From a21ba54dd5ca38cd05da9035fc65374d7af54f13 Mon Sep 17 00:00:00 2001 From: Vivek Goyal Date: Fri, 29 Jul 2022 09:17:06 -0400 Subject: [PATCH] virtiofsd: Disable killpriv_v2 by default We are having bunch of issues with killpriv_v2 enabled by default. First of all it relies on clearing suid/sgid bits as needed by dropping capability CAP_FSETID. This does not work for remote filesystems like NFS (and possibly others). Secondly, we are noticing other issues related to clearing of SGID which leads to failures for xfstests generic/355 and generic/193. Thirdly, there are other issues w.r.t caching of metadata (suid/sgid) bits in fuse client with killpriv_v2 enabled. Guest can cache that data for sometime even if cleared on server. Second and Third issue are fixable. Just that it might take a little while to get it fixed in kernel. First one will probably not see any movement for a long time. Given these issues, killpriv_v2 does not seem to be a good candidate for enabling by default. We have already disabled it by default in rust version of virtiofsd. Hence this patch disabled killpriv_v2 by default. User can choose to enable it by passing option "-o killpriv_v2". Signed-off-by: Vivek Goyal Message-Id: Reviewed-by: Dr. David Alan Gilbert Signed-off-by: Dr. David Alan Gilbert --- tools/virtiofsd/passthrough_ll.c | 13 ++----------- 1 file changed, 2 insertions(+), 11 deletions(-) diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c index 7a73dfcce9..371a7bead6 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -767,19 +767,10 @@ static void lo_init(void *userdata, struct fuse_conn_info *conn) fuse_log(FUSE_LOG_DEBUG, "lo_init: enabling killpriv_v2\n"); conn->want |= FUSE_CAP_HANDLE_KILLPRIV_V2; lo->killpriv_v2 = 1; - } else if (lo->user_killpriv_v2 == -1 && - conn->capable & FUSE_CAP_HANDLE_KILLPRIV_V2) { - /* - * User did not specify a value for killpriv_v2. By default enable it - * if connection offers this capability - */ - fuse_log(FUSE_LOG_DEBUG, "lo_init: enabling killpriv_v2\n"); - conn->want |= FUSE_CAP_HANDLE_KILLPRIV_V2; - lo->killpriv_v2 = 1; } else { /* - * Either user specified to disable killpriv_v2, or connection does - * not offer this capability. Disable killpriv_v2 in both the cases + * Either user specified to disable killpriv_v2, or did not + * specify anything. Disable killpriv_v2 in both the cases. */ fuse_log(FUSE_LOG_DEBUG, "lo_init: disabling killpriv_v2\n"); conn->want &= ~FUSE_CAP_HANDLE_KILLPRIV_V2; -- 2.30.2