From 3179216135ec09825d7c7875580951a6e69dc5df Mon Sep 17 00:00:00 2001 From: Vivek Goyal Date: Fri, 9 Oct 2020 14:15:09 -0400 Subject: fuse: setattr should set FATTR_KILL_SUIDGID If fc->handle_killpriv_v2 is enabled, we expect file server to clear suid/sgid/security.capbility upon chown/truncate/write as appropriate. Upon truncate (ATTR_SIZE), suid/sgid are cleared only if caller does not have CAP_FSETID. File server does not know whether caller has CAP_FSETID or not. Hence set FATTR_KILL_SUIDGID upon truncate to let file server know that caller does not have CAP_FSETID and it should kill suid/sgid as appropriate. On chown (ATTR_UID/ATTR_GID) suid/sgid need to be cleared irrespective of capabilities of calling process, so set FATTR_KILL_SUIDGID unconditionally in that case. Signed-off-by: Vivek Goyal Signed-off-by: Miklos Szeredi --- fs/fuse/dir.c | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'fs/fuse/dir.c') diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c index c3e22a3dd323..28b07ae5e55f 100644 --- a/fs/fuse/dir.c +++ b/fs/fuse/dir.c @@ -1648,10 +1648,20 @@ int fuse_do_setattr(struct dentry *dentry, struct iattr *attr, inarg.valid |= FATTR_FH; inarg.fh = ff->fh; } + + /* Kill suid/sgid for non-directory chown unconditionally */ + if (fc->handle_killpriv_v2 && !S_ISDIR(inode->i_mode) && + attr->ia_valid & (ATTR_UID | ATTR_GID)) + inarg.valid |= FATTR_KILL_SUIDGID; + if (attr->ia_valid & ATTR_SIZE) { /* For mandatory locking in truncate */ inarg.valid |= FATTR_LOCKOWNER; inarg.lock_owner = fuse_lock_owner_id(fc, current->files); + + /* Kill suid/sgid for truncate only if no CAP_FSETID */ + if (fc->handle_killpriv_v2 && !capable(CAP_FSETID)) + inarg.valid |= FATTR_KILL_SUIDGID; } fuse_setattr_fill(fc, &args, inode, &inarg, &outarg); err = fuse_simple_request(fm, &args); -- cgit v1.2.3