Merge branch 'next-general' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security

Pull general security layer updates from James Morris:

 - Convert security hooks from list to hlist, a nice cleanup, saving
   about 50% of space, from Sargun Dhillon.

 - Only pass the cred, not the secid, to kill_pid_info_as_cred and
   security_task_kill (as the secid can be determined from the cred),
   from Stephen Smalley.

 - Close a potential race in kernel_read_file(), by making the file
   unwritable before calling the LSM check (vs after), from Kees Cook.

* 'next-general' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
  security: convert security hooks to use hlist
  exec: Set file unwritable before LSM check
  usb, signal, security: only pass the cred, not the secid, to kill_pid_info_as_cred and security_task_kill

4 files changed, 35 insertions, 27 deletions

diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
index 6134302c143c..528f59b580a8 100644
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c
@@ -716,16 +716,23 @@ static int apparmor_task_setrlimit(struct task_struct *task,
 }
 
 static int apparmor_task_kill(struct task_struct *target, struct siginfo *info,
-			      int sig, u32 secid)
+			      int sig, const struct cred *cred)
 {
 	struct aa_label *cl, *tl;
 	int error;
 
-	if (secid)
-		/* TODO: after secid to label mapping is done.
-		 *  Dealing with USB IO specific behavior
+	if (cred) {
+		/*
+		 * Dealing with USB IO specific behavior
 		 */
-		return 0;
+		cl = aa_get_newest_cred_label(cred);
+		tl = aa_get_task_label(target);
+		error = aa_may_signal(cl, tl, sig);
+		aa_put_label(cl);
+		aa_put_label(tl);
+		return error;
+	}
+
 	cl = __begin_current_label_crit_section();
 	tl = aa_get_task_label(target);
 	error = aa_may_signal(cl, tl, sig);
diff --git a/security/security.c b/security/security.c
index af53d2834e20..7301902a8721 100644
--- a/security/security.c
+++ b/security/security.c
@@ -61,11 +61,11 @@ static void __init do_security_initcalls(void)
 int __init security_init(void)
 {
 	int i;
-	struct list_head *list = (struct list_head *) &security_hook_heads;
+	struct hlist_head *list = (struct hlist_head *) &security_hook_heads;
 
-	for (i = 0; i < sizeof(security_hook_heads) / sizeof(struct list_head);
+	for (i = 0; i < sizeof(security_hook_heads) / sizeof(struct hlist_head);
 	     i++)
-		INIT_LIST_HEAD(&list[i]);
+		INIT_HLIST_HEAD(&list[i]);
 	pr_info("Security Framework initialized\n");
 
 	/*
@@ -163,7 +163,7 @@ void __init security_add_hooks(struct security_hook_list *hooks, int count,
 
 	for (i = 0; i < count; i++) {
 		hooks[i].lsm = lsm;
-		list_add_tail_rcu(&hooks[i].list, hooks[i].head);
+		hlist_add_tail_rcu(&hooks[i].list, hooks[i].head);
 	}
 	if (lsm_append(lsm, &lsm_names) < 0)
 		panic("%s - Cannot get early memory.\n", __func__);
@@ -201,7 +201,7 @@ EXPORT_SYMBOL(unregister_lsm_notifier);
 	do {							\
 		struct security_hook_list *P;			\
 								\
-		list_for_each_entry(P, &security_hook_heads.FUNC, list)	\
+		hlist_for_each_entry(P, &security_hook_heads.FUNC, list) \
 			P->hook.FUNC(__VA_ARGS__);		\
 	} while (0)
 
@@ -210,7 +210,7 @@ EXPORT_SYMBOL(unregister_lsm_notifier);
 	do {							\
 		struct security_hook_list *P;			\
 								\
-		list_for_each_entry(P, &security_hook_heads.FUNC, list) { \
+		hlist_for_each_entry(P, &security_hook_heads.FUNC, list) { \
 			RC = P->hook.FUNC(__VA_ARGS__);		\
 			if (RC != 0)				\
 				break;				\
@@ -317,7 +317,7 @@ int security_vm_enough_memory_mm(struct mm_struct *mm, long pages)
 	 * agree that it should be set it will. If any module
 	 * thinks it should not be set it won't.
 	 */
-	list_for_each_entry(hp, &security_hook_heads.vm_enough_memory, list) {
+	hlist_for_each_entry(hp, &security_hook_heads.vm_enough_memory, list) {
 		rc = hp->hook.vm_enough_memory(mm, pages);
 		if (rc <= 0) {
 			cap_sys_admin = 0;
@@ -805,7 +805,7 @@ int security_inode_getsecurity(struct inode *inode, const char *name, void **buf
 	/*
 	 * Only one module will provide an attribute with a given name.
 	 */
-	list_for_each_entry(hp, &security_hook_heads.inode_getsecurity, list) {
+	hlist_for_each_entry(hp, &security_hook_heads.inode_getsecurity, list) {
 		rc = hp->hook.inode_getsecurity(inode, name, buffer, alloc);
 		if (rc != -EOPNOTSUPP)
 			return rc;
@@ -823,7 +823,7 @@ int security_inode_setsecurity(struct inode *inode, const char *name, const void
 	/*
 	 * Only one module will provide an attribute with a given name.
 	 */
-	list_for_each_entry(hp, &security_hook_heads.inode_setsecurity, list) {
+	hlist_for_each_entry(hp, &security_hook_heads.inode_setsecurity, list) {
 		rc = hp->hook.inode_setsecurity(inode, name, value, size,
 								flags);
 		if (rc != -EOPNOTSUPP)
@@ -1114,9 +1114,9 @@ int security_task_movememory(struct task_struct *p)
 }
 
 int security_task_kill(struct task_struct *p, struct siginfo *info,
-			int sig, u32 secid)
+			int sig, const struct cred *cred)
 {
-	return call_int_hook(task_kill, 0, p, info, sig, secid);
+	return call_int_hook(task_kill, 0, p, info, sig, cred);
 }
 
 int security_task_prctl(int option, unsigned long arg2, unsigned long arg3,
@@ -1126,7 +1126,7 @@ int security_task_prctl(int option, unsigned long arg2, unsigned long arg3,
 	int rc = -ENOSYS;
 	struct security_hook_list *hp;
 
-	list_for_each_entry(hp, &security_hook_heads.task_prctl, list) {
+	hlist_for_each_entry(hp, &security_hook_heads.task_prctl, list) {
 		thisrc = hp->hook.task_prctl(option, arg2, arg3, arg4, arg5);
 		if (thisrc != -ENOSYS) {
 			rc = thisrc;
@@ -1651,7 +1651,7 @@ int security_xfrm_state_pol_flow_match(struct xfrm_state *x,
 	 * For speed optimization, we explicitly break the loop rather than
 	 * using the macro
 	 */
-	list_for_each_entry(hp, &security_hook_heads.xfrm_state_pol_flow_match,
+	hlist_for_each_entry(hp, &security_hook_heads.xfrm_state_pol_flow_match,
 				list) {
 		rc = hp->hook.xfrm_state_pol_flow_match(x, xp, fl);
 		break;
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 0314fc766134..2b8c55e181ae 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -4156,16 +4156,19 @@ static int selinux_task_movememory(struct task_struct *p)
 }
 
 static int selinux_task_kill(struct task_struct *p, struct siginfo *info,
-				int sig, u32 secid)
+				int sig, const struct cred *cred)
 {
+	u32 secid;
 	u32 perm;
 
 	if (!sig)
 		perm = PROCESS__SIGNULL; /* null signal; existence test */
 	else
 		perm = signal_to_av(sig);
-	if (!secid)
+	if (!cred)
 		secid = current_sid();
+	else
+		secid = cred_sid(cred);
 	return avc_has_perm(&selinux_state,
 			    secid, task_sid(p), SECCLASS_PROCESS, perm, NULL);
 }
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 0735b8db158b..57fef8e04658 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -2228,15 +2228,13 @@ static int smack_task_movememory(struct task_struct *p)
  * @p: the task object
  * @info: unused
  * @sig: unused
- * @secid: identifies the smack to use in lieu of current's
+ * @cred: identifies the cred to use in lieu of current's
  *
  * Return 0 if write access is permitted
  *
- * The secid behavior is an artifact of an SELinux hack
- * in the USB code. Someday it may go away.
  */
 static int smack_task_kill(struct task_struct *p, struct siginfo *info,
-			   int sig, u32 secid)
+			   int sig, const struct cred *cred)
 {
 	struct smk_audit_info ad;
 	struct smack_known *skp;
@@ -2252,17 +2250,17 @@ static int smack_task_kill(struct task_struct *p, struct siginfo *info,
 	 * Sending a signal requires that the sender
 	 * can write the receiver.
 	 */
-	if (secid == 0) {
+	if (cred == NULL) {
 		rc = smk_curacc(tkp, MAY_DELIVER, &ad);
 		rc = smk_bu_task(p, MAY_DELIVER, rc);
 		return rc;
 	}
 	/*
-	 * If the secid isn't 0 we're dealing with some USB IO
+	 * If the cred isn't NULL we're dealing with some USB IO
 	 * specific behavior. This is not clean. For one thing
 	 * we can't take privilege into account.
 	 */
-	skp = smack_from_secid(secid);
+	skp = smk_of_task(cred->security);
 	rc = smk_access(skp, tkp, MAY_DELIVER, &ad);
 	rc = smk_bu_note("USB signal", skp, tkp, MAY_DELIVER, rc);
 	return rc;