From e45bfde644faa112bbc877013667c9292d70c2a9 Mon Sep 17 00:00:00 2001 From: Simon McVittie Date: Thu, 21 Oct 2021 17:39:08 +0100 Subject: [PATCH] tests: Add try-syscall helper This exercises various syscalls. It's heavily based on the one from , but with the addition of a mode to output the numeric values of various expected errno codes, which are not otherwise available to shell scripts. Signed-off-by: Simon McVittie --- tests/Makefile.am.inc | 5 ++ tests/try-syscall.c | 173 ++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 178 insertions(+) create mode 100644 tests/try-syscall.c diff --git a/tests/Makefile.am.inc b/tests/Makefile.am.inc index 45612fd665..1c7485d92a 100644 --- a/tests/Makefile.am.inc +++ b/tests/Makefile.am.inc @@ -143,6 +143,10 @@ tests_test_authenticator_CFLAGS = $(AM_CFLAGS) $(BASE_CFLAGS) \ tests_test_authenticator_LDADD = $(AM_LDADD) $(BASE_LIBS) libflatpak-common.la libflatpak-common-base.la libglnx.la tests_test_authenticator_SOURCES = tests/test-authenticator.c +tests_try_syscall_CFLAGS = $(AM_CFLAGS) +tests_try_syscall_LDADD = $(AM_LDADD) +tests_try_syscall_SOURCES = tests/try-syscall.c + tests_list_unused_CFLAGS = $(AM_CFLAGS) $(BASE_CFLAGS) $(OSTREE_CFLAGS) $(SOUP_CFLAGS) $(JSON_CFLAGS) $(APPSTREAM_GLIB_CFLAGS) \ -DFLATPAK_COMPILATION \ -DLOCALEDIR=\"$(localedir)\" @@ -317,6 +321,7 @@ test_extra_programs = \ tests/test-authenticator \ tests/test-portal-impl \ tests/test-update-portal \ + tests/try-syscall \ $(NULL) @VALGRIND_CHECK_RULES@ diff --git a/tests/try-syscall.c b/tests/try-syscall.c new file mode 100644 index 0000000000..84a0ca6673 --- /dev/null +++ b/tests/try-syscall.c @@ -0,0 +1,173 @@ +/* + * Copyright 2021 Simon McVittie + * SPDX-License-Identifier: LGPL-2.0-or-later + * + * Try one or more system calls that might have been blocked by a + * seccomp filter. Return the last value of errno seen. + * + * In general, we pass a bad fd or pointer to each syscall that will + * accept one, so that it will fail with EBADF or EFAULT without side-effects. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#if defined(_MIPS_SIM) +# if _MIPS_SIM == _MIPS_SIM_ABI32 +# define MISSING_SYSCALL_BASE 4000 +# elif _MIPS_SIM == _MIPS_SIM_ABI64 +# define MISSING_SYSCALL_BASE 5000 +# elif _MIPS_SIM == _MIPS_SIM_NABI32 +# define MISSING_SYSCALL_BASE 6000 +# else +# error "Unknown MIPS ABI" +# endif +#endif + +#if defined(__ia64__) +# define MISSING_SYSCALL_BASE 1024 +#endif + +#if defined(__alpha__) +# define MISSING_SYSCALL_BASE 110 +#endif + +#if defined(__x86_64__) && defined(__ILP32__) +# define MISSING_SYSCALL_BASE 0x40000000 +#endif + +/* + * MISSING_SYSCALL_BASE: + * + * Number to add to the syscall numbers of recently-added syscalls + * to get the appropriate syscall for the current ABI. + */ +#ifndef MISSING_SYSCALL_BASE +# define MISSING_SYSCALL_BASE 0 +#endif + +#ifndef __NR_clone3 +# define __NR_clone3 (MISSING_SYSCALL_BASE + 435) +#endif + +/* + * The size of clone3's parameter (as of 2021) + */ +#define SIZEOF_STRUCT_CLONE_ARGS ((size_t) 88) + +/* + * An invalid pointer that will cause syscalls to fail with EFAULT + */ +#define WRONG_POINTER ((char *) 1) + +int +main (int argc, char **argv) +{ + int errsv = 0; + int i; + + for (i = 1; i < argc; i++) + { + const char *arg = argv[i]; + + if (strcmp (arg, "print-errno-values") == 0) + { + printf ("EBADF=%d\n", EBADF); + printf ("EFAULT=%d\n", EFAULT); + printf ("ENOENT=%d\n", ENOENT); + printf ("ENOSYS=%d\n", ENOSYS); + printf ("EPERM=%d\n", EPERM); + } + else if (strcmp (arg, "chmod") == 0) + { + /* If not blocked by seccomp, this will fail with EFAULT */ + if (chmod (WRONG_POINTER, 0700) != 0) + { + errsv = errno; + perror (arg); + } + } + else if (strcmp (arg, "chroot") == 0) + { + /* If not blocked by seccomp, this will fail with EFAULT */ + if (chroot (WRONG_POINTER) != 0) + { + errsv = errno; + perror (arg); + } + } + else if (strcmp (arg, "clone3") == 0) + { + /* If not blocked by seccomp, this will fail with EFAULT */ + if (syscall (__NR_clone3, WRONG_POINTER, SIZEOF_STRUCT_CLONE_ARGS) != 0) + { + errsv = errno; + perror (arg); + } + } + else if (strcmp (arg, "ioctl TIOCNOTTY") == 0) + { + /* If not blocked by seccomp, this will fail with EBADF */ + if (ioctl (-1, TIOCNOTTY) != 0) + { + errsv = errno; + perror (arg); + } + } + else if (strcmp (arg, "ioctl TIOCSTI") == 0) + { + /* If not blocked by seccomp, this will fail with EBADF */ + if (ioctl (-1, TIOCSTI, WRONG_POINTER) != 0) + { + errsv = errno; + perror (arg); + } + } +#ifdef __LP64__ + else if (strcmp (arg, "ioctl TIOCSTI CVE-2019-10063") == 0) + { + unsigned long not_TIOCSTI = (0x123UL << 32) | (unsigned long) TIOCSTI; + + /* If not blocked by seccomp, this will fail with EBADF */ + if (syscall (__NR_ioctl, -1, not_TIOCSTI, WRONG_POINTER) != 0) + { + errsv = errno; + perror (arg); + } + } +#endif + else if (strcmp (arg, "listen") == 0) + { + /* If not blocked by seccomp, this will fail with EBADF */ + if (listen (-1, 42) != 0) + { + errsv = errno; + perror (arg); + } + } + else if (strcmp (arg, "prctl") == 0) + { + /* If not blocked by seccomp, this will fail with EFAULT */ + if (prctl (PR_GET_CHILD_SUBREAPER, WRONG_POINTER, 0, 0, 0) != 0) + { + errsv = errno; + perror (arg); + } + } + else + { + fprintf (stderr, "Unsupported syscall \"%s\"\n", arg); + errsv = ENOENT; + } + } + + return errsv; +}