linux-kernel - [PATCH v3 2/4] Fix apparmor for PR_{GET,SET}_NO_NEW

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Date:	Mon, 30 Jan 2012 08:17:27 -0800
From:	Andy Lutomirski <luto@...capital.net>
To:	Will Drewry <wad@...omium.org>, linux-kernel@...r.kernel.org
Cc:	Casey Schaufler <casey@...aufler-ca.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Jamie Lokier <jamie@...reable.org>, keescook@...omium.org,
	john.johansen@...onical.com, serge.hallyn@...onical.com,
	coreyb@...ux.vnet.ibm.com, pmoore@...hat.com, eparis@...hat.com,
	djm@...drot.org, segoon@...nwall.com, rostedt@...dmis.org,
	jmorris@...ei.org, scarybeasts@...il.com, avi@...hat.com,
	penberg@...helsinki.fi, viro@...iv.linux.org.uk, mingo@...e.hu,
	akpm@...ux-foundation.org, khilman@...com, borislav.petkov@....com,
	amwang@...hat.com, oleg@...hat.com, ak@...ux.intel.com,
	eric.dumazet@...il.com, gregkh@...e.de, dhowells@...hat.com,
	daniel.lezcano@...e.fr, linux-fsdevel@...r.kernel.org,
	linux-security-module@...r.kernel.org, olofj@...omium.org,
	mhalcrow@...gle.com, dlaor@...hat.com, corbet@....net,
	alan@...rguk.ukuu.org.uk, Al Viro <viro@...IV.linux.org.uk>,
	Andy Lutomirski <luto@...capital.net>
Subject: [PATCH v3 2/4] Fix apparmor for PR_{GET,SET}_NO_NEW_PRIVS

From: John Johansen <john.johansen@...onical.com>

Signed-off-by: John Johansen <john.johansen@...onical.com>
Signed-off-by: Andy Lutomirski <luto@...capital.net>
---
 security/apparmor/domain.c |   39 +++++++++++++++++++++++++++++++++++----
 1 files changed, 35 insertions(+), 4 deletions(-)

diff --git a/security/apparmor/domain.c b/security/apparmor/domain.c
index fcfb610..7316d77 100644
--- a/security/apparmor/domain.c
+++ b/security/apparmor/domain.c
@@ -360,10 +360,6 @@ int apparmor_bprm_set_creds(struct linux_binprm *bprm)
 	if (bprm->cred_prepared)
 		return 0;
 
-	/* XXX: no_new_privs is not usable with AppArmor yet */
-	if (bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS)
-		return -EPERM;
-
 	cxt = bprm->cred->security;
 	BUG_ON(!cxt);
 
@@ -399,6 +395,11 @@ int apparmor_bprm_set_creds(struct linux_binprm *bprm)
 			new_profile = find_attach(ns, &ns->base.profiles, name);
 		if (!new_profile)
 			goto cleanup;
+		/*
+		 * NOTE: Domain transitions from unconfined are allowed
+		 * even when no_new_privs is set because this aways results
+		 * in a further reduction of permissions.
+		 */
 		goto apply;
 	}
 
@@ -459,6 +460,16 @@ int apparmor_bprm_set_creds(struct linux_binprm *bprm)
 		/* fail exec */
 		error = -EACCES;
 
+	/*
+	 * Policy has specified a domain transition, if no_new_privs then
+	 * fail the exec.
+	 */
+	if (bprm->unsafe & LSM_UNSAFE_NO_NEW_PRIVS) {
+		aa_put_profile(new_profile);
+		error = -EPERM;
+		goto cleanup;
+	}
+
 	if (!new_profile)
 		goto audit;
 
@@ -613,6 +624,14 @@ int aa_change_hat(const char *hats[], int count, u64 token, bool permtest)
 	const char *target = NULL, *info = NULL;
 	int error = 0;
 
+	/*
+	 * Fail explicitly requested domain transitions if no_new_privs.
+	 * There is no exception for unconfined as change_hat is not
+	 * available.
+	 */
+	if (current->no_new_privs)
+		return -EPERM;
+
 	/* released below */
 	cred = get_current_cred();
 	cxt = cred->security;
@@ -754,6 +773,18 @@ int aa_change_profile(const char *ns_name, const char *hname, bool onexec,
 	cxt = cred->security;
 	profile = aa_cred_profile(cred);
 
+	/*
+	 * Fail explicitly requested domain transitions if no_new_privs
+	 * and not unconfined.
+	 * Domain transitions from unconfined are allowed even when
+	 * no_new_privs is set because this aways results in a reduction
+	 * of permissions.
+	 */
+	if (current->no_new_privs && !unconfined(profile)) {
+		put_cred(cred);
+		return -EPERM;
+	}
+
 	if (ns_name) {
 		/* released below */
 		ns = aa_find_namespace(profile->ns, ns_name);
-- 
1.7.7.6

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