[PATCH 5.4 28/71] cipso: Fix data-races around sysctl.

Greg Kroah-Hartman
2022-07-19T12:13:29Z

From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ Upstream commit dd44f04b9214adb68ef5684ae87a81ba03632250 ]

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

Fixes: 446fda4f2682 ("[NetLabel]: CIPSOv4 engine")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
Documentation/networking/ip-sysctl.txt | 2 +-
net/ipv4/cipso_ipv4.c | 12 +++++++-----
2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index 8af3771a3ebf..f60d4159fff4 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -876,7 +876,7 @@ 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.
diff --git a/net/ipv4/cipso_ipv4.c b/net/ipv4/cipso_ipv4.c
index c1ac802d6894..42eaad5e515f 100644
--- a/net/ipv4/cipso_ipv4.c
+++ b/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;
@@ -1603,7 +1605,7 @@ 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;
--
2.35.1