linux-kernel - [PATCH 3.16 121/192] hfsplus: Don't clear SGID when inheriting ACLs

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Message-ID: <lsq.1507553064.328753784@decadent.org.uk>
Date:   Mon, 09 Oct 2017 13:44:24 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Jan Kara" <jack@...e.cz>
Subject: [PATCH 3.16 121/192] hfsplus: Don't clear SGID when inheriting ACLs

3.16.49-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Jan Kara <jack@...e.cz>

commit 84969465ddc4f8aeb3b993123b571aa01c5f2683 upstream.

When new directory 'DIR1' is created in a directory 'DIR0' with SGID bit
set, DIR1 is expected to have SGID bit set (and owning group equal to
the owning group of 'DIR0'). However when 'DIR0' also has some default
ACLs that 'DIR1' inherits, setting these ACLs will result in SGID bit on
'DIR1' to get cleared if user is not member of the owning group.

Fix the problem by creating __hfsplus_set_posix_acl() function that does
not call posix_acl_update_mode() and use it when inheriting ACLs. That
prevents SGID bit clearing and the mode has been properly set by
posix_acl_create() anyway.

Fixes: 073931017b49d9458aa351605b43a7e34598caef
Signed-off-by: Jan Kara <jack@...e.cz>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 fs/hfsplus/posix_acl.c | 30 ++++++++++++++++++------------
 1 file changed, 18 insertions(+), 12 deletions(-)

--- a/fs/hfsplus/posix_acl.c
+++ b/fs/hfsplus/posix_acl.c
@@ -54,8 +54,8 @@ struct posix_acl *hfsplus_get_posix_acl(
 	return acl;
 }
 
-int hfsplus_set_posix_acl(struct inode *inode, struct posix_acl *acl,
-		int type)
+static int __hfsplus_set_posix_acl(struct inode *inode, struct posix_acl *acl,
+				   int type)
 {
 	int err;
 	char *xattr_name;
@@ -67,12 +67,6 @@ int hfsplus_set_posix_acl(struct inode *
 	switch (type) {
 	case ACL_TYPE_ACCESS:
 		xattr_name = POSIX_ACL_XATTR_ACCESS;
-		if (acl) {
-			err = posix_acl_update_mode(inode, &inode->i_mode, &acl);
-			if (err)
-				return err;
-		}
-		err = 0;
 		break;
 
 	case ACL_TYPE_DEFAULT:
@@ -108,6 +102,18 @@ end_set_acl:
 	return err;
 }
 
+int hfsplus_set_posix_acl(struct inode *inode, struct posix_acl *acl, int type)
+{
+	int err;
+
+	if (type == ACL_TYPE_ACCESS && acl) {
+		err = posix_acl_update_mode(inode, &inode->i_mode, &acl);
+		if (err)
+			return err;
+	}
+	return __hfsplus_set_posix_acl(inode, acl, type);
+}
+
 int hfsplus_init_posix_acl(struct inode *inode, struct inode *dir)
 {
 	int err = 0;
@@ -125,15 +131,15 @@ int hfsplus_init_posix_acl(struct inode
 		return err;
 
 	if (default_acl) {
-		err = hfsplus_set_posix_acl(inode, default_acl,
-					    ACL_TYPE_DEFAULT);
+		err = __hfsplus_set_posix_acl(inode, default_acl,
+					      ACL_TYPE_DEFAULT);
 		posix_acl_release(default_acl);
 	}
 
 	if (acl) {
 		if (!err)
-			err = hfsplus_set_posix_acl(inode, acl,
-						    ACL_TYPE_ACCESS);
+			err = __hfsplus_set_posix_acl(inode, acl,
+						      ACL_TYPE_ACCESS);
 		posix_acl_release(acl);
 	}
 	return err;