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[Qemu-devel] [PATCH v3 1/6] seccomp: changing from whitelist to blacklist

Eduardo Otubo posted 6 patches 8 years, 6 months ago
[Qemu-devel] [PATCH v3 1/6] seccomp: changing from whitelist to blacklist
Posted by Eduardo Otubo 8 years, 6 months ago 
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>
---
 qemu-seccomp.c | 256 +++++++--------------------------------------------------
 vl.c           |   5 +-
 2 files changed, 32 insertions(+), 229 deletions(-)

diff --git a/qemu-seccomp.c b/qemu-seccomp.c
index df75d9c471..f8877b07b5 100644
--- a/qemu-seccomp.c
+++ b/qemu-seccomp.c
@@ -31,229 +31,29 @@ struct QemuSeccompSyscall {
     uint8_t priority;
 };
 
-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[] = {
+    { SCMP_SYS(reboot), 255 },
+    { SCMP_SYS(swapon), 255 },
+    { SCMP_SYS(swapoff), 255 },
+    { SCMP_SYS(syslog), 255 },
+    { SCMP_SYS(mount), 255 },
+    { SCMP_SYS(umount), 255 },
+    { SCMP_SYS(kexec_load), 255 },
+    { SCMP_SYS(afs_syscall), 255 },
+    { SCMP_SYS(break), 255 },
+    { SCMP_SYS(ftime), 255 },
+    { SCMP_SYS(getpmsg), 255 },
+    { SCMP_SYS(gtty), 255 },
+    { SCMP_SYS(lock), 255 },
+    { SCMP_SYS(mpx), 255 },
+    { SCMP_SYS(prof), 255 },
+    { SCMP_SYS(profil), 255 },
+    { SCMP_SYS(putpmsg), 255 },
+    { SCMP_SYS(security), 255 },
+    { SCMP_SYS(stty), 255 },
+    { SCMP_SYS(tuxcall), 255 },
+    { SCMP_SYS(ulimit), 255 },
+    { SCMP_SYS(vserver), 255 },
 };
 
 int seccomp_start(void)
@@ -262,19 +62,19 @@ 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);
+    for (i = 0; i < ARRAY_SIZE(blacklist); i++) {
+        rc = seccomp_rule_add(ctx, SCMP_ACT_KILL, blacklist[i].num, 0);
         if (rc < 0) {
             goto seccomp_return;
         }
-        rc = seccomp_syscall_priority(ctx, seccomp_whitelist[i].num,
-                                      seccomp_whitelist[i].priority);
+        rc = seccomp_syscall_priority(ctx, blacklist[i].num,
+                                      blacklist[i].priority);
         if (rc < 0) {
             goto seccomp_return;
         }
diff --git a/vl.c b/vl.c
index fb6b2efafa..15b98800e9 100644
--- a/vl.c
+++ b/vl.c
@@ -1030,13 +1030,16 @@ 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) {
             error_report("failed to install seccomp syscall filter "
                          "in the kernel");
             return -1;
+        } else {
+            error_report("warning: -sandbox on has been converted to blacklist "
+                         "approach. Refer to the manual for new sandbox "
+                         "options in order to increase security.");
         }
 #else
         error_report("seccomp support is disabled");
-- 
2.13.3
Re: [Qemu-devel] [PATCH v3 1/6] seccomp: changing from whitelist to blacklist
Posted by Daniel P. Berrange 8 years, 6 months ago 
On Fri, Jul 28, 2017 at 02:10:35PM +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>
> ---
>  qemu-seccomp.c | 256 +++++++--------------------------------------------------
>  vl.c           |   5 +-
>  2 files changed, 32 insertions(+), 229 deletions(-)
> 
> diff --git a/qemu-seccomp.c b/qemu-seccomp.c
> index df75d9c471..f8877b07b5 100644
> --- a/qemu-seccomp.c
> +++ b/qemu-seccomp.c
> @@ -31,229 +31,29 @@ struct QemuSeccompSyscall {
>      uint8_t priority;
>  };
>  
> -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[] = {
> +    { SCMP_SYS(reboot), 255 },
> +    { SCMP_SYS(swapon), 255 },
> +    { SCMP_SYS(swapoff), 255 },
> +    { SCMP_SYS(syslog), 255 },
> +    { SCMP_SYS(mount), 255 },
> +    { SCMP_SYS(umount), 255 },
> +    { SCMP_SYS(kexec_load), 255 },
> +    { SCMP_SYS(afs_syscall), 255 },
> +    { SCMP_SYS(break), 255 },
> +    { SCMP_SYS(ftime), 255 },
> +    { SCMP_SYS(getpmsg), 255 },
> +    { SCMP_SYS(gtty), 255 },
> +    { SCMP_SYS(lock), 255 },
> +    { SCMP_SYS(mpx), 255 },
> +    { SCMP_SYS(prof), 255 },
> +    { SCMP_SYS(profil), 255 },
> +    { SCMP_SYS(putpmsg), 255 },
> +    { SCMP_SYS(security), 255 },
> +    { SCMP_SYS(stty), 255 },
> +    { SCMP_SYS(tuxcall), 255 },
> +    { SCMP_SYS(ulimit), 255 },
> +    { SCMP_SYS(vserver), 255 },
>  };
>  
>  int seccomp_start(void)
> @@ -262,19 +62,19 @@ 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);
> +    for (i = 0; i < ARRAY_SIZE(blacklist); i++) {
> +        rc = seccomp_rule_add(ctx, SCMP_ACT_KILL, blacklist[i].num, 0);
>          if (rc < 0) {
>              goto seccomp_return;
>          }
> -        rc = seccomp_syscall_priority(ctx, seccomp_whitelist[i].num,
> -                                      seccomp_whitelist[i].priority);
> +        rc = seccomp_syscall_priority(ctx, blacklist[i].num,
> +                                      blacklist[i].priority);
>          if (rc < 0) {
>              goto seccomp_return;
>          }
> diff --git a/vl.c b/vl.c
> index fb6b2efafa..15b98800e9 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -1030,13 +1030,16 @@ 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) {
>              error_report("failed to install seccomp syscall filter "
>                           "in the kernel");
>              return -1;
> +        } else {
> +            error_report("warning: -sandbox on has been converted to blacklist "
> +                         "approach. Refer to the manual for new sandbox "
> +                         "options in order to increase security.");

This is just noise that will pollute everyone's logs. This kind of thing can
just be put in the QEMU release notes.

If you remove this, then 

Reviewed-by: Daniel P. Berrange <berrange@redhat.com>


Regards,
Daniel
-- 
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Re: [Qemu-devel] [PATCH v3 1/6] seccomp: changing from whitelist to blacklist
Posted by Thomas Huth 8 years, 6 months ago 
On 28.07.2017 14:10, 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>
> ---
>  qemu-seccomp.c | 256 +++++++--------------------------------------------------
>  vl.c           |   5 +-
>  2 files changed, 32 insertions(+), 229 deletions(-)
> 
> diff --git a/qemu-seccomp.c b/qemu-seccomp.c
> index df75d9c471..f8877b07b5 100644
> --- a/qemu-seccomp.c
> +++ b/qemu-seccomp.c
> @@ -31,229 +31,29 @@ struct QemuSeccompSyscall {
>      uint8_t priority;
>  };
[...]
> +static const struct QemuSeccompSyscall blacklist[] = {
> +    { SCMP_SYS(reboot), 255 },
> +    { SCMP_SYS(swapon), 255 },
> +    { SCMP_SYS(swapoff), 255 },
> +    { SCMP_SYS(syslog), 255 },
> +    { SCMP_SYS(mount), 255 },
> +    { SCMP_SYS(umount), 255 },
> +    { SCMP_SYS(kexec_load), 255 },
> +    { SCMP_SYS(afs_syscall), 255 },
> +    { SCMP_SYS(break), 255 },
> +    { SCMP_SYS(ftime), 255 },
> +    { SCMP_SYS(getpmsg), 255 },
> +    { SCMP_SYS(gtty), 255 },
> +    { SCMP_SYS(lock), 255 },
> +    { SCMP_SYS(mpx), 255 },
> +    { SCMP_SYS(prof), 255 },
> +    { SCMP_SYS(profil), 255 },
> +    { SCMP_SYS(putpmsg), 255 },
> +    { SCMP_SYS(security), 255 },
> +    { SCMP_SYS(stty), 255 },
> +    { SCMP_SYS(tuxcall), 255 },
> +    { SCMP_SYS(ulimit), 255 },
> +    { SCMP_SYS(vserver), 255 },
>  };

Does it makes sense to still keep the priority field? Everything is now
marked with the value 255 and I currently fail to see the point of
priorities when using blacklisting ... so maybe just get rid of it?

 Thomas
Re: [Qemu-devel] [PATCH v3 1/6] seccomp: changing from whitelist to blacklist
Posted by Eduardo Otubo 8 years, 6 months ago 
On Thu, Aug 03, 2017 at 06:54:15PM +0200, Thomas Huth wrote:
> On 28.07.2017 14:10, 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>
> > ---
> >  qemu-seccomp.c | 256 +++++++--------------------------------------------------
> >  vl.c           |   5 +-
> >  2 files changed, 32 insertions(+), 229 deletions(-)
> > 
> > diff --git a/qemu-seccomp.c b/qemu-seccomp.c
> > index df75d9c471..f8877b07b5 100644
> > --- a/qemu-seccomp.c
> > +++ b/qemu-seccomp.c
> > @@ -31,229 +31,29 @@ struct QemuSeccompSyscall {
> >      uint8_t priority;
> >  };
> [...]
> > +static const struct QemuSeccompSyscall blacklist[] = {
> > +    { SCMP_SYS(reboot), 255 },
> > +    { SCMP_SYS(swapon), 255 },
> > +    { SCMP_SYS(swapoff), 255 },
> > +    { SCMP_SYS(syslog), 255 },
> > +    { SCMP_SYS(mount), 255 },
> > +    { SCMP_SYS(umount), 255 },
> > +    { SCMP_SYS(kexec_load), 255 },
> > +    { SCMP_SYS(afs_syscall), 255 },
> > +    { SCMP_SYS(break), 255 },
> > +    { SCMP_SYS(ftime), 255 },
> > +    { SCMP_SYS(getpmsg), 255 },
> > +    { SCMP_SYS(gtty), 255 },
> > +    { SCMP_SYS(lock), 255 },
> > +    { SCMP_SYS(mpx), 255 },
> > +    { SCMP_SYS(prof), 255 },
> > +    { SCMP_SYS(profil), 255 },
> > +    { SCMP_SYS(putpmsg), 255 },
> > +    { SCMP_SYS(security), 255 },
> > +    { SCMP_SYS(stty), 255 },
> > +    { SCMP_SYS(tuxcall), 255 },
> > +    { SCMP_SYS(ulimit), 255 },
> > +    { SCMP_SYS(vserver), 255 },
> >  };
> 
> Does it makes sense to still keep the priority field? Everything is now
> marked with the value 255 and I currently fail to see the point of
> priorities when using blacklisting ... so maybe just get rid of it?

I think that's a fair point here. Don't see much of a point on such a
small number of syscalls. I just need to double check the libseccomp
docs if I can build the list without any priority information, but I'm
pretty sure I've seen this before.

-- 
Eduardo Otubo
Senior Software Engineer @ RedHat
Re: [Qemu-devel] [PATCH v3 1/6] seccomp: changing from whitelist to blacklist
Posted by Daniel P. Berrange 8 years, 6 months ago 
On Fri, Aug 11, 2017 at 11:51:12AM +0200, Eduardo Otubo wrote:
> On Thu, Aug 03, 2017 at 06:54:15PM +0200, Thomas Huth wrote:
> > On 28.07.2017 14:10, 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>
> > > ---
> > >  qemu-seccomp.c | 256 +++++++--------------------------------------------------
> > >  vl.c           |   5 +-
> > >  2 files changed, 32 insertions(+), 229 deletions(-)
> > > 
> > > diff --git a/qemu-seccomp.c b/qemu-seccomp.c
> > > index df75d9c471..f8877b07b5 100644
> > > --- a/qemu-seccomp.c
> > > +++ b/qemu-seccomp.c
> > > @@ -31,229 +31,29 @@ struct QemuSeccompSyscall {
> > >      uint8_t priority;
> > >  };
> > [...]
> > > +static const struct QemuSeccompSyscall blacklist[] = {
> > > +    { SCMP_SYS(reboot), 255 },
> > > +    { SCMP_SYS(swapon), 255 },
> > > +    { SCMP_SYS(swapoff), 255 },
> > > +    { SCMP_SYS(syslog), 255 },
> > > +    { SCMP_SYS(mount), 255 },
> > > +    { SCMP_SYS(umount), 255 },
> > > +    { SCMP_SYS(kexec_load), 255 },
> > > +    { SCMP_SYS(afs_syscall), 255 },
> > > +    { SCMP_SYS(break), 255 },
> > > +    { SCMP_SYS(ftime), 255 },
> > > +    { SCMP_SYS(getpmsg), 255 },
> > > +    { SCMP_SYS(gtty), 255 },
> > > +    { SCMP_SYS(lock), 255 },
> > > +    { SCMP_SYS(mpx), 255 },
> > > +    { SCMP_SYS(prof), 255 },
> > > +    { SCMP_SYS(profil), 255 },
> > > +    { SCMP_SYS(putpmsg), 255 },
> > > +    { SCMP_SYS(security), 255 },
> > > +    { SCMP_SYS(stty), 255 },
> > > +    { SCMP_SYS(tuxcall), 255 },
> > > +    { SCMP_SYS(ulimit), 255 },
> > > +    { SCMP_SYS(vserver), 255 },
> > >  };
> > 
> > Does it makes sense to still keep the priority field? Everything is now
> > marked with the value 255 and I currently fail to see the point of
> > priorities when using blacklisting ... so maybe just get rid of it?
> 
> I think that's a fair point here. Don't see much of a point on such a
> small number of syscalls. I just need to double check the libseccomp
> docs if I can build the list without any priority information, but I'm
> pretty sure I've seen this before.

Just always pass 255 to libseccomp apis directly. Its merely redundant
to store the value 255 in this QEMU  specific struct.

Regards,
Daniel
-- 
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Patchew 2.1-devel-b67e4c2

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