lsm: infrastructure management of the sock security

Move management of the sock->sk_security blob out
of the individual security modules and into the security
infrastructure. Instead of allocating the blobs from within
the modules the modules tell the infrastructure how much
space is required, and the space is allocated there.

Acked-by: Paul Moore <paul@paul-moore.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: John Johansen <john.johansen@canonical.com>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
[PM: subject tweak]
Signed-off-by: Paul Moore <paul@paul-moore.com>

3 files changed, 3 insertions, 19 deletions

diff --git a/security/apparmor/include/net.h b/security/apparmor/include/net.h
index 67bf888c3bd6..c42ed8a73f1c 100644
--- a/security/apparmor/include/net.h
+++ b/security/apparmor/include/net.h
@@ -51,10 +51,9 @@ struct aa_sk_ctx {
 	struct aa_label *peer;
 };
 
-#define SK_CTX(X) ((X)->sk_security)
 static inline struct aa_sk_ctx *aa_sock(const struct sock *sk)
 {
-	return sk->sk_security;
+	return sk->sk_security + apparmor_blob_sizes.lbs_sock;
 }
 
 #define DEFINE_AUDIT_NET(NAME, OP, SK, F, T, P)				  \
diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
index 808060f9effb..f5d05297d59e 100644
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c
@@ -1058,27 +1058,12 @@ static int apparmor_userns_create(const struct cred *cred)
 	return error;
 }
 
-static int apparmor_sk_alloc_security(struct sock *sk, int family, gfp_t flags)
-{
-	struct aa_sk_ctx *ctx;
-
-	ctx = kzalloc(sizeof(*ctx), flags);
-	if (!ctx)
-		return -ENOMEM;
-
-	sk->sk_security = ctx;
-
-	return 0;
-}
-
 static void apparmor_sk_free_security(struct sock *sk)
 {
 	struct aa_sk_ctx *ctx = aa_sock(sk);
 
-	sk->sk_security = NULL;
 	aa_put_label(ctx->label);
 	aa_put_label(ctx->peer);
-	kfree(ctx);
 }
 
 /**
@@ -1433,6 +1418,7 @@ struct lsm_blob_sizes apparmor_blob_sizes __ro_after_init = {
 	.lbs_cred = sizeof(struct aa_label *),
 	.lbs_file = sizeof(struct aa_file_ctx),
 	.lbs_task = sizeof(struct aa_task_ctx),
+	.lbs_sock = sizeof(struct aa_sk_ctx),
 };
 
 static const struct lsm_id apparmor_lsmid = {
@@ -1478,7 +1464,6 @@ static struct security_hook_list apparmor_hooks[] __ro_after_init = {
 	LSM_HOOK_INIT(getprocattr, apparmor_getprocattr),
 	LSM_HOOK_INIT(setprocattr, apparmor_setprocattr),
 
-	LSM_HOOK_INIT(sk_alloc_security, apparmor_sk_alloc_security),
 	LSM_HOOK_INIT(sk_free_security, apparmor_sk_free_security),
 	LSM_HOOK_INIT(sk_clone_security, apparmor_sk_clone_security),
 
diff --git a/security/apparmor/net.c b/security/apparmor/net.c
index 87e934b2b548..77413a519117 100644
--- a/security/apparmor/net.c
+++ b/security/apparmor/net.c
@@ -151,7 +151,7 @@ static int aa_label_sk_perm(const struct cred *subj_cred,
 			    const char *op, u32 request,
 			    struct sock *sk)
 {
-	struct aa_sk_ctx *ctx = SK_CTX(sk);
+	struct aa_sk_ctx *ctx = aa_sock(sk);
 	int error = 0;
 
 	AA_BUG(!label);