From fe26569eb9197d845d73abe7dd20f603d79eb031 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Ernesto=20A=2E=20Fern=C3=A1ndez?= Date: Wed, 12 Jul 2017 06:54:19 -0300 Subject: [PATCH] ext2: preserve i_mode if ext2_set_acl() fails MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit When changing a file's acl mask, ext2_set_acl() will first set the group bits of i_mode to the value of the mask, and only then set the actual extended attribute representing the new acl. If the second part fails (due to lack of space, for example) and the file had no acl attribute to begin with, the system will from now on assume that the mask permission bits are actual group permission bits, potentially granting access to the wrong users. Prevent this by only changing the inode mode after the acl has been set. [JK: Rebased on top of "ext2: Don't clear SGID when inheriting ACLs"] Signed-off-by: Ernesto A. Fernández Signed-off-by: Jan Kara --- fs/ext2/acl.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/fs/ext2/acl.c b/fs/ext2/acl.c index 069c0dceda01..51f0aea70cb4 100644 --- a/fs/ext2/acl.c +++ b/fs/ext2/acl.c @@ -218,15 +218,22 @@ int ext2_set_acl(struct inode *inode, struct posix_acl *acl, int type) { int error; + int update_mode = 0; + umode_t mode = inode->i_mode; if (type == ACL_TYPE_ACCESS && acl) { - error = posix_acl_update_mode(inode, &inode->i_mode, &acl); + error = posix_acl_update_mode(inode, &mode, &acl); if (error) return error; + update_mode = 1; + } + error = __ext2_set_acl(inode, acl, type); + if (!error && update_mode) { + inode->i_mode = mode; inode->i_ctime = current_time(inode); mark_inode_dirty(inode); } - return __ext2_set_acl(inode, acl, type); + return error; } /* -- 2.20.1