[PATCH v3 03/15] apparmor: Refactor to remove bprm_secureexec hook

From: Kees Cook
Date: Tue Jul 18 2017 - 18:28:49 EST


The AppArmor bprm_secureexec hook can be merged with the bprm_set_creds
hook since it's dealing with the same information, and all of the details
are finalized during the first call to the bprm_set_creds hook via
prepare_binprm() (subsequent calls due to binfmt_script, etc, are ignored
via bprm->called_set_creds).

Here, all the comments describe how secureexec is actually calculated
during bprm_set_creds, so this actually does it, drops the bprm flag that
was being used internally by AppArmor, and drops the bprm_secureexec hook.

Cc: John Johansen <john.johansen@xxxxxxxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
security/apparmor/domain.c | 22 +---------------------
security/apparmor/include/domain.h | 1 -
security/apparmor/include/file.h | 3 ---
security/apparmor/lsm.c | 1 -
4 files changed, 1 insertion(+), 26 deletions(-)

diff --git a/security/apparmor/domain.c b/security/apparmor/domain.c
index 878407e023e3..1a1b1ec89d9d 100644
--- a/security/apparmor/domain.c
+++ b/security/apparmor/domain.c
@@ -485,14 +485,11 @@ int apparmor_bprm_set_creds(struct linux_binprm *bprm)
*
* Cases 2 and 3 are marked as requiring secure exec
* (unless policy specified "unsafe exec")
- *
- * bprm->unsafe is used to cache the AA_X_UNSAFE permission
- * to avoid having to recompute in secureexec
*/
if (!(perms.xindex & AA_X_UNSAFE)) {
AA_DEBUG("scrubbing environment variables for %s profile=%s\n",
name, new_profile->base.hname);
- bprm->unsafe |= AA_SECURE_X_NEEDED;
+ bprm->secureexec = 1;
}
apply:
/* when transitioning profiles clear unsafe personality bits */
@@ -521,23 +518,6 @@ int apparmor_bprm_set_creds(struct linux_binprm *bprm)
}

/**
- * apparmor_bprm_secureexec - determine if secureexec is needed
- * @bprm: binprm for exec (NOT NULL)
- *
- * Returns: %1 if secureexec is needed else %0
- */
-int apparmor_bprm_secureexec(struct linux_binprm *bprm)
-{
- /* the decision to use secure exec is computed in set_creds
- * and stored in bprm->unsafe.
- */
- if (bprm->unsafe & AA_SECURE_X_NEEDED)
- return 1;
-
- return 0;
-}
-
-/**
* apparmor_bprm_committing_creds - do task cleanup on committing new creds
* @bprm: binprm for the exec (NOT NULL)
*/
diff --git a/security/apparmor/include/domain.h b/security/apparmor/include/domain.h
index 30544729878a..2495af293587 100644
--- a/security/apparmor/include/domain.h
+++ b/security/apparmor/include/domain.h
@@ -24,7 +24,6 @@ struct aa_domain {
};

int apparmor_bprm_set_creds(struct linux_binprm *bprm);
-int apparmor_bprm_secureexec(struct linux_binprm *bprm);
void apparmor_bprm_committing_creds(struct linux_binprm *bprm);
void apparmor_bprm_committed_creds(struct linux_binprm *bprm);

diff --git a/security/apparmor/include/file.h b/security/apparmor/include/file.h
index 38f821bf49b6..076ac4501d97 100644
--- a/security/apparmor/include/file.h
+++ b/security/apparmor/include/file.h
@@ -66,9 +66,6 @@ struct path;
#define AA_X_INHERIT 0x4000
#define AA_X_UNCONFINED 0x8000

-/* AA_SECURE_X_NEEDED - is passed in the bprm->unsafe field */
-#define AA_SECURE_X_NEEDED 0x8000
-
/* need to make conditional which ones are being set */
struct path_cond {
kuid_t uid;
diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
index 8f3c0f7aca5a..291c7126350f 100644
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c
@@ -624,7 +624,6 @@ static struct security_hook_list apparmor_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(bprm_set_creds, apparmor_bprm_set_creds),
LSM_HOOK_INIT(bprm_committing_creds, apparmor_bprm_committing_creds),
LSM_HOOK_INIT(bprm_committed_creds, apparmor_bprm_committed_creds),
- LSM_HOOK_INIT(bprm_secureexec, apparmor_bprm_secureexec),

LSM_HOOK_INIT(task_setrlimit, apparmor_task_setrlimit),
};
--
2.7.4