netdev - [PATCH v1 net 14/16] cipso: Fix data-races around boolean sysctl.

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Message-ID: <20220706052130.16368-15-kuniyu@amazon.com>
Date:   Tue, 5 Jul 2022 22:21:28 -0700
From:   Kuniyuki Iwashima <kuniyu@...zon.com>
To:     "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Luis Chamberlain <mcgrof@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        Iurii Zaikin <yzaikin@...gle.com>
CC:     Kuniyuki Iwashima <kuniyu@...zon.com>,
        Kuniyuki Iwashima <kuni1840@...il.com>,
        <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Paul Moore <paul.moore@...com>
Subject: [PATCH v1 net 14/16] cipso: Fix data-races around boolean sysctl.

While reading sysctl variables, they can be changed concurrently.  So,
we need to add READ_ONCE().  Then we can set lockless variants as the
handler to mark it safe.

Also, these sysctl knob are boolean, so this patch changes their int
handler to boolean one.

  - cipso_v4_cache_enabled
  - cipso_v4_rbm_optfmt
  - cipso_v4_rbm_strictvalid

Fixes: 446fda4f2682 ("[NetLabel]: CIPSOv4 engine")
Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.com>
---
CC: Paul Moore <paul.moore@...com>
---
 net/ipv4/cipso_ipv4.c      | 9 +++++----
 net/ipv4/sysctl_net_ipv4.c | 6 +++---
 2 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/net/ipv4/cipso_ipv4.c b/net/ipv4/cipso_ipv4.c
index 0600e9b06e1a..2756170e470f 100644
--- a/net/ipv4/cipso_ipv4.c
+++ b/net/ipv4/cipso_ipv4.c
@@ -239,7 +239,7 @@ 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);
@@ -302,7 +302,7 @@ int cipso_v4_cache_add(const unsigned char *cipso_ptr,
 	u32 bkt, cipso_ptr_len;
 	int ret_val = -EPERM;
 
-	if (!cipso_v4_cache_enabled || bkt_size <= 0)
+	if (!READ_ONCE(cipso_v4_cache_enabled) || bkt_size <= 0)
 		return 0;
 
 	cipso_ptr_len = cipso_ptr[1];
@@ -1199,7 +1199,8 @@ 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 +1604,7 @@ 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;
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 5cd32b33bbac..706795a3b369 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -520,7 +520,7 @@ static struct ctl_table ipv4_table[] = {
 		.data		= &cipso_v4_cache_enabled,
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec,
+		.proc_handler	= proc_dobool_lockless,
 	},
 	{
 		.procname	= "cipso_cache_bucket_size",
@@ -534,14 +534,14 @@ static struct ctl_table ipv4_table[] = {
 		.data		= &cipso_v4_rbm_optfmt,
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec,
+		.proc_handler	= proc_dobool_lockless,
 	},
 	{
 		.procname	= "cipso_rbm_strictvalid",
 		.data		= &cipso_v4_rbm_strictvalid,
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec,
+		.proc_handler	= proc_dobool_lockless,
 	},
 #endif /* CONFIG_NETLABEL */
 	{
-- 
2.30.2