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[PATCH v2 051/109] virtiofsd: add seccomp whitelist
From: |
Dr. David Alan Gilbert (git) |
Subject: |
[PATCH v2 051/109] virtiofsd: add seccomp whitelist |
Date: |
Tue, 21 Jan 2020 12:23:35 +0000 |
From: Stefan Hajnoczi <address@hidden>
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 <address@hidden>
with additional entries by:
Signed-off-by: Ganesh Maharaj Mahalingam <address@hidden>
Signed-off-by: Masayoshi Mizuma <address@hidden>
Signed-off-by: Misono Tomohiro <address@hidden>
Signed-off-by: piaojun <address@hidden>
Signed-off-by: Vivek Goyal <address@hidden>
Signed-off-by: Eric Ren <address@hidden>
Signed-off-by: Dr. David Alan Gilbert <address@hidden>
---
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)
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 */
--
2.24.1
- [PATCH v2 040/109] virtiofsd: Plumb fuse_bufvec through to do_write_buf, (continued)
- [PATCH v2 040/109] virtiofsd: Plumb fuse_bufvec through to do_write_buf, Dr. David Alan Gilbert (git), 2020/01/21
- [PATCH v2 041/109] virtiofsd: Pass write iov's all the way through, Dr. David Alan Gilbert (git), 2020/01/21
- [PATCH v2 042/109] virtiofsd: add fuse_mbuf_iter API, Dr. David Alan Gilbert (git), 2020/01/21
- [PATCH v2 043/109] virtiofsd: validate input buffer sizes in do_write_buf(), Dr. David Alan Gilbert (git), 2020/01/21
- [PATCH v2 045/109] virtiofsd: prevent ".." escape in lo_do_lookup(), Dr. David Alan Gilbert (git), 2020/01/21
- [PATCH v2 044/109] virtiofsd: check input buffer size in fuse_lowlevel.c ops, Dr. David Alan Gilbert (git), 2020/01/21
- [PATCH v2 046/109] virtiofsd: prevent ".." escape in lo_do_readdir(), Dr. David Alan Gilbert (git), 2020/01/21
- [PATCH v2 047/109] virtiofsd: use /proc/self/fd/ O_PATH file descriptor, Dr. David Alan Gilbert (git), 2020/01/21
- [PATCH v2 048/109] virtiofsd: sandbox mount namespace, Dr. David Alan Gilbert (git), 2020/01/21
- [PATCH v2 049/109] virtiofsd: move to an empty network namespace, Dr. David Alan Gilbert (git), 2020/01/21
- [PATCH v2 051/109] virtiofsd: add seccomp whitelist,
Dr. David Alan Gilbert (git) <=
- Re: [PATCH v2 051/109] virtiofsd: add seccomp whitelist, Florian Weimer, 2020/01/24
[PATCH v2 050/109] virtiofsd: move to a new pid namespace, Dr. David Alan Gilbert (git), 2020/01/21
[PATCH v2 052/109] virtiofsd: Parse flag FUSE_WRITE_KILL_PRIV, Dr. David Alan Gilbert (git), 2020/01/21
[PATCH v2 053/109] virtiofsd: cap-ng helpers, Dr. David Alan Gilbert (git), 2020/01/21