[PATCH v5 25/38] AppArmor: Abstract use of cred security blob

From: Casey Schaufler
Date: Mon Nov 26 2018 - 18:45:59 EST


Don't use the cred->security pointer directly.
Provide a helper function that provides the security blob pointer.

Signed-off-by: Casey Schaufler <casey@xxxxxxxxxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
[kees: adjusted for ordered init series]
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
security/apparmor/domain.c | 2 +-
security/apparmor/include/cred.h | 16 +++++++++++++++-
security/apparmor/lsm.c | 10 +++++-----
security/apparmor/task.c | 6 +++---
4 files changed, 24 insertions(+), 10 deletions(-)

diff --git a/security/apparmor/domain.c b/security/apparmor/domain.c
index 08c88de0ffda..726910bba84b 100644
--- a/security/apparmor/domain.c
+++ b/security/apparmor/domain.c
@@ -975,7 +975,7 @@ int apparmor_bprm_set_creds(struct linux_binprm *bprm)
}
aa_put_label(cred_label(bprm->cred));
/* transfer reference, released when cred is freed */
- cred_label(bprm->cred) = new;
+ set_cred_label(bprm->cred, new);

done:
aa_put_label(label);
diff --git a/security/apparmor/include/cred.h b/security/apparmor/include/cred.h
index 265ae6641a06..a757370f2a0c 100644
--- a/security/apparmor/include/cred.h
+++ b/security/apparmor/include/cred.h
@@ -23,8 +23,22 @@
#include "policy_ns.h"
#include "task.h"

-#define cred_label(X) ((X)->security)
+static inline struct aa_label *cred_label(const struct cred *cred)
+{
+ struct aa_label **blob = cred->security;
+
+ AA_BUG(!blob);
+ return *blob;
+}

+static inline void set_cred_label(const struct cred *cred,
+ struct aa_label *label)
+{
+ struct aa_label **blob = cred->security;
+
+ AA_BUG(!blob);
+ *blob = label;
+}

/**
* aa_cred_raw_label - obtain cred's label
diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
index e8b40008d58c..803ec0a63d87 100644
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c
@@ -59,7 +59,7 @@ DEFINE_PER_CPU(struct aa_buffers, aa_buffers);
static void apparmor_cred_free(struct cred *cred)
{
aa_put_label(cred_label(cred));
- cred_label(cred) = NULL;
+ set_cred_label(cred, NULL);
}

/*
@@ -67,7 +67,7 @@ static void apparmor_cred_free(struct cred *cred)
*/
static int apparmor_cred_alloc_blank(struct cred *cred, gfp_t gfp)
{
- cred_label(cred) = NULL;
+ set_cred_label(cred, NULL);
return 0;
}

@@ -77,7 +77,7 @@ static int apparmor_cred_alloc_blank(struct cred *cred, gfp_t gfp)
static int apparmor_cred_prepare(struct cred *new, const struct cred *old,
gfp_t gfp)
{
- cred_label(new) = aa_get_newest_label(cred_label(old));
+ set_cred_label(new, aa_get_newest_label(cred_label(old)));
return 0;
}

@@ -86,7 +86,7 @@ static int apparmor_cred_prepare(struct cred *new, const struct cred *old,
*/
static void apparmor_cred_transfer(struct cred *new, const struct cred *old)
{
- cred_label(new) = aa_get_newest_label(cred_label(old));
+ set_cred_label(new, aa_get_newest_label(cred_label(old)));
}

static void apparmor_task_free(struct task_struct *task)
@@ -1484,7 +1484,7 @@ static int __init set_init_ctx(void)
if (!ctx)
return -ENOMEM;

- cred_label(cred) = aa_get_label(ns_unconfined(root_ns));
+ set_cred_label(cred, aa_get_label(ns_unconfined(root_ns)));
task_ctx(current) = ctx;

return 0;
diff --git a/security/apparmor/task.c b/security/apparmor/task.c
index c6b78a14da91..4551110f0496 100644
--- a/security/apparmor/task.c
+++ b/security/apparmor/task.c
@@ -81,7 +81,7 @@ int aa_replace_current_label(struct aa_label *label)
*/
aa_get_label(label);
aa_put_label(cred_label(new));
- cred_label(new) = label;
+ set_cred_label(new, label);

commit_creds(new);
return 0;
@@ -138,7 +138,7 @@ int aa_set_current_hat(struct aa_label *label, u64 token)
return -EACCES;
}

- cred_label(new) = aa_get_newest_label(label);
+ set_cred_label(new, aa_get_newest_label(label));
/* clear exec on switching context */
aa_put_label(ctx->onexec);
ctx->onexec = NULL;
@@ -172,7 +172,7 @@ int aa_restore_previous_label(u64 token)
return -ENOMEM;

aa_put_label(cred_label(new));
- cred_label(new) = aa_get_newest_label(ctx->previous);
+ set_cred_label(new, aa_get_newest_label(ctx->previous));
AA_BUG(!cred_label(new));
/* clear exec && prev information when restoring to previous context */
aa_clear_task_ctx_trans(ctx);
--
2.14.5