cipso: Fix data-races around sysctl.

stable inclusion
from stable-v5.10.132
commit fe2a35fa2c4f9c8ce5ef970eb927031387f9446a
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5YS3T

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fe2a35fa2c4f9c8ce5ef970eb927031387f9446a

--------------------------------

[ Upstream commit dd44f04b ]

While reading cipso sysctl variables, they can be changed concurrently.
So, we need to add READ_ONCE() to avoid data-races.

Fixes: 446fda4f ("[NetLabel]: CIPSOv4 engine")
Signed-off-by: NKuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: NPaul Moore <paul@paul-moore.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Acked-by: NXie XiuQi <xiexiuqi@huawei.com>

Documentation/networking/ip-sysctl.rst

@@ -988,7 +988,7 @@ cipso_cache_enable - BOOLEAN
 cipso_cache_bucket_size - INTEGER
 	The CIPSO label cache consists of a fixed size hash table with each
 	hash bucket containing a number of cache entries.  This variable limits
-	the number of entries in each hash bucket; the larger the value the
+	the number of entries in each hash bucket; the larger the value is, the
 	more CIPSO label mappings that can be cached.  When the number of
 	entries in a given hash bucket reaches this limit adding new entries
 	causes the oldest entry in the bucket to be removed to make room.

net/ipv4/cipso_ipv4.c

@@ -240,7 +240,7 @@ static int cipso_v4_cache_check(const unsigned char *key,
 	struct cipso_v4_map_cache_entry *prev_entry = NULL;
 	u32 hash;
 
-	if (!cipso_v4_cache_enabled)
+	if (!READ_ONCE(cipso_v4_cache_enabled))
 		return -ENOENT;
 
 	hash = cipso_v4_map_cache_hash(key, key_len);
@@ -297,13 +297,14 @@ static int cipso_v4_cache_check(const unsigned char *key,
 int cipso_v4_cache_add(const unsigned char *cipso_ptr,
 		       const struct netlbl_lsm_secattr *secattr)
 {
+	int bkt_size = READ_ONCE(cipso_v4_cache_bucketsize);
 	int ret_val = -EPERM;
 	u32 bkt;
 	struct cipso_v4_map_cache_entry *entry = NULL;
 	struct cipso_v4_map_cache_entry *old_entry = NULL;
 	u32 cipso_ptr_len;
 
-	if (!cipso_v4_cache_enabled || cipso_v4_cache_bucketsize <= 0)
+	if (!READ_ONCE(cipso_v4_cache_enabled) || bkt_size <= 0)
 		return 0;
 
 	cipso_ptr_len = cipso_ptr[1];
@@ -323,7 +324,7 @@ int cipso_v4_cache_add(const unsigned char *cipso_ptr,
 
 	bkt = entry->hash & (CIPSO_V4_CACHE_BUCKETS - 1);
 	spin_lock_bh(&cipso_v4_cache[bkt].lock);
-	if (cipso_v4_cache[bkt].size < cipso_v4_cache_bucketsize) {
+	if (cipso_v4_cache[bkt].size < bkt_size) {
 		list_add(&entry->list, &cipso_v4_cache[bkt].list);
 		cipso_v4_cache[bkt].size += 1;
 	} else {
@@ -1200,7 +1201,8 @@ static int cipso_v4_gentag_rbm(const struct cipso_v4_doi *doi_def,
 		/* This will send packets using the "optimized" format when
 		 * possible as specified in  section 3.4.2.6 of the
 		 * CIPSO draft. */
-		if (cipso_v4_rbm_optfmt && ret_val > 0 && ret_val <= 10)
+		if (READ_ONCE(cipso_v4_rbm_optfmt) && ret_val > 0 &&
+		    ret_val <= 10)
 			tag_len = 14;
 		else
 			tag_len = 4 + ret_val;
@@ -1604,7 +1606,7 @@ int cipso_v4_validate(const struct sk_buff *skb, unsigned char **option)
 			 * all the CIPSO validations here but it doesn't
 			 * really specify _exactly_ what we need to validate
 			 * ... so, just make it a sysctl tunable. */
-			if (cipso_v4_rbm_strictvalid) {
+			if (READ_ONCE(cipso_v4_rbm_strictvalid)) {
 				if (cipso_v4_map_lvl_valid(doi_def,
 							   tag[3]) < 0) {
 					err_offset = opt_iter + 3;