Update from chromium 62675d9fb31fb8cedc40f68e78e8445a74f362e7

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 "sandbox/linux/seccomp-bpf/syscall.h"
+
+#include <asm/unistd.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <sys/syscall.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/posix/eintr_wrapper.h"
+#include "build/build_config.h"
+#include "sandbox/linux/bpf_dsl/bpf_dsl.h"
+#include "sandbox/linux/seccomp-bpf/bpf_tests.h"
+#include "sandbox/linux/seccomp-bpf/sandbox_bpf.h"
+#include "sandbox/linux/tests/unit_tests.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+using sandbox::bpf_dsl::Allow;
+using sandbox::bpf_dsl::ResultExpr;
+using sandbox::bpf_dsl::Trap;
+using sandbox::bpf_dsl::SandboxBPFDSLPolicy;
+
+namespace sandbox {
+
+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, InvalidCallReturnsENOSYS) {
+  EXPECT_EQ(-ENOSYS, Syscall::InvalidCall());
+}
+
+TEST(Syscall, WellKnownEntryPoint) {
+// Test that Syscall::Call(-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__) && !defined(__aarch64__)
+  EXPECT_NE(Syscall::Call(-1), syscall(-1));
+#endif
+
+// If possible, test that Syscall::Call(-1) returns the address right
+// after
+// a kernel entry point.
+#if defined(__i386__)
+  EXPECT_EQ(0x80CDu, ((uint16_t*)Syscall::Call(-1))[-1]);  // INT 0x80
+#elif defined(__x86_64__)
+  EXPECT_EQ(0x050Fu, ((uint16_t*)Syscall::Call(-1))[-1]);  // SYSCALL
+#elif defined(__arm__)
+#if defined(__thumb__)
+  EXPECT_EQ(0xDF00u, ((uint16_t*)Syscall::Call(-1))[-1]);  // SWI 0
+#else
+  EXPECT_EQ(0xEF000000u, ((uint32_t*)Syscall::Call(-1))[-1]);  // SVC 0
+#endif
+#elif defined(__mips__)
+  // Opcode for MIPS sycall is in the lower 16-bits
+  EXPECT_EQ(0x0cu, (((uint32_t*)Syscall::Call(-1))[-1]) & 0x0000FFFF);
+#elif defined(__aarch64__)
+  EXPECT_EQ(0xD4000001u, ((uint32_t*)Syscall::Call(-1))[-1]);  // SVC 0
+#else
+#warning Incomplete test case; need port for target platform
+#endif
+}
+
+TEST(Syscall, TrivialSyscallNoArgs) {
+  // Test that we can do basic system calls
+  EXPECT_EQ(Syscall::Call(__NR_getpid), syscall(__NR_getpid));
+}
+
+TEST(Syscall, TrivialSyscallOneArg) {
+  int new_fd;
+  // Duplicate standard error and close it.
+  ASSERT_GE(new_fd = Syscall::Call(__NR_dup, 2), 0);
+  int close_return_value = IGNORE_EINTR(Syscall::Call(__NR_close, new_fd));
+  ASSERT_EQ(close_return_value, 0);
+}
+
+TEST(Syscall, TrivialFailingSyscall) {
+  errno = -42;
+  int ret = Syscall::Call(__NR_dup, -1);
+  ASSERT_EQ(-EBADF, ret);
+  // Verify that Syscall::Call does not touch errno.
+  ASSERT_EQ(-42, errno);
+}
+
+// SIGSYS trap handler that will be called on __NR_uname.
+intptr_t CopySyscallArgsToAux(const struct arch_seccomp_data& args, void* aux) {
+  // |aux| is our BPF_AUX pointer.
+  std::vector<uint64_t>* const seen_syscall_args =
+      static_cast<std::vector<uint64_t>*>(aux);
+  BPF_ASSERT(arraysize(args.args) == 6);
+  seen_syscall_args->assign(args.args, args.args + arraysize(args.args));
+  return -ENOMEM;
+}
+
+class CopyAllArgsOnUnamePolicy : public SandboxBPFDSLPolicy {
+ public:
+  explicit CopyAllArgsOnUnamePolicy(std::vector<uint64_t>* aux) : aux_(aux) {}
+  virtual ~CopyAllArgsOnUnamePolicy() {}
+
+  virtual ResultExpr EvaluateSyscall(int sysno) const override {
+    DCHECK(SandboxBPF::IsValidSyscallNumber(sysno));
+    if (sysno == __NR_uname) {
+      return Trap(CopySyscallArgsToAux, aux_);
+    } else {
+      return Allow();
+    }
+  }
+
+ private:
+  std::vector<uint64_t>* aux_;
+
+  DISALLOW_COPY_AND_ASSIGN(CopyAllArgsOnUnamePolicy);
+};
+
+// We are testing Syscall::Call() by making use of a BPF filter that
+// allows us
+// to inspect the system call arguments that the kernel saw.
+BPF_TEST(Syscall,
+         SyntheticSixArgs,
+         CopyAllArgsOnUnamePolicy,
+         std::vector<uint64_t> /* (*BPF_AUX) */) {
+  const int kExpectedValue = 42;
+  // In this test we only pass integers to the kernel. We might want to make
+  // additional tests to try other types. What we will see depends on
+  // implementation details of kernel BPF filters and we will need to document
+  // the expected behavior very clearly.
+  int syscall_args[6];
+  for (size_t i = 0; i < arraysize(syscall_args); ++i) {
+    syscall_args[i] = kExpectedValue + i;
+  }
+
+  // We could use pretty much any system call we don't need here. uname() is
+  // nice because it doesn't have any dangerous side effects.
+  BPF_ASSERT(Syscall::Call(__NR_uname,
+                           syscall_args[0],
+                           syscall_args[1],
+                           syscall_args[2],
+                           syscall_args[3],
+                           syscall_args[4],
+                           syscall_args[5]) == -ENOMEM);
+
+  // We expect the trap handler to have copied the 6 arguments.
+  BPF_ASSERT(BPF_AUX->size() == 6);
+
+  // Don't loop here so that we can see which argument does cause the failure
+  // easily from the failing line.
+  // uint64_t is the type passed to our SIGSYS handler.
+  BPF_ASSERT((*BPF_AUX)[0] == static_cast<uint64_t>(syscall_args[0]));
+  BPF_ASSERT((*BPF_AUX)[1] == static_cast<uint64_t>(syscall_args[1]));
+  BPF_ASSERT((*BPF_AUX)[2] == static_cast<uint64_t>(syscall_args[2]));
+  BPF_ASSERT((*BPF_AUX)[3] == static_cast<uint64_t>(syscall_args[3]));
+  BPF_ASSERT((*BPF_AUX)[4] == static_cast<uint64_t>(syscall_args[4]));
+  BPF_ASSERT((*BPF_AUX)[5] == static_cast<uint64_t>(syscall_args[5]));
+}
+
+TEST(Syscall, ComplexSyscallSixArgs) {
+  int fd;
+  ASSERT_LE(0,
+            fd = Syscall::Call(__NR_openat, AT_FDCWD, "/dev/null", O_RDWR, 0L));
+
+  // Use mmap() to allocate some read-only memory
+  char* addr0;
+  ASSERT_NE(
+      (char*)NULL,
+      addr0 = reinterpret_cast<char*>(Syscall::Call(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*>(
+                Syscall::Call(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, Syscall::Call(__NR_munmap, addr1, 4096L));
+  EXPECT_EQ(0, IGNORE_EINTR(Syscall::Call(__NR_close, fd)));
+
+  // Check that the offset argument (i.e. the sixth argument) is processed
+  // correctly.
+  ASSERT_GE(
+      fd = Syscall::Call(__NR_openat, AT_FDCWD, "/proc/self/exe", O_RDONLY, 0L),
+      0);
+  char* addr2, *addr3;
+  ASSERT_NE((char*)NULL,
+            addr2 = reinterpret_cast<char*>(Syscall::Call(
+                kMMapNr, (void*)NULL, 8192L, PROT_READ, MAP_PRIVATE, fd, 0L)));
+  ASSERT_NE((char*)NULL,
+            addr3 = reinterpret_cast<char*>(Syscall::Call(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, Syscall::Call(__NR_read, fd, buf, 8192L));
+  EXPECT_EQ(0, memcmp(addr2, buf, 8192));
+
+  // Clean up
+  EXPECT_EQ(0, Syscall::Call(__NR_munmap, addr2, 8192L));
+  EXPECT_EQ(0, Syscall::Call(__NR_munmap, addr3, 4096L));
+  EXPECT_EQ(0, IGNORE_EINTR(Syscall::Call(__NR_close, fd)));
+}
+
+}  // namespace
+
+}  // namespace sandbox