linux-kernel - [PATCH] fs: fix xattr permission checking error

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Date:   Sat, 21 Oct 2017 15:39:47 +0200
From:   Nicolas Belouin <nicolas@...ouin.fr>
To:     Dave Kleikamp <shaggy@...nel.org>, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, jfs-discussion@...ts.sourceforge.net
Cc:     Nicolas Belouin <nicolas@...ouin.fr>
Subject: [PATCH] fs: fix xattr permission checking error

Fix an issue making trusted xattr world readable and other
cap_sys_admin only

Signed-off-by: Nicolas Belouin <nicolas@...ouin.fr>
---
 fs/hfsplus/xattr.c | 2 +-
 fs/jfs/xattr.c     | 5 ++---
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/fs/hfsplus/xattr.c b/fs/hfsplus/xattr.c
index d37bb88dc746..ae03a19196ef 100644
--- a/fs/hfsplus/xattr.c
+++ b/fs/hfsplus/xattr.c
@@ -604,7 +604,7 @@ static inline int can_list(const char *xattr_name)
 	if (!xattr_name)
 		return 0;
 
-	return strncmp(xattr_name, XATTR_TRUSTED_PREFIX,
+	return !strncmp(xattr_name, XATTR_TRUSTED_PREFIX,
 			XATTR_TRUSTED_PREFIX_LEN) ||
 				capable(CAP_SYS_ADMIN);
 }
diff --git a/fs/jfs/xattr.c b/fs/jfs/xattr.c
index c60f3d32ee91..1c46573a96ed 100644
--- a/fs/jfs/xattr.c
+++ b/fs/jfs/xattr.c
@@ -858,9 +858,8 @@ ssize_t __jfs_getxattr(struct inode *inode, const char *name, void *data,
  */
 static inline int can_list(struct jfs_ea *ea)
 {
-	return (strncmp(ea->name, XATTR_TRUSTED_PREFIX,
-			    XATTR_TRUSTED_PREFIX_LEN) ||
-		capable(CAP_SYS_ADMIN));
+	return (!strncmp(ea->name, XATTR_TRUSTED_PREFIX,
+			 XATTR_TRUSTED_PREFIX_LEN) || capable(CAP_SYS_ADMIN));
 }
 
 ssize_t jfs_listxattr(struct dentry * dentry, char *data, size_t buf_size)
-- 
2.14.2