From 073931017b49d9458aa351605b43a7e34598caef Mon Sep 17 00:00:00 2001 From: Jan Kara 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 Reviewed-by: Jeff Layton Signed-off-by: Jan Kara Signed-off-by: Andreas Gruenbacher --- fs/ceph/acl.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) (limited to 'fs/ceph/acl.c') diff --git a/fs/ceph/acl.c b/fs/ceph/acl.c index 4f67227f69a5..d0b6b342dff9 100644 --- a/fs/ceph/acl.c +++ b/fs/ceph/acl.c @@ -95,11 +95,9 @@ int ceph_set_acl(struct inode *inode, struct posix_acl *acl, int type) case ACL_TYPE_ACCESS: name = XATTR_NAME_POSIX_ACL_ACCESS; if (acl) { - ret = posix_acl_equiv_mode(acl, &new_mode); - if (ret < 0) + ret = posix_acl_update_mode(inode, &new_mode, &acl); + if (ret) goto out; - if (ret == 0) - acl = NULL; } break; case ACL_TYPE_DEFAULT: -- cgit v1.2.3 From fd5472ed44683cf593322a2ef54b9a7675dc780a Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Thu, 26 May 2016 16:10:38 +0200 Subject: ceph: Propagate dentry down to inode_change_ok() To avoid clearing of capabilities or security related extended attributes too early, inode_change_ok() will need to take dentry instead of inode. ceph_setattr() has the dentry easily available but __ceph_setattr() is also called from ceph_set_acl() where dentry is not easily available. Luckily that call path does not need inode_change_ok() to be called anyway. So reorganize functions a bit so that inode_change_ok() is called only from paths where dentry is available. Reviewed-by: Christoph Hellwig Acked-by: Jeff Layton Signed-off-by: Jan Kara --- fs/ceph/acl.c | 5 +++++ fs/ceph/inode.c | 19 +++++++++++-------- 2 files changed, 16 insertions(+), 8 deletions(-) (limited to 'fs/ceph/acl.c') diff --git a/fs/ceph/acl.c b/fs/ceph/acl.c index d0b6b342dff9..987044bca1c2 100644 --- a/fs/ceph/acl.c +++ b/fs/ceph/acl.c @@ -125,6 +125,11 @@ int ceph_set_acl(struct inode *inode, struct posix_acl *acl, int type) goto out_free; } + if (ceph_snap(inode) != CEPH_NOSNAP) { + ret = -EROFS; + goto out_free; + } + if (new_mode != old_mode) { newattrs.ia_mode = new_mode; newattrs.ia_valid = ATTR_MODE; diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c index dd3a6dbf71eb..2aa3c0bcf3a5 100644 --- a/fs/ceph/inode.c +++ b/fs/ceph/inode.c @@ -1905,13 +1905,6 @@ int __ceph_setattr(struct inode *inode, struct iattr *attr) int inode_dirty_flags = 0; bool lock_snap_rwsem = false; - if (ceph_snap(inode) != CEPH_NOSNAP) - return -EROFS; - - err = inode_change_ok(inode, attr); - if (err != 0) - return err; - prealloc_cf = ceph_alloc_cap_flush(); if (!prealloc_cf) return -ENOMEM; @@ -2124,7 +2117,17 @@ out_put: */ int ceph_setattr(struct dentry *dentry, struct iattr *attr) { - return __ceph_setattr(d_inode(dentry), attr); + struct inode *inode = d_inode(dentry); + int err; + + if (ceph_snap(inode) != CEPH_NOSNAP) + return -EROFS; + + err = inode_change_ok(inode, attr); + if (err != 0) + return err; + + return __ceph_setattr(inode, attr); } /* -- cgit v1.2.3