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authorStephen Smalley <stephen.smalley.work@gmail.com>2020-08-11 22:01:56 +0300
committerPaul Moore <paul@paul-moore.com>2020-08-18 04:00:33 +0300
commitc7c556f1e81bb9e09656ed6650d0c44c84b7c016 (patch)
treef59001467a93880927534c5bb484bfb72d918cdb /security/selinux/ss/services.h
parent02a52c5c8c3b8cbad0f12009cde9f36dbefb6972 (diff)
downloadlinux-c7c556f1e81bb9e09656ed6650d0c44c84b7c016.tar.xz
selinux: refactor changing booleans
Refactor the logic for changing SELinux policy booleans in a similar manner to the refactoring of policy load, thereby reducing the size of the critical section when the policy write-lock is held and making it easier to convert the policy rwlock to RCU in the future. Instead of directly modifying the policydb in place, modify a copy and then swap it into place through a single pointer update. Only fully copy the portions of the policydb that are affected by boolean changes to avoid the full cost of a deep policydb copy. Introduce another level of indirection for the sidtab since changing booleans does not require updating the sidtab, unlike policy load. While we are here, create a common helper for notifying other kernel components and userspace of a policy change and call it from both security_set_bools() and selinux_policy_commit(). Based on an old (2004) patch by Kaigai Kohei [1] to convert the policy rwlock to RCU that was deferred at the time since it did not significantly improve performance and introduced complexity. Peter Enderborg later submitted a patch series to convert to RCU [2] that would have made changing booleans a much more expensive operation by requiring a full policydb_write();policydb_read(); sequence to deep copy the entire policydb and also had concerns regarding atomic allocations. This change is now simplified by the earlier work to encapsulate policy state in the selinux_policy struct and to refactor policy load. After this change, the last major obstacle to converting the policy rwlock to RCU is likely the sidtab live convert support. [1] https://lore.kernel.org/selinux/6e2f9128-e191-ebb3-0e87-74bfccb0767f@tycho.nsa.gov/ [2] https://lore.kernel.org/selinux/20180530141104.28569-1-peter.enderborg@sony.com/ Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
Diffstat (limited to 'security/selinux/ss/services.h')
-rw-r--r--security/selinux/ss/services.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/security/selinux/ss/services.h b/security/selinux/ss/services.h
index c36933c1c363..06931e34cb24 100644
--- a/security/selinux/ss/services.h
+++ b/security/selinux/ss/services.h
@@ -23,7 +23,7 @@ struct selinux_map {
};
struct selinux_policy {
- struct sidtab sidtab;
+ struct sidtab *sidtab;
struct policydb policydb;
struct selinux_map map;
};