releases/5.9.5/selinux-access-policycaps-with-read_once-write_once.patch

From 58be58c2aefa794692c3a73312a68e175dd374f1 Mon Sep 17 00:00:00 2001
From: Sasha Levin <sashal@kernel.org>
Date: Thu, 10 Sep 2020 10:28:05 -0400
Subject: selinux: access policycaps with READ_ONCE/WRITE_ONCE

From: Stephen Smalley <stephen.smalley.work@gmail.com>

[ Upstream commit e8ba53d0023a76ba0f50e6ee3e6288c5442f9d33 ]

Use READ_ONCE/WRITE_ONCE for all accesses to the
selinux_state.policycaps booleans to prevent compiler
mischief.

Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 security/selinux/include/security.h | 14 +++++++-------
 security/selinux/ss/services.c      |  3 ++-
 2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/security/selinux/include/security.h b/security/selinux/include/security.h
index b0e02cfe3ce14..8a432f646967e 100644
--- a/security/selinux/include/security.h
+++ b/security/selinux/include/security.h
@@ -177,49 +177,49 @@ static inline bool selinux_policycap_netpeer(void)
 {
 	struct selinux_state *state = &selinux_state;
 
-	return state->policycap[POLICYDB_CAPABILITY_NETPEER];
+	return READ_ONCE(state->policycap[POLICYDB_CAPABILITY_NETPEER]);
 }
 
 static inline bool selinux_policycap_openperm(void)
 {
 	struct selinux_state *state = &selinux_state;
 
-	return state->policycap[POLICYDB_CAPABILITY_OPENPERM];
+	return READ_ONCE(state->policycap[POLICYDB_CAPABILITY_OPENPERM]);
 }
 
 static inline bool selinux_policycap_extsockclass(void)
 {
 	struct selinux_state *state = &selinux_state;
 
-	return state->policycap[POLICYDB_CAPABILITY_EXTSOCKCLASS];
+	return READ_ONCE(state->policycap[POLICYDB_CAPABILITY_EXTSOCKCLASS]);
 }
 
 static inline bool selinux_policycap_alwaysnetwork(void)
 {
 	struct selinux_state *state = &selinux_state;
 
-	return state->policycap[POLICYDB_CAPABILITY_ALWAYSNETWORK];
+	return READ_ONCE(state->policycap[POLICYDB_CAPABILITY_ALWAYSNETWORK]);
 }
 
 static inline bool selinux_policycap_cgroupseclabel(void)
 {
 	struct selinux_state *state = &selinux_state;
 
-	return state->policycap[POLICYDB_CAPABILITY_CGROUPSECLABEL];
+	return READ_ONCE(state->policycap[POLICYDB_CAPABILITY_CGROUPSECLABEL]);
 }
 
 static inline bool selinux_policycap_nnp_nosuid_transition(void)
 {
 	struct selinux_state *state = &selinux_state;
 
-	return state->policycap[POLICYDB_CAPABILITY_NNP_NOSUID_TRANSITION];
+	return READ_ONCE(state->policycap[POLICYDB_CAPABILITY_NNP_NOSUID_TRANSITION]);
 }
 
 static inline bool selinux_policycap_genfs_seclabel_symlinks(void)
 {
 	struct selinux_state *state = &selinux_state;
 
-	return state->policycap[POLICYDB_CAPABILITY_GENFS_SECLABEL_SYMLINKS];
+	return READ_ONCE(state->policycap[POLICYDB_CAPABILITY_GENFS_SECLABEL_SYMLINKS]);
 }
 
 int security_mls_enabled(struct selinux_state *state);
diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c
index 1caf4e6033096..c55b3063753ab 100644
--- a/security/selinux/ss/services.c
+++ b/security/selinux/ss/services.c
@@ -2103,7 +2103,8 @@ static void security_load_policycaps(struct selinux_state *state)
 	struct ebitmap_node *node;
 
 	for (i = 0; i < ARRAY_SIZE(state->policycap); i++)
-		state->policycap[i] = ebitmap_get_bit(&p->policycaps, i);
+		WRITE_ONCE(state->policycap[i],
+			ebitmap_get_bit(&p->policycaps, i));
 
 	for (i = 0; i < ARRAY_SIZE(selinux_policycap_names); i++)
 		pr_info("SELinux:  policy capability %s=%d\n",
-- 
2.27.0