From 4df8fe8415eaf4abd5b93c3447452547c6ea9e5f Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Thu, 14 Nov 2019 17:51:30 +0100
Subject: [PATCH] seccomp: more comprehensive protection against libseccomp's
 __NR_xyz namespace invasion

A follow-up for 59b657296a2fe104f112b91bbf9301724067cc81, adding the
same conditioning for all cases of our __NR_xyz use.

Fixes: #14031
---
 src/basic/missing_syscall.h | 10 +++++-----
 src/test/test-seccomp.c     | 19 ++++++++++---------
 2 files changed, 15 insertions(+), 14 deletions(-)

diff --git a/src/basic/missing_syscall.h b/src/basic/missing_syscall.h
index 6d9b125..1255d8b 100644
--- a/src/basic/missing_syscall.h
+++ b/src/basic/missing_syscall.h
@@ -274,7 +274,7 @@ static inline int missing_renameat2(int oldfd, const char *oldname, int newfd, c
 
 #if !HAVE_KCMP
 static inline int missing_kcmp(pid_t pid1, pid_t pid2, int type, unsigned long idx1, unsigned long idx2) {
-#  ifdef __NR_kcmp
+#  if defined __NR_kcmp && __NR_kcmp > 0
         return syscall(__NR_kcmp, pid1, pid2, type, idx1, idx2);
 #  else
         errno = ENOSYS;
@@ -289,7 +289,7 @@ static inline int missing_kcmp(pid_t pid1, pid_t pid2, int type, unsigned long i
 
 #if !HAVE_KEYCTL
 static inline long missing_keyctl(int cmd, unsigned long arg2, unsigned long arg3, unsigned long arg4, unsigned long arg5) {
-#  ifdef __NR_keyctl
+#  if defined __NR_keyctl && __NR_keyctl > 0
         return syscall(__NR_keyctl, cmd, arg2, arg3, arg4, arg5);
 #  else
         errno = ENOSYS;
@@ -300,7 +300,7 @@ static inline long missing_keyctl(int cmd, unsigned long arg2, unsigned long arg
 }
 
 static inline key_serial_t missing_add_key(const char *type, const char *description, const void *payload, size_t plen, key_serial_t ringid) {
-#  ifdef __NR_add_key
+#  if defined __NR_add_key && __NR_add_key > 0
         return syscall(__NR_add_key, type, description, payload, plen, ringid);
 #  else
         errno = ENOSYS;
@@ -311,7 +311,7 @@ static inline key_serial_t missing_add_key(const char *type, const char *descrip
 }
 
 static inline key_serial_t missing_request_key(const char *type, const char *description, const char * callout_info, key_serial_t destringid) {
-#  ifdef __NR_request_key
+#  if defined __NR_request_key && __NR_request_key > 0
         return syscall(__NR_request_key, type, description, callout_info, destringid);
 #  else
         errno = ENOSYS;
@@ -496,7 +496,7 @@ enum {
 static inline long missing_set_mempolicy(int mode, const unsigned long *nodemask,
                            unsigned long maxnode) {
         long i;
-#  ifdef __NR_set_mempolicy
+#  if defined __NR_set_mempolicy && __NR_set_mempolicy > 0
         i = syscall(__NR_set_mempolicy, mode, nodemask, maxnode);
 #  else
         errno = ENOSYS;
diff --git a/src/test/test-seccomp.c b/src/test/test-seccomp.c
index 018c20f..c669204 100644
--- a/src/test/test-seccomp.c
+++ b/src/test/test-seccomp.c
@@ -28,7 +28,8 @@
 #include "tmpfile-util.h"
 #include "virt.h"
 
-#if SCMP_SYS(socket) < 0 || defined(__i386__) || defined(__s390x__) || defined(__s390__)
+/* __NR_socket may be invalid due to libseccomp */
+#if !defined(__NR_socket) || __NR_socket <= 0 || defined(__i386__) || defined(__s390x__) || defined(__s390__)
 /* On these archs, socket() is implemented via the socketcall() syscall multiplexer,
  * and we can't restrict it hence via seccomp. */
 #  define SECCOMP_RESTRICT_ADDRESS_FAMILIES_BROKEN 1
@@ -304,14 +305,14 @@ static void test_protect_sysctl(void) {
         assert_se(pid >= 0);
 
         if (pid == 0) {
-#if __NR__sysctl > 0
+#if defined __NR__sysctl && __NR__sysctl > 0
                 assert_se(syscall(__NR__sysctl, NULL) < 0);
                 assert_se(errno == EFAULT);
 #endif
 
                 assert_se(seccomp_protect_sysctl() >= 0);
 
-#if __NR__sysctl > 0
+#if defined __NR__sysctl && __NR__sysctl > 0
                 assert_se(syscall(__NR__sysctl, 0, 0, 0) < 0);
                 assert_se(errno == EPERM);
 #endif
@@ -640,7 +641,7 @@ static void test_load_syscall_filter_set_raw(void) {
                 assert_se(poll(NULL, 0, 0) == 0);
 
                 assert_se(s = hashmap_new(NULL));
-#if SCMP_SYS(access) >= 0
+#if defined __NR_access && __NR_access > 0
                 assert_se(hashmap_put(s, UINT32_TO_PTR(__NR_access + 1), INT_TO_PTR(-1)) >= 0);
 #else
                 assert_se(hashmap_put(s, UINT32_TO_PTR(__NR_faccessat + 1), INT_TO_PTR(-1)) >= 0);
@@ -656,7 +657,7 @@ static void test_load_syscall_filter_set_raw(void) {
                 s = hashmap_free(s);
 
                 assert_se(s = hashmap_new(NULL));
-#if SCMP_SYS(access) >= 0
+#if defined __NR_access && __NR_access > 0
                 assert_se(hashmap_put(s, UINT32_TO_PTR(__NR_access + 1), INT_TO_PTR(EILSEQ)) >= 0);
 #else
                 assert_se(hashmap_put(s, UINT32_TO_PTR(__NR_faccessat + 1), INT_TO_PTR(EILSEQ)) >= 0);
@@ -672,7 +673,7 @@ static void test_load_syscall_filter_set_raw(void) {
                 s = hashmap_free(s);
 
                 assert_se(s = hashmap_new(NULL));
-#if SCMP_SYS(poll) >= 0
+#if defined __NR_poll && __NR_poll > 0
                 assert_se(hashmap_put(s, UINT32_TO_PTR(__NR_poll + 1), INT_TO_PTR(-1)) >= 0);
 #else
                 assert_se(hashmap_put(s, UINT32_TO_PTR(__NR_ppoll + 1), INT_TO_PTR(-1)) >= 0);
@@ -689,7 +690,7 @@ static void test_load_syscall_filter_set_raw(void) {
                 s = hashmap_free(s);
 
                 assert_se(s = hashmap_new(NULL));
-#if SCMP_SYS(poll) >= 0
+#if defined __NR_poll && __NR_poll > 0
                 assert_se(hashmap_put(s, UINT32_TO_PTR(__NR_poll + 1), INT_TO_PTR(EILSEQ)) >= 0);
 #else
                 assert_se(hashmap_put(s, UINT32_TO_PTR(__NR_ppoll + 1), INT_TO_PTR(EILSEQ)) >= 0);
@@ -767,8 +768,8 @@ static int real_open(const char *path, int flags, mode_t mode) {
          * testing purposes that calls the real syscall, on architectures where SYS_open is defined. On
          * other architectures, let's just fall back to the glibc call. */
 
-#ifdef SYS_open
-        return (int) syscall(SYS_open, path, flags, mode);
+#if defined __NR_open && __NR_open > 0
+        return (int) syscall(__NR_open, path, flags, mode);
 #else
         return open(path, flags, mode);
 #endif
-- 
1.8.3.1

