[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[PULL 09/19] virtiofsd: Don't allow file creation with FUSE_OPEN
From: |
Dr. David Alan Gilbert (git) |
Subject: |
[PULL 09/19] virtiofsd: Don't allow file creation with FUSE_OPEN |
Date: |
Mon, 5 Jul 2021 11:02:25 +0100 |
From: Greg Kurz <groug@kaod.org>
A well behaved FUSE client uses FUSE_CREATE to create files. It isn't
supposed to pass O_CREAT along a FUSE_OPEN request, as documented in
the "fuse_lowlevel.h" header :
/**
* Open a file
*
* Open flags are available in fi->flags. The following rules
* apply.
*
* - Creation (O_CREAT, O_EXCL, O_NOCTTY) flags will be
* filtered out / handled by the kernel.
But if the client happens to do it anyway, the server ends up passing
this flag to open() without the mandatory mode_t 4th argument. Since
open() is a variadic function, glibc will happily pass whatever it
finds on the stack to the syscall. If this file is compiled with
-D_FORTIFY_SOURCE=2, glibc will even detect that and abort:
*** invalid openat64 call: O_CREAT or O_TMPFILE without mode ***: terminated
Specifying O_CREAT with FUSE_OPEN is a protocol violation. Check this
in do_open(), print out a message and return an error to the client,
EINVAL like we already do when fuse_mbuf_iter_advance() fails.
The FUSE filesystem doesn't currently support O_TMPFILE, but the very
same would happen if O_TMPFILE was passed in a FUSE_OPEN request. Check
that as well.
Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <20210624101809.48032-1-groug@kaod.org>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
tools/virtiofsd/fuse_lowlevel.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/tools/virtiofsd/fuse_lowlevel.c b/tools/virtiofsd/fuse_lowlevel.c
index 7fe2cef1eb..3d725bcba2 100644
--- a/tools/virtiofsd/fuse_lowlevel.c
+++ b/tools/virtiofsd/fuse_lowlevel.c
@@ -1084,6 +1084,12 @@ static void do_open(fuse_req_t req, fuse_ino_t nodeid,
return;
}
+ /* File creation is handled by do_create() or do_mknod() */
+ if (arg->flags & (O_CREAT | O_TMPFILE)) {
+ fuse_reply_err(req, EINVAL);
+ return;
+ }
+
memset(&fi, 0, sizeof(fi));
fi.flags = arg->flags;
fi.kill_priv = arg->open_flags & FUSE_OPEN_KILL_SUIDGID;
--
2.31.1
- [PULL v2 00/19] migration queue, Dr. David Alan Gilbert (git), 2021/07/05
- [PULL 01/19] tests: migration-test: Add dirty ring test, Dr. David Alan Gilbert (git), 2021/07/05
- [PULL 02/19] migration: fix the memory overwriting risk in add_to_iovec, Dr. David Alan Gilbert (git), 2021/07/05
- [PULL 03/19] migration: Move yank outside qemu_start_incoming_migration(), Dr. David Alan Gilbert (git), 2021/07/05
- [PULL 04/19] migration: Allow reset of postcopy_recover_triggered when failed, Dr. David Alan Gilbert (git), 2021/07/05
- [PULL 06/19] migration: failover: continue to wait card unplug on error, Dr. David Alan Gilbert (git), 2021/07/05
- [PULL 05/19] migration: move wait-unplug loop to its own function, Dr. David Alan Gilbert (git), 2021/07/05
- [PULL 07/19] virtiofsd: use GDateTime for formatting timestamp for debug messages, Dr. David Alan Gilbert (git), 2021/07/05
- [PULL 08/19] docs: describe the security considerations with virtiofsd xattr mapping, Dr. David Alan Gilbert (git), 2021/07/05
- [PULL 09/19] virtiofsd: Don't allow file creation with FUSE_OPEN,
Dr. David Alan Gilbert (git) <=
- [PULL 10/19] virtiofsd: Fix fuse setxattr() API change issue, Dr. David Alan Gilbert (git), 2021/07/05
- [PULL 11/19] virtiofsd: Fix xattr operations overwriting errno, Dr. David Alan Gilbert (git), 2021/07/05
- [PULL 12/19] virtiofsd: Add support for extended setxattr, Dr. David Alan Gilbert (git), 2021/07/05
- [PULL 13/19] virtiofsd: Add umask to seccom allow list, Dr. David Alan Gilbert (git), 2021/07/05
- [PULL 14/19] virtiofsd: Add capability to change/restore umask, Dr. David Alan Gilbert (git), 2021/07/05
- [PULL 15/19] virtiofsd: Switch creds, drop FSETID for system.posix_acl_access xattr, Dr. David Alan Gilbert (git), 2021/07/05
- [PULL 16/19] virtiofsd: Add an option to enable/disable posix acls, Dr. David Alan Gilbert (git), 2021/07/05
- [PULL 17/19] tests/migration: parse the thread-id key of CpuInfoFast, Dr. David Alan Gilbert (git), 2021/07/05
- [PULL 18/19] tests/migration: fix "downtime_limit" type when "migrate-set-parameters", Dr. David Alan Gilbert (git), 2021/07/05
- [PULL 19/19] migration/rdma: Use error_report to suppress errno message, Dr. David Alan Gilbert (git), 2021/07/05