SECCOMP-BPF: Added support for greylisting of system calls.

sandbox/linux/seccomp-bpf/syscall_unittest.cc

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <asm/unistd.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <unistd.h>
+
+#include "base/posix/eintr_wrapper.h"
+#include "sandbox/linux/seccomp-bpf/syscall.h"
+#include "sandbox/linux/tests/unit_tests.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+using namespace playground2;
+
+namespace {
+
+// Different platforms use different symbols for the six-argument version
+// of the mmap() system call. Test for the correct symbol at compile time.
+#ifdef __NR_mmap2
+const int kMMapNr = __NR_mmap2;
+#else
+const int kMMapNr = __NR_mmap;
+#endif
+
+TEST(Syscall, WellKnownEntryPoint) {
+  // Test that SandboxSyscall(-1) is handled specially. Don't do this on ARM,
+  // where syscall(-1) crashes with SIGILL. Not running the test is fine, as we
+  // are still testing ARM code in the next set of tests.
+#if !defined(__arm__)
+  EXPECT_NE(SandboxSyscall(-1), syscall(-1));
+#endif
+
+  // If possible, test that SandboxSyscall(-1) returns the address right after
+  // a kernel entry point.
+#if defined(__i386__)
+  EXPECT_EQ(0x80CDu, ((uint16_t *)SandboxSyscall(-1))[-1]);      // INT 0x80
+#elif defined(__x86_64__)
+  EXPECT_EQ(0x050Fu, ((uint16_t *)SandboxSyscall(-1))[-1]);      // SYSCALL
+#elif defined(__arm__)
+#if defined(__thumb__)
+  EXPECT_EQ(0xDF00u, ((uint16_t *)SandboxSyscall(-1))[-1]);      // SWI 0
+#else
+  EXPECT_EQ(0xEF000000u, ((uint32_t *)SandboxSyscall(-1))[-1]);  // SVC 0
+#endif
+#else
+  #warning Incomplete test case; need port for target platform
+#endif
+}
+
+TEST(Syscall, TrivialSyscallNoArgs) {
+  // Test that we can do basic system calls
+  EXPECT_EQ(SandboxSyscall(__NR_getpid), syscall(__NR_getpid));
+}
+
+TEST(Syscall, ComplexSyscallSixArgs) {
+  int fd;
+  ASSERT_LE(0, fd = SandboxSyscall(__NR_open, "/dev/null", O_RDWR, 0L));
+
+  // Use mmap() to allocate some read-only memory
+  char *addr0;
+  ASSERT_NE((char *)NULL,
+            addr0 = reinterpret_cast<char *>(
+              SandboxSyscall(kMMapNr, (void *)NULL, 4096, PROT_READ,
+                             MAP_PRIVATE|MAP_ANONYMOUS, fd, 0L)));
+
+  // Try to replace the existing mapping with a read-write mapping
+  char *addr1;
+  ASSERT_EQ(addr0,
+            addr1 = reinterpret_cast<char *>(
+              SandboxSyscall(kMMapNr, addr0, 4096L, PROT_READ|PROT_WRITE,
+                             MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED,
+                             fd, 0L)));
+  ++*addr1; // This should not seg fault
+
+  // Clean up
+  EXPECT_EQ(0, SandboxSyscall(__NR_munmap, addr1, 4096L));
+  EXPECT_EQ(0, HANDLE_EINTR(SandboxSyscall(__NR_close, fd)));
+
+  // Check that the offset argument (i.e. the sixth argument) is processed
+  // correctly.
+  ASSERT_GE(fd = SandboxSyscall(__NR_open, "/proc/self/exe", O_RDONLY, 0L), 0);
+  char *addr2, *addr3;
+  ASSERT_NE((char *)NULL,
+            addr2 = reinterpret_cast<char *>(
+              SandboxSyscall(kMMapNr, (void *)NULL, 8192L, PROT_READ,
+                             MAP_PRIVATE, fd, 0L)));
+  ASSERT_NE((char *)NULL,
+            addr3 = reinterpret_cast<char *>(
+              SandboxSyscall(kMMapNr, (void *)NULL, 4096L, PROT_READ,
+                             MAP_PRIVATE, fd,
+#if defined(__NR_mmap2)
+                      1L
+#else
+                      4096L
+#endif
+                      )));
+  EXPECT_EQ(0, memcmp(addr2 + 4096, addr3, 4096));
+
+  // Just to be absolutely on the safe side, also verify that the file
+  // contents matches what we are getting from a read() operation.
+  char buf[8192];
+  EXPECT_EQ(8192, SandboxSyscall(__NR_read, fd, buf, 8192L));
+  EXPECT_EQ(0, memcmp(addr2, buf, 8192));
+
+  // Clean up
+  EXPECT_EQ(0, SandboxSyscall(__NR_munmap, addr2, 8192L));
+  EXPECT_EQ(0, SandboxSyscall(__NR_munmap, addr3, 4096L));
+  EXPECT_EQ(0, HANDLE_EINTR(SandboxSyscall(__NR_close, fd)));
+}
+
+} // namespace