linux-kernel - [PATCH v3 5/5] SELinux: Support SELinux determination of side-channel

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Message-Id: <20180821000444.7004-6-casey.schaufler@intel.com>
Date:   Mon, 20 Aug 2018 17:04:44 -0700
From:   Casey Schaufler <casey.schaufler@...el.com>
To:     kernel-hardening@...ts.openwall.com, linux-kernel@...r.kernel.org,
        linux-security-module@...r.kernel.org, selinux@...ho.nsa.gov,
        casey.schaufler@...el.com, dave.hansen@...el.com,
        deneen.t.dock@...el.com, kristen@...ux.intel.com,
        arjan@...ux.intel.com
Subject: [PATCH v3 5/5] SELinux: Support SELinux determination of side-channel

SELinux considers tasks to be side-channel safe if they
have FILE__READ access.

Signed-off-by: Casey Schaufler <casey.schaufler@...el.com>
---
 security/selinux/hooks.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index a8bf324130f5..992f2402edaa 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -4219,6 +4219,14 @@ static void selinux_task_to_inode(struct task_struct *p,
 	spin_unlock(&isec->lock);
 }
 
+static int selinux_task_safe_sidechannel(struct task_struct *p)
+{
+	struct av_decision avd;
+
+	return avc_has_perm_noaudit(&selinux_state, current_sid(), task_sid(p),
+				    SECCLASS_FILE, FILE__READ, 0, &avd);
+}
+
 /* Returns error only if unable to parse addresses */
 static int selinux_parse_skb_ipv4(struct sk_buff *skb,
 			struct common_audit_data *ad, u8 *proto)
@@ -7002,6 +7010,7 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(task_movememory, selinux_task_movememory),
 	LSM_HOOK_INIT(task_kill, selinux_task_kill),
 	LSM_HOOK_INIT(task_to_inode, selinux_task_to_inode),
+	LSM_HOOK_INIT(task_safe_sidechannel, selinux_task_safe_sidechannel),
 
 	LSM_HOOK_INIT(ipc_permission, selinux_ipc_permission),
 	LSM_HOOK_INIT(ipc_getsecid, selinux_ipc_getsecid),
-- 
2.17.1