From 073931017b49d9458aa351605b43a7e34598caef Mon Sep 17 00:00:00 2001 From: Jan Kara <jack@suse.cz> Date: Mon, 19 Sep 2016 17:39:09 +0200 Subject: posix_acl: Clear SGID bit when setting file permissions When file permissions are modified via chmod(2) and the user is not in the owning group or capable of CAP_FSETID, the setgid bit is cleared in inode_change_ok(). Setting a POSIX ACL via setxattr(2) sets the file permissions as well as the new ACL, but doesn't clear the setgid bit in a similar way; this allows to bypass the check in chmod(2). Fix that. References: CVE-2016-7097 Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com> --- fs/ext4/acl.c | 12 ++++-------- 1 file changed, 4 insertions(+), 8 deletions(-) (limited to 'fs/ext4') diff --git a/fs/ext4/acl.c b/fs/ext4/acl.c index c6601a4..dfa5199 100644 --- a/fs/ext4/acl.c +++ b/fs/ext4/acl.c @@ -193,15 +193,11 @@ __ext4_set_acl(handle_t *handle, struct inode *inode, int type, case ACL_TYPE_ACCESS: name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS; if (acl) { - error = posix_acl_equiv_mode(acl, &inode->i_mode); - if (error < 0) + error = posix_acl_update_mode(inode, &inode->i_mode, &acl); + if (error) return error; - else { - inode->i_ctime = ext4_current_time(inode); - ext4_mark_inode_dirty(handle, inode); - if (error == 0) - acl = NULL; - } + inode->i_ctime = ext4_current_time(inode); + ext4_mark_inode_dirty(handle, inode); } break; -- cgit v1.1 From 31051c85b5e2aaaf6315f74c72a732673632a905 Mon Sep 17 00:00:00 2001 From: Jan Kara <jack@suse.cz> Date: Thu, 26 May 2016 16:55:18 +0200 Subject: fs: Give dentry to inode_change_ok() instead of inode inode_change_ok() will be resposible for clearing capabilities and IMA extended attributes and as such will need dentry. Give it as an argument to inode_change_ok() instead of an inode. Also rename inode_change_ok() to setattr_prepare() to better relect that it does also some modifications in addition to checks. Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jan Kara <jack@suse.cz> --- fs/ext4/inode.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs/ext4') diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 3131747..fdf9bee 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -5073,7 +5073,7 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr) int orphan = 0; const unsigned int ia_valid = attr->ia_valid; - error = inode_change_ok(inode, attr); + error = setattr_prepare(dentry, attr); if (error) return error; -- cgit v1.1