selinux: access policycaps with READ_ONCE/WRITE_ONCE

Commit Message

Stephen Smalley Sept. 10, 2020, 2:28 p.m. UTC

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

Signed-off-by: Stephen Smalley <[e-mail]>
---
 security/selinux/include/security.h | 14 +++++++-------
 security/selinux/ss/services.c      |  3 ++-
 2 files changed, 9 insertions(+), 8 deletions(-)

Comments

Paul Moore Sept. 11, 2020, 2:11 p.m. UTC | #1

On Thu, Sep 10, 2020 at 10:28 AM Stephen Smalley
<[e-mail]> wrote:
>
> Use READ_ONCE/WRITE_ONCE for all accesses to the
> selinux_state.policycaps booleans to prevent compiler
> mischief.
>
> Signed-off-by: Stephen Smalley <[e-mail]>
> ---
>  security/selinux/include/security.h | 14 +++++++-------
>  security/selinux/ss/services.c      |  3 ++-
>  2 files changed, 9 insertions(+), 8 deletions(-)

Merged into selinux/next, thanks.

Patch

diff --git a/security/selinux/include/security.h b/security/selinux/include/security.h
index cc29177c8858..c17fed7db80a 100644
--- a/security/selinux/include/security.h
+++ b/security/selinux/include/security.h
@@ -174,49 +174,49 @@  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 8dc111fbe23a..9704c8a32303 100644
--- a/security/selinux/ss/services.c
+++ b/security/selinux/ss/services.c
@@ -2123,7 +2123,8 @@  static void security_load_policycaps(struct selinux_state *state,
 	p = &policy->policydb;
 
 	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",