apparmor/kernel-patches/for-mainline/change_profile-spin-onstale.diff

change the way change_profile/change_hat work so that they spin on stale
instead of taking the interface lock

---
 security/apparmor/main.c     |   85 ++++++++++++++++++++++++++++---------------
 security/apparmor/procattr.c |    4 --
 2 files changed, 56 insertions(+), 33 deletions(-)

--- a/security/apparmor/main.c
+++ b/security/apparmor/main.c
@@ -931,8 +931,8 @@ repeat:
 
 enum { change_profile, permanent_change_profile, restore_profile };
 
-static int do_change_profile(const char *name, u64 cookie, int mode,
-			     struct aa_audit *sa)
+static int do_change_profile(struct aa_profile *expected, const char *name,
+			     u64 cookie, int mode, struct aa_audit *sa)
 {
 	struct aa_profile *profile = NULL, *previous_profile = NULL;
 	struct aa_task_context *new_cxt, *cxt;
@@ -954,6 +954,11 @@ static int do_change_profile(const char 
 		goto out;
 	}
 
+	if (cxt->profile != expected) {
+		error = -ESTALE;
+		goto out;
+	}
+
 	if (cxt->previous_profile) {
 		if (cxt->cookie != cookie) {
 			error = -EACCES;
@@ -1020,7 +1025,7 @@ out:
  */
 int aa_change_profile(const char *name, u64 cookie, int permanent)
 {
-	struct aa_task_context *cxt;
+	struct aa_profile *profile;
 	struct aa_audit sa;
 	int error = 0;
 
@@ -1029,41 +1034,49 @@ int aa_change_profile(const char *name, 
 	sa.cookie = cookie;
 	sa.operation = "change_profile";
 
-	mutex_lock(&aa_interface_lock);
-
-	cxt = aa_task_context(current);
-	if (!cxt) {
-		mutex_unlock(&aa_interface_lock);
+repeat:
+	profile = aa_get_profile(current);
+	if (!profile)
 		return -EPERM;
-	}
 
 	if (name) {
-		if (cxt->profile != null_complain_profile &&
-		    !(aa_match(cxt->profile->file_rules, name) &
+		if (profile != null_complain_profile &&
+		    !(aa_match(profile->file_rules, name) &
 		      AA_CHANGE_PROFILE)) {
 			/* no permission to transition to profile @name */
-			mutex_unlock(&aa_interface_lock);
+			aa_put_profile(profile);
 			return -EACCES;
 		}
 		if (permanent)
-			error = do_change_profile(name, cookie,
+			error = do_change_profile(profile, name, cookie,
 						  permanent_change_profile,
 						  &sa);
 		else
-			error = do_change_profile(name, cookie, change_profile,
-						  &sa);
+			error = do_change_profile(profile, name, cookie,
+						  change_profile, &sa);
 	} else {
-		if (cxt->previous_profile)
-			error = do_change_profile(cxt->previous_profile->name,
+		struct aa_profile *previous_profile;
+		task_lock(current);
+		previous_profile =
+		    aa_dup_profile(aa_task_context(current)->previous_profile);
+		task_unlock(current);
+
+		if (previous_profile)
+			error = do_change_profile(profile,
+						  previous_profile->name,
 						  cookie, restore_profile,
 						  &sa);
+		aa_put_profile(previous_profile);
 		/* else
 		 * Ignore change_profile to restore_previous profile when
 		 * it doesn't exist
 		 */
 	}
 
-	mutex_unlock(&aa_interface_lock);
+	aa_put_profile(profile);
+	if (error == -ESTALE)
+		goto repeat;
+
 	return error;
 }
 
@@ -1081,6 +1094,7 @@ int aa_change_profile(const char *name, 
 int aa_change_hat(const char *hat_name, u64 cookie)
 {
 	struct aa_task_context *cxt;
+	struct aa_profile *profile, *previous_profile;
 	struct aa_audit sa;
 	int error = 0;
 
@@ -1089,35 +1103,42 @@ int aa_change_hat(const char *hat_name, 
 	sa.cookie = cookie;
 	sa.operation = "change_hat";
 
-	mutex_lock(&aa_interface_lock);
+repeat:
+	task_lock(current);
 	cxt = aa_task_context(current);
 	if (!cxt) {
-		mutex_unlock(&aa_interface_lock);
+		task_unlock(current);
 		return -EPERM;
 	}
 	/* FIXME: there is currently no way to tell if a profile doesn't have
 	 * hats so that we can return -ECHILD
 	 */
 
+	profile = aa_dup_profile(cxt->profile);
+	previous_profile = aa_dup_profile(cxt->previous_profile);
+	task_unlock(current);
+
 	if (hat_name) {
 		char *name, *profile_name;
-		if (cxt->previous_profile)
-			profile_name = cxt->previous_profile->name;
+		if (previous_profile)
+			profile_name = previous_profile->name;
 		else
-			profile_name = cxt->profile->name;
+			profile_name = profile->name;
 
 		name = kmalloc(strlen(hat_name) + 3 + strlen(profile_name),
 			       GFP_KERNEL);
 		if (!name) {
-			mutex_unlock(&aa_interface_lock);
-			return -ENOMEM;
+			error = -ENOMEM;
+			goto out;
 		}
 		sprintf(name, "%s//%s", profile_name, hat_name);
-		error = do_change_profile(name, cookie, change_profile, &sa);
+		error = do_change_profile(profile, name, cookie,
+					  change_profile, &sa);
 		kfree(name);
 	} else {
-		if (cxt->previous_profile)
-			error = do_change_profile(cxt->previous_profile->name,
+		if (previous_profile)
+			error = do_change_profile(profile,
+						  previous_profile->name,
 						  cookie, restore_profile,
 						  &sa);
 		/* else
@@ -1125,7 +1146,13 @@ int aa_change_hat(const char *hat_name, 
 		 * no profile to restore
 		 */
 	}
-	mutex_unlock(&aa_interface_lock);
+
+out:
+	aa_put_profile(previous_profile);
+	aa_put_profile(profile);
+	if (error == -ESTALE)
+		goto repeat;
+
 	return error;
 }
 
--- a/security/apparmor/procattr.c
+++ b/security/apparmor/procattr.c
@@ -118,7 +118,6 @@ int aa_setprocattr_setprofile(struct tas
 	AA_DEBUG("%s: current %d\n",
 		 __FUNCTION__, current->pid);
 
-	mutex_lock(&aa_interface_lock);
 repeat:
 	if (strcmp(args, "unconfined") == 0)
 		new_profile = NULL;
@@ -128,7 +127,6 @@ repeat:
 			sa.name = args;
 			sa.info = "unknown profile";
 			aa_audit_reject(NULL, &sa);
-			mutex_unlock(&aa_interface_lock);
 			return -EINVAL;
 		}
 	}
@@ -141,7 +139,6 @@ repeat:
 		error = PTR_ERR(old_profile);
 		if (error == -ESTALE)
 			goto repeat;
-		mutex_unlock(&aa_interface_lock);
 		return error;
 	}
 
@@ -162,6 +159,5 @@ repeat:
 	}
 	aa_put_profile(old_profile);
 	aa_put_profile(new_profile);
-	mutex_unlock(&aa_interface_lock);
 	return 0;
 }