netlabel: fix RCU annotation for IPv4 options on socket creation

Xiumei reports the following splat when netlabel and TCP socket are used:

 =============================
 WARNING: suspicious RCU usage
 6.9.0-rc2+ #637 Not tainted
 -----------------------------
 net/ipv4/cipso_ipv4.c:1880 suspicious rcu_dereference_protected() usage!

 other info that might help us debug this:

 rcu_scheduler_active = 2, debug_locks = 1
 1 lock held by ncat/23333:
  #0: ffffffff906030c0 (rcu_read_lock){....}-{1:2}, at: netlbl_sock_setattr+0x25/0x1b0

 stack backtrace:
 CPU: 11 PID: 23333 Comm: ncat Kdump: loaded Not tainted 6.9.0-rc2+ #637
 Hardware name: Supermicro SYS-6027R-72RF/X9DRH-7TF/7F/iTF/iF, BIOS 3.0  07/26/2013
 Call Trace:
  <TASK>
  dump_stack_lvl+0xa9/0xc0
  lockdep_rcu_suspicious+0x117/0x190
  cipso_v4_sock_setattr+0x1ab/0x1b0
  netlbl_sock_setattr+0x13e/0x1b0
  selinux_netlbl_socket_post_create+0x3f/0x80
  selinux_socket_post_create+0x1a0/0x460
  security_socket_post_create+0x42/0x60
  __sock_create+0x342/0x3a0
  __sys_socket_create.part.22+0x42/0x70
  __sys_socket+0x37/0xb0
  __x64_sys_socket+0x16/0x20
  do_syscall_64+0x96/0x180
  ? do_user_addr_fault+0x68d/0xa30
  ? exc_page_fault+0x171/0x280
  ? asm_exc_page_fault+0x22/0x30
  entry_SYSCALL_64_after_hwframe+0x71/0x79
 RIP: 0033:0x7fbc0ca3fc1b
 Code: 73 01 c3 48 8b 0d 05 f2 1b 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa b8 29 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d d5 f1 1b 00 f7 d8 64 89 01 48
 RSP: 002b:00007fff18635208 EFLAGS: 00000246 ORIG_RAX: 0000000000000029
 RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007fbc0ca3fc1b
 RDX: 0000000000000006 RSI: 0000000000000001 RDI: 0000000000000002
 RBP: 000055d24f80f8a0 R08: 0000000000000003 R09: 0000000000000001

R10: 0000000000020000 R11: 0000000000000246 R12: 000055d24f80f8a0
 R13: 0000000000000000 R14: 000055d24f80fb88 R15: 0000000000000000
  </TASK>

The current implementation of cipso_v4_sock_setattr() replaces IP options
under the assumption that the caller holds the socket lock; however, such
assumption is not true, nor needed, in selinux_socket_post_create() hook.

Let all callers of cipso_v4_sock_setattr() specify the "socket lock held"
condition, except selinux_socket_post_create() _ where such condition can
safely be set as true even without holding the socket lock.

Fixes: f6d8bd051c39 ("inet: add RCU protection to inet->opt")
Reported-by: Xiumei Mu <xmu@redhat.com>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Acked-by: Paul Moore <paul@paul-moore.com>
Link: https://lore.kernel.org/r/f4260d000a3a55b9e8b6a3b4e3fffc7da9f82d41.1715359817.git.dcaratti@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 28 insertions, 3 deletions

diff --git a/net/netlabel/netlabel_kapi.c b/net/netlabel/netlabel_kapi.c
index 1ba4f58e1d35..cd9160bbc919 100644
--- a/net/netlabel/netlabel_kapi.c
+++ b/net/netlabel/netlabel_kapi.c
@@ -965,6 +965,7 @@ int netlbl_enabled(void)
  * @sk: the socket to label
  * @family: protocol family
  * @secattr: the security attributes
+ * @sk_locked: true if caller holds the socket lock
  *
  * Description:
  * Attach the correct label to the given socket using the security attributes
@@ -977,7 +978,8 @@ int netlbl_enabled(void)
  */
 int netlbl_sock_setattr(struct sock *sk,
 			u16 family,
-			const struct netlbl_lsm_secattr *secattr)
+			const struct netlbl_lsm_secattr *secattr,
+			bool sk_locked)
 {
 	int ret_val;
 	struct netlbl_dom_map *dom_entry;
@@ -997,7 +999,7 @@ int netlbl_sock_setattr(struct sock *sk,
 		case NETLBL_NLTYPE_CIPSOV4:
 			ret_val = cipso_v4_sock_setattr(sk,
 							dom_entry->def.cipso,
-							secattr);
+							secattr, sk_locked);
 			break;
 		case NETLBL_NLTYPE_UNLABELED:
 			ret_val = 0;
@@ -1091,6 +1093,28 @@ int netlbl_sock_getattr(struct sock *sk,
 }
 
 /**
+ * netlbl_sk_lock_check - Check if the socket lock has been acquired.
+ * @sk: the socket to be checked
+ *
+ * Return: true if socket @sk is locked or if lock debugging is disabled at
+ * runtime or compile-time; false otherwise
+ *
+ */
+#ifdef CONFIG_LOCKDEP
+bool netlbl_sk_lock_check(struct sock *sk)
+{
+	if (debug_locks)
+		return lockdep_sock_is_held(sk);
+	return true;
+}
+#else
+bool netlbl_sk_lock_check(struct sock *sk)
+{
+	return true;
+}
+#endif
+
+/**
  * netlbl_conn_setattr - Label a connected socket using the correct protocol
  * @sk: the socket to label
  * @addr: the destination address
@@ -1126,7 +1150,8 @@ int netlbl_conn_setattr(struct sock *sk,
 		switch (entry->type) {
 		case NETLBL_NLTYPE_CIPSOV4:
 			ret_val = cipso_v4_sock_setattr(sk,
-							entry->cipso, secattr);
+							entry->cipso, secattr,
+							netlbl_sk_lock_check(sk));
 			break;
 		case NETLBL_NLTYPE_UNLABELED:
 			/* just delete the protocols we support for right now