The error paths of aa_replace_profiles() and aa_unpack() do not break
the refcount cycle between label and proxy. They just aa_put_profile()
the new profiles, which drops the label refcount from 2 to 1, and the
proxy keeps the profile alive. Every failed atomic policy load
(e.g. "profile can not be replaced", or a later profile in the blob
failing to unpack) leaks every new profile in the set, along with its
proxy, rules and its loaddata reference.
The leak is usually not visible from userspace, because the raw_data
directory for a failed load is not created, but it becomes visible
when the blob is deduplicated onto an existing loaddata, which then
keeps its policy/raw_data/<rev> directory forever.
Add aa_put_unpublished_profile(), which drops the profile's own proxy
before putting the profile, and use it on those error paths. The
proxy of an unpacked profile is always freshly allocated and not
referenced by anything else before the profile is published, so
putting it is safe.
Fixes: 637f688dc3dc ("apparmor: switch from profiles to using labels on
contexts")
Signed-off-by: Georgia Garcia <[email protected]>
---
security/apparmor/include/policy.h | 20 ++++++++++++++++++++
security/apparmor/policy.c | 3 +++
security/apparmor/policy_unpack.c | 4 +++-
3 files changed, 26 insertions(+), 1 deletion(-)
diff --git a/security/apparmor/include/policy.h
b/security/apparmor/include/policy.h
index 123814baea7b..e33da77ff63b 100644
--- a/security/apparmor/include/policy.h
+++ b/security/apparmor/include/policy.h
@@ -439,6 +439,26 @@ static inline void aa_put_profile(struct aa_profile *p)
kref_put(&p->label.count.count, aa_label_kref);
}
+/**
+ * aa_put_unpublished_profile - put a profile that was never made visible
+ * @p: profile (MAYBE NULL)
+ *
+ * A newly allocated profile and its proxy reference each other
+ * (proxy->label holds a label refcount). That cycle is normally broken
+ * when the profile is replaced or removed, which redirects the proxy.
+ * A profile that is discarded before being added to the policy tree
+ * never goes through either path, so break the cycle here, otherwise
+ * the profile, its proxy and its rawdata are leaked.
+ */
+static inline void aa_put_unpublished_profile(struct aa_profile *p)
+{
+ if (p && p->label.proxy) {
+ aa_put_proxy(p->label.proxy);
+ p->label.proxy = NULL;
+ }
+ aa_put_profile(p);
+}
+
static inline int AUDIT_MODE(const struct aa_profile *profile)
{
if (aa_g_audit != AUDIT_NORMAL)
diff --git a/security/apparmor/policy.c b/security/apparmor/policy.c
index f6f7cdcb6212..8f23f99d2a58 100644
--- a/security/apparmor/policy.c
+++ b/security/apparmor/policy.c
@@ -1460,6 +1460,9 @@ ssize_t aa_replace_profiles(struct aa_ns *policy_ns,
struct aa_label *label,
}
list_for_each_entry_safe(ent, tmp, &lh, list) {
list_del_init(&ent->list);
+ /* new was never added to the policy tree */
+ aa_put_unpublished_profile(ent->new);
+ ent->new = NULL;
aa_load_ent_free(ent);
}
diff --git a/security/apparmor/policy_unpack.c
b/security/apparmor/policy_unpack.c
index f1fc48e72d0e..02e50bafa00a 100644
--- a/security/apparmor/policy_unpack.c
+++ b/security/apparmor/policy_unpack.c
@@ -1807,13 +1807,15 @@ int aa_unpack(struct aa_loaddata *udata, struct
list_head *lh,
fail_profile:
kfree(ns_name);
- aa_put_profile(profile);
+ aa_put_unpublished_profile(profile);
fail:
if (compressed_data)
kvfree(compressed_data);
list_for_each_entry_safe(ent, tmp, lh, list) {
list_del_init(&ent->list);
+ aa_put_unpublished_profile(ent->new);
+ ent->new = NULL;
aa_load_ent_free(ent);
}
--
2.43.0
