On 1/21/20 8:49 PM, Dr. David Alan Gilbert wrote:
> * Philippe Mathieu-Daudé (philmd@redhat.com) wrote:
>> On 1/21/20 1:23 PM, Dr. David Alan Gilbert (git) wrote:
>>> From: Stefan Hajnoczi <stefanha@redhat.com>
>>>
>>> Only allow system calls that are needed by virtiofsd. All other system
>>> calls cause SIGSYS to be directed at the thread and the process will
>>> coredump.
>>>
>>> Restricting system calls reduces the kernel attack surface and limits
>>> what the process can do when compromised.
>>>
>>> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
>>> with additional entries by:
>>> Signed-off-by: Ganesh Maharaj Mahalingam <ganesh.mahalingam@intel.com>
>>> Signed-off-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
>>> Signed-off-by: Misono Tomohiro <misono.tomohiro@jp.fujitsu.com>
>>> Signed-off-by: piaojun <piaojun@huawei.com>
>>> Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
>>> Signed-off-by: Eric Ren <renzhen@linux.alibaba.com>
>>> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
>>> ---
>>> Makefile | 2 +-
>>> tools/virtiofsd/Makefile.objs | 5 +-
>>> tools/virtiofsd/passthrough_ll.c | 2 +
>>> tools/virtiofsd/seccomp.c | 150 +++++++++++++++++++++++++++++++
>>> tools/virtiofsd/seccomp.h | 14 +++
>>> 5 files changed, 171 insertions(+), 2 deletions(-)
>>> create mode 100644 tools/virtiofsd/seccomp.c
>>> create mode 100644 tools/virtiofsd/seccomp.h
>>>
>>> diff --git a/Makefile b/Makefile
>>> index a87e06ad93..967d59c98a 100644
>>> --- a/Makefile
>>> +++ b/Makefile
>>> @@ -327,7 +327,7 @@ HELPERS-y += vhost-user-gpu$(EXESUF)
>>> vhost-user-json-y += contrib/vhost-user-gpu/50-qemu-gpu.json
>>> endif
>>> -ifdef CONFIG_LINUX
>>> +ifeq ($(CONFIG_LINUX)$(CONFIG_SECCOMP),yy)
>>> HELPERS-y += virtiofsd$(EXESUF)
>>
>> Something is weird here, because I got:
>>
>> $ make virtiofsd
>> ...
>> CC tools/virtiofsd/seccomp.o
>> tools/virtiofsd/seccomp.c:14:21: fatal error: seccomp.h: No such file or
>> directory
>> #include <seccomp.h>
>> ^
>>
>> Indeed I don't have libseccomp installed, ./configure reported:
>>
>> ...
>> QGA MSI support no
>> seccomp support no
>> coroutine backend ucontext
>> coroutine pool yes
>> debug stack usage no
>> ...
>>
>> Note also:
>>
>> $ make print-CONFIG_LINUX
>> CONFIG_LINUX=y
>> $ make print-CONFIG_SECCOMP
>> CONFIG_SECCOMP=
>> $ make print-CONFIG_LIBCAP_NG
>> CONFIG_LIBCAP_NG=y
>> $ make print-HELPERS-y
>> HELPERS-y=qemu-bridge-helper
>
> The same thing happens if you uninstall mesa-libgbm-devel and do a
> 'make vhost-user-gpu'
>
> These ifeq's don't remove the definition of the target, they just remove
> it from the HELPERS-y list, so stop it being built on an unqualified
> 'make' but don't change the behaviour when you explicitly ask for the
> target.
>
> Can you try:
>
> diff --git a/Makefile b/Makefile
> index ba7e2e5ebc..346a981f0e 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -676,8 +676,9 @@ vhost-user-blk$(EXESUF): $(vhost-user-blk-obj-y) libvhost-user.a
> rdmacm-mux$(EXESUF): LIBS += "-libumad"
> rdmacm-mux$(EXESUF): $(rdmacm-mux-obj-y) $(COMMON_LDADDS)
> $(call LINK, $^)
> -
> -ifdef CONFIG_LINUX # relies on Linux-specific syscalls
> +#
> +# relies on Linux specific syscalls
> +ifeq ($(CONFIG_LINUX)$(CONFIG_SECCOMP)$(CONFIG_LIBCAP_NG),yyy)
> virtiofsd$(EXESUF): $(virtiofsd-obj-y) libvhost-user.a $(COMMON_LDADDS)
> $(call LINK, $^)
> endif
$ make print-HELPERS-y
HELPERS-y=qemu-bridge-helper
$ make virtiofsd
GEN config-host.h
make[1]: Entering directory 'slirp'
CC slirp/src/state.o
CC slirp/src/tcp_timer.o
CC slirp/src/dhcpv6.o
CC slirp/src/ip_input.o
CC slirp/src/ip6_icmp.o
CC slirp/src/bootp.o
CC slirp/src/ip6_input.o
CC slirp/src/slirp.o
CC slirp/src/vmstate.o
CC slirp/src/ip_output.o
CC slirp/src/ncsi.o
CC slirp/src/tcp_output.o
CC slirp/src/ndp_table.o
CC slirp/src/version.o
CC slirp/src/misc.o
CC slirp/src/ip6_output.o
CC slirp/src/mbuf.o
CC slirp/src/tftp.o
CC slirp/src/arp_table.o
CC slirp/src/util.o
CC slirp/src/socket.o
CC slirp/src/sbuf.o
CC slirp/src/stream.o
CC slirp/src/dnssearch.o
CC slirp/src/udp.o
CC slirp/src/tcp_input.o
CC slirp/src/if.o
CC slirp/src/cksum.o
CC slirp/src/tcp_subr.o
CC slirp/src/udp6.o
CC slirp/src/ip_icmp.o
AR slirp/libslirp.a
make[1]: Leaving directory 'slirp'
DEP dtc/libfdt/fdt_overlay.c
DEP dtc/libfdt/fdt_addresses.c
DEP dtc/libfdt/fdt_empty_tree.c
DEP dtc/libfdt/fdt_strerror.c
DEP dtc/libfdt/fdt_rw.c
DEP dtc/libfdt/fdt_sw.c
DEP dtc/libfdt/fdt_wip.c
DEP dtc/libfdt/fdt_ro.c
DEP dtc/libfdt/fdt.c
DEP dtc/util.c
DEP dtc/fdtoverlay.c
DEP dtc/fdtput.c
DEP dtc/fdtget.c
DEP dtc/fdtdump.c
DEP convert-dtsv0-lexer.lex.c
DEP dtc/srcpos.c
DEP dtc-parser.tab.c
DEP dtc-lexer.lex.c
DEP dtc/treesource.c
DEP dtc/livetree.c
DEP dtc/fstree.c
DEP dtc/flattree.c
DEP dtc/dtc.c
DEP dtc/data.c
DEP dtc/checks.c
CC libfdt/fdt.o
CC libfdt/fdt_ro.o
CC libfdt/fdt_wip.o
CC libfdt/fdt_sw.o
CC libfdt/fdt_rw.o
CC libfdt/fdt_strerror.o
CC libfdt/fdt_empty_tree.o
CC libfdt/fdt_addresses.o
CC libfdt/fdt_overlay.o
AR libfdt/libfdt.a
r - libfdt/fdt.o
r - libfdt/fdt_ro.o
r - libfdt/fdt_wip.o
r - libfdt/fdt_sw.o
r - libfdt/fdt_rw.o
r - libfdt/fdt_strerror.o
r - libfdt/fdt_empty_tree.o
r - libfdt/fdt_addresses.o
r - libfdt/fdt_overlay.o
CC cs.o
CC utils.o
CC SStream.o
CC MCInstrDesc.o
CC MCRegisterInfo.o
CC arch/ARM/ARMDisassembler.o
CC arch/ARM/ARMInstPrinter.o
CC arch/ARM/ARMMapping.o
CC arch/ARM/ARMModule.o
CC arch/AArch64/AArch64BaseInfo.o
CC arch/AArch64/AArch64Disassembler.o
CC arch/AArch64/AArch64InstPrinter.o
CC arch/AArch64/AArch64Mapping.o
CC arch/AArch64/AArch64Module.o
CC arch/Mips/MipsDisassembler.o
CC arch/Mips/MipsInstPrinter.o
CC arch/Mips/MipsMapping.o
CC arch/Mips/MipsModule.o
CC arch/PowerPC/PPCDisassembler.o
CC arch/PowerPC/PPCInstPrinter.o
CC arch/PowerPC/PPCMapping.o
CC arch/PowerPC/PPCModule.o
CC arch/Sparc/SparcDisassembler.o
CC arch/Sparc/SparcInstPrinter.o
CC arch/Sparc/SparcMapping.o
CC arch/Sparc/SparcModule.o
CC arch/SystemZ/SystemZDisassembler.o
CC arch/SystemZ/SystemZInstPrinter.o
CC arch/SystemZ/SystemZMapping.o
CC arch/SystemZ/SystemZModule.o
CC arch/SystemZ/SystemZMCTargetDesc.o
CC arch/X86/X86DisassemblerDecoder.o
CC arch/X86/X86Disassembler.o
CC arch/X86/X86IntelInstPrinter.o
CC arch/X86/X86ATTInstPrinter.o
CC arch/X86/X86Mapping.o
CC arch/X86/X86Module.o
CC arch/XCore/XCoreDisassembler.o
CC arch/XCore/XCoreInstPrinter.o
CC arch/XCore/XCoreMapping.o
CC arch/XCore/XCoreModule.o
CC MCInst.o
AR libcapstone.a
GEN trace/generated-tcg-tracers.h
GEN trace/generated-helpers-wrappers.h
GEN trace/generated-helpers.h
GEN trace/generated-helpers.c
GEN module_block.h
GEN trace-root.h
GEN accel/kvm/trace.h
GEN accel/tcg/trace.h
GEN backends/trace.h
GEN crypto/trace.h
GEN monitor/trace.h
GEN linux-user/trace.h
GEN authz/trace.h
GEN block/trace.h
GEN io/trace.h
GEN nbd/trace.h
GEN scsi/trace.h
GEN chardev/trace.h
GEN audio/trace.h
GEN hw/9pfs/trace.h
GEN hw/acpi/trace.h
GEN hw/alpha/trace.h
GEN hw/arm/trace.h
GEN hw/audio/trace.h
GEN hw/block/trace.h
GEN hw/block/dataplane/trace.h
GEN hw/char/trace.h
GEN hw/dma/trace.h
GEN hw/hppa/trace.h
GEN hw/i2c/trace.h
GEN hw/i386/trace.h
GEN hw/i386/xen/trace.h
GEN hw/ide/trace.h
GEN hw/input/trace.h
GEN hw/intc/trace.h
GEN hw/isa/trace.h
GEN hw/mem/trace.h
GEN hw/mips/trace.h
GEN hw/misc/trace.h
GEN hw/misc/macio/trace.h
GEN hw/net/trace.h
GEN hw/nvram/trace.h
GEN hw/pci/trace.h
GEN hw/pci-host/trace.h
GEN hw/ppc/trace.h
GEN hw/rdma/trace.h
GEN hw/rdma/vmw/trace.h
GEN hw/rtc/trace.h
GEN hw/s390x/trace.h
GEN hw/scsi/trace.h
GEN hw/sd/trace.h
GEN hw/sparc/trace.h
GEN hw/sparc64/trace.h
GEN hw/timer/trace.h
GEN hw/tpm/trace.h
GEN hw/usb/trace.h
GEN hw/vfio/trace.h
GEN hw/virtio/trace.h
GEN hw/watchdog/trace.h
GEN hw/xen/trace.h
GEN hw/gpio/trace.h
GEN hw/riscv/trace.h
GEN migration/trace.h
GEN net/trace.h
GEN ui/trace.h
GEN hw/display/trace.h
GEN qapi/trace.h
GEN qom/trace.h
GEN target/arm/trace.h
GEN target/hppa/trace.h
GEN target/i386/trace.h
GEN target/mips/trace.h
GEN target/ppc/trace.h
GEN target/riscv/trace.h
GEN target/s390x/trace.h
GEN target/sparc/trace.h
GEN util/trace.h
GEN hw/core/trace.h
GEN trace-root.c
GEN accel/kvm/trace.c
GEN accel/tcg/trace.c
GEN backends/trace.c
GEN crypto/trace.c
GEN monitor/trace.c
GEN linux-user/trace.c
GEN authz/trace.c
GEN block/trace.c
GEN io/trace.c
GEN nbd/trace.c
GEN scsi/trace.c
GEN chardev/trace.c
GEN audio/trace.c
GEN hw/9pfs/trace.c
GEN hw/acpi/trace.c
GEN hw/alpha/trace.c
GEN hw/arm/trace.c
GEN hw/audio/trace.c
GEN hw/block/trace.c
GEN hw/block/dataplane/trace.c
GEN hw/char/trace.c
GEN hw/dma/trace.c
GEN hw/hppa/trace.c
GEN hw/i2c/trace.c
GEN hw/i386/trace.c
GEN hw/i386/xen/trace.c
GEN hw/ide/trace.c
GEN hw/input/trace.c
GEN hw/intc/trace.c
GEN hw/isa/trace.c
GEN hw/mem/trace.c
GEN hw/mips/trace.c
GEN hw/misc/trace.c
GEN hw/misc/macio/trace.c
GEN hw/net/trace.c
GEN hw/nvram/trace.c
GEN hw/pci/trace.c
GEN hw/pci-host/trace.c
GEN hw/ppc/trace.c
GEN hw/rdma/trace.c
GEN hw/rdma/vmw/trace.c
GEN hw/rtc/trace.c
GEN hw/s390x/trace.c
GEN hw/scsi/trace.c
GEN hw/sd/trace.c
GEN hw/sparc/trace.c
GEN hw/sparc64/trace.c
GEN hw/timer/trace.c
GEN hw/tpm/trace.c
GEN hw/usb/trace.c
GEN hw/vfio/trace.c
GEN hw/virtio/trace.c
GEN hw/watchdog/trace.c
GEN hw/xen/trace.c
GEN hw/gpio/trace.c
GEN hw/riscv/trace.c
GEN migration/trace.c
GEN net/trace.c
GEN ui/trace.c
GEN hw/display/trace.c
GEN qapi/trace.c
GEN qom/trace.c
GEN target/arm/trace.c
GEN target/hppa/trace.c
GEN target/i386/trace.c
GEN target/mips/trace.c
GEN target/ppc/trace.c
GEN target/riscv/trace.c
GEN target/s390x/trace.c
GEN target/sparc/trace.c
GEN util/trace.c
GEN hw/core/trace.c
make: *** No rule to make target 'virtiofsd'. Stop.
This is better, thanks!
(We should also fix vhost-user-gpu, but this is out of the scope of this
series).
>>> vhost-user-json-y += tools/virtiofsd/50-qemu-virtiofsd.json
>>> endif
>>> diff --git a/tools/virtiofsd/Makefile.objs b/tools/virtiofsd/Makefile.objs
>>> index 45a807500d..076f667e46 100644
>>> --- a/tools/virtiofsd/Makefile.objs
>>> +++ b/tools/virtiofsd/Makefile.objs
>>> @@ -5,5 +5,8 @@ virtiofsd-obj-y = buffer.o \
>>> fuse_signals.o \
>>> fuse_virtio.o \
>>> helper.o \
>>> - passthrough_ll.o
>>> + passthrough_ll.o \
>>> + seccomp.o
>>> +seccomp.o-cflags := $(SECCOMP_CFLAGS)
>>> +seccomp.o-libs := $(SECCOMP_LIBS)
>>> diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
>>> index 752beb459a..8748e64f33 100644
>>> --- a/tools/virtiofsd/passthrough_ll.c
>>> +++ b/tools/virtiofsd/passthrough_ll.c
>>> @@ -58,6 +58,7 @@
>>> #include <unistd.h>
>>> #include "passthrough_helpers.h"
>>> +#include "seccomp.h"
>>> struct lo_map_elem {
>>> union {
>>> @@ -2090,6 +2091,7 @@ static void setup_sandbox(struct lo_data *lo, struct fuse_session *se)
>>> {
>>> setup_namespaces(lo, se);
>>> setup_mounts(lo->source);
>>> + setup_seccomp();
>>> }
>>> int main(int argc, char *argv[])
>>> diff --git a/tools/virtiofsd/seccomp.c b/tools/virtiofsd/seccomp.c
>>> new file mode 100644
>>> index 0000000000..2aa4d3cc66
>>> --- /dev/null
>>> +++ b/tools/virtiofsd/seccomp.c
>>> @@ -0,0 +1,150 @@
>>> +/*
>>> + * Seccomp sandboxing for virtiofsd
>>> + *
>>> + * Copyright (C) 2019 Red Hat, Inc.
>>> + *
>>> + * SPDX-License-Identifier: GPL-2.0-or-later
>>> + */
>>> +
>>> +#include "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(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(linkat),
>>> + 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(rt_sigaction),
>>> + SCMP_SYS(rt_sigprocmask),
>>> + SCMP_SYS(rt_sigreturn),
>>> + 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(symlinkat),
>>> + SCMP_SYS(time), /* Rarely needed, except on static builds */
>>> + SCMP_SYS(tgkill),
>>> + SCMP_SYS(unlinkat),
>>> + SCMP_SYS(utimensat),
>>> + SCMP_SYS(write),
>>> + SCMP_SYS(writev),
>>> +};
>>> +
>>> +void setup_seccomp(void)
>>> +{
>>> + scmp_filter_ctx ctx;
>>> + size_t i;
>>> +
>>> +#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);
>>> + }
>>> +
>>> + for (i = 0; i < G_N_ELEMENTS(syscall_whitelist); i++) {
>>> + if (seccomp_rule_add(ctx, SCMP_ACT_ALLOW,
>>> + syscall_whitelist[i], 0) != 0) {
>>> + fuse_log(FUSE_LOG_ERR, "seccomp_rule_add syscall %d",
>>> + syscall_whitelist[i]);
>>> + exit(1);
>>> + }
>>> + }
>>> +
>>> + /* 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);
>>> +}
>>> diff --git a/tools/virtiofsd/seccomp.h b/tools/virtiofsd/seccomp.h
>>> new file mode 100644
>>> index 0000000000..86bce72652
>>> --- /dev/null
>>> +++ b/tools/virtiofsd/seccomp.h
>>> @@ -0,0 +1,14 @@
>>> +/*
>>> + * Seccomp sandboxing for virtiofsd
>>> + *
>>> + * Copyright (C) 2019 Red Hat, Inc.
>>> + *
>>> + * SPDX-License-Identifier: GPL-2.0-or-later
>>> + */
>>> +
>>> +#ifndef VIRTIOFSD_SECCOMP_H
>>> +#define VIRTIOFSD_SECCOMP_H
>>> +
>>> +void setup_seccomp(void);
>>> +
>>> +#endif /* VIRTIOFSD_SECCOMP_H */
>>>
>>
> --
> Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
>