* [Qemu-devel] [PATCHv5 0/6] seccomp: feature refactoring
@ 2017-09-08 9:10 Eduardo Otubo
2017-09-08 9:10 ` [Qemu-devel] [PATCHv5 1/5] seccomp: changing from whitelist to blacklist Eduardo Otubo
` (4 more replies)
0 siblings, 5 replies; 18+ messages in thread
From: Eduardo Otubo @ 2017-09-08 9:10 UTC (permalink / raw)
To: qemu-devel; +Cc: thuth, Daniel P . Berrange
v5:
* replaced strcmp by g_str_equal
* removed useless goto
* fixed style problems
v4:
* include another field on the struct for the modes
* remove priority
* fixed typos
* error handling for prctl
* add allow|deny values for all options
* error hanlding for wrong values for all options
* change how binary values are treated
* reformat help text
v3:
* Style problems fixed
v2:
* The semantics of the options "allow/deny" instead of booleans "on/off" remains.
* Added option 'children' to elevateprivileges
* Added documentation to docs/
v1:
* First version based on the discussion
https://lists.gnu.org/archive/html/qemu-devel/2017-02/msg03348.html
Eduardo Otubo (6):
seccomp: changing from whitelist to blacklist
seccomp: add obsolete argument to command line
seccomp: add elevateprivileges argument to command line
seccomp: add spawn argument to command line
seccomp: add resourcecontrol argument to command line
seccomp: adding documentation to new seccomp model
docs/seccomp.txt | 31 +++++
include/sysemu/seccomp.h | 8 +-
qemu-options.hx | 26 +++-
qemu-seccomp.c | 325 ++++++++++++++---------------------------------
vl.c | 82 +++++++++++-
5 files changed, 235 insertions(+), 237 deletions(-)
create mode 100644 docs/seccomp.txt
--
2.13.5
^ permalink raw reply [flat|nested] 18+ messages in thread
* [Qemu-devel] [PATCHv5 1/5] seccomp: changing from whitelist to blacklist
2017-09-08 9:10 [Qemu-devel] [PATCHv5 0/6] seccomp: feature refactoring Eduardo Otubo
@ 2017-09-08 9:10 ` Eduardo Otubo
2017-09-08 9:31 ` Daniel P. Berrange
2017-09-08 9:43 ` Thomas Huth
2017-09-08 9:10 ` [Qemu-devel] [PATCHv5 2/5] seccomp: add obsolete argument to command line Eduardo Otubo
` (3 subsequent siblings)
4 siblings, 2 replies; 18+ messages in thread
From: Eduardo Otubo @ 2017-09-08 9:10 UTC (permalink / raw)
To: qemu-devel; +Cc: thuth, Daniel P . Berrange
This patch changes the default behavior of the seccomp filter from
whitelist to blacklist. By default now all system calls are allowed and
a small black list of definitely forbidden ones was created.
Signed-off-by: Eduardo Otubo <otubo@redhat.com>
---
include/sysemu/seccomp.h | 2 +
qemu-seccomp.c | 264 ++++++-----------------------------------------
vl.c | 1 -
3 files changed, 35 insertions(+), 232 deletions(-)
diff --git a/include/sysemu/seccomp.h b/include/sysemu/seccomp.h
index cfc06008cb..23b9c3c789 100644
--- a/include/sysemu/seccomp.h
+++ b/include/sysemu/seccomp.h
@@ -15,6 +15,8 @@
#ifndef QEMU_SECCOMP_H
#define QEMU_SECCOMP_H
+#define QEMU_SECCOMP_SET_DEFAULT (1 << 0)
+
#include <seccomp.h>
int seccomp_start(void);
diff --git a/qemu-seccomp.c b/qemu-seccomp.c
index df75d9c471..bc9a1f77ff 100644
--- a/qemu-seccomp.c
+++ b/qemu-seccomp.c
@@ -28,232 +28,34 @@
struct QemuSeccompSyscall {
int32_t num;
- uint8_t priority;
+ int type;
+ uint8_t set;
};
-static const struct QemuSeccompSyscall seccomp_whitelist[] = {
- { SCMP_SYS(timer_settime), 255 },
- { SCMP_SYS(timer_gettime), 254 },
- { SCMP_SYS(futex), 253 },
- { SCMP_SYS(select), 252 },
- { SCMP_SYS(recvfrom), 251 },
- { SCMP_SYS(sendto), 250 },
- { SCMP_SYS(socketcall), 250 },
- { SCMP_SYS(read), 249 },
- { SCMP_SYS(io_submit), 249 },
- { SCMP_SYS(brk), 248 },
- { SCMP_SYS(clone), 247 },
- { SCMP_SYS(mmap), 247 },
- { SCMP_SYS(mprotect), 246 },
- { SCMP_SYS(execve), 245 },
- { SCMP_SYS(open), 245 },
- { SCMP_SYS(ioctl), 245 },
- { SCMP_SYS(socket), 245 },
- { SCMP_SYS(setsockopt), 245 },
- { SCMP_SYS(recvmsg), 245 },
- { SCMP_SYS(sendmsg), 245 },
- { SCMP_SYS(accept), 245 },
- { SCMP_SYS(connect), 245 },
- { SCMP_SYS(socketpair), 245 },
- { SCMP_SYS(bind), 245 },
- { SCMP_SYS(listen), 245 },
- { SCMP_SYS(semget), 245 },
- { SCMP_SYS(ipc), 245 },
- { SCMP_SYS(gettimeofday), 245 },
- { SCMP_SYS(readlink), 245 },
- { SCMP_SYS(access), 245 },
- { SCMP_SYS(prctl), 245 },
- { SCMP_SYS(signalfd), 245 },
- { SCMP_SYS(getrlimit), 245 },
- { SCMP_SYS(getrusage), 245 },
- { SCMP_SYS(set_tid_address), 245 },
- { SCMP_SYS(statfs), 245 },
- { SCMP_SYS(unlink), 245 },
- { SCMP_SYS(wait4), 245 },
- { SCMP_SYS(fcntl64), 245 },
- { SCMP_SYS(fstat64), 245 },
- { SCMP_SYS(stat64), 245 },
- { SCMP_SYS(getgid32), 245 },
- { SCMP_SYS(getegid32), 245 },
- { SCMP_SYS(getuid32), 245 },
- { SCMP_SYS(geteuid32), 245 },
- { SCMP_SYS(sigreturn), 245 },
- { SCMP_SYS(_newselect), 245 },
- { SCMP_SYS(_llseek), 245 },
- { SCMP_SYS(mmap2), 245 },
- { SCMP_SYS(sigprocmask), 245 },
- { SCMP_SYS(sched_getparam), 245 },
- { SCMP_SYS(sched_getscheduler), 245 },
- { SCMP_SYS(fstat), 245 },
- { SCMP_SYS(clock_getres), 245 },
- { SCMP_SYS(sched_get_priority_min), 245 },
- { SCMP_SYS(sched_get_priority_max), 245 },
- { SCMP_SYS(stat), 245 },
- { SCMP_SYS(uname), 245 },
- { SCMP_SYS(eventfd2), 245 },
- { SCMP_SYS(io_getevents), 245 },
- { SCMP_SYS(dup), 245 },
- { SCMP_SYS(dup2), 245 },
- { SCMP_SYS(dup3), 245 },
- { SCMP_SYS(gettid), 245 },
- { SCMP_SYS(getgid), 245 },
- { SCMP_SYS(getegid), 245 },
- { SCMP_SYS(getuid), 245 },
- { SCMP_SYS(geteuid), 245 },
- { SCMP_SYS(timer_create), 245 },
- { SCMP_SYS(times), 245 },
- { SCMP_SYS(exit), 245 },
- { SCMP_SYS(clock_gettime), 245 },
- { SCMP_SYS(time), 245 },
- { SCMP_SYS(restart_syscall), 245 },
- { SCMP_SYS(pwrite64), 245 },
- { SCMP_SYS(nanosleep), 245 },
- { SCMP_SYS(chown), 245 },
- { SCMP_SYS(openat), 245 },
- { SCMP_SYS(getdents), 245 },
- { SCMP_SYS(timer_delete), 245 },
- { SCMP_SYS(exit_group), 245 },
- { SCMP_SYS(rt_sigreturn), 245 },
- { SCMP_SYS(sync), 245 },
- { SCMP_SYS(pread64), 245 },
- { SCMP_SYS(madvise), 245 },
- { SCMP_SYS(set_robust_list), 245 },
- { SCMP_SYS(lseek), 245 },
- { SCMP_SYS(pselect6), 245 },
- { SCMP_SYS(fork), 245 },
- { SCMP_SYS(rt_sigprocmask), 245 },
- { SCMP_SYS(write), 244 },
- { SCMP_SYS(fcntl), 243 },
- { SCMP_SYS(tgkill), 242 },
- { SCMP_SYS(kill), 242 },
- { SCMP_SYS(rt_sigaction), 242 },
- { SCMP_SYS(pipe2), 242 },
- { SCMP_SYS(munmap), 242 },
- { SCMP_SYS(mremap), 242 },
- { SCMP_SYS(fdatasync), 242 },
- { SCMP_SYS(close), 242 },
- { SCMP_SYS(rt_sigpending), 242 },
- { SCMP_SYS(rt_sigtimedwait), 242 },
- { SCMP_SYS(readv), 242 },
- { SCMP_SYS(writev), 242 },
- { SCMP_SYS(preadv), 242 },
- { SCMP_SYS(pwritev), 242 },
- { SCMP_SYS(setrlimit), 242 },
- { SCMP_SYS(ftruncate), 242 },
- { SCMP_SYS(lstat), 242 },
- { SCMP_SYS(pipe), 242 },
- { SCMP_SYS(umask), 242 },
- { SCMP_SYS(chdir), 242 },
- { SCMP_SYS(setitimer), 242 },
- { SCMP_SYS(setsid), 242 },
- { SCMP_SYS(poll), 242 },
- { SCMP_SYS(epoll_create), 242 },
- { SCMP_SYS(epoll_ctl), 242 },
- { SCMP_SYS(epoll_wait), 242 },
- { SCMP_SYS(waitpid), 242 },
- { SCMP_SYS(getsockname), 242 },
- { SCMP_SYS(getpeername), 242 },
- { SCMP_SYS(accept4), 242 },
- { SCMP_SYS(timerfd_settime), 242 },
- { SCMP_SYS(newfstatat), 241 },
- { SCMP_SYS(shutdown), 241 },
- { SCMP_SYS(getsockopt), 241 },
- { SCMP_SYS(semop), 241 },
- { SCMP_SYS(semtimedop), 241 },
- { SCMP_SYS(epoll_ctl_old), 241 },
- { SCMP_SYS(epoll_wait_old), 241 },
- { SCMP_SYS(epoll_pwait), 241 },
- { SCMP_SYS(epoll_create1), 241 },
- { SCMP_SYS(ppoll), 241 },
- { SCMP_SYS(creat), 241 },
- { SCMP_SYS(link), 241 },
- { SCMP_SYS(getpid), 241 },
- { SCMP_SYS(getppid), 241 },
- { SCMP_SYS(getpgrp), 241 },
- { SCMP_SYS(getpgid), 241 },
- { SCMP_SYS(getsid), 241 },
- { SCMP_SYS(getdents64), 241 },
- { SCMP_SYS(getresuid), 241 },
- { SCMP_SYS(getresgid), 241 },
- { SCMP_SYS(getgroups), 241 },
- { SCMP_SYS(getresuid32), 241 },
- { SCMP_SYS(getresgid32), 241 },
- { SCMP_SYS(getgroups32), 241 },
- { SCMP_SYS(signal), 241 },
- { SCMP_SYS(sigaction), 241 },
- { SCMP_SYS(sigsuspend), 241 },
- { SCMP_SYS(sigpending), 241 },
- { SCMP_SYS(truncate64), 241 },
- { SCMP_SYS(ftruncate64), 241 },
- { SCMP_SYS(fchown32), 241 },
- { SCMP_SYS(chown32), 241 },
- { SCMP_SYS(lchown32), 241 },
- { SCMP_SYS(statfs64), 241 },
- { SCMP_SYS(fstatfs64), 241 },
- { SCMP_SYS(fstatat64), 241 },
- { SCMP_SYS(lstat64), 241 },
- { SCMP_SYS(sendfile64), 241 },
- { SCMP_SYS(ugetrlimit), 241 },
- { SCMP_SYS(alarm), 241 },
- { SCMP_SYS(rt_sigsuspend), 241 },
- { SCMP_SYS(rt_sigqueueinfo), 241 },
- { SCMP_SYS(rt_tgsigqueueinfo), 241 },
- { SCMP_SYS(sigaltstack), 241 },
- { SCMP_SYS(signalfd4), 241 },
- { SCMP_SYS(truncate), 241 },
- { SCMP_SYS(fchown), 241 },
- { SCMP_SYS(lchown), 241 },
- { SCMP_SYS(fchownat), 241 },
- { SCMP_SYS(fstatfs), 241 },
- { SCMP_SYS(getitimer), 241 },
- { SCMP_SYS(syncfs), 241 },
- { SCMP_SYS(fsync), 241 },
- { SCMP_SYS(fchdir), 241 },
- { SCMP_SYS(msync), 241 },
- { SCMP_SYS(sched_setparam), 241 },
- { SCMP_SYS(sched_setscheduler), 241 },
- { SCMP_SYS(sched_yield), 241 },
- { SCMP_SYS(sched_rr_get_interval), 241 },
- { SCMP_SYS(sched_setaffinity), 241 },
- { SCMP_SYS(sched_getaffinity), 241 },
- { SCMP_SYS(readahead), 241 },
- { SCMP_SYS(timer_getoverrun), 241 },
- { SCMP_SYS(unlinkat), 241 },
- { SCMP_SYS(readlinkat), 241 },
- { SCMP_SYS(faccessat), 241 },
- { SCMP_SYS(get_robust_list), 241 },
- { SCMP_SYS(splice), 241 },
- { SCMP_SYS(vmsplice), 241 },
- { SCMP_SYS(getcpu), 241 },
- { SCMP_SYS(sendmmsg), 241 },
- { SCMP_SYS(recvmmsg), 241 },
- { SCMP_SYS(prlimit64), 241 },
- { SCMP_SYS(waitid), 241 },
- { SCMP_SYS(io_cancel), 241 },
- { SCMP_SYS(io_setup), 241 },
- { SCMP_SYS(io_destroy), 241 },
- { SCMP_SYS(arch_prctl), 240 },
- { SCMP_SYS(mkdir), 240 },
- { SCMP_SYS(fchmod), 240 },
- { SCMP_SYS(shmget), 240 },
- { SCMP_SYS(shmat), 240 },
- { SCMP_SYS(shmdt), 240 },
- { SCMP_SYS(timerfd_create), 240 },
- { SCMP_SYS(shmctl), 240 },
- { SCMP_SYS(mlockall), 240 },
- { SCMP_SYS(mlock), 240 },
- { SCMP_SYS(munlock), 240 },
- { SCMP_SYS(semctl), 240 },
- { SCMP_SYS(fallocate), 240 },
- { SCMP_SYS(fadvise64), 240 },
- { SCMP_SYS(inotify_init1), 240 },
- { SCMP_SYS(inotify_add_watch), 240 },
- { SCMP_SYS(mbind), 240 },
- { SCMP_SYS(memfd_create), 240 },
-#ifdef HAVE_CACHEFLUSH
- { SCMP_SYS(cacheflush), 240 },
-#endif
- { SCMP_SYS(sysinfo), 240 },
+static const struct QemuSeccompSyscall blacklist[] = {
+ /* default set of syscalls to blacklist */
+ { SCMP_SYS(reboot), 1, QEMU_SECCOMP_SET_DEFAULT },
+ { SCMP_SYS(swapon), 1, QEMU_SECCOMP_SET_DEFAULT },
+ { SCMP_SYS(swapoff), 1, QEMU_SECCOMP_SET_DEFAULT },
+ { SCMP_SYS(syslog), 1, QEMU_SECCOMP_SET_DEFAULT },
+ { SCMP_SYS(mount), 1, QEMU_SECCOMP_SET_DEFAULT },
+ { SCMP_SYS(umount), 1, QEMU_SECCOMP_SET_DEFAULT },
+ { SCMP_SYS(kexec_load), 1, QEMU_SECCOMP_SET_DEFAULT },
+ { SCMP_SYS(afs_syscall), 1, QEMU_SECCOMP_SET_DEFAULT },
+ { SCMP_SYS(break), 1, QEMU_SECCOMP_SET_DEFAULT },
+ { SCMP_SYS(ftime), 1, QEMU_SECCOMP_SET_DEFAULT },
+ { SCMP_SYS(getpmsg), 1, QEMU_SECCOMP_SET_DEFAULT },
+ { SCMP_SYS(gtty), 1, QEMU_SECCOMP_SET_DEFAULT },
+ { SCMP_SYS(lock), 1, QEMU_SECCOMP_SET_DEFAULT },
+ { SCMP_SYS(mpx), 1, QEMU_SECCOMP_SET_DEFAULT },
+ { SCMP_SYS(prof), 1, QEMU_SECCOMP_SET_DEFAULT },
+ { SCMP_SYS(profil), 1, QEMU_SECCOMP_SET_DEFAULT },
+ { SCMP_SYS(putpmsg), 1, QEMU_SECCOMP_SET_DEFAULT },
+ { SCMP_SYS(security), 1, QEMU_SECCOMP_SET_DEFAULT },
+ { SCMP_SYS(stty), 1, QEMU_SECCOMP_SET_DEFAULT },
+ { SCMP_SYS(tuxcall), 1, QEMU_SECCOMP_SET_DEFAULT },
+ { SCMP_SYS(ulimit), 1, QEMU_SECCOMP_SET_DEFAULT },
+ { SCMP_SYS(vserver), 1, QEMU_SECCOMP_SET_DEFAULT },
};
int seccomp_start(void)
@@ -262,19 +64,19 @@ int seccomp_start(void)
unsigned int i = 0;
scmp_filter_ctx ctx;
- ctx = seccomp_init(SCMP_ACT_KILL);
+ ctx = seccomp_init(SCMP_ACT_ALLOW);
if (ctx == NULL) {
rc = -1;
goto seccomp_return;
}
- for (i = 0; i < ARRAY_SIZE(seccomp_whitelist); i++) {
- rc = seccomp_rule_add(ctx, SCMP_ACT_ALLOW, seccomp_whitelist[i].num, 0);
- if (rc < 0) {
- goto seccomp_return;
+ for (i = 0; i < ARRAY_SIZE(blacklist); i++) {
+ switch (blacklist[i].set) {
+ default:
+ break;
}
- rc = seccomp_syscall_priority(ctx, seccomp_whitelist[i].num,
- seccomp_whitelist[i].priority);
+
+ rc = seccomp_rule_add(ctx, SCMP_ACT_KILL, blacklist[i].num, 0);
if (rc < 0) {
goto seccomp_return;
}
diff --git a/vl.c b/vl.c
index fb1f05b937..76e0b3a946 100644
--- a/vl.c
+++ b/vl.c
@@ -1032,7 +1032,6 @@ static int bt_parse(const char *opt)
static int parse_sandbox(void *opaque, QemuOpts *opts, Error **errp)
{
- /* FIXME: change this to true for 1.3 */
if (qemu_opt_get_bool(opts, "enable", false)) {
#ifdef CONFIG_SECCOMP
if (seccomp_start() < 0) {
--
2.13.5
^ permalink raw reply related [flat|nested] 18+ messages in thread
* [Qemu-devel] [PATCHv5 2/5] seccomp: add obsolete argument to command line
2017-09-08 9:10 [Qemu-devel] [PATCHv5 0/6] seccomp: feature refactoring Eduardo Otubo
2017-09-08 9:10 ` [Qemu-devel] [PATCHv5 1/5] seccomp: changing from whitelist to blacklist Eduardo Otubo
@ 2017-09-08 9:10 ` Eduardo Otubo
2017-09-08 9:31 ` Daniel P. Berrange
2017-09-08 9:10 ` [Qemu-devel] [PATCHv5 3/5] seccomp: add elevateprivileges " Eduardo Otubo
` (2 subsequent siblings)
4 siblings, 1 reply; 18+ messages in thread
From: Eduardo Otubo @ 2017-09-08 9:10 UTC (permalink / raw)
To: qemu-devel; +Cc: thuth, Daniel P . Berrange
This patch introduces the argument [,obsolete=allow] to the `-sandbox on'
option. It allows Qemu to run safely on old system that still relies on
old system calls.
Signed-off-by: Eduardo Otubo <otubo@redhat.com>
---
include/sysemu/seccomp.h | 3 ++-
qemu-options.hx | 12 ++++++++++--
qemu-seccomp.c | 20 +++++++++++++++++++-
vl.c | 22 +++++++++++++++++++++-
4 files changed, 52 insertions(+), 5 deletions(-)
diff --git a/include/sysemu/seccomp.h b/include/sysemu/seccomp.h
index 23b9c3c789..215138a372 100644
--- a/include/sysemu/seccomp.h
+++ b/include/sysemu/seccomp.h
@@ -16,8 +16,9 @@
#define QEMU_SECCOMP_H
#define QEMU_SECCOMP_SET_DEFAULT (1 << 0)
+#define QEMU_SECCOMP_SET_OBSOLETE (1 << 1)
#include <seccomp.h>
-int seccomp_start(void);
+int seccomp_start(uint32_t seccomp_opts);
#endif
diff --git a/qemu-options.hx b/qemu-options.hx
index 9f6e2adfff..72150c6b84 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -4017,13 +4017,21 @@ Old param mode (ARM only).
ETEXI
DEF("sandbox", HAS_ARG, QEMU_OPTION_sandbox, \
- "-sandbox <arg> Enable seccomp mode 2 system call filter (default 'off').\n",
+ "-sandbox on[,obsolete=allow|deny]\n" \
+ " Enable seccomp mode 2 system call filter (default 'off').\n" \
+ " use 'obsolete' to allow obsolete system calls that are provided\n" \
+ " by the kernel, but typically no longer used by modern\n" \
+ " C library implementations.\n",
QEMU_ARCH_ALL)
STEXI
-@item -sandbox @var{arg}
+@item -sandbox @var{arg}[,obsolete=@var{string}]
@findex -sandbox
Enable Seccomp mode 2 system call filter. 'on' will enable syscall filtering and 'off' will
disable it. The default is 'off'.
+@table @option
+@item obsolete=@var{string}
+Enable Obsolete system calls
+@end table
ETEXI
DEF("readconfig", HAS_ARG, QEMU_OPTION_readconfig,
diff --git a/qemu-seccomp.c b/qemu-seccomp.c
index bc9a1f77ff..126e5ee2d5 100644
--- a/qemu-seccomp.c
+++ b/qemu-seccomp.c
@@ -56,9 +56,22 @@ static const struct QemuSeccompSyscall blacklist[] = {
{ SCMP_SYS(tuxcall), 1, QEMU_SECCOMP_SET_DEFAULT },
{ SCMP_SYS(ulimit), 1, QEMU_SECCOMP_SET_DEFAULT },
{ SCMP_SYS(vserver), 1, QEMU_SECCOMP_SET_DEFAULT },
+ /* obsolete */
+ { SCMP_SYS(readdir), 2, QEMU_SECCOMP_SET_OBSOLETE },
+ { SCMP_SYS(_sysctl), 2, QEMU_SECCOMP_SET_OBSOLETE },
+ { SCMP_SYS(bdflush), 2, QEMU_SECCOMP_SET_OBSOLETE },
+ { SCMP_SYS(create_module), 2, QEMU_SECCOMP_SET_OBSOLETE },
+ { SCMP_SYS(get_kernel_syms), 2, QEMU_SECCOMP_SET_OBSOLETE },
+ { SCMP_SYS(query_module), 2, QEMU_SECCOMP_SET_OBSOLETE },
+ { SCMP_SYS(sgetmask), 2, QEMU_SECCOMP_SET_OBSOLETE },
+ { SCMP_SYS(ssetmask), 2, QEMU_SECCOMP_SET_OBSOLETE },
+ { SCMP_SYS(sysfs), 2, QEMU_SECCOMP_SET_OBSOLETE },
+ { SCMP_SYS(uselib), 2, QEMU_SECCOMP_SET_OBSOLETE },
+ { SCMP_SYS(ustat), 2, QEMU_SECCOMP_SET_OBSOLETE },
};
-int seccomp_start(void)
+
+int seccomp_start(uint32_t seccomp_opts)
{
int rc = 0;
unsigned int i = 0;
@@ -72,6 +85,11 @@ int seccomp_start(void)
for (i = 0; i < ARRAY_SIZE(blacklist); i++) {
switch (blacklist[i].set) {
+ case QEMU_SECCOMP_SET_OBSOLETE:
+ if ((seccomp_opts & QEMU_SECCOMP_SET_OBSOLETE)) {
+ continue;
+ }
+ break;
default:
break;
}
diff --git a/vl.c b/vl.c
index 76e0b3a946..dafbe30e2b 100644
--- a/vl.c
+++ b/vl.c
@@ -271,6 +271,10 @@ static QemuOptsList qemu_sandbox_opts = {
.name = "enable",
.type = QEMU_OPT_BOOL,
},
+ {
+ .name = "obsolete",
+ .type = QEMU_OPT_STRING,
+ },
{ /* end of list */ }
},
};
@@ -1034,7 +1038,23 @@ static int parse_sandbox(void *opaque, QemuOpts *opts, Error **errp)
{
if (qemu_opt_get_bool(opts, "enable", false)) {
#ifdef CONFIG_SECCOMP
- if (seccomp_start() < 0) {
+ uint32_t seccomp_opts = 0x00000;
+ const char *value = NULL;
+
+ value = qemu_opt_get(opts, "obsolete");
+ if (value) {
+ if (g_str_equal(value, "allow")) {
+ seccomp_opts |= QEMU_SECCOMP_SET_OBSOLETE;
+ } else if (g_str_equal(value, "deny")) {
+ /* this is the default option, this if is here
+ * to provide a little bit of consistency for
+ * the command line */
+ } else {
+ error_report("invalid argument for obsolete");
+ }
+ }
+
+ if (seccomp_start(seccomp_opts) < 0) {
error_report("failed to install seccomp syscall filter "
"in the kernel");
return -1;
--
2.13.5
^ permalink raw reply related [flat|nested] 18+ messages in thread
* [Qemu-devel] [PATCHv5 3/5] seccomp: add elevateprivileges argument to command line
2017-09-08 9:10 [Qemu-devel] [PATCHv5 0/6] seccomp: feature refactoring Eduardo Otubo
2017-09-08 9:10 ` [Qemu-devel] [PATCHv5 1/5] seccomp: changing from whitelist to blacklist Eduardo Otubo
2017-09-08 9:10 ` [Qemu-devel] [PATCHv5 2/5] seccomp: add obsolete argument to command line Eduardo Otubo
@ 2017-09-08 9:10 ` Eduardo Otubo
2017-09-08 9:32 ` Daniel P. Berrange
2017-09-08 9:10 ` [Qemu-devel] [PATCHv5 4/5] seccomp: add spawn " Eduardo Otubo
2017-09-08 9:10 ` [Qemu-devel] [PATCHv5 5/5] seccomp: add resourcecontrol " Eduardo Otubo
4 siblings, 1 reply; 18+ messages in thread
From: Eduardo Otubo @ 2017-09-08 9:10 UTC (permalink / raw)
To: qemu-devel; +Cc: thuth, Daniel P . Berrange
This patch introduces the new argument
[,elevateprivileges=allow|deny|children] to the `-sandbox on'. It allows
or denies Qemu process to elevate its privileges by blacklisting all
set*uid|gid system calls. The 'children' option will let forks and
execves run unprivileged.
Signed-off-by: Eduardo Otubo <otubo@redhat.com>
---
include/sysemu/seccomp.h | 1 +
qemu-options.hx | 12 +++++++++---
qemu-seccomp.c | 19 +++++++++++++++++++
vl.c | 27 +++++++++++++++++++++++++++
4 files changed, 56 insertions(+), 3 deletions(-)
diff --git a/include/sysemu/seccomp.h b/include/sysemu/seccomp.h
index 215138a372..4a9e63c7cd 100644
--- a/include/sysemu/seccomp.h
+++ b/include/sysemu/seccomp.h
@@ -17,6 +17,7 @@
#define QEMU_SECCOMP_SET_DEFAULT (1 << 0)
#define QEMU_SECCOMP_SET_OBSOLETE (1 << 1)
+#define QEMU_SECCOMP_SET_PRIVILEGED (1 << 2)
#include <seccomp.h>
diff --git a/qemu-options.hx b/qemu-options.hx
index 72150c6b84..5c1b163fb5 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -4017,20 +4017,26 @@ Old param mode (ARM only).
ETEXI
DEF("sandbox", HAS_ARG, QEMU_OPTION_sandbox, \
- "-sandbox on[,obsolete=allow|deny]\n" \
+ "-sandbox on[,obsolete=allow|deny][,elevateprivileges=allow|deny|children]\n" \
" Enable seccomp mode 2 system call filter (default 'off').\n" \
" use 'obsolete' to allow obsolete system calls that are provided\n" \
" by the kernel, but typically no longer used by modern\n" \
- " C library implementations.\n",
+ " C library implementations.\n" \
+ " use 'elevateprivileges' to allow or deny QEMU process to elevate\n" \
+ " its privileges by blacklisting all set*uid|gid system calls.\n" \
+ " The value 'children' will deny set*uid|gid system calls for\n" \
+ " main QEMU process but will allow forks and execves to run unprivileged\n",
QEMU_ARCH_ALL)
STEXI
-@item -sandbox @var{arg}[,obsolete=@var{string}]
+@item -sandbox @var{arg}[,obsolete=@var{string}][,elevateprivileges=@var{string}]
@findex -sandbox
Enable Seccomp mode 2 system call filter. 'on' will enable syscall filtering and 'off' will
disable it. The default is 'off'.
@table @option
@item obsolete=@var{string}
Enable Obsolete system calls
+@item elevateprivileges=@var{string}
+Disable set*uid|gid system calls
@end table
ETEXI
diff --git a/qemu-seccomp.c b/qemu-seccomp.c
index 126e5ee2d5..2bad16cafb 100644
--- a/qemu-seccomp.c
+++ b/qemu-seccomp.c
@@ -68,6 +68,17 @@ static const struct QemuSeccompSyscall blacklist[] = {
{ SCMP_SYS(sysfs), 2, QEMU_SECCOMP_SET_OBSOLETE },
{ SCMP_SYS(uselib), 2, QEMU_SECCOMP_SET_OBSOLETE },
{ SCMP_SYS(ustat), 2, QEMU_SECCOMP_SET_OBSOLETE },
+ /* privileged */
+ { SCMP_SYS(setuid), 4, QEMU_SECCOMP_SET_PRIVILEGED },
+ { SCMP_SYS(setgid), 4, QEMU_SECCOMP_SET_PRIVILEGED },
+ { SCMP_SYS(setpgid), 4, QEMU_SECCOMP_SET_PRIVILEGED },
+ { SCMP_SYS(setsid), 4, QEMU_SECCOMP_SET_PRIVILEGED },
+ { SCMP_SYS(setreuid), 4, QEMU_SECCOMP_SET_PRIVILEGED },
+ { SCMP_SYS(setregid), 4, QEMU_SECCOMP_SET_PRIVILEGED },
+ { SCMP_SYS(setresuid), 4, QEMU_SECCOMP_SET_PRIVILEGED },
+ { SCMP_SYS(setresgid), 4, QEMU_SECCOMP_SET_PRIVILEGED },
+ { SCMP_SYS(setfsuid), 4, QEMU_SECCOMP_SET_PRIVILEGED },
+ { SCMP_SYS(setfsgid), 4, QEMU_SECCOMP_SET_PRIVILEGED },
};
@@ -90,6 +101,14 @@ int seccomp_start(uint32_t seccomp_opts)
continue;
}
break;
+ case QEMU_SECCOMP_SET_PRIVILEGED:
+ if (seccomp_opts & QEMU_SECCOMP_SET_PRIVILEGED) {
+ break;
+ } else {
+ continue;
+ }
+
+ break;
default:
break;
}
diff --git a/vl.c b/vl.c
index dafbe30e2b..413cfe8504 100644
--- a/vl.c
+++ b/vl.c
@@ -29,6 +29,7 @@
#ifdef CONFIG_SECCOMP
#include "sysemu/seccomp.h"
+#include "sys/prctl.h"
#endif
#if defined(CONFIG_VDE)
@@ -275,6 +276,10 @@ static QemuOptsList qemu_sandbox_opts = {
.name = "obsolete",
.type = QEMU_OPT_STRING,
},
+ {
+ .name = "elevateprivileges",
+ .type = QEMU_OPT_STRING,
+ },
{ /* end of list */ }
},
};
@@ -1054,6 +1059,28 @@ static int parse_sandbox(void *opaque, QemuOpts *opts, Error **errp)
}
}
+ value = qemu_opt_get(opts, "elevateprivileges");
+ if (value) {
+ if (g_str_equal(value, "deny")) {
+ seccomp_opts |= QEMU_SECCOMP_SET_PRIVILEGED;
+ } else if (g_str_equal(value, "children")) {
+ seccomp_opts |= QEMU_SECCOMP_SET_PRIVILEGED;
+
+ /* calling prctl directly because we're
+ * not sure if host has CAP_SYS_ADMIN set*/
+ if (prctl(PR_SET_NO_NEW_PRIVS, 1)) {
+ error_report("failed to set no_new_privs "
+ "aborting");
+ return -1;
+ }
+ } else if (g_str_equal(value, "allow")) {
+ /* default value */
+ } else {
+ error_report("invalid argument for elevateprivileges");
+ return -1;
+ }
+ }
+
if (seccomp_start(seccomp_opts) < 0) {
error_report("failed to install seccomp syscall filter "
"in the kernel");
--
2.13.5
^ permalink raw reply related [flat|nested] 18+ messages in thread
* [Qemu-devel] [PATCHv5 4/5] seccomp: add spawn argument to command line
2017-09-08 9:10 [Qemu-devel] [PATCHv5 0/6] seccomp: feature refactoring Eduardo Otubo
` (2 preceding siblings ...)
2017-09-08 9:10 ` [Qemu-devel] [PATCHv5 3/5] seccomp: add elevateprivileges " Eduardo Otubo
@ 2017-09-08 9:10 ` Eduardo Otubo
2017-09-08 9:33 ` Daniel P. Berrange
2017-09-08 9:50 ` Thomas Huth
2017-09-08 9:10 ` [Qemu-devel] [PATCHv5 5/5] seccomp: add resourcecontrol " Eduardo Otubo
4 siblings, 2 replies; 18+ messages in thread
From: Eduardo Otubo @ 2017-09-08 9:10 UTC (permalink / raw)
To: qemu-devel; +Cc: thuth, Daniel P . Berrange
This patch adds [,spawn=deny] argument to `-sandbox on' option. It
blacklists fork and execve system calls, avoiding Qemu to spawn new
threads or processes.
Signed-off-by: Eduardo Otubo <otubo@redhat.com>
---
include/sysemu/seccomp.h | 1 +
qemu-options.hx | 9 +++++++--
qemu-seccomp.c | 12 ++++++++++++
vl.c | 16 ++++++++++++++++
4 files changed, 36 insertions(+), 2 deletions(-)
diff --git a/include/sysemu/seccomp.h b/include/sysemu/seccomp.h
index 4a9e63c7cd..3ab5fc4f61 100644
--- a/include/sysemu/seccomp.h
+++ b/include/sysemu/seccomp.h
@@ -18,6 +18,7 @@
#define QEMU_SECCOMP_SET_DEFAULT (1 << 0)
#define QEMU_SECCOMP_SET_OBSOLETE (1 << 1)
#define QEMU_SECCOMP_SET_PRIVILEGED (1 << 2)
+#define QEMU_SECCOMP_SET_SPAWN (1 << 3)
#include <seccomp.h>
diff --git a/qemu-options.hx b/qemu-options.hx
index 5c1b163fb5..2b04b9f170 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -4018,6 +4018,7 @@ ETEXI
DEF("sandbox", HAS_ARG, QEMU_OPTION_sandbox, \
"-sandbox on[,obsolete=allow|deny][,elevateprivileges=allow|deny|children]\n" \
+ " [,spawn=allow|deny]\n" \
" Enable seccomp mode 2 system call filter (default 'off').\n" \
" use 'obsolete' to allow obsolete system calls that are provided\n" \
" by the kernel, but typically no longer used by modern\n" \
@@ -4025,10 +4026,12 @@ DEF("sandbox", HAS_ARG, QEMU_OPTION_sandbox, \
" use 'elevateprivileges' to allow or deny QEMU process to elevate\n" \
" its privileges by blacklisting all set*uid|gid system calls.\n" \
" The value 'children' will deny set*uid|gid system calls for\n" \
- " main QEMU process but will allow forks and execves to run unprivileged\n",
+ " main QEMU process but will allow forks and execves to run unprivileged\n" \
+ " use 'spawn' to avoid QEMU to spawn new threads or processes by\n" \
+ " blacklisting *fork and execve\n",
QEMU_ARCH_ALL)
STEXI
-@item -sandbox @var{arg}[,obsolete=@var{string}][,elevateprivileges=@var{string}]
+@item -sandbox @var{arg}[,obsolete=@var{string}][,elevateprivileges=@var{string}][,spawn=@var{string}]
@findex -sandbox
Enable Seccomp mode 2 system call filter. 'on' will enable syscall filtering and 'off' will
disable it. The default is 'off'.
@@ -4037,6 +4040,8 @@ disable it. The default is 'off'.
Enable Obsolete system calls
@item elevateprivileges=@var{string}
Disable set*uid|gid system calls
+@item spawn=@var{string}
+Disable *fork and execve
@end table
ETEXI
diff --git a/qemu-seccomp.c b/qemu-seccomp.c
index 2bad16cafb..4c169febf8 100644
--- a/qemu-seccomp.c
+++ b/qemu-seccomp.c
@@ -79,6 +79,10 @@ static const struct QemuSeccompSyscall blacklist[] = {
{ SCMP_SYS(setresgid), 4, QEMU_SECCOMP_SET_PRIVILEGED },
{ SCMP_SYS(setfsuid), 4, QEMU_SECCOMP_SET_PRIVILEGED },
{ SCMP_SYS(setfsgid), 4, QEMU_SECCOMP_SET_PRIVILEGED },
+ /* spawn */
+ { SCMP_SYS(fork), 8, QEMU_SECCOMP_SET_SPAWN },
+ { SCMP_SYS(vfork), 8, QEMU_SECCOMP_SET_SPAWN },
+ { SCMP_SYS(execve), 8, QEMU_SECCOMP_SET_SPAWN },
};
@@ -109,6 +113,14 @@ int seccomp_start(uint32_t seccomp_opts)
}
break;
+ case QEMU_SECCOMP_SET_SPAWN:
+ if (seccomp_opts & QEMU_SECCOMP_SET_SPAWN) {
+ break;
+ } else {
+ continue;
+ }
+
+ break;
default:
break;
}
diff --git a/vl.c b/vl.c
index 413cfe8504..0af137da17 100644
--- a/vl.c
+++ b/vl.c
@@ -280,6 +280,10 @@ static QemuOptsList qemu_sandbox_opts = {
.name = "elevateprivileges",
.type = QEMU_OPT_STRING,
},
+ {
+ .name = "spawn",
+ .type = QEMU_OPT_STRING,
+ },
{ /* end of list */ }
},
};
@@ -1081,6 +1085,18 @@ static int parse_sandbox(void *opaque, QemuOpts *opts, Error **errp)
}
}
+ value = qemu_opt_get(opts, "spawn");
+ if (value) {
+ if (g_str_equal(value, "deny")) {
+ seccomp_opts |= QEMU_SECCOMP_SET_SPAWN;
+ } else if (g_str_equal(value, "allow")) {
+ /* default value */
+ } else {
+ error_report("invalid argument for spawn");
+ return -1;
+ }
+ }
+
if (seccomp_start(seccomp_opts) < 0) {
error_report("failed to install seccomp syscall filter "
"in the kernel");
--
2.13.5
^ permalink raw reply related [flat|nested] 18+ messages in thread
* [Qemu-devel] [PATCHv5 5/5] seccomp: add resourcecontrol argument to command line
2017-09-08 9:10 [Qemu-devel] [PATCHv5 0/6] seccomp: feature refactoring Eduardo Otubo
` (3 preceding siblings ...)
2017-09-08 9:10 ` [Qemu-devel] [PATCHv5 4/5] seccomp: add spawn " Eduardo Otubo
@ 2017-09-08 9:10 ` Eduardo Otubo
2017-09-08 9:33 ` Daniel P. Berrange
4 siblings, 1 reply; 18+ messages in thread
From: Eduardo Otubo @ 2017-09-08 9:10 UTC (permalink / raw)
To: qemu-devel; +Cc: thuth, Daniel P . Berrange
This patch adds [,resourcecontrol=deny] to `-sandbox on' option. It
blacklists all process affinity and scheduler priority system calls to
avoid any bigger of the process.
Signed-off-by: Eduardo Otubo <otubo@redhat.com>
---
include/sysemu/seccomp.h | 1 +
qemu-options.hx | 9 ++++++---
qemu-seccomp.c | 19 +++++++++++++++++++
vl.c | 16 ++++++++++++++++
4 files changed, 42 insertions(+), 3 deletions(-)
diff --git a/include/sysemu/seccomp.h b/include/sysemu/seccomp.h
index 3ab5fc4f61..e67c2dc840 100644
--- a/include/sysemu/seccomp.h
+++ b/include/sysemu/seccomp.h
@@ -19,6 +19,7 @@
#define QEMU_SECCOMP_SET_OBSOLETE (1 << 1)
#define QEMU_SECCOMP_SET_PRIVILEGED (1 << 2)
#define QEMU_SECCOMP_SET_SPAWN (1 << 3)
+#define QEMU_SECCOMP_SET_RESOURCECTL (1 << 4)
#include <seccomp.h>
diff --git a/qemu-options.hx b/qemu-options.hx
index 2b04b9f170..600614f6e5 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -4018,7 +4018,7 @@ ETEXI
DEF("sandbox", HAS_ARG, QEMU_OPTION_sandbox, \
"-sandbox on[,obsolete=allow|deny][,elevateprivileges=allow|deny|children]\n" \
- " [,spawn=allow|deny]\n" \
+ " [,spawn=allow|deny][,resourcecontrol=allow|deny]\n" \
" Enable seccomp mode 2 system call filter (default 'off').\n" \
" use 'obsolete' to allow obsolete system calls that are provided\n" \
" by the kernel, but typically no longer used by modern\n" \
@@ -4028,10 +4028,11 @@ DEF("sandbox", HAS_ARG, QEMU_OPTION_sandbox, \
" The value 'children' will deny set*uid|gid system calls for\n" \
" main QEMU process but will allow forks and execves to run unprivileged\n" \
" use 'spawn' to avoid QEMU to spawn new threads or processes by\n" \
- " blacklisting *fork and execve\n",
+ " blacklisting *fork and execve\n" \
+ " use 'resourcecontrol' to disable process affinity and schedular priority\n",
QEMU_ARCH_ALL)
STEXI
-@item -sandbox @var{arg}[,obsolete=@var{string}][,elevateprivileges=@var{string}][,spawn=@var{string}]
+@item -sandbox @var{arg}[,obsolete=@var{string}][,elevateprivileges=@var{string}][,spawn=@var{string}][,resourcecontrol=@var{string}]
@findex -sandbox
Enable Seccomp mode 2 system call filter. 'on' will enable syscall filtering and 'off' will
disable it. The default is 'off'.
@@ -4042,6 +4043,8 @@ Enable Obsolete system calls
Disable set*uid|gid system calls
@item spawn=@var{string}
Disable *fork and execve
+@item resourcecontrol=@var{string}
+Disable process affinity and schedular priority
@end table
ETEXI
diff --git a/qemu-seccomp.c b/qemu-seccomp.c
index 4c169febf8..e7c19c8165 100644
--- a/qemu-seccomp.c
+++ b/qemu-seccomp.c
@@ -83,6 +83,17 @@ static const struct QemuSeccompSyscall blacklist[] = {
{ SCMP_SYS(fork), 8, QEMU_SECCOMP_SET_SPAWN },
{ SCMP_SYS(vfork), 8, QEMU_SECCOMP_SET_SPAWN },
{ SCMP_SYS(execve), 8, QEMU_SECCOMP_SET_SPAWN },
+ /* resource control */
+ { SCMP_SYS(getpriority), 16, QEMU_SECCOMP_SET_RESOURCECTL },
+ { SCMP_SYS(setpriority), 16, QEMU_SECCOMP_SET_RESOURCECTL },
+ { SCMP_SYS(sched_setparam), 16, QEMU_SECCOMP_SET_RESOURCECTL },
+ { SCMP_SYS(sched_getparam), 16, QEMU_SECCOMP_SET_RESOURCECTL },
+ { SCMP_SYS(sched_setscheduler), 16, QEMU_SECCOMP_SET_RESOURCECTL },
+ { SCMP_SYS(sched_getscheduler), 16, QEMU_SECCOMP_SET_RESOURCECTL },
+ { SCMP_SYS(sched_setaffinity), 16, QEMU_SECCOMP_SET_RESOURCECTL },
+ { SCMP_SYS(sched_getaffinity), 16, QEMU_SECCOMP_SET_RESOURCECTL },
+ { SCMP_SYS(sched_get_priority_max), 16, QEMU_SECCOMP_SET_RESOURCECTL },
+ { SCMP_SYS(sched_get_priority_min), 16, QEMU_SECCOMP_SET_RESOURCECTL },
};
@@ -121,6 +132,14 @@ int seccomp_start(uint32_t seccomp_opts)
}
break;
+ case QEMU_SECCOMP_SET_RESOURCECTL:
+ if (seccomp_opts & QEMU_SECCOMP_SET_RESOURCECTL) {
+ break;
+ } else {
+ continue;
+ }
+
+ break;
default:
break;
}
diff --git a/vl.c b/vl.c
index 0af137da17..ce3883ccb1 100644
--- a/vl.c
+++ b/vl.c
@@ -284,6 +284,10 @@ static QemuOptsList qemu_sandbox_opts = {
.name = "spawn",
.type = QEMU_OPT_STRING,
},
+ {
+ .name = "resourcecontrol",
+ .type = QEMU_OPT_STRING,
+ },
{ /* end of list */ }
},
};
@@ -1097,6 +1101,18 @@ static int parse_sandbox(void *opaque, QemuOpts *opts, Error **errp)
}
}
+ value = qemu_opt_get(opts, "resourcecontrol");
+ if (value) {
+ if (g_str_equal(value, "deny")) {
+ seccomp_opts |= QEMU_SECCOMP_SET_RESOURCECTL;
+ } else if (g_str_equal(value, "allow")) {
+ /* default value */
+ } else {
+ error_report("invalid argument for resourcecontrol");
+ return -1;
+ }
+ }
+
if (seccomp_start(seccomp_opts) < 0) {
error_report("failed to install seccomp syscall filter "
"in the kernel");
--
2.13.5
^ permalink raw reply related [flat|nested] 18+ messages in thread
* Re: [Qemu-devel] [PATCHv5 1/5] seccomp: changing from whitelist to blacklist
2017-09-08 9:10 ` [Qemu-devel] [PATCHv5 1/5] seccomp: changing from whitelist to blacklist Eduardo Otubo
@ 2017-09-08 9:31 ` Daniel P. Berrange
2017-09-08 9:43 ` Thomas Huth
1 sibling, 0 replies; 18+ messages in thread
From: Daniel P. Berrange @ 2017-09-08 9:31 UTC (permalink / raw)
To: Eduardo Otubo; +Cc: qemu-devel, thuth
On Fri, Sep 08, 2017 at 11:10:23AM +0200, Eduardo Otubo wrote:
> This patch changes the default behavior of the seccomp filter from
> whitelist to blacklist. By default now all system calls are allowed and
> a small black list of definitely forbidden ones was created.
>
> Signed-off-by: Eduardo Otubo <otubo@redhat.com>
> ---
> include/sysemu/seccomp.h | 2 +
> qemu-seccomp.c | 264 ++++++-----------------------------------------
> vl.c | 1 -
> 3 files changed, 35 insertions(+), 232 deletions(-)
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Regards,
Daniel
--
|: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org -o- https://fstop138.berrange.com :|
|: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [Qemu-devel] [PATCHv5 2/5] seccomp: add obsolete argument to command line
2017-09-08 9:10 ` [Qemu-devel] [PATCHv5 2/5] seccomp: add obsolete argument to command line Eduardo Otubo
@ 2017-09-08 9:31 ` Daniel P. Berrange
0 siblings, 0 replies; 18+ messages in thread
From: Daniel P. Berrange @ 2017-09-08 9:31 UTC (permalink / raw)
To: Eduardo Otubo; +Cc: qemu-devel, thuth
On Fri, Sep 08, 2017 at 11:10:24AM +0200, Eduardo Otubo wrote:
> This patch introduces the argument [,obsolete=allow] to the `-sandbox on'
> option. It allows Qemu to run safely on old system that still relies on
> old system calls.
>
> Signed-off-by: Eduardo Otubo <otubo@redhat.com>
> ---
> include/sysemu/seccomp.h | 3 ++-
> qemu-options.hx | 12 ++++++++++--
> qemu-seccomp.c | 20 +++++++++++++++++++-
> vl.c | 22 +++++++++++++++++++++-
> 4 files changed, 52 insertions(+), 5 deletions(-)
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Regards,
Daniel
--
|: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org -o- https://fstop138.berrange.com :|
|: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [Qemu-devel] [PATCHv5 3/5] seccomp: add elevateprivileges argument to command line
2017-09-08 9:10 ` [Qemu-devel] [PATCHv5 3/5] seccomp: add elevateprivileges " Eduardo Otubo
@ 2017-09-08 9:32 ` Daniel P. Berrange
0 siblings, 0 replies; 18+ messages in thread
From: Daniel P. Berrange @ 2017-09-08 9:32 UTC (permalink / raw)
To: Eduardo Otubo; +Cc: qemu-devel, thuth
On Fri, Sep 08, 2017 at 11:10:25AM +0200, Eduardo Otubo wrote:
> This patch introduces the new argument
> [,elevateprivileges=allow|deny|children] to the `-sandbox on'. It allows
> or denies Qemu process to elevate its privileges by blacklisting all
> set*uid|gid system calls. The 'children' option will let forks and
> execves run unprivileged.
>
> Signed-off-by: Eduardo Otubo <otubo@redhat.com>
> ---
> include/sysemu/seccomp.h | 1 +
> qemu-options.hx | 12 +++++++++---
> qemu-seccomp.c | 19 +++++++++++++++++++
> vl.c | 27 +++++++++++++++++++++++++++
> 4 files changed, 56 insertions(+), 3 deletions(-)
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Regards,
Daniel
--
|: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org -o- https://fstop138.berrange.com :|
|: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [Qemu-devel] [PATCHv5 4/5] seccomp: add spawn argument to command line
2017-09-08 9:10 ` [Qemu-devel] [PATCHv5 4/5] seccomp: add spawn " Eduardo Otubo
@ 2017-09-08 9:33 ` Daniel P. Berrange
2017-09-08 9:50 ` Thomas Huth
1 sibling, 0 replies; 18+ messages in thread
From: Daniel P. Berrange @ 2017-09-08 9:33 UTC (permalink / raw)
To: Eduardo Otubo; +Cc: qemu-devel, thuth
On Fri, Sep 08, 2017 at 11:10:26AM +0200, Eduardo Otubo wrote:
> This patch adds [,spawn=deny] argument to `-sandbox on' option. It
> blacklists fork and execve system calls, avoiding Qemu to spawn new
> threads or processes.
>
> Signed-off-by: Eduardo Otubo <otubo@redhat.com>
> ---
> include/sysemu/seccomp.h | 1 +
> qemu-options.hx | 9 +++++++--
> qemu-seccomp.c | 12 ++++++++++++
> vl.c | 16 ++++++++++++++++
> 4 files changed, 36 insertions(+), 2 deletions(-)
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Regards,
Daniel
--
|: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org -o- https://fstop138.berrange.com :|
|: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [Qemu-devel] [PATCHv5 5/5] seccomp: add resourcecontrol argument to command line
2017-09-08 9:10 ` [Qemu-devel] [PATCHv5 5/5] seccomp: add resourcecontrol " Eduardo Otubo
@ 2017-09-08 9:33 ` Daniel P. Berrange
0 siblings, 0 replies; 18+ messages in thread
From: Daniel P. Berrange @ 2017-09-08 9:33 UTC (permalink / raw)
To: Eduardo Otubo; +Cc: qemu-devel, thuth
On Fri, Sep 08, 2017 at 11:10:27AM +0200, Eduardo Otubo wrote:
> This patch adds [,resourcecontrol=deny] to `-sandbox on' option. It
> blacklists all process affinity and scheduler priority system calls to
> avoid any bigger of the process.
>
> Signed-off-by: Eduardo Otubo <otubo@redhat.com>
> ---
> include/sysemu/seccomp.h | 1 +
> qemu-options.hx | 9 ++++++---
> qemu-seccomp.c | 19 +++++++++++++++++++
> vl.c | 16 ++++++++++++++++
> 4 files changed, 42 insertions(+), 3 deletions(-)
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Regards,
Daniel
--
|: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org -o- https://fstop138.berrange.com :|
|: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [Qemu-devel] [PATCHv5 1/5] seccomp: changing from whitelist to blacklist
2017-09-08 9:10 ` [Qemu-devel] [PATCHv5 1/5] seccomp: changing from whitelist to blacklist Eduardo Otubo
2017-09-08 9:31 ` Daniel P. Berrange
@ 2017-09-08 9:43 ` Thomas Huth
2017-09-08 9:50 ` Eduardo Otubo
1 sibling, 1 reply; 18+ messages in thread
From: Thomas Huth @ 2017-09-08 9:43 UTC (permalink / raw)
To: Eduardo Otubo, qemu-devel
On 08.09.2017 11:10, Eduardo Otubo wrote:
> This patch changes the default behavior of the seccomp filter from
> whitelist to blacklist. By default now all system calls are allowed and
> a small black list of definitely forbidden ones was created.
>
> Signed-off-by: Eduardo Otubo <otubo@redhat.com>
> ---
> include/sysemu/seccomp.h | 2 +
> qemu-seccomp.c | 264 ++++++-----------------------------------------
> vl.c | 1 -
> 3 files changed, 35 insertions(+), 232 deletions(-)
>
> diff --git a/include/sysemu/seccomp.h b/include/sysemu/seccomp.h
> index cfc06008cb..23b9c3c789 100644
> --- a/include/sysemu/seccomp.h
> +++ b/include/sysemu/seccomp.h
> @@ -15,6 +15,8 @@
> #ifndef QEMU_SECCOMP_H
> #define QEMU_SECCOMP_H
>
> +#define QEMU_SECCOMP_SET_DEFAULT (1 << 0)
> +
> #include <seccomp.h>
>
> int seccomp_start(void);
> diff --git a/qemu-seccomp.c b/qemu-seccomp.c
> index df75d9c471..bc9a1f77ff 100644
> --- a/qemu-seccomp.c
> +++ b/qemu-seccomp.c
> @@ -28,232 +28,34 @@
>
> struct QemuSeccompSyscall {
> int32_t num;
> - uint8_t priority;
> + int type;
What's this "type" field good for? I failed to spot the place in the
sources where you are using it...? Anyway, some comments here right
after the struct members would be useful.
Thomas
> + uint8_t set;
> };
>
> -static const struct QemuSeccompSyscall seccomp_whitelist[] = {
> - { SCMP_SYS(timer_settime), 255 },
[...]
> - { SCMP_SYS(memfd_create), 240 },
> -#ifdef HAVE_CACHEFLUSH
> - { SCMP_SYS(cacheflush), 240 },
> -#endif
> - { SCMP_SYS(sysinfo), 240 },
> +static const struct QemuSeccompSyscall blacklist[] = {
> + /* default set of syscalls to blacklist */
> + { SCMP_SYS(reboot), 1, QEMU_SECCOMP_SET_DEFAULT },
> + { SCMP_SYS(swapon), 1, QEMU_SECCOMP_SET_DEFAULT },
> + { SCMP_SYS(swapoff), 1, QEMU_SECCOMP_SET_DEFAULT },
> + { SCMP_SYS(syslog), 1, QEMU_SECCOMP_SET_DEFAULT },
> + { SCMP_SYS(mount), 1, QEMU_SECCOMP_SET_DEFAULT },
> + { SCMP_SYS(umount), 1, QEMU_SECCOMP_SET_DEFAULT },
> + { SCMP_SYS(kexec_load), 1, QEMU_SECCOMP_SET_DEFAULT },
> + { SCMP_SYS(afs_syscall), 1, QEMU_SECCOMP_SET_DEFAULT },
> + { SCMP_SYS(break), 1, QEMU_SECCOMP_SET_DEFAULT },
> + { SCMP_SYS(ftime), 1, QEMU_SECCOMP_SET_DEFAULT },
> + { SCMP_SYS(getpmsg), 1, QEMU_SECCOMP_SET_DEFAULT },
> + { SCMP_SYS(gtty), 1, QEMU_SECCOMP_SET_DEFAULT },
> + { SCMP_SYS(lock), 1, QEMU_SECCOMP_SET_DEFAULT },
> + { SCMP_SYS(mpx), 1, QEMU_SECCOMP_SET_DEFAULT },
> + { SCMP_SYS(prof), 1, QEMU_SECCOMP_SET_DEFAULT },
> + { SCMP_SYS(profil), 1, QEMU_SECCOMP_SET_DEFAULT },
> + { SCMP_SYS(putpmsg), 1, QEMU_SECCOMP_SET_DEFAULT },
> + { SCMP_SYS(security), 1, QEMU_SECCOMP_SET_DEFAULT },
> + { SCMP_SYS(stty), 1, QEMU_SECCOMP_SET_DEFAULT },
> + { SCMP_SYS(tuxcall), 1, QEMU_SECCOMP_SET_DEFAULT },
> + { SCMP_SYS(ulimit), 1, QEMU_SECCOMP_SET_DEFAULT },
> + { SCMP_SYS(vserver), 1, QEMU_SECCOMP_SET_DEFAULT },
> };
>
> int seccomp_start(void)
> @@ -262,19 +64,19 @@ int seccomp_start(void)
> unsigned int i = 0;
> scmp_filter_ctx ctx;
>
> - ctx = seccomp_init(SCMP_ACT_KILL);
> + ctx = seccomp_init(SCMP_ACT_ALLOW);
> if (ctx == NULL) {
> rc = -1;
> goto seccomp_return;
> }
>
> - for (i = 0; i < ARRAY_SIZE(seccomp_whitelist); i++) {
> - rc = seccomp_rule_add(ctx, SCMP_ACT_ALLOW, seccomp_whitelist[i].num, 0);
> - if (rc < 0) {
> - goto seccomp_return;
> + for (i = 0; i < ARRAY_SIZE(blacklist); i++) {
> + switch (blacklist[i].set) {
> + default:
> + break;
> }
> - rc = seccomp_syscall_priority(ctx, seccomp_whitelist[i].num,
> - seccomp_whitelist[i].priority);
> +
> + rc = seccomp_rule_add(ctx, SCMP_ACT_KILL, blacklist[i].num, 0);
> if (rc < 0) {
> goto seccomp_return;
> }
> diff --git a/vl.c b/vl.c
> index fb1f05b937..76e0b3a946 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -1032,7 +1032,6 @@ static int bt_parse(const char *opt)
>
> static int parse_sandbox(void *opaque, QemuOpts *opts, Error **errp)
> {
> - /* FIXME: change this to true for 1.3 */
> if (qemu_opt_get_bool(opts, "enable", false)) {
> #ifdef CONFIG_SECCOMP
> if (seccomp_start() < 0) {
>
^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [Qemu-devel] [PATCHv5 4/5] seccomp: add spawn argument to command line
2017-09-08 9:10 ` [Qemu-devel] [PATCHv5 4/5] seccomp: add spawn " Eduardo Otubo
2017-09-08 9:33 ` Daniel P. Berrange
@ 2017-09-08 9:50 ` Thomas Huth
2017-09-08 11:15 ` Eduardo Otubo
1 sibling, 1 reply; 18+ messages in thread
From: Thomas Huth @ 2017-09-08 9:50 UTC (permalink / raw)
To: Eduardo Otubo, qemu-devel
On 08.09.2017 11:10, Eduardo Otubo wrote:
> This patch adds [,spawn=deny] argument to `-sandbox on' option. It
> blacklists fork and execve system calls, avoiding Qemu to spawn new
> threads or processes.
>
> Signed-off-by: Eduardo Otubo <otubo@redhat.com>
> ---
> include/sysemu/seccomp.h | 1 +
> qemu-options.hx | 9 +++++++--
> qemu-seccomp.c | 12 ++++++++++++
> vl.c | 16 ++++++++++++++++
> 4 files changed, 36 insertions(+), 2 deletions(-)
>
> diff --git a/include/sysemu/seccomp.h b/include/sysemu/seccomp.h
> index 4a9e63c7cd..3ab5fc4f61 100644
> --- a/include/sysemu/seccomp.h
> +++ b/include/sysemu/seccomp.h
> @@ -18,6 +18,7 @@
> #define QEMU_SECCOMP_SET_DEFAULT (1 << 0)
> #define QEMU_SECCOMP_SET_OBSOLETE (1 << 1)
> #define QEMU_SECCOMP_SET_PRIVILEGED (1 << 2)
> +#define QEMU_SECCOMP_SET_SPAWN (1 << 3)
>
> #include <seccomp.h>
>
> diff --git a/qemu-options.hx b/qemu-options.hx
> index 5c1b163fb5..2b04b9f170 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -4018,6 +4018,7 @@ ETEXI
>
> DEF("sandbox", HAS_ARG, QEMU_OPTION_sandbox, \
> "-sandbox on[,obsolete=allow|deny][,elevateprivileges=allow|deny|children]\n" \
> + " [,spawn=allow|deny]\n" \
> " Enable seccomp mode 2 system call filter (default 'off').\n" \
> " use 'obsolete' to allow obsolete system calls that are provided\n" \
> " by the kernel, but typically no longer used by modern\n" \
> @@ -4025,10 +4026,12 @@ DEF("sandbox", HAS_ARG, QEMU_OPTION_sandbox, \
> " use 'elevateprivileges' to allow or deny QEMU process to elevate\n" \
> " its privileges by blacklisting all set*uid|gid system calls.\n" \
> " The value 'children' will deny set*uid|gid system calls for\n" \
> - " main QEMU process but will allow forks and execves to run unprivileged\n",
> + " main QEMU process but will allow forks and execves to run unprivileged\n" \
> + " use 'spawn' to avoid QEMU to spawn new threads or processes by\n" \
> + " blacklisting *fork and execve\n",
> QEMU_ARCH_ALL)
> STEXI
> -@item -sandbox @var{arg}[,obsolete=@var{string}][,elevateprivileges=@var{string}]
> +@item -sandbox @var{arg}[,obsolete=@var{string}][,elevateprivileges=@var{string}][,spawn=@var{string}]
> @findex -sandbox
> Enable Seccomp mode 2 system call filter. 'on' will enable syscall filtering and 'off' will
> disable it. The default is 'off'.
> @@ -4037,6 +4040,8 @@ disable it. The default is 'off'.
> Enable Obsolete system calls
> @item elevateprivileges=@var{string}
> Disable set*uid|gid system calls
> +@item spawn=@var{string}
> +Disable *fork and execve
> @end table
> ETEXI
>
> diff --git a/qemu-seccomp.c b/qemu-seccomp.c
> index 2bad16cafb..4c169febf8 100644
> --- a/qemu-seccomp.c
> +++ b/qemu-seccomp.c
> @@ -79,6 +79,10 @@ static const struct QemuSeccompSyscall blacklist[] = {
> { SCMP_SYS(setresgid), 4, QEMU_SECCOMP_SET_PRIVILEGED },
> { SCMP_SYS(setfsuid), 4, QEMU_SECCOMP_SET_PRIVILEGED },
> { SCMP_SYS(setfsgid), 4, QEMU_SECCOMP_SET_PRIVILEGED },
> + /* spawn */
> + { SCMP_SYS(fork), 8, QEMU_SECCOMP_SET_SPAWN },
> + { SCMP_SYS(vfork), 8, QEMU_SECCOMP_SET_SPAWN },
> + { SCMP_SYS(execve), 8, QEMU_SECCOMP_SET_SPAWN },
> };
>
>
> @@ -109,6 +113,14 @@ int seccomp_start(uint32_t seccomp_opts)
> }
>
> break;
> + case QEMU_SECCOMP_SET_SPAWN:
> + if (seccomp_opts & QEMU_SECCOMP_SET_SPAWN) {
> + break;
> + } else {
> + continue;
> + }
> +
Remove the above empty line?
Anyway, it's somewhat ugly that you need a switch-case statement here at
all. Couldn't you simply check it like this:
if (!(seccomp_opts & blacklist[i].set)) {
continue;
}
?
You then just have to invert the meaning of the
QEMU_SECCOMP_SET_OBSOLETE bit in the second patch, so that this bit is
treated in the same way as the others (i.e. use
uint32_t seccomp_opts = QEMU_SECCOMP_SET_OBSOLETE;
instead of
uint32_t seccomp_opts = 0x00000;
in vl.c in the second patch).
Thomas
^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [Qemu-devel] [PATCHv5 1/5] seccomp: changing from whitelist to blacklist
2017-09-08 9:43 ` Thomas Huth
@ 2017-09-08 9:50 ` Eduardo Otubo
2017-09-08 9:52 ` Thomas Huth
0 siblings, 1 reply; 18+ messages in thread
From: Eduardo Otubo @ 2017-09-08 9:50 UTC (permalink / raw)
To: Thomas Huth; +Cc: qemu-devel
On Fri, Sep 08, 2017 at 11:43:27AM +0200, Thomas Huth wrote:
> On 08.09.2017 11:10, Eduardo Otubo wrote:
> > This patch changes the default behavior of the seccomp filter from
> > whitelist to blacklist. By default now all system calls are allowed and
> > a small black list of definitely forbidden ones was created.
> >
> > Signed-off-by: Eduardo Otubo <otubo@redhat.com>
> > ---
> > include/sysemu/seccomp.h | 2 +
> > qemu-seccomp.c | 264 ++++++-----------------------------------------
> > vl.c | 1 -
> > 3 files changed, 35 insertions(+), 232 deletions(-)
> >
> > diff --git a/include/sysemu/seccomp.h b/include/sysemu/seccomp.h
> > index cfc06008cb..23b9c3c789 100644
> > --- a/include/sysemu/seccomp.h
> > +++ b/include/sysemu/seccomp.h
> > @@ -15,6 +15,8 @@
> > #ifndef QEMU_SECCOMP_H
> > #define QEMU_SECCOMP_H
> >
> > +#define QEMU_SECCOMP_SET_DEFAULT (1 << 0)
> > +
> > #include <seccomp.h>
> >
> > int seccomp_start(void);
> > diff --git a/qemu-seccomp.c b/qemu-seccomp.c
> > index df75d9c471..bc9a1f77ff 100644
> > --- a/qemu-seccomp.c
> > +++ b/qemu-seccomp.c
> > @@ -28,232 +28,34 @@
> >
> > struct QemuSeccompSyscall {
> > int32_t num;
> > - uint8_t priority;
> > + int type;
>
> What's this "type" field good for? I failed to spot the place in the
> sources where you are using it...? Anyway, some comments here right
> after the struct members would be useful.
The type is exactly the type of the system call on the blacklist array
below. Being QEMU_SECCOMP_SET_DEFAULT, QEMU_SECCOMP_SET_OBSOLETE, etc.
Do you think comments here worth a full v6?
>
> Thomas
>
> > + uint8_t set;
> > };
> >
> > -static const struct QemuSeccompSyscall seccomp_whitelist[] = {
> > - { SCMP_SYS(timer_settime), 255 },
> [...]
> > - { SCMP_SYS(memfd_create), 240 },
> > -#ifdef HAVE_CACHEFLUSH
> > - { SCMP_SYS(cacheflush), 240 },
> > -#endif
> > - { SCMP_SYS(sysinfo), 240 },
> > +static const struct QemuSeccompSyscall blacklist[] = {
> > + /* default set of syscalls to blacklist */
> > + { SCMP_SYS(reboot), 1, QEMU_SECCOMP_SET_DEFAULT },
> > + { SCMP_SYS(swapon), 1, QEMU_SECCOMP_SET_DEFAULT },
> > + { SCMP_SYS(swapoff), 1, QEMU_SECCOMP_SET_DEFAULT },
> > + { SCMP_SYS(syslog), 1, QEMU_SECCOMP_SET_DEFAULT },
> > + { SCMP_SYS(mount), 1, QEMU_SECCOMP_SET_DEFAULT },
> > + { SCMP_SYS(umount), 1, QEMU_SECCOMP_SET_DEFAULT },
> > + { SCMP_SYS(kexec_load), 1, QEMU_SECCOMP_SET_DEFAULT },
> > + { SCMP_SYS(afs_syscall), 1, QEMU_SECCOMP_SET_DEFAULT },
> > + { SCMP_SYS(break), 1, QEMU_SECCOMP_SET_DEFAULT },
> > + { SCMP_SYS(ftime), 1, QEMU_SECCOMP_SET_DEFAULT },
> > + { SCMP_SYS(getpmsg), 1, QEMU_SECCOMP_SET_DEFAULT },
> > + { SCMP_SYS(gtty), 1, QEMU_SECCOMP_SET_DEFAULT },
> > + { SCMP_SYS(lock), 1, QEMU_SECCOMP_SET_DEFAULT },
> > + { SCMP_SYS(mpx), 1, QEMU_SECCOMP_SET_DEFAULT },
> > + { SCMP_SYS(prof), 1, QEMU_SECCOMP_SET_DEFAULT },
> > + { SCMP_SYS(profil), 1, QEMU_SECCOMP_SET_DEFAULT },
> > + { SCMP_SYS(putpmsg), 1, QEMU_SECCOMP_SET_DEFAULT },
> > + { SCMP_SYS(security), 1, QEMU_SECCOMP_SET_DEFAULT },
> > + { SCMP_SYS(stty), 1, QEMU_SECCOMP_SET_DEFAULT },
> > + { SCMP_SYS(tuxcall), 1, QEMU_SECCOMP_SET_DEFAULT },
> > + { SCMP_SYS(ulimit), 1, QEMU_SECCOMP_SET_DEFAULT },
> > + { SCMP_SYS(vserver), 1, QEMU_SECCOMP_SET_DEFAULT },
> > };
> >
> > int seccomp_start(void)
> > @@ -262,19 +64,19 @@ int seccomp_start(void)
> > unsigned int i = 0;
> > scmp_filter_ctx ctx;
> >
> > - ctx = seccomp_init(SCMP_ACT_KILL);
> > + ctx = seccomp_init(SCMP_ACT_ALLOW);
> > if (ctx == NULL) {
> > rc = -1;
> > goto seccomp_return;
> > }
> >
> > - for (i = 0; i < ARRAY_SIZE(seccomp_whitelist); i++) {
> > - rc = seccomp_rule_add(ctx, SCMP_ACT_ALLOW, seccomp_whitelist[i].num, 0);
> > - if (rc < 0) {
> > - goto seccomp_return;
> > + for (i = 0; i < ARRAY_SIZE(blacklist); i++) {
> > + switch (blacklist[i].set) {
> > + default:
> > + break;
> > }
> > - rc = seccomp_syscall_priority(ctx, seccomp_whitelist[i].num,
> > - seccomp_whitelist[i].priority);
> > +
> > + rc = seccomp_rule_add(ctx, SCMP_ACT_KILL, blacklist[i].num, 0);
> > if (rc < 0) {
> > goto seccomp_return;
> > }
> > diff --git a/vl.c b/vl.c
> > index fb1f05b937..76e0b3a946 100644
> > --- a/vl.c
> > +++ b/vl.c
> > @@ -1032,7 +1032,6 @@ static int bt_parse(const char *opt)
> >
> > static int parse_sandbox(void *opaque, QemuOpts *opts, Error **errp)
> > {
> > - /* FIXME: change this to true for 1.3 */
> > if (qemu_opt_get_bool(opts, "enable", false)) {
> > #ifdef CONFIG_SECCOMP
> > if (seccomp_start() < 0) {
> >
>
>
--
Eduardo Otubo
Senior Software Engineer @ RedHat
^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [Qemu-devel] [PATCHv5 1/5] seccomp: changing from whitelist to blacklist
2017-09-08 9:50 ` Eduardo Otubo
@ 2017-09-08 9:52 ` Thomas Huth
2017-09-08 10:57 ` Eduardo Otubo
0 siblings, 1 reply; 18+ messages in thread
From: Thomas Huth @ 2017-09-08 9:52 UTC (permalink / raw)
To: Eduardo Otubo; +Cc: qemu-devel
On 08.09.2017 11:50, Eduardo Otubo wrote:
> On Fri, Sep 08, 2017 at 11:43:27AM +0200, Thomas Huth wrote:
>> On 08.09.2017 11:10, Eduardo Otubo wrote:
>>> This patch changes the default behavior of the seccomp filter from
>>> whitelist to blacklist. By default now all system calls are allowed and
>>> a small black list of definitely forbidden ones was created.
>>>
>>> Signed-off-by: Eduardo Otubo <otubo@redhat.com>
>>> ---
>>> include/sysemu/seccomp.h | 2 +
>>> qemu-seccomp.c | 264 ++++++-----------------------------------------
>>> vl.c | 1 -
>>> 3 files changed, 35 insertions(+), 232 deletions(-)
>>>
>>> diff --git a/include/sysemu/seccomp.h b/include/sysemu/seccomp.h
>>> index cfc06008cb..23b9c3c789 100644
>>> --- a/include/sysemu/seccomp.h
>>> +++ b/include/sysemu/seccomp.h
>>> @@ -15,6 +15,8 @@
>>> #ifndef QEMU_SECCOMP_H
>>> #define QEMU_SECCOMP_H
>>>
>>> +#define QEMU_SECCOMP_SET_DEFAULT (1 << 0)
>>> +
>>> #include <seccomp.h>
>>>
>>> int seccomp_start(void);
>>> diff --git a/qemu-seccomp.c b/qemu-seccomp.c
>>> index df75d9c471..bc9a1f77ff 100644
>>> --- a/qemu-seccomp.c
>>> +++ b/qemu-seccomp.c
>>> @@ -28,232 +28,34 @@
>>>
>>> struct QemuSeccompSyscall {
>>> int32_t num;
>>> - uint8_t priority;
>>> + int type;
>>
>> What's this "type" field good for? I failed to spot the place in the
>> sources where you are using it...? Anyway, some comments here right
>> after the struct members would be useful.
>
> The type is exactly the type of the system call on the blacklist array
> below. Being QEMU_SECCOMP_SET_DEFAULT, QEMU_SECCOMP_SET_OBSOLETE, etc.
Sorry, I still do not understand. If that's the case, what's the
difference between the "type" field and the "set" field? Where do you
use the "type" field?
Thomas
>>> + uint8_t set;
>>> };
>>>
>>> -static const struct QemuSeccompSyscall seccomp_whitelist[] = {
>>> - { SCMP_SYS(timer_settime), 255 },
>> [...]
>>> - { SCMP_SYS(memfd_create), 240 },
>>> -#ifdef HAVE_CACHEFLUSH
>>> - { SCMP_SYS(cacheflush), 240 },
>>> -#endif
>>> - { SCMP_SYS(sysinfo), 240 },
>>> +static const struct QemuSeccompSyscall blacklist[] = {
>>> + /* default set of syscalls to blacklist */
>>> + { SCMP_SYS(reboot), 1, QEMU_SECCOMP_SET_DEFAULT },
>>> + { SCMP_SYS(swapon), 1, QEMU_SECCOMP_SET_DEFAULT },
>>> + { SCMP_SYS(swapoff), 1, QEMU_SECCOMP_SET_DEFAULT },
>>> + { SCMP_SYS(syslog), 1, QEMU_SECCOMP_SET_DEFAULT },
>>> + { SCMP_SYS(mount), 1, QEMU_SECCOMP_SET_DEFAULT },
>>> + { SCMP_SYS(umount), 1, QEMU_SECCOMP_SET_DEFAULT },
>>> + { SCMP_SYS(kexec_load), 1, QEMU_SECCOMP_SET_DEFAULT },
>>> + { SCMP_SYS(afs_syscall), 1, QEMU_SECCOMP_SET_DEFAULT },
>>> + { SCMP_SYS(break), 1, QEMU_SECCOMP_SET_DEFAULT },
>>> + { SCMP_SYS(ftime), 1, QEMU_SECCOMP_SET_DEFAULT },
>>> + { SCMP_SYS(getpmsg), 1, QEMU_SECCOMP_SET_DEFAULT },
>>> + { SCMP_SYS(gtty), 1, QEMU_SECCOMP_SET_DEFAULT },
>>> + { SCMP_SYS(lock), 1, QEMU_SECCOMP_SET_DEFAULT },
>>> + { SCMP_SYS(mpx), 1, QEMU_SECCOMP_SET_DEFAULT },
>>> + { SCMP_SYS(prof), 1, QEMU_SECCOMP_SET_DEFAULT },
>>> + { SCMP_SYS(profil), 1, QEMU_SECCOMP_SET_DEFAULT },
>>> + { SCMP_SYS(putpmsg), 1, QEMU_SECCOMP_SET_DEFAULT },
>>> + { SCMP_SYS(security), 1, QEMU_SECCOMP_SET_DEFAULT },
>>> + { SCMP_SYS(stty), 1, QEMU_SECCOMP_SET_DEFAULT },
>>> + { SCMP_SYS(tuxcall), 1, QEMU_SECCOMP_SET_DEFAULT },
>>> + { SCMP_SYS(ulimit), 1, QEMU_SECCOMP_SET_DEFAULT },
>>> + { SCMP_SYS(vserver), 1, QEMU_SECCOMP_SET_DEFAULT },
>>> };
>>>
>>> int seccomp_start(void)
>>> @@ -262,19 +64,19 @@ int seccomp_start(void)
>>> unsigned int i = 0;
>>> scmp_filter_ctx ctx;
>>>
>>> - ctx = seccomp_init(SCMP_ACT_KILL);
>>> + ctx = seccomp_init(SCMP_ACT_ALLOW);
>>> if (ctx == NULL) {
>>> rc = -1;
>>> goto seccomp_return;
>>> }
>>>
>>> - for (i = 0; i < ARRAY_SIZE(seccomp_whitelist); i++) {
>>> - rc = seccomp_rule_add(ctx, SCMP_ACT_ALLOW, seccomp_whitelist[i].num, 0);
>>> - if (rc < 0) {
>>> - goto seccomp_return;
>>> + for (i = 0; i < ARRAY_SIZE(blacklist); i++) {
>>> + switch (blacklist[i].set) {
>>> + default:
>>> + break;
>>> }
>>> - rc = seccomp_syscall_priority(ctx, seccomp_whitelist[i].num,
>>> - seccomp_whitelist[i].priority);
>>> +
>>> + rc = seccomp_rule_add(ctx, SCMP_ACT_KILL, blacklist[i].num, 0);
>>> if (rc < 0) {
>>> goto seccomp_return;
>>> }
>>> diff --git a/vl.c b/vl.c
>>> index fb1f05b937..76e0b3a946 100644
>>> --- a/vl.c
>>> +++ b/vl.c
>>> @@ -1032,7 +1032,6 @@ static int bt_parse(const char *opt)
>>>
>>> static int parse_sandbox(void *opaque, QemuOpts *opts, Error **errp)
>>> {
>>> - /* FIXME: change this to true for 1.3 */
>>> if (qemu_opt_get_bool(opts, "enable", false)) {
>>> #ifdef CONFIG_SECCOMP
>>> if (seccomp_start() < 0) {
>>>
>>
>>
>
^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [Qemu-devel] [PATCHv5 1/5] seccomp: changing from whitelist to blacklist
2017-09-08 9:52 ` Thomas Huth
@ 2017-09-08 10:57 ` Eduardo Otubo
0 siblings, 0 replies; 18+ messages in thread
From: Eduardo Otubo @ 2017-09-08 10:57 UTC (permalink / raw)
To: Thomas Huth; +Cc: qemu-devel
On Fri, Sep 08, 2017 at 11:52:42AM +0200, Thomas Huth wrote:
> On 08.09.2017 11:50, Eduardo Otubo wrote:
> > On Fri, Sep 08, 2017 at 11:43:27AM +0200, Thomas Huth wrote:
> >> On 08.09.2017 11:10, Eduardo Otubo wrote:
> >>> This patch changes the default behavior of the seccomp filter from
> >>> whitelist to blacklist. By default now all system calls are allowed and
> >>> a small black list of definitely forbidden ones was created.
> >>>
> >>> Signed-off-by: Eduardo Otubo <otubo@redhat.com>
> >>> ---
> >>> include/sysemu/seccomp.h | 2 +
> >>> qemu-seccomp.c | 264 ++++++-----------------------------------------
> >>> vl.c | 1 -
> >>> 3 files changed, 35 insertions(+), 232 deletions(-)
> >>>
> >>> diff --git a/include/sysemu/seccomp.h b/include/sysemu/seccomp.h
> >>> index cfc06008cb..23b9c3c789 100644
> >>> --- a/include/sysemu/seccomp.h
> >>> +++ b/include/sysemu/seccomp.h
> >>> @@ -15,6 +15,8 @@
> >>> #ifndef QEMU_SECCOMP_H
> >>> #define QEMU_SECCOMP_H
> >>>
> >>> +#define QEMU_SECCOMP_SET_DEFAULT (1 << 0)
> >>> +
> >>> #include <seccomp.h>
> >>>
> >>> int seccomp_start(void);
> >>> diff --git a/qemu-seccomp.c b/qemu-seccomp.c
> >>> index df75d9c471..bc9a1f77ff 100644
> >>> --- a/qemu-seccomp.c
> >>> +++ b/qemu-seccomp.c
> >>> @@ -28,232 +28,34 @@
> >>>
> >>> struct QemuSeccompSyscall {
> >>> int32_t num;
> >>> - uint8_t priority;
> >>> + int type;
> >>
> >> What's this "type" field good for? I failed to spot the place in the
> >> sources where you are using it...? Anyway, some comments here right
> >> after the struct members would be useful.
> >
> > The type is exactly the type of the system call on the blacklist array
> > below. Being QEMU_SECCOMP_SET_DEFAULT, QEMU_SECCOMP_SET_OBSOLETE, etc.
>
> Sorry, I still do not understand. If that's the case, what's the
> difference between the "type" field and the "set" field? Where do you
> use the "type" field?
HARGH, sorry. Perhaps I was debugging tis for too long and didn't
notice it. This was for debug purposes only. I'll remove and resend.
Thanks for spotting this.
> >>> + uint8_t set;
> >>> };
> >>>
> >>> -static const struct QemuSeccompSyscall seccomp_whitelist[] = {
> >>> - { SCMP_SYS(timer_settime), 255 },
> >> [...]
> >>> - { SCMP_SYS(memfd_create), 240 },
> >>> -#ifdef HAVE_CACHEFLUSH
> >>> - { SCMP_SYS(cacheflush), 240 },
> >>> -#endif
> >>> - { SCMP_SYS(sysinfo), 240 },
> >>> +static const struct QemuSeccompSyscall blacklist[] = {
> >>> + /* default set of syscalls to blacklist */
> >>> + { SCMP_SYS(reboot), 1, QEMU_SECCOMP_SET_DEFAULT },
> >>> + { SCMP_SYS(swapon), 1, QEMU_SECCOMP_SET_DEFAULT },
> >>> + { SCMP_SYS(swapoff), 1, QEMU_SECCOMP_SET_DEFAULT },
> >>> + { SCMP_SYS(syslog), 1, QEMU_SECCOMP_SET_DEFAULT },
> >>> + { SCMP_SYS(mount), 1, QEMU_SECCOMP_SET_DEFAULT },
> >>> + { SCMP_SYS(umount), 1, QEMU_SECCOMP_SET_DEFAULT },
> >>> + { SCMP_SYS(kexec_load), 1, QEMU_SECCOMP_SET_DEFAULT },
> >>> + { SCMP_SYS(afs_syscall), 1, QEMU_SECCOMP_SET_DEFAULT },
> >>> + { SCMP_SYS(break), 1, QEMU_SECCOMP_SET_DEFAULT },
> >>> + { SCMP_SYS(ftime), 1, QEMU_SECCOMP_SET_DEFAULT },
> >>> + { SCMP_SYS(getpmsg), 1, QEMU_SECCOMP_SET_DEFAULT },
> >>> + { SCMP_SYS(gtty), 1, QEMU_SECCOMP_SET_DEFAULT },
> >>> + { SCMP_SYS(lock), 1, QEMU_SECCOMP_SET_DEFAULT },
> >>> + { SCMP_SYS(mpx), 1, QEMU_SECCOMP_SET_DEFAULT },
> >>> + { SCMP_SYS(prof), 1, QEMU_SECCOMP_SET_DEFAULT },
> >>> + { SCMP_SYS(profil), 1, QEMU_SECCOMP_SET_DEFAULT },
> >>> + { SCMP_SYS(putpmsg), 1, QEMU_SECCOMP_SET_DEFAULT },
> >>> + { SCMP_SYS(security), 1, QEMU_SECCOMP_SET_DEFAULT },
> >>> + { SCMP_SYS(stty), 1, QEMU_SECCOMP_SET_DEFAULT },
> >>> + { SCMP_SYS(tuxcall), 1, QEMU_SECCOMP_SET_DEFAULT },
> >>> + { SCMP_SYS(ulimit), 1, QEMU_SECCOMP_SET_DEFAULT },
> >>> + { SCMP_SYS(vserver), 1, QEMU_SECCOMP_SET_DEFAULT },
> >>> };
> >>>
> >>> int seccomp_start(void)
> >>> @@ -262,19 +64,19 @@ int seccomp_start(void)
> >>> unsigned int i = 0;
> >>> scmp_filter_ctx ctx;
> >>>
> >>> - ctx = seccomp_init(SCMP_ACT_KILL);
> >>> + ctx = seccomp_init(SCMP_ACT_ALLOW);
> >>> if (ctx == NULL) {
> >>> rc = -1;
> >>> goto seccomp_return;
> >>> }
> >>>
> >>> - for (i = 0; i < ARRAY_SIZE(seccomp_whitelist); i++) {
> >>> - rc = seccomp_rule_add(ctx, SCMP_ACT_ALLOW, seccomp_whitelist[i].num, 0);
> >>> - if (rc < 0) {
> >>> - goto seccomp_return;
> >>> + for (i = 0; i < ARRAY_SIZE(blacklist); i++) {
> >>> + switch (blacklist[i].set) {
> >>> + default:
> >>> + break;
> >>> }
> >>> - rc = seccomp_syscall_priority(ctx, seccomp_whitelist[i].num,
> >>> - seccomp_whitelist[i].priority);
> >>> +
> >>> + rc = seccomp_rule_add(ctx, SCMP_ACT_KILL, blacklist[i].num, 0);
> >>> if (rc < 0) {
> >>> goto seccomp_return;
> >>> }
> >>> diff --git a/vl.c b/vl.c
> >>> index fb1f05b937..76e0b3a946 100644
> >>> --- a/vl.c
> >>> +++ b/vl.c
> >>> @@ -1032,7 +1032,6 @@ static int bt_parse(const char *opt)
> >>>
> >>> static int parse_sandbox(void *opaque, QemuOpts *opts, Error **errp)
> >>> {
> >>> - /* FIXME: change this to true for 1.3 */
> >>> if (qemu_opt_get_bool(opts, "enable", false)) {
> >>> #ifdef CONFIG_SECCOMP
> >>> if (seccomp_start() < 0) {
> >>>
> >>
> >>
> >
>
--
Eduardo Otubo
Senior Software Engineer @ RedHat
^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [Qemu-devel] [PATCHv5 4/5] seccomp: add spawn argument to command line
2017-09-08 9:50 ` Thomas Huth
@ 2017-09-08 11:15 ` Eduardo Otubo
2017-09-08 11:31 ` Thomas Huth
0 siblings, 1 reply; 18+ messages in thread
From: Eduardo Otubo @ 2017-09-08 11:15 UTC (permalink / raw)
To: Thomas Huth; +Cc: qemu-devel
On Fri, Sep 08, 2017 at 11:50:12AM +0200, Thomas Huth wrote:
> On 08.09.2017 11:10, Eduardo Otubo wrote:
> > This patch adds [,spawn=deny] argument to `-sandbox on' option. It
> > blacklists fork and execve system calls, avoiding Qemu to spawn new
> > threads or processes.
> >
> > Signed-off-by: Eduardo Otubo <otubo@redhat.com>
> > ---
> > include/sysemu/seccomp.h | 1 +
> > qemu-options.hx | 9 +++++++--
> > qemu-seccomp.c | 12 ++++++++++++
> > vl.c | 16 ++++++++++++++++
> > 4 files changed, 36 insertions(+), 2 deletions(-)
> >
> > diff --git a/include/sysemu/seccomp.h b/include/sysemu/seccomp.h
> > index 4a9e63c7cd..3ab5fc4f61 100644
> > --- a/include/sysemu/seccomp.h
> > +++ b/include/sysemu/seccomp.h
> > @@ -18,6 +18,7 @@
> > #define QEMU_SECCOMP_SET_DEFAULT (1 << 0)
> > #define QEMU_SECCOMP_SET_OBSOLETE (1 << 1)
> > #define QEMU_SECCOMP_SET_PRIVILEGED (1 << 2)
> > +#define QEMU_SECCOMP_SET_SPAWN (1 << 3)
> >
> > #include <seccomp.h>
> >
> > diff --git a/qemu-options.hx b/qemu-options.hx
> > index 5c1b163fb5..2b04b9f170 100644
> > --- a/qemu-options.hx
> > +++ b/qemu-options.hx
> > @@ -4018,6 +4018,7 @@ ETEXI
> >
> > DEF("sandbox", HAS_ARG, QEMU_OPTION_sandbox, \
> > "-sandbox on[,obsolete=allow|deny][,elevateprivileges=allow|deny|children]\n" \
> > + " [,spawn=allow|deny]\n" \
> > " Enable seccomp mode 2 system call filter (default 'off').\n" \
> > " use 'obsolete' to allow obsolete system calls that are provided\n" \
> > " by the kernel, but typically no longer used by modern\n" \
> > @@ -4025,10 +4026,12 @@ DEF("sandbox", HAS_ARG, QEMU_OPTION_sandbox, \
> > " use 'elevateprivileges' to allow or deny QEMU process to elevate\n" \
> > " its privileges by blacklisting all set*uid|gid system calls.\n" \
> > " The value 'children' will deny set*uid|gid system calls for\n" \
> > - " main QEMU process but will allow forks and execves to run unprivileged\n",
> > + " main QEMU process but will allow forks and execves to run unprivileged\n" \
> > + " use 'spawn' to avoid QEMU to spawn new threads or processes by\n" \
> > + " blacklisting *fork and execve\n",
> > QEMU_ARCH_ALL)
> > STEXI
> > -@item -sandbox @var{arg}[,obsolete=@var{string}][,elevateprivileges=@var{string}]
> > +@item -sandbox @var{arg}[,obsolete=@var{string}][,elevateprivileges=@var{string}][,spawn=@var{string}]
> > @findex -sandbox
> > Enable Seccomp mode 2 system call filter. 'on' will enable syscall filtering and 'off' will
> > disable it. The default is 'off'.
> > @@ -4037,6 +4040,8 @@ disable it. The default is 'off'.
> > Enable Obsolete system calls
> > @item elevateprivileges=@var{string}
> > Disable set*uid|gid system calls
> > +@item spawn=@var{string}
> > +Disable *fork and execve
> > @end table
> > ETEXI
> >
> > diff --git a/qemu-seccomp.c b/qemu-seccomp.c
> > index 2bad16cafb..4c169febf8 100644
> > --- a/qemu-seccomp.c
> > +++ b/qemu-seccomp.c
> > @@ -79,6 +79,10 @@ static const struct QemuSeccompSyscall blacklist[] = {
> > { SCMP_SYS(setresgid), 4, QEMU_SECCOMP_SET_PRIVILEGED },
> > { SCMP_SYS(setfsuid), 4, QEMU_SECCOMP_SET_PRIVILEGED },
> > { SCMP_SYS(setfsgid), 4, QEMU_SECCOMP_SET_PRIVILEGED },
> > + /* spawn */
> > + { SCMP_SYS(fork), 8, QEMU_SECCOMP_SET_SPAWN },
> > + { SCMP_SYS(vfork), 8, QEMU_SECCOMP_SET_SPAWN },
> > + { SCMP_SYS(execve), 8, QEMU_SECCOMP_SET_SPAWN },
> > };
> >
> >
> > @@ -109,6 +113,14 @@ int seccomp_start(uint32_t seccomp_opts)
> > }
> >
> > break;
> > + case QEMU_SECCOMP_SET_SPAWN:
> > + if (seccomp_opts & QEMU_SECCOMP_SET_SPAWN) {
> > + break;
> > + } else {
> > + continue;
> > + }
> > +
>
> Remove the above empty line?
>
> Anyway, it's somewhat ugly that you need a switch-case statement here at
> all. Couldn't you simply check it like this:
>
> if (!(seccomp_opts & blacklist[i].set)) {
> continue;
> }
> ?
>
> You then just have to invert the meaning of the
> QEMU_SECCOMP_SET_OBSOLETE bit in the second patch, so that this bit is
> treated in the same way as the others (i.e. use
> uint32_t seccomp_opts = QEMU_SECCOMP_SET_OBSOLETE;
> instead of
> uint32_t seccomp_opts = 0x00000;
> in vl.c in the second patch).
That's indeed much better, but perhaps:
uint32_t seccomp_opts = QEMU_SECCOMP_SET_DEFAULT | QEMU_SECCOMP_SET_OBSOLETE;
?
--
Eduardo Otubo
Senior Software Engineer @ RedHat
^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [Qemu-devel] [PATCHv5 4/5] seccomp: add spawn argument to command line
2017-09-08 11:15 ` Eduardo Otubo
@ 2017-09-08 11:31 ` Thomas Huth
0 siblings, 0 replies; 18+ messages in thread
From: Thomas Huth @ 2017-09-08 11:31 UTC (permalink / raw)
To: Eduardo Otubo; +Cc: qemu-devel
On 08.09.2017 13:15, Eduardo Otubo wrote:
> On Fri, Sep 08, 2017 at 11:50:12AM +0200, Thomas Huth wrote:
>> On 08.09.2017 11:10, Eduardo Otubo wrote:
>>> This patch adds [,spawn=deny] argument to `-sandbox on' option. It
>>> blacklists fork and execve system calls, avoiding Qemu to spawn new
>>> threads or processes.
>>>
>>> Signed-off-by: Eduardo Otubo <otubo@redhat.com>
>>> ---
>>> include/sysemu/seccomp.h | 1 +
>>> qemu-options.hx | 9 +++++++--
>>> qemu-seccomp.c | 12 ++++++++++++
>>> vl.c | 16 ++++++++++++++++
>>> 4 files changed, 36 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/include/sysemu/seccomp.h b/include/sysemu/seccomp.h
>>> index 4a9e63c7cd..3ab5fc4f61 100644
>>> --- a/include/sysemu/seccomp.h
>>> +++ b/include/sysemu/seccomp.h
>>> @@ -18,6 +18,7 @@
>>> #define QEMU_SECCOMP_SET_DEFAULT (1 << 0)
>>> #define QEMU_SECCOMP_SET_OBSOLETE (1 << 1)
>>> #define QEMU_SECCOMP_SET_PRIVILEGED (1 << 2)
>>> +#define QEMU_SECCOMP_SET_SPAWN (1 << 3)
>>>
>>> #include <seccomp.h>
>>>
>>> diff --git a/qemu-options.hx b/qemu-options.hx
>>> index 5c1b163fb5..2b04b9f170 100644
>>> --- a/qemu-options.hx
>>> +++ b/qemu-options.hx
>>> @@ -4018,6 +4018,7 @@ ETEXI
>>>
>>> DEF("sandbox", HAS_ARG, QEMU_OPTION_sandbox, \
>>> "-sandbox on[,obsolete=allow|deny][,elevateprivileges=allow|deny|children]\n" \
>>> + " [,spawn=allow|deny]\n" \
>>> " Enable seccomp mode 2 system call filter (default 'off').\n" \
>>> " use 'obsolete' to allow obsolete system calls that are provided\n" \
>>> " by the kernel, but typically no longer used by modern\n" \
>>> @@ -4025,10 +4026,12 @@ DEF("sandbox", HAS_ARG, QEMU_OPTION_sandbox, \
>>> " use 'elevateprivileges' to allow or deny QEMU process to elevate\n" \
>>> " its privileges by blacklisting all set*uid|gid system calls.\n" \
>>> " The value 'children' will deny set*uid|gid system calls for\n" \
>>> - " main QEMU process but will allow forks and execves to run unprivileged\n",
>>> + " main QEMU process but will allow forks and execves to run unprivileged\n" \
>>> + " use 'spawn' to avoid QEMU to spawn new threads or processes by\n" \
>>> + " blacklisting *fork and execve\n",
>>> QEMU_ARCH_ALL)
>>> STEXI
>>> -@item -sandbox @var{arg}[,obsolete=@var{string}][,elevateprivileges=@var{string}]
>>> +@item -sandbox @var{arg}[,obsolete=@var{string}][,elevateprivileges=@var{string}][,spawn=@var{string}]
>>> @findex -sandbox
>>> Enable Seccomp mode 2 system call filter. 'on' will enable syscall filtering and 'off' will
>>> disable it. The default is 'off'.
>>> @@ -4037,6 +4040,8 @@ disable it. The default is 'off'.
>>> Enable Obsolete system calls
>>> @item elevateprivileges=@var{string}
>>> Disable set*uid|gid system calls
>>> +@item spawn=@var{string}
>>> +Disable *fork and execve
>>> @end table
>>> ETEXI
>>>
>>> diff --git a/qemu-seccomp.c b/qemu-seccomp.c
>>> index 2bad16cafb..4c169febf8 100644
>>> --- a/qemu-seccomp.c
>>> +++ b/qemu-seccomp.c
>>> @@ -79,6 +79,10 @@ static const struct QemuSeccompSyscall blacklist[] = {
>>> { SCMP_SYS(setresgid), 4, QEMU_SECCOMP_SET_PRIVILEGED },
>>> { SCMP_SYS(setfsuid), 4, QEMU_SECCOMP_SET_PRIVILEGED },
>>> { SCMP_SYS(setfsgid), 4, QEMU_SECCOMP_SET_PRIVILEGED },
>>> + /* spawn */
>>> + { SCMP_SYS(fork), 8, QEMU_SECCOMP_SET_SPAWN },
>>> + { SCMP_SYS(vfork), 8, QEMU_SECCOMP_SET_SPAWN },
>>> + { SCMP_SYS(execve), 8, QEMU_SECCOMP_SET_SPAWN },
>>> };
>>>
>>>
>>> @@ -109,6 +113,14 @@ int seccomp_start(uint32_t seccomp_opts)
>>> }
>>>
>>> break;
>>> + case QEMU_SECCOMP_SET_SPAWN:
>>> + if (seccomp_opts & QEMU_SECCOMP_SET_SPAWN) {
>>> + break;
>>> + } else {
>>> + continue;
>>> + }
>>> +
>>
>> Remove the above empty line?
>>
>> Anyway, it's somewhat ugly that you need a switch-case statement here at
>> all. Couldn't you simply check it like this:
>>
>> if (!(seccomp_opts & blacklist[i].set)) {
>> continue;
>> }
>> ?
>>
>> You then just have to invert the meaning of the
>> QEMU_SECCOMP_SET_OBSOLETE bit in the second patch, so that this bit is
>> treated in the same way as the others (i.e. use
>> uint32_t seccomp_opts = QEMU_SECCOMP_SET_OBSOLETE;
>> instead of
>> uint32_t seccomp_opts = 0x00000;
>> in vl.c in the second patch).
>
> That's indeed much better, but perhaps:
> uint32_t seccomp_opts = QEMU_SECCOMP_SET_DEFAULT | QEMU_SECCOMP_SET_OBSOLETE;
Right, the default set should be excluded by default of course, too! :-)
Thomas
^ permalink raw reply [flat|nested] 18+ messages in thread
end of thread, other threads:[~2017-09-08 11:31 UTC | newest]
Thread overview: 18+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2017-09-08 9:10 [Qemu-devel] [PATCHv5 0/6] seccomp: feature refactoring Eduardo Otubo
2017-09-08 9:10 ` [Qemu-devel] [PATCHv5 1/5] seccomp: changing from whitelist to blacklist Eduardo Otubo
2017-09-08 9:31 ` Daniel P. Berrange
2017-09-08 9:43 ` Thomas Huth
2017-09-08 9:50 ` Eduardo Otubo
2017-09-08 9:52 ` Thomas Huth
2017-09-08 10:57 ` Eduardo Otubo
2017-09-08 9:10 ` [Qemu-devel] [PATCHv5 2/5] seccomp: add obsolete argument to command line Eduardo Otubo
2017-09-08 9:31 ` Daniel P. Berrange
2017-09-08 9:10 ` [Qemu-devel] [PATCHv5 3/5] seccomp: add elevateprivileges " Eduardo Otubo
2017-09-08 9:32 ` Daniel P. Berrange
2017-09-08 9:10 ` [Qemu-devel] [PATCHv5 4/5] seccomp: add spawn " Eduardo Otubo
2017-09-08 9:33 ` Daniel P. Berrange
2017-09-08 9:50 ` Thomas Huth
2017-09-08 11:15 ` Eduardo Otubo
2017-09-08 11:31 ` Thomas Huth
2017-09-08 9:10 ` [Qemu-devel] [PATCHv5 5/5] seccomp: add resourcecontrol " Eduardo Otubo
2017-09-08 9:33 ` Daniel P. Berrange
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