linux-kernel - Re: [RFC v7 22/41] richacl: Propagate everyone@ permissions to other aces

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Date:	Wed, 23 Sep 2015 03:39:44 +0200
From:	Andreas Gruenbacher <agruenba@...hat.com>
To:	"J. Bruce Fields" <bfields@...ldses.org>
Cc:	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	linux-nfs@...r.kernel.org, linux-api@...r.kernel.org,
	linux-cifs@...r.kernel.org, linux-security-module@...r.kernel.org
Subject: Re: [RFC v7 22/41] richacl: Propagate everyone@ permissions to other aces

Here are my improvements; hope that helps ...

Thanks,
Andreas

diff --git a/fs/richacl_compat.c b/fs/richacl_compat.c
index 9b76fc0..21af9a0 100644
--- a/fs/richacl_compat.c
+++ b/fs/richacl_compat.c
@@ -351,26 +351,26 @@ richacl_propagate_everyone(struct richacl_alloc *alloc)
 	struct richace *ace;
 	unsigned int owner_allow, group_allow;
 
-	/*
-	 * If the owner mask contains permissions which are not in the group
-	 * mask, the group mask contains permissions which are not in the other
-	 * mask, or the owner class contains permissions which are not in the
-	 * other mask, we may need to propagate permissions up from the
-	 * everyone@ allow ace.  The third condition is implied by the first
-	 * two.
-	 */
-	if (!((acl->a_owner_mask & ~acl->a_group_mask) ||
-	      (acl->a_group_mask & ~acl->a_other_mask)))
-		return 0;
 	if (!acl->a_count)
 		return 0;
 	ace = acl->a_entries + acl->a_count - 1;
 	if (richace_is_inherit_only(ace) || !richace_is_everyone(ace))
 		return 0;
 
+	/*
+	 * Permissions the owner and group class are granted through the
+	 * trailing everyone@ allow ace.
+	 */
 	owner_allow = ace->e_mask & acl->a_owner_mask;
 	group_allow = ace->e_mask & acl->a_group_mask;
 
+	/*
+	 * If the group or other masks hide permissions which the owner should
+	 * be allowed, we need to propagate those permissions up.  Otherwise,
+	 * those permissions may be lost when applying the other mask to the
+	 * trailing everyone@ allow ace, or when isolating the group class from
+	 * the other class through additional deny aces.
+	 */
 	if (owner_allow & ~(acl->a_group_mask & acl->a_other_mask)) {
 		/* Propagate everyone@ permissions through to owner@. */
 		who.e_id.special = RICHACE_OWNER_SPECIAL_ID;
@@ -379,6 +379,11 @@ richacl_propagate_everyone(struct richacl_alloc *alloc)
 		acl = alloc->acl;
 	}
 
+	/*
+	 * If the other mask hides permissions which the group class should be
+	 * allowed, we need to propagate those permissions up to the owning
+	 * group and to all other members in the group class.
+	 */
 	if (group_allow & ~acl->a_other_mask) {
 		int n;
 
@@ -399,16 +404,15 @@ richacl_propagate_everyone(struct richacl_alloc *alloc)
 			    richace_is_owner(ace) ||
 			    richace_is_group(ace))
 				continue;
-			if (richace_is_allow(ace) || richace_is_deny(ace)) {
-				/*
-				 * Any inserted entry will end up below the
-				 * current entry
-				 */
-				if (__richacl_propagate_everyone(alloc, ace,
-								 group_allow))
-					return -1;
-				acl = alloc->acl;
-			}
+
+			/*
+			 * Any inserted entry will end up below the current
+			 * entry.
+			 */
+			if (__richacl_propagate_everyone(alloc, ace,
+							 group_allow))
+				return -1;
+			acl = alloc->acl;
 		}
 	}
 	return 0;
-- 
2.4.3

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