diff options
| -rw-r--r-- | pkg/sentry/loader/elf.go | 2 | ||||
| -rw-r--r-- | pkg/sentry/loader/loader.go | 2 | ||||
| -rw-r--r-- | test/syscalls/linux/exec.cc | 41 |
3 files changed, 45 insertions, 0 deletions
diff --git a/pkg/sentry/loader/elf.go b/pkg/sentry/loader/elf.go index 3ea037e4d..c2c3ec06e 100644 --- a/pkg/sentry/loader/elf.go +++ b/pkg/sentry/loader/elf.go @@ -644,6 +644,8 @@ func loadELF(ctx context.Context, args LoadArgs) (loadedELF, arch.Context, error // resolved, the interpreter should still be resolved if it is // a symlink. args.ResolveFinal = true + // Refresh the traversal limit. + *args.RemainingTraversals = linux.MaxSymlinkTraversals args.Filename = bin.interpreter d, i, err := openPath(ctx, args) if err != nil { diff --git a/pkg/sentry/loader/loader.go b/pkg/sentry/loader/loader.go index 803e7d41e..b03eeb005 100644 --- a/pkg/sentry/loader/loader.go +++ b/pkg/sentry/loader/loader.go @@ -293,6 +293,8 @@ func loadExecutable(ctx context.Context, args LoadArgs) (loadedELF, arch.Context ctx.Infof("Error loading interpreter script: %v", err) return loadedELF{}, nil, nil, nil, err } + // Refresh the traversal limit for the interpreter. + *args.RemainingTraversals = linux.MaxSymlinkTraversals default: ctx.Infof("Unknown magic: %v", hdr) return loadedELF{}, nil, nil, nil, syserror.ENOEXEC diff --git a/test/syscalls/linux/exec.cc b/test/syscalls/linux/exec.cc index a9067df2a..581f03533 100644 --- a/test/syscalls/linux/exec.cc +++ b/test/syscalls/linux/exec.cc @@ -533,6 +533,47 @@ TEST(ExecTest, CloexecEventfd) { W_EXITCODE(0, 0), ""); } +constexpr int kLinuxMaxSymlinks = 40; + +TEST(ExecTest, SymlinkLimitExceeded) { + std::string path = WorkloadPath(kBasicWorkload); + + // Hold onto TempPath objects so they are not destructed prematurely. + std::vector<TempPath> symlinks; + for (int i = 0; i < kLinuxMaxSymlinks + 1; i++) { + symlinks.push_back( + ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateSymlinkTo("/tmp", path))); + path = symlinks[i].path(); + } + + int execve_errno; + ASSERT_NO_ERRNO_AND_VALUE( + ForkAndExec(path, {path}, {}, /*child=*/nullptr, &execve_errno)); + EXPECT_EQ(execve_errno, ELOOP); +} + +TEST(ExecTest, SymlinkLimitRefreshedForInterpreter) { + std::string tmp_dir = "/tmp"; + std::string interpreter_path = "/bin/echo"; + TempPath script = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFileWith( + tmp_dir, absl::StrCat("#!", interpreter_path), 0755)); + std::string script_path = script.path(); + + // Hold onto TempPath objects so they are not destructed prematurely. + std::vector<TempPath> interpreter_symlinks; + std::vector<TempPath> script_symlinks; + for (int i = 0; i < kLinuxMaxSymlinks; i++) { + interpreter_symlinks.push_back(ASSERT_NO_ERRNO_AND_VALUE( + TempPath::CreateSymlinkTo(tmp_dir, interpreter_path))); + interpreter_path = interpreter_symlinks[i].path(); + script_symlinks.push_back(ASSERT_NO_ERRNO_AND_VALUE( + TempPath::CreateSymlinkTo(tmp_dir, script_path))); + script_path = script_symlinks[i].path(); + } + + CheckExec(script_path, {script_path}, {}, ArgEnvExitStatus(0, 0), ""); +} + TEST(ExecveatTest, BasicWithFDCWD) { std::string path = WorkloadPath(kBasicWorkload); CheckExecveat(AT_FDCWD, path, {path}, {}, /*flags=*/0, ArgEnvExitStatus(0, 0), |