qemu/tools/virtiofsd/passthrough_seccomp.c
Vivek Goyal 04d325e86f virtiofsd: Used glib "shared" thread pool
glib offers thread pools and it seems to support "exclusive" and "shared"
thread pools.

https://developer.gnome.org/glib/stable/glib-Thread-Pools.html#g-thread-pool-new

Currently we use "exlusive" thread pools but its performance seems to be
poor. I tried using "shared" thread pools and performance seems much
better. I posted performance results here.

https://www.redhat.com/archives/virtio-fs/2020-September/msg00080.html

So lets switch to shared thread pools. We can think of making it optional
once somebody can show in what cases exclusive thread pools offer better
results. For now, my simple performance tests across the board see
better results with shared thread pools.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Message-Id: <20200921213216.GE13362@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
  With seccomp fix from Miklos
2020-09-25 12:45:58 +01:00

175 lines
4.2 KiB
C

/*
* Seccomp sandboxing for virtiofsd
*
* Copyright (C) 2019 Red Hat, Inc.
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "qemu/osdep.h"
#include "passthrough_seccomp.h"
#include "fuse_i.h"
#include "fuse_log.h"
#include <errno.h>
#include <glib.h>
#include <seccomp.h>
#include <stdlib.h>
/* Bodge for libseccomp 2.4.2 which broke ppoll */
#if !defined(__SNR_ppoll) && defined(__SNR_brk)
#ifdef __NR_ppoll
#define __SNR_ppoll __NR_ppoll
#else
#define __SNR_ppoll __PNR_ppoll
#endif
#endif
static const int syscall_whitelist[] = {
/* TODO ireg sem*() syscalls */
SCMP_SYS(brk),
SCMP_SYS(capget), /* For CAP_FSETID */
SCMP_SYS(capset),
SCMP_SYS(clock_gettime),
SCMP_SYS(clone),
#ifdef __NR_clone3
SCMP_SYS(clone3),
#endif
SCMP_SYS(close),
SCMP_SYS(copy_file_range),
SCMP_SYS(dup),
SCMP_SYS(eventfd2),
SCMP_SYS(exit),
SCMP_SYS(exit_group),
SCMP_SYS(fallocate),
SCMP_SYS(fchdir),
SCMP_SYS(fchmod),
SCMP_SYS(fchmodat),
SCMP_SYS(fchownat),
SCMP_SYS(fcntl),
SCMP_SYS(fdatasync),
SCMP_SYS(fgetxattr),
SCMP_SYS(flistxattr),
SCMP_SYS(flock),
SCMP_SYS(fremovexattr),
SCMP_SYS(fsetxattr),
SCMP_SYS(fstat),
SCMP_SYS(fstatfs),
SCMP_SYS(fsync),
SCMP_SYS(ftruncate),
SCMP_SYS(futex),
SCMP_SYS(getdents),
SCMP_SYS(getdents64),
SCMP_SYS(getegid),
SCMP_SYS(geteuid),
SCMP_SYS(getpid),
SCMP_SYS(gettid),
SCMP_SYS(gettimeofday),
SCMP_SYS(getxattr),
SCMP_SYS(linkat),
SCMP_SYS(listxattr),
SCMP_SYS(lseek),
SCMP_SYS(madvise),
SCMP_SYS(mkdirat),
SCMP_SYS(mknodat),
SCMP_SYS(mmap),
SCMP_SYS(mprotect),
SCMP_SYS(mremap),
SCMP_SYS(munmap),
SCMP_SYS(newfstatat),
SCMP_SYS(open),
SCMP_SYS(openat),
SCMP_SYS(ppoll),
SCMP_SYS(prctl), /* TODO restrict to just PR_SET_NAME? */
SCMP_SYS(preadv),
SCMP_SYS(pread64),
SCMP_SYS(pwritev),
SCMP_SYS(pwrite64),
SCMP_SYS(read),
SCMP_SYS(readlinkat),
SCMP_SYS(recvmsg),
SCMP_SYS(renameat),
SCMP_SYS(renameat2),
SCMP_SYS(removexattr),
SCMP_SYS(rt_sigaction),
SCMP_SYS(rt_sigprocmask),
SCMP_SYS(rt_sigreturn),
SCMP_SYS(sched_getattr),
SCMP_SYS(sched_setattr),
SCMP_SYS(sendmsg),
SCMP_SYS(setresgid),
SCMP_SYS(setresuid),
#ifdef __NR_setresgid32
SCMP_SYS(setresgid32),
#endif
#ifdef __NR_setresuid32
SCMP_SYS(setresuid32),
#endif
SCMP_SYS(set_robust_list),
SCMP_SYS(setxattr),
SCMP_SYS(symlinkat),
SCMP_SYS(time), /* Rarely needed, except on static builds */
SCMP_SYS(tgkill),
SCMP_SYS(unlinkat),
SCMP_SYS(unshare),
SCMP_SYS(utimensat),
SCMP_SYS(write),
SCMP_SYS(writev),
};
/* Syscalls used when --syslog is enabled */
static const int syscall_whitelist_syslog[] = {
SCMP_SYS(sendto),
};
static void add_whitelist(scmp_filter_ctx ctx, const int syscalls[], size_t len)
{
size_t i;
for (i = 0; i < len; i++) {
if (seccomp_rule_add(ctx, SCMP_ACT_ALLOW, syscalls[i], 0) != 0) {
fuse_log(FUSE_LOG_ERR, "seccomp_rule_add syscall %d failed\n",
syscalls[i]);
exit(1);
}
}
}
void setup_seccomp(bool enable_syslog)
{
scmp_filter_ctx ctx;
#ifdef SCMP_ACT_KILL_PROCESS
ctx = seccomp_init(SCMP_ACT_KILL_PROCESS);
/* Handle a newer libseccomp but an older kernel */
if (!ctx && errno == EOPNOTSUPP) {
ctx = seccomp_init(SCMP_ACT_TRAP);
}
#else
ctx = seccomp_init(SCMP_ACT_TRAP);
#endif
if (!ctx) {
fuse_log(FUSE_LOG_ERR, "seccomp_init() failed\n");
exit(1);
}
add_whitelist(ctx, syscall_whitelist, G_N_ELEMENTS(syscall_whitelist));
if (enable_syslog) {
add_whitelist(ctx, syscall_whitelist_syslog,
G_N_ELEMENTS(syscall_whitelist_syslog));
}
/* libvhost-user calls this for post-copy migration, we don't need it */
if (seccomp_rule_add(ctx, SCMP_ACT_ERRNO(ENOSYS),
SCMP_SYS(userfaultfd), 0) != 0) {
fuse_log(FUSE_LOG_ERR, "seccomp_rule_add userfaultfd failed\n");
exit(1);
}
if (seccomp_load(ctx) < 0) {
fuse_log(FUSE_LOG_ERR, "seccomp_load() failed\n");
exit(1);
}
seccomp_release(ctx);
}