diff options
Diffstat (limited to 'test/syscalls/linux/chroot.cc')
| -rw-r--r-- | test/syscalls/linux/chroot.cc | 365 |
1 files changed, 0 insertions, 365 deletions
diff --git a/test/syscalls/linux/chroot.cc b/test/syscalls/linux/chroot.cc deleted file mode 100644 index de1611c21..000000000 --- a/test/syscalls/linux/chroot.cc +++ /dev/null @@ -1,365 +0,0 @@ -// Copyright 2018 The gVisor Authors. -// -// Licensed under the Apache License, Version 2.0 (the "License"); -// you may not use this file except in compliance with the License. -// You may obtain a copy of the License at -// -// http://www.apache.org/licenses/LICENSE-2.0 -// -// Unless required by applicable law or agreed to in writing, software -// distributed under the License is distributed on an "AS IS" BASIS, -// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -// See the License for the specific language governing permissions and -// limitations under the License. - -#include <errno.h> -#include <fcntl.h> -#include <stddef.h> -#include <sys/mman.h> -#include <sys/stat.h> -#include <syscall.h> -#include <unistd.h> -#include <string> -#include <vector> - -#include "gmock/gmock.h" -#include "gtest/gtest.h" -#include "absl/strings/str_cat.h" -#include "absl/strings/str_split.h" -#include "absl/strings/string_view.h" -#include "test/util/capability_util.h" -#include "test/util/cleanup.h" -#include "test/util/file_descriptor.h" -#include "test/util/fs_util.h" -#include "test/util/mount_util.h" -#include "test/util/temp_path.h" -#include "test/util/test_util.h" - -using ::testing::HasSubstr; -using ::testing::Not; - -namespace gvisor { -namespace testing { - -namespace { - -TEST(ChrootTest, Success) { - SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SYS_CHROOT))); - - auto temp_dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir()); - EXPECT_THAT(chroot(temp_dir.path().c_str()), SyscallSucceeds()); -} - -TEST(ChrootTest, PermissionDenied) { - SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SYS_CHROOT))); - - // CAP_DAC_READ_SEARCH and CAP_DAC_OVERRIDE may override Execute permission on - // directories. - ASSERT_NO_ERRNO(SetCapability(CAP_DAC_READ_SEARCH, false)); - ASSERT_NO_ERRNO(SetCapability(CAP_DAC_OVERRIDE, false)); - - auto temp_dir = ASSERT_NO_ERRNO_AND_VALUE( - TempPath::CreateDirWith(GetAbsoluteTestTmpdir(), 0666 /* mode */)); - EXPECT_THAT(chroot(temp_dir.path().c_str()), SyscallFailsWithErrno(EACCES)); -} - -TEST(ChrootTest, NotDir) { - SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SYS_CHROOT))); - - auto temp_file = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFile()); - EXPECT_THAT(chroot(temp_file.path().c_str()), SyscallFailsWithErrno(ENOTDIR)); -} - -TEST(ChrootTest, NotExist) { - SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SYS_CHROOT))); - - EXPECT_THAT(chroot("/foo/bar"), SyscallFailsWithErrno(ENOENT)); -} - -TEST(ChrootTest, WithoutCapability) { - // Unset CAP_SYS_CHROOT. - ASSERT_NO_ERRNO(SetCapability(CAP_SYS_CHROOT, false)); - - auto temp_dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir()); - EXPECT_THAT(chroot(temp_dir.path().c_str()), SyscallFailsWithErrno(EPERM)); -} - -TEST(ChrootTest, CreatesNewRoot) { - SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SYS_CHROOT))); - - // Grab the initial cwd. - char initial_cwd[1024]; - ASSERT_THAT(syscall(__NR_getcwd, initial_cwd, sizeof(initial_cwd)), - SyscallSucceeds()); - - auto new_root = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir()); - auto file_in_new_root = - ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFileIn(new_root.path())); - - // chroot into new_root. - ASSERT_THAT(chroot(new_root.path().c_str()), SyscallSucceeds()); - - // getcwd should return "(unreachable)" followed by the initial_cwd. - char cwd[1024]; - ASSERT_THAT(syscall(__NR_getcwd, cwd, sizeof(cwd)), SyscallSucceeds()); - std::string expected_cwd = "(unreachable)"; - expected_cwd += initial_cwd; - EXPECT_STREQ(cwd, expected_cwd.c_str()); - - // Should not be able to stat file by its full path. - struct stat statbuf; - EXPECT_THAT(stat(file_in_new_root.path().c_str(), &statbuf), - SyscallFailsWithErrno(ENOENT)); - - // Should be able to stat file at new rooted path. - auto basename = std::string(Basename(file_in_new_root.path())); - auto rootedFile = "/" + basename; - ASSERT_THAT(stat(rootedFile.c_str(), &statbuf), SyscallSucceeds()); - - // Should be able to stat cwd at '.' even though it's outside root. - ASSERT_THAT(stat(".", &statbuf), SyscallSucceeds()); - - // chdir into new root. - ASSERT_THAT(chdir("/"), SyscallSucceeds()); - - // getcwd should return "/". - EXPECT_THAT(syscall(__NR_getcwd, cwd, sizeof(cwd)), SyscallSucceeds()); - EXPECT_STREQ(cwd, "/"); - - // Statting '.', '..', '/', and '/..' all return the same dev and inode. - struct stat statbuf_dot; - ASSERT_THAT(stat(".", &statbuf_dot), SyscallSucceeds()); - struct stat statbuf_dotdot; - ASSERT_THAT(stat("..", &statbuf_dotdot), SyscallSucceeds()); - EXPECT_EQ(statbuf_dot.st_dev, statbuf_dotdot.st_dev); - EXPECT_EQ(statbuf_dot.st_ino, statbuf_dotdot.st_ino); - struct stat statbuf_slash; - ASSERT_THAT(stat("/", &statbuf_slash), SyscallSucceeds()); - EXPECT_EQ(statbuf_dot.st_dev, statbuf_slash.st_dev); - EXPECT_EQ(statbuf_dot.st_ino, statbuf_slash.st_ino); - struct stat statbuf_slashdotdot; - ASSERT_THAT(stat("/..", &statbuf_slashdotdot), SyscallSucceeds()); - EXPECT_EQ(statbuf_dot.st_dev, statbuf_slashdotdot.st_dev); - EXPECT_EQ(statbuf_dot.st_ino, statbuf_slashdotdot.st_ino); -} - -TEST(ChrootTest, DotDotFromOpenFD) { - SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SYS_CHROOT))); - - auto dir_outside_root = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir()); - auto fd = ASSERT_NO_ERRNO_AND_VALUE( - Open(dir_outside_root.path(), O_RDONLY | O_DIRECTORY)); - auto new_root = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir()); - - // chroot into new_root. - ASSERT_THAT(chroot(new_root.path().c_str()), SyscallSucceeds()); - - // openat on fd with path .. will succeed. - int other_fd; - ASSERT_THAT(other_fd = openat(fd.get(), "..", O_RDONLY), SyscallSucceeds()); - EXPECT_THAT(close(other_fd), SyscallSucceeds()); - - // getdents on fd should not error. - char buf[1024]; - ASSERT_THAT(syscall(SYS_getdents, fd.get(), buf, sizeof(buf)), - SyscallSucceeds()); -} - -// Test that link resolution in a chroot can escape the root by following an -// open proc fd. -TEST(ChrootTest, ProcFdLinkResolutionInChroot) { - SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SYS_CHROOT))); - - const TempPath file_outside_chroot = - ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFile()); - const FileDescriptor fd = - ASSERT_NO_ERRNO_AND_VALUE(Open(file_outside_chroot.path(), O_RDONLY)); - - const FileDescriptor proc_fd = ASSERT_NO_ERRNO_AND_VALUE( - Open("/proc", O_DIRECTORY | O_RDONLY | O_CLOEXEC)); - - auto temp_dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir()); - ASSERT_THAT(chroot(temp_dir.path().c_str()), SyscallSucceeds()); - - // Opening relative to an already open fd to a node outside the chroot works. - const FileDescriptor proc_self_fd = ASSERT_NO_ERRNO_AND_VALUE( - OpenAt(proc_fd.get(), "self/fd", O_DIRECTORY | O_RDONLY | O_CLOEXEC)); - - // Proc fd symlinks can escape the chroot if the fd the symlink refers to - // refers to an object outside the chroot. - struct stat s = {}; - EXPECT_THAT( - fstatat(proc_self_fd.get(), absl::StrCat(fd.get()).c_str(), &s, 0), - SyscallSucceeds()); - - // Try to stat the stdin fd. Internally, this is handled differently from a - // proc fd entry pointing to a file, since stdin is backed by a host fd, and - // isn't a walkable path on the filesystem inside the sandbox. - EXPECT_THAT(fstatat(proc_self_fd.get(), "0", &s, 0), SyscallSucceeds()); -} - -// This test will verify that when you hold a fd to proc before entering -// a chroot that any files inside the chroot will appear rooted to the -// base chroot when examining /proc/self/fd/{num}. -TEST(ChrootTest, ProcMemSelfFdsNoEscapeProcOpen) { - SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SYS_CHROOT))); - - // Get a FD to /proc before we enter the chroot. - const FileDescriptor proc = - ASSERT_NO_ERRNO_AND_VALUE(Open("/proc", O_RDONLY)); - - // Create and enter a chroot directory. - const auto temp_dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir()); - ASSERT_THAT(chroot(temp_dir.path().c_str()), SyscallSucceeds()); - - // Open a file inside the chroot at /foo. - const FileDescriptor foo = - ASSERT_NO_ERRNO_AND_VALUE(Open("/foo", O_CREAT | O_RDONLY, 0644)); - - // Examine /proc/self/fd/{foo_fd} to see if it exposes the fact that we're - // inside a chroot, the path should be /foo and NOT {chroot_dir}/foo. - const std::string fd_path = absl::StrCat("self/fd/", foo.get()); - char buf[1024] = {}; - size_t bytes_read = 0; - ASSERT_THAT(bytes_read = - readlinkat(proc.get(), fd_path.c_str(), buf, sizeof(buf) - 1), - SyscallSucceeds()); - - // The link should resolve to something. - ASSERT_GT(bytes_read, 0); - - // Assert that the link doesn't contain the chroot path and is only /foo. - EXPECT_STREQ(buf, "/foo"); -} - -// This test will verify that a file inside a chroot when mmapped will not -// expose the full file path via /proc/self/maps and instead honor the chroot. -TEST(ChrootTest, ProcMemSelfMapsNoEscapeProcOpen) { - SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SYS_CHROOT))); - - // Get a FD to /proc before we enter the chroot. - const FileDescriptor proc = - ASSERT_NO_ERRNO_AND_VALUE(Open("/proc", O_RDONLY)); - - // Create and enter a chroot directory. - const auto temp_dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir()); - ASSERT_THAT(chroot(temp_dir.path().c_str()), SyscallSucceeds()); - - // Open a file inside the chroot at /foo. - const FileDescriptor foo = - ASSERT_NO_ERRNO_AND_VALUE(Open("/foo", O_CREAT | O_RDONLY, 0644)); - - // Mmap the newly created file. - void* foo_map = mmap(nullptr, kPageSize, PROT_READ | PROT_WRITE, MAP_PRIVATE, - foo.get(), 0); - ASSERT_THAT(reinterpret_cast<int64_t>(foo_map), SyscallSucceeds()); - - // Always unmap. - auto cleanup_map = Cleanup( - [&] { EXPECT_THAT(munmap(foo_map, kPageSize), SyscallSucceeds()); }); - - // Examine /proc/self/maps to be sure that /foo doesn't appear to be - // mapped with the full chroot path. - const FileDescriptor maps = - ASSERT_NO_ERRNO_AND_VALUE(OpenAt(proc.get(), "self/maps", O_RDONLY)); - - size_t bytes_read = 0; - char buf[8 * 1024] = {}; - ASSERT_THAT(bytes_read = ReadFd(maps.get(), buf, sizeof(buf)), - SyscallSucceeds()); - - // The maps file should have something. - ASSERT_GT(bytes_read, 0); - - // Finally we want to make sure the maps don't contain the chroot path - ASSERT_EQ(std::string(buf, bytes_read).find(temp_dir.path()), - std::string::npos); -} - -// Test that mounts outside the chroot will not appear in /proc/self/mounts or -// /proc/self/mountinfo. -TEST(ChrootTest, ProcMountsMountinfoNoEscape) { - SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SYS_ADMIN))); - SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SYS_CHROOT))); - - // We are going to create some mounts and then chroot. In order to be able to - // unmount the mounts after the test run, we must chdir to the root and use - // relative paths for all mounts. That way, as long as we never chdir into - // the new root, we can access the mounts via relative paths and unmount them. - ASSERT_THAT(chdir("/"), SyscallSucceeds()); - - // Create nested tmpfs mounts. Note the use of relative paths in Mount calls. - auto const outer_dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir()); - auto const outer_mount = ASSERT_NO_ERRNO_AND_VALUE(Mount( - "none", JoinPath(".", outer_dir.path()), "tmpfs", 0, "mode=0700", 0)); - - auto const inner_dir = - ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDirIn(outer_dir.path())); - auto const inner_mount = ASSERT_NO_ERRNO_AND_VALUE(Mount( - "none", JoinPath(".", inner_dir.path()), "tmpfs", 0, "mode=0700", 0)); - - // Filenames that will be checked for mounts, all relative to /proc dir. - std::string paths[3] = {"mounts", "self/mounts", "self/mountinfo"}; - - for (const std::string& path : paths) { - // We should have both inner and outer mounts. - const std::string contents = - ASSERT_NO_ERRNO_AND_VALUE(GetContents(JoinPath("/proc", path))); - EXPECT_THAT(contents, AllOf(HasSubstr(outer_dir.path()), - HasSubstr(inner_dir.path()))); - // We better have at least two mounts: the mounts we created plus the root. - std::vector<absl::string_view> submounts = - absl::StrSplit(contents, '\n', absl::SkipWhitespace()); - EXPECT_GT(submounts.size(), 2); - } - - // Get a FD to /proc before we enter the chroot. - const FileDescriptor proc = - ASSERT_NO_ERRNO_AND_VALUE(Open("/proc", O_RDONLY)); - - // Chroot to outer mount. - ASSERT_THAT(chroot(outer_dir.path().c_str()), SyscallSucceeds()); - - for (const std::string& path : paths) { - const FileDescriptor proc_file = - ASSERT_NO_ERRNO_AND_VALUE(OpenAt(proc.get(), path, O_RDONLY)); - - // Only two mounts visible from this chroot: the inner and outer. Both - // paths should be relative to the new chroot. - const std::string contents = - ASSERT_NO_ERRNO_AND_VALUE(GetContentsFD(proc_file.get())); - EXPECT_THAT(contents, - AllOf(HasSubstr(absl::StrCat(Basename(inner_dir.path()))), - Not(HasSubstr(outer_dir.path())), - Not(HasSubstr(inner_dir.path())))); - std::vector<absl::string_view> submounts = - absl::StrSplit(contents, '\n', absl::SkipWhitespace()); - EXPECT_EQ(submounts.size(), 2); - } - - // Chroot to inner mount. We must use an absolute path accessible to our - // chroot. - const std::string inner_dir_basename = - absl::StrCat("/", Basename(inner_dir.path())); - ASSERT_THAT(chroot(inner_dir_basename.c_str()), SyscallSucceeds()); - - for (const std::string& path : paths) { - const FileDescriptor proc_file = - ASSERT_NO_ERRNO_AND_VALUE(OpenAt(proc.get(), path, O_RDONLY)); - const std::string contents = - ASSERT_NO_ERRNO_AND_VALUE(GetContentsFD(proc_file.get())); - - // Only the inner mount visible from this chroot. - std::vector<absl::string_view> submounts = - absl::StrSplit(contents, '\n', absl::SkipWhitespace()); - EXPECT_EQ(submounts.size(), 1); - } - - // Chroot back to ".". - ASSERT_THAT(chroot("."), SyscallSucceeds()); -} - -} // namespace - -} // namespace testing -} // namespace gvisor |