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Message-Id: <1477914225-11298-9-git-send-email-elena.reshetova@intel.com>
Date: Mon, 31 Oct 2016 13:43:40 +0200
From: Elena Reshetova <elena.reshetova@...el.com>
To: kernel-hardening@...ts.openwall.com
Cc: keescook@...omium.org,
arnd@...db.de,
tglx@...utronix.de,
mingo@...hat.com,
h.peter.anvin@...el.com,
David Windsor <dwindsor@...il.com>,
Hans Liljestrand <ishkamiel@...il.com>,
Elena Reshetova <elena.reshetova@...el.com>
Subject: [RFC v3 PATCH 08/13] security: identify wrapping atomic usage
From: David Windsor <dwindsor@...il.com>
In some cases atomic is not used for reference
counting and therefore should be allowed to overflow.
Identify such cases and make a switch to non-hardened
atomic version.
The copyright for the original PAX_REFCOUNT code:
- all REFCOUNT code in general: PaX Team <pageexec@...email.hu>
- various false positive fixes: Mathias Krause <minipli@...glemail.com>
Signed-off-by: Hans Liljestrand <ishkamiel@...il.com>
Signed-off-by: Elena Reshetova <elena.reshetova@...el.com>
Signed-off-by: David Windsor <dwindsor@...il.com>
---
security/integrity/ima/ima.h | 4 ++--
security/integrity/ima/ima_api.c | 2 +-
security/integrity/ima/ima_fs.c | 4 ++--
security/integrity/ima/ima_queue.c | 2 +-
security/selinux/avc.c | 7 ++++---
5 files changed, 10 insertions(+), 9 deletions(-)
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index db25f54..4f10f05 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -130,8 +130,8 @@ int ima_init_template(void);
extern spinlock_t ima_queue_lock;
struct ima_h_table {
- atomic_long_t len; /* number of stored measurements in the list */
- atomic_long_t violations;
+ atomic_long_wrap_t len; /* number of stored measurements in the list */
+ atomic_long_wrap_t violations;
struct hlist_head queue[IMA_MEASURE_HTABLE_SIZE];
};
extern struct ima_h_table ima_htable;
diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
index 9df26a2..097bd47 100644
--- a/security/integrity/ima/ima_api.c
+++ b/security/integrity/ima/ima_api.c
@@ -138,7 +138,7 @@ void ima_add_violation(struct file *file, const unsigned char *filename,
int result;
/* can overflow, only indicator */
- atomic_long_inc(&ima_htable.violations);
+ atomic_long_inc_wrap(&ima_htable.violations);
result = ima_alloc_init_template(&event_data, &entry);
if (result < 0) {
diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
index c07a384..675e597 100644
--- a/security/integrity/ima/ima_fs.c
+++ b/security/integrity/ima/ima_fs.c
@@ -31,12 +31,12 @@ static DEFINE_MUTEX(ima_write_mutex);
static int valid_policy = 1;
#define TMPBUFLEN 12
static ssize_t ima_show_htable_value(char __user *buf, size_t count,
- loff_t *ppos, atomic_long_t *val)
+ loff_t *ppos, atomic_long_wrap_t *val)
{
char tmpbuf[TMPBUFLEN];
ssize_t len;
- len = scnprintf(tmpbuf, TMPBUFLEN, "%li\n", atomic_long_read(val));
+ len = scnprintf(tmpbuf, TMPBUFLEN, "%li\n", atomic_long_read_wrap(val));
return simple_read_from_buffer(buf, count, ppos, tmpbuf, len);
}
diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/ima_queue.c
index 32f6ac0..b46999e 100644
--- a/security/integrity/ima/ima_queue.c
+++ b/security/integrity/ima/ima_queue.c
@@ -84,7 +84,7 @@ static int ima_add_digest_entry(struct ima_template_entry *entry)
INIT_LIST_HEAD(&qe->later);
list_add_tail_rcu(&qe->later, &ima_measurements);
- atomic_long_inc(&ima_htable.len);
+ atomic_long_inc_wrap(&ima_htable.len);
key = ima_hash_key(entry->digest);
hlist_add_head_rcu(&qe->hnext, &ima_htable.queue[key]);
return 0;
diff --git a/security/selinux/avc.c b/security/selinux/avc.c
index e60c79d..6fa5ace 100644
--- a/security/selinux/avc.c
+++ b/security/selinux/avc.c
@@ -71,7 +71,7 @@ struct avc_xperms_node {
struct avc_cache {
struct hlist_head slots[AVC_CACHE_SLOTS]; /* head for avc_node->list */
spinlock_t slots_lock[AVC_CACHE_SLOTS]; /* lock for writes */
- atomic_t lru_hint; /* LRU hint for reclaim scan */
+ atomic_wrap_t lru_hint; /* LRU hint for reclaim scan */
atomic_t active_nodes;
u32 latest_notif; /* latest revocation notification */
};
@@ -183,7 +183,7 @@ void __init avc_init(void)
spin_lock_init(&avc_cache.slots_lock[i]);
}
atomic_set(&avc_cache.active_nodes, 0);
- atomic_set(&avc_cache.lru_hint, 0);
+ atomic_set_wrap(&avc_cache.lru_hint, 0);
avc_node_cachep = kmem_cache_create("avc_node", sizeof(struct avc_node),
0, SLAB_PANIC, NULL);
@@ -521,7 +521,8 @@ static inline int avc_reclaim_node(void)
spinlock_t *lock;
for (try = 0, ecx = 0; try < AVC_CACHE_SLOTS; try++) {
- hvalue = atomic_inc_return(&avc_cache.lru_hint) & (AVC_CACHE_SLOTS - 1);
+ hvalue = atomic_inc_return_wrap(&avc_cache.lru_hint) &
+ (AVC_CACHE_SLOTS - 1);
head = &avc_cache.slots[hvalue];
lock = &avc_cache.slots_lock[hvalue];
--
2.7.4
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