Merge pull request #20777 from benzea/benzea/fix-seccomp-filter

seccomp: Always install filters for native architecture

src/shared/seccomp-util.c

@@ -1789,6 +1789,10 @@ int seccomp_restrict_archs(Set *archs) {
         for (unsigned i = 0; seccomp_local_archs[i] != SECCOMP_LOCAL_ARCH_END; ++i) {
                 uint32_t arch = seccomp_local_archs[i];
 
+                /* See above comment, our "native" architecture is never blocked. */
+                if (arch == seccomp_arch_native())
+                        continue;
+
                 /* That architecture might have already been blocked by a previous call to seccomp_restrict_archs. */
                 if (arch == SECCOMP_LOCAL_ARCH_BLOCKED)
                         continue;

src/test/test-execute.c

@@ -713,8 +713,10 @@ static void test_exec_systemcallfilter(Manager *m) {
 
         test(m, "exec-systemcallfilter-not-failing.service", 0, CLD_EXITED);
         test(m, "exec-systemcallfilter-not-failing2.service", 0, CLD_EXITED);
+        test(m, "exec-systemcallfilter-not-failing3.service", 0, CLD_EXITED);
         test(m, "exec-systemcallfilter-failing.service", SIGSYS, CLD_KILLED);
         test(m, "exec-systemcallfilter-failing2.service", SIGSYS, CLD_KILLED);
+        test(m, "exec-systemcallfilter-failing3.service", SIGSYS, CLD_KILLED);
 
         r = find_executable("python3", NULL);
         if (r < 0) {

src/test/test-seccomp.c

@@ -890,6 +890,66 @@ static void test_load_syscall_filter_set_raw(void) {
         assert_se(wait_for_terminate_and_check("syscallrawseccomp", pid, WAIT_LOG) == EXIT_SUCCESS);
 }
 
+static void test_native_syscalls_filtered(void) {
+        pid_t pid;
+
+        log_info("/* %s */", __func__);
+
+        if (!is_seccomp_available()) {
+                log_notice("Seccomp not available, skipping %s", __func__);
+                return;
+        }
+        if (!have_seccomp_privs()) {
+                log_notice("Not privileged, skipping %s", __func__);
+                return;
+        }
+
+        pid = fork();
+        assert_se(pid >= 0);
+
+        if (pid == 0) {
+                _cleanup_set_free_ Set *arch_s = NULL;
+                _cleanup_hashmap_free_ Hashmap *s = NULL;
+
+                /* Passing "native" or an empty set is equivalent, just do both here. */
+                assert_se(arch_s = set_new(NULL));
+                assert_se(seccomp_restrict_archs(arch_s) >= 0);
+                assert_se(set_put(arch_s, SCMP_ARCH_NATIVE) >= 0);
+                assert_se(seccomp_restrict_archs(arch_s) >= 0);
+
+                assert_se(access("/", F_OK) >= 0);
+                assert_se(poll(NULL, 0, 0) == 0);
+
+                assert_se(seccomp_load_syscall_filter_set_raw(SCMP_ACT_ALLOW, NULL, scmp_act_kill_process(), true) >= 0);
+                assert_se(access("/", F_OK) >= 0);
+                assert_se(poll(NULL, 0, 0) == 0);
+
+                assert_se(s = hashmap_new(NULL));
+#if defined __NR_access && __NR_access >= 0
+                assert_se(hashmap_put(s, UINT32_TO_PTR(__NR_access + 1), INT_TO_PTR(-1)) >= 0);
+                log_debug("has access()");
+#endif
+#if defined __NR_faccessat && __NR_faccessat >= 0
+                assert_se(hashmap_put(s, UINT32_TO_PTR(__NR_faccessat + 1), INT_TO_PTR(-1)) >= 0);
+                log_debug("has faccessat()");
+#endif
+#if defined __NR_faccessat2 && __NR_faccessat2 >= 0
+                assert_se(hashmap_put(s, UINT32_TO_PTR(__NR_faccessat2 + 1), INT_TO_PTR(-1)) >= 0);
+                log_debug("has faccessat2()");
+#endif
+
+                assert_se(!hashmap_isempty(s));
+                assert_se(seccomp_load_syscall_filter_set_raw(SCMP_ACT_ALLOW, s, SCMP_ACT_ERRNO(EUCLEAN), true) >= 0);
+
+                assert_se(access("/", F_OK) < 0);
+                assert_se(errno == EUCLEAN);
+
+                _exit(EXIT_SUCCESS);
+        }
+
+        assert_se(wait_for_terminate_and_check("nativeseccomp", pid, WAIT_LOG) == EXIT_SUCCESS);
+}
+
 static void test_lock_personality(void) {
         unsigned long current;
         pid_t pid;
@@ -1171,6 +1231,7 @@ int main(int argc, char *argv[]) {
         test_memory_deny_write_execute_shmat();
         test_restrict_archs();
         test_load_syscall_filter_set_raw();
+        test_native_syscalls_filtered();
         test_lock_personality();
         test_restrict_suid_sgid();
 

test/test-execute/exec-systemcallfilter-failing3.service

@@ -0,0 +1,9 @@
+[Unit]
+Description=Test for SystemCallFilter
+
+[Service]
+ExecStart=/bin/sh -c '/bin/echo "This should not be seen"'
+Type=oneshot
+LimitCORE=0
+SystemCallArchitectures=native
+SystemCallFilter=~write open execve fexecve execveat exit_group close mmap munmap fstat DONOTEXIST

test/test-execute/exec-systemcallfilter-not-failing3.service

@@ -0,0 +1,8 @@
+[Unit]
+Description=Test for SystemCallFilter
+
+[Service]
+ExecStart=/bin/sh -c 'echo "Foo bar"'
+Type=oneshot
+SystemCallArchitectures=native
+SystemCallFilter=

test/units/testsuite-29.sh

@@ -4,6 +4,13 @@
 set -eux
 set -o pipefail
 
+ARGS=()
+if [[ -v ASAN_OPTIONS || -v UBSAN_OPTIONS ]]; then
+    # If we're running under sanitizers, we need to use a less restrictive
+    # profile, otherwise LSan syscall would get blocked by seccomp
+    ARGS+=(--profile=trusted)
+fi
+
 export SYSTEMD_LOG_LEVEL=debug
 mkdir -p /run/systemd/system/systemd-portabled.service.d/
 cat <<EOF >/run/systemd/system/systemd-portabled.service.d/override.conf
@@ -11,7 +18,7 @@ cat <<EOF >/run/systemd/system/systemd-portabled.service.d/override.conf
 Environment=SYSTEMD_LOG_LEVEL=debug
 EOF
 
-portablectl attach --now --runtime /usr/share/minimal_0.raw app0
+portablectl "${ARGS[@]}" attach --now --runtime /usr/share/minimal_0.raw app0
 
 systemctl is-active app0.service
 systemctl is-active app0-foo.service
@@ -21,7 +28,7 @@ systemctl is-active app0-bar.service && exit 1
 set -e
 set -o pipefail
 
-portablectl reattach --now --runtime /usr/share/minimal_1.raw app0
+portablectl "${ARGS[@]}" reattach --now --runtime /usr/share/minimal_1.raw app0
 
 systemctl is-active app0.service
 systemctl is-active app0-bar.service
@@ -42,7 +49,7 @@ portablectl list | grep -q -F "No images."
 unsquashfs -dest /tmp/minimal_0 /usr/share/minimal_0.raw
 unsquashfs -dest /tmp/minimal_1 /usr/share/minimal_1.raw
 
-portablectl attach --copy=symlink --now --runtime /tmp/minimal_0 app0
+portablectl "${ARGS[@]}" attach --copy=symlink --now --runtime /tmp/minimal_0 app0
 
 systemctl is-active app0.service
 systemctl is-active app0-foo.service
@@ -52,7 +59,7 @@ systemctl is-active app0-bar.service && exit 1
 set -e
 set -o pipefail
 
-portablectl reattach --now --enable --runtime /tmp/minimal_1 app0
+portablectl "${ARGS[@]}" reattach --now --enable --runtime /tmp/minimal_1 app0
 
 systemctl is-active app0.service
 systemctl is-active app0-bar.service
@@ -68,21 +75,21 @@ portablectl detach --now --enable --runtime /tmp/minimal_1 app0
 
 portablectl list | grep -q -F "No images."
 
-portablectl attach --now --runtime --extension /usr/share/app0.raw /usr/share/minimal_0.raw app0
+portablectl "${ARGS[@]}" attach --now --runtime --extension /usr/share/app0.raw /usr/share/minimal_0.raw app0
 
 systemctl is-active app0.service
 
-portablectl reattach --now --runtime --extension /usr/share/app0.raw /usr/share/minimal_1.raw app0
+portablectl "${ARGS[@]}" reattach --now --runtime --extension /usr/share/app0.raw /usr/share/minimal_1.raw app0
 
 systemctl is-active app0.service
 
 portablectl detach --now --runtime --extension /usr/share/app0.raw /usr/share/minimal_1.raw app0
 
-portablectl attach --now --runtime --extension /usr/share/app1.raw /usr/share/minimal_0.raw app1
+portablectl "${ARGS[@]}" attach --now --runtime --extension /usr/share/app1.raw /usr/share/minimal_0.raw app1
 
 systemctl is-active app1.service
 
-portablectl reattach --now --runtime --extension /usr/share/app1.raw /usr/share/minimal_1.raw app1
+portablectl "${ARGS[@]}" reattach --now --runtime --extension /usr/share/app1.raw /usr/share/minimal_1.raw app1
 
 systemctl is-active app1.service
 
@@ -95,7 +102,7 @@ mount /usr/share/app1.raw /tmp/app1
 mount /usr/share/minimal_0.raw /tmp/rootdir
 mount -t overlay overlay -o lowerdir=/tmp/app1:/tmp/rootdir /tmp/overlay
 
-portablectl attach --copy=symlink --now --runtime /tmp/overlay app1
+portablectl "${ARGS[@]}" attach --copy=symlink --now --runtime /tmp/overlay app1
 
 systemctl is-active app1.service