whole execve() operation using SRCU,
* we need to recheck domain->users at this point.
*
* (1) Reader starts SRCU section upon execve().
* (2) Reader traverses tomoyo_domain_list and finds this domain.
* (3) Writer marks this domain as deleted.
* (4) Garbage collector removes this domain from tomoyo_domain_list
* because this domain is marked as deleted and used by nobody.
* (5) Reader saves reference to this domain into
* "struct linux_binprm"->cred->security .
* (6) Reader finishes SRCU section, although execve() operation has
* not finished yet.
* (7) Garbage collector waits for SRCU synchronization.
* (8) Garbage collector kfree() this domain because this domain is
* used by nobody.
* (9) Reader finishes execve() operation and restores this domain from
* "struct linux_binprm"->cred->security.
*
* By updating domain->users at (5), we can solve this race problem
* by rechecking domain->users at (8).
*/
if (atomic_read(&domain->users))
return false;
list_for_each_entry_safe(acl, tmp, &domain->acl_info_list, list) {
tomoyo_del_acl(&acl->list);
tomoyo_memory_free(acl);
}
tomoyo_put_name(domain->domainname);
return true;
}
/**
* tomoyo_del_name - Delete members in "struct tomoyo_name".
*
* @element: Pointer to "struct list_head".
*
* Returns nothing.
*/
static void tomoyo_del_name(struct list_head *element)
{
const struct tomoyo_name *ptr =
container_of(element, typeof(*ptr), head.list);
}
/**
* tomoyo_del_path_group - Delete members in "struct tomoyo_path_group".
*
* @element: Pointer to "struct list_head".
*
* Returns nothing.
*/
static void tomoyo_del_path_group(struct list_head *element)
{
struct tomoyo_path_group *member =
container_of(element, typeof(*member), head.list);
tomoyo_put_name(member->member_name);
}
/**
* tomoyo_del_group - Delete "struct tomoyo_group".
*
* @element: Pointer to "struct list_head".
*
* Returns nothing.
*/
static void tomoyo_del_group(struct list_head *element)
{
struct tomoyo_group *group =
container_of(element, typeof(*group), head.list);
tomoyo_put_name(group->group_name);
}
/**
* tomoyo_del_number_group - Delete members in "struct tomoyo_number_group".
*
* @element: Pointer to "struct list_head".
*
* Returns nothing.
*/
static void tomoyo_del_number_group(struct list_head *element)
{
struct tomoyo_number_group *member =
container_of(element, typeof(*member), head.list);
}
/**
* tomoyo_collect_member - Delete elements with "struct tomoyo_acl_head".
*
* @id: One of values in "enum tomoyo_policy_id".
* @member_list: Pointer to "struct list_head".
*
* Returns true if some elements are deleted, false otherwise.
*/
static bool tomoyo_collect_member(const enum tomoyo_policy_id id,
struct list_head *member_list)
{
struct tomoyo_acl_head *member;
list_for_each_entry(member, member_list, list) {
if (!member->is_deleted)
continue;
if (!tomoyo_add_to_gc(id, &member->list))
return false;
}
return true;
}
/**
* tomoyo_collect_acl - Delete elements in "struct tomoyo_domain_info".
*
* @list: Pointer to "struct list_head".
*
* Returns true if some elements are deleted, false otherwise.
*/
static bool tomoyo_collect_acl(struct list_head *list)
{
struct tomoyo_acl_info *acl;
list_for_each_entry(acl, list, list) {
if (!acl->is_deleted)
continue;
if (!tomoyo_add_to_gc(TOMOYO_ID_ACL, &acl->list))
return false;
}
return true;
}
/**
* tomoyo_collect_entry - Scan lists for deleted elements.
*
* Returns nothing.
*/
static void tomoyo_collect_entry(void)
{
int i;
if (mutex_lock_interruptible(&tomoyo_policy_lock))
return;
for (i = 0; i < TOMOYO_MAX_POLICY; i++) {
if (!tomoyo_collect_member(i, &tomoyo_policy_list[i]))
goto unlock;
}
for (i = 0; i < TOMOYO_MAX_ACL_GROUPS; i++)
if (!tomoyo_collect_acl(&tomoyo_acl_group[i]))
goto unlock;
{
struct tomoyo_domain_info *domain;
list_for_each_entry_rcu(domain, &tomoyo_domain_list, list) {
if (!tomoyo_collect_acl(&domain->acl_info_list))
goto unlock;
if (!domain->is_deleted || atomic_read(&domain->users))
continue;
/*
* Nobody is referring this domain. But somebody may
* refer this domain after successful execve().
* We recheck domain->users after SRCU synchronization.
*/
if (!tomoyo_add_to_gc(TOMOYO_ID_DOMAIN, &domain->list))
goto unlock;
}
}
for (i = 0; i < TOMOYO_MAX_HASH; i++) {
struct tomoyo_name *ptr;
list_for_each_entry_rcu(ptr, &tomoyo_name_list[i], head.list) {
if (atomic_read(&ptr->head.users))
continue;
if (!tomoyo_add_to_gc(TOMOYO_ID_NAME, &ptr->head.list))
goto unlock;
}
}
for (i = 0; i < TOMOYO_MAX_GROUP; i++) {
struct list_head *list = &tomoyo_group_list[i];
int id;
struct tomoyo_group *group;
switch (i) {
case 0:
id = TOMOYO_ID_PATH_GROUP;
break;
default:
id = TOMOYO_ID_NUMBER_GROUP;
break;
}
list_for_each_entry(group, list, head.list) {
if (!tomoyo_collect_member(id, &group->member_list))
goto unlock;
if (!list_empty(&group->member_list) ||
atomic_read(&group->head.users))
continue;
if (!tomoyo_add_to_gc(TOMOYO_ID_GROUP,
&group->head.list))
goto unlock;
}
}
unlock:
mutex_unlock(&tomoyo_policy_lock);
}
static void tomoyo_kfree_entry(void)
{
struct tomoyo_gc *p;
struct tomoyo_gc *tmp;
list_for_each_entry_safe(p, tmp, &tomoyo_gc_queue, list) {
struct list_head *element = p->element;
switch (p->type) {
case TOMOYO_ID_TRANSITION_CONTROL:
tomoyo_del_transition_control(element);
break;
case TOMOYO_ID_AGGREGATOR:
tomoyo_del_aggregator(element);
break;
case TOMOYO_ID_MANAGER:
tomoyo_del_manager(element);
break;
case TOMOYO_ID_NAME:
tomoyo_del_name(element);
break;
case TOMOYO_ID_ACL:
tomoyo_del_acl(element);
break;
case TOMOYO_ID_DOMAIN:
if (!tomoyo_del_domain(element))
continue;
break;
case TOMOYO_ID_PATH_GROUP:
tomoyo_del_path_group(element);
break;
case TOMOYO_ID_GROUP:
tomoyo_del_group(element);
break;
case TOMOYO_ID_NUMBER_GROUP:
tomoyo_del_number_group(element);
break;
case TOMOYO_MAX_POLICY:
break;
}
tomoyo_memory_free(element);
list_del(&p->list);
kfree(p);
}
}
/**
* tomoyo_gc_thread - Garbage collector thread function.
*
* @unused: Unused.
*
* In case OOM-killer choose this thread for termination, we create this thread
* as a short live thread whenever /sys/kernel/security/tomoyo/ interface was
* close()d.
*
* Returns 0.
*/
static int tomoyo_gc_thread(void *unused)
{
daemonize("GC for TOMOYO");
if (mutex_trylock(&tomoyo_gc_mutex)) {
int i;
for (i = 0; i < 10; i++) {
tomoyo_collect_entry();
if (list_empty(&tomoyo_gc_queue))
break;
synchronize_srcu(&tomoyo_ss);
tomoyo_kfree_entry();
}
mutex_unlock(&tomoyo_gc_mutex);
}
do_exit(0);
}
void tomoyo_run_gc(void)
{
struct task_struct *task = kthread_create(tomoyo_gc_thread, NULL,
"GC for TOMOYO");
if (!IS_ERR(task))
wake_up_process(task);
}