Add some arm64/signal specific boilerplate and utility code to help further testcases' development.

Introduce also one simple testcase mangle_pstate_invalid_compat_toggle and some related helpers: it is a simple mangle testcase which messes with the ucontext_t from within the signal handler, trying to toggle PSTATE state bits to switch the system between 32bit/64bit execution state. Expects SIGSEGV on test PASS.

Signed-off-by: Cristian Marussi cristian.marussi@arm.com --- v3 --> v4 - removed standalone mode - fixed arm64/signal/README - add file level comments: test layout / test description - reduced verbosity - removed spurious headers includes - reviewed ID_AA64MMFR[1,2]_EL1 macros - removed unused feats_ok - simplified CPU features gathering - reviewed included headers - fixed/refactored get_header() and validation routines - added test description --- tools/testing/selftests/arm64/Makefile | 2 +- tools/testing/selftests/arm64/signal/Makefile | 50 ++++ tools/testing/selftests/arm64/signal/README | 59 ++++ .../selftests/arm64/signal/test_signals.c | 29 ++ .../selftests/arm64/signal/test_signals.h | 113 ++++++++ .../arm64/signal/test_signals_utils.c | 269 ++++++++++++++++++ .../arm64/signal/test_signals_utils.h | 13 + .../arm64/signal/testcases/.gitignore | 3 + .../mangle_pstate_invalid_compat_toggle.c | 31 ++ .../arm64/signal/testcases/testcases.c | 151 ++++++++++ .../arm64/signal/testcases/testcases.h | 86 ++++++ 11 files changed, 805 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/arm64/signal/Makefile create mode 100644 tools/testing/selftests/arm64/signal/README create mode 100644 tools/testing/selftests/arm64/signal/test_signals.c create mode 100644 tools/testing/selftests/arm64/signal/test_signals.h create mode 100644 tools/testing/selftests/arm64/signal/test_signals_utils.c create mode 100644 tools/testing/selftests/arm64/signal/test_signals_utils.h create mode 100644 tools/testing/selftests/arm64/signal/testcases/.gitignore create mode 100644 tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_compat_toggle.c create mode 100644 tools/testing/selftests/arm64/signal/testcases/testcases.c create mode 100644 tools/testing/selftests/arm64/signal/testcases/testcases.h

diff --git a/tools/testing/selftests/arm64/Makefile b/tools/testing/selftests/arm64/Makefile index 03a0d4f71218..af59dc74e0dc 100644 --- a/tools/testing/selftests/arm64/Makefile +++ b/tools/testing/selftests/arm64/Makefile @@ -6,7 +6,7 @@ ARCH ?= $(shell uname -m) ARCH := $(shell echo $(ARCH) | sed -e s/aarch64/arm64/)

ifeq ("x$(ARCH)", "xarm64") -SUBDIRS := +SUBDIRS := signal else SUBDIRS := endif diff --git a/tools/testing/selftests/arm64/signal/Makefile b/tools/testing/selftests/arm64/signal/Makefile new file mode 100644 index 000000000000..852f0a73ca00 --- /dev/null +++ b/tools/testing/selftests/arm64/signal/Makefile @@ -0,0 +1,50 @@ +# SPDX-License-Identifier: GPL-2.0 +# Copyright (C) 2019 ARM Limited + +# A proper top_srcdir is needed by KSFT(lib.mk) +top_srcdir = ../../../../.. + +# Additional include paths needed by kselftest.h and local headers +CFLAGS += -D_GNU_SOURCE -std=gnu99 -I. -I$(top_srcdir)/tools/testing/selftests/ + +# Guessing as best as we can where the Kernel headers +# could have been installed depending on ENV config and +# type of invocation. +ifeq ($(KBUILD_OUTPUT),) +khdr_dir = $(top_srcdir)/usr/include +else +# the KSFT preferred location when KBUILD_OUTPUT is set +khdr_dir = $(KBUILD_OUTPUT)/kselftest/usr/include +endif +CFLAGS += -I$(khdr_dir) + +SRCS := $(filter-out testcases/testcases.c,$(wildcard testcases/*.c)) +PROGS := $(patsubst %.c,%,$(SRCS)) + +# Generated binaries to be installed by top KSFT script +TEST_GEN_PROGS := $(notdir $(PROGS)) + +# Get Kernel headers installed and use them. +KSFT_KHDR_INSTALL := 1 + +# Including KSFT lib.mk here will also mangle the TEST_GEN_PROGS list +# to account for any OUTPUT target-dirs optionally provided by +# the toplevel makefile +include ../../lib.mk + +$(TEST_GEN_PROGS): $(PROGS) + cp $(PROGS) $(OUTPUT)/ + +clean: + $(CLEAN) + rm -f $(PROGS) + +# Common test-unit targets to build common-layout test-cases executables +# Needs secondary expansion to properly include the testcase c-file in pre-reqs +.SECONDEXPANSION: +$(PROGS): test_signals.c test_signals_utils.c testcases/testcases.c $$@.c test_signals.h test_signals_utils.h testcases/testcases.h + @if [ ! -d $(khdr_dir) ]; then \ + echo -n "\n!!! WARNING: $(khdr_dir) NOT FOUND."; \ + echo "===> Are you sure Kernel Headers have been installed properly ?\n"; \ + fi + $(CC) $(CFLAGS) $^ -o $@ diff --git a/tools/testing/selftests/arm64/signal/README b/tools/testing/selftests/arm64/signal/README new file mode 100644 index 000000000000..967a531b245c --- /dev/null +++ b/tools/testing/selftests/arm64/signal/README @@ -0,0 +1,59 @@ +KSelfTest arm64/signal/ +======================= + +Signals Tests ++++++++++++++ + +- Tests are built around a common main compilation unit: such shared main + enforces a standard sequence of operations needed to perform a single + signal-test (setup/trigger/run/result/cleanup) + +- The above mentioned ops are configurable on a test-by-test basis: each test + is described (and configured) using the descriptor signals.h::struct tdescr + +- Each signal testcase is compiled into its own executable: a separate + executable is used for each test since many tests complete successfully + by receiving some kind of fatal signal from the Kernel, so it's safer + to run each test unit in its own standalone process, so as to start each + test from a clean slate. + +- New tests can be simply defined in testcases/ dir providing a proper struct + tdescr overriding all the defaults we wish to change (as of now providing a + custom run method is mandatory though) + +- Signals' test-cases hereafter defined belong currently to two + principal families: + + - 'mangle_' tests: a real signal (SIGUSR1) is raised and used as a trigger + and then the test case code modifies the signal frame from inside the + signal handler itself. + + - 'fake_sigreturn_' tests: a brand new custom artificial sigframe structure + is placed on the stack and a sigreturn syscall is called to simulate a + real signal return. This kind of tests does not use a trigger usually and + they are just fired using some simple included assembly trampoline code. + + - Most of these tests are successfully passing if the process gets killed by + some fatal signal: usually SIGSEGV or SIGBUS. Since while writing this + kind of tests it is extremely easy in fact to end-up injecting other + unrelated SEGV bugs in the testcases, it becomes extremely tricky to + be really sure that the tests are really addressing what they are meant + to address and they are not instead falling apart due to unplanned bugs + in the test code. + In order to alleviate the misery of the life of such test-developer, a few + helpers are provided: + + - a couple of ASSERT_BAD/GOOD_CONTEXT() macros to easily parse a ucontext_t + and verify if it is indeed GOOD or BAD (depending on what we were + expecting), using the same logic/perspective as in the arm64 Kernel signals + routines. + + - a sanity mechanism to be used in 'fake_sigreturn_'-alike tests: enabled by + default it takes care to verify that the test-execution had at least + successfully progressed up to the stage of triggering the fake sigreturn + call. + + In both cases test results are expected in terms of: + - some fatal signal sent by the Kernel to the test process + or + - analyzing some final regs state diff --git a/tools/testing/selftests/arm64/signal/test_signals.c b/tools/testing/selftests/arm64/signal/test_signals.c new file mode 100644 index 000000000000..f05c6dbf8659 --- /dev/null +++ b/tools/testing/selftests/arm64/signal/test_signals.c @@ -0,0 +1,29 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2019 ARM Limited + * + * Generic test wrapper for arm64 signal tests. + * + * Each test provides its own tde struct tddescr descriptor to link with + * this wrapper. Framework provides common helpers. + */ +#include <kselftest.h> + +#include "test_signals.h" +#include "test_signals_utils.h" + +struct tdescr *current; + +int main(int argc, char *argv[]) +{ + current = &tde; + + ksft_print_msg("%s :: %s\n", current->name, current->descr); + if (test_setup(current)) { + if (test_run(current)) + test_result(current); + test_cleanup(current); + } + + return current->pass ? KSFT_PASS : KSFT_FAIL; +} diff --git a/tools/testing/selftests/arm64/signal/test_signals.h b/tools/testing/selftests/arm64/signal/test_signals.h new file mode 100644 index 000000000000..a1cf69997604 --- /dev/null +++ b/tools/testing/selftests/arm64/signal/test_signals.h @@ -0,0 +1,113 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* Copyright (C) 2019 ARM Limited */ + +#ifndef __TEST_SIGNALS_H__ +#define __TEST_SIGNALS_H__ + +#include <signal.h> +#include <stdbool.h> +#include <ucontext.h> + +/* + * Using ARCH specific and sanitized Kernel headers installed by KSFT + * framework since we asked for it by setting flag KSFT_KHDR_INSTALL + * in our Makefile. + */ +#include <asm/ptrace.h> +#include <asm/hwcap.h> + +#define __stringify_1(x...) #x +#define __stringify(x...) __stringify_1(x) + +#define get_regval(regname, out) \ +{ \ + asm volatile("mrs %0, " __stringify(regname) \ + : "=r" (out) \ + : \ + : "memory"); \ +} + +/* Regs encoding and masks naming copied in from sysreg.h */ +#define SYS_ID_AA64MMFR1_EL1 S3_0_C0_C7_1 /* MRS Emulated */ +#define SYS_ID_AA64MMFR2_EL1 S3_0_C0_C7_2 /* MRS Emulated */ +#define ID_AA64MMFR1_PAN_SHIFT 20 +#define ID_AA64MMFR2_UAO_SHIFT 4 + +/* Local Helpers */ +#define ID_AA64MMFR1_EL1_PAN_SUPPORTED(val) \ + (!!((val) & (0xfUL << ID_AA64MMFR1_PAN_SHIFT))) +#define ID_AA64MMFR2_EL1_UAO_SUPPORTED(val) \ + (!!((val) & (0xfUL << ID_AA64MMFR2_UAO_SHIFT))) + +#define SSBS_SYSREG S3_3_C4_C2_6 /* EL0 supported */ + +/* + * Feature flags used in tdescr.feats_required to specify + * any feature by the test + */ +enum { + FSSBS_BIT, + FPAN_BIT, + FUAO_BIT, + FMAX_END +}; + +#define FEAT_SSBS (1UL << FSSBS_BIT) +#define FEAT_PAN (1UL << FPAN_BIT) +#define FEAT_UAO (1UL << FUAO_BIT) + +/* + * A descriptor used to describe and configure a test case. + * Fields with a non-trivial meaning are described inline in the following. + */ +struct tdescr { + /* KEEP THIS FIELD FIRST for easier lookup from assembly */ + void *token; + /* when disabled token based sanity checking is skipped in handler */ + bool sanity_disabled; + /* just a name for the test-case; manadatory field */ + char *name; + char *descr; + unsigned long feats_required; + /* bitmask of effectively supported feats: populated at run-time */ + unsigned long feats_supported; + bool initialized; + unsigned int minsigstksz; + /* signum used as a test trigger. Zero if no trigger-signal is used */ + int sig_trig; + /* + * signum considered as a successful test completion. + * Zero when no signal is expected on success + */ + int sig_ok; + /* signum expected on unsupported CPU features. */ + int sig_unsupp; + /* a timeout in second for test completion */ + unsigned int timeout; + bool triggered; + bool pass; + /* optional sa_flags for the installed handler */ + int sa_flags; + ucontext_t saved_uc; + + /* a custom setup function to be called before test starts */ + int (*setup)(struct tdescr *td); + /* a custom cleanup function called before test exits */ + void (*cleanup)(struct tdescr *td); + + /* an optional function to be used as a trigger for test starting */ + int (*trigger)(struct tdescr *td); + /* + * the actual test-core: invoked differently depending on the + * presence of the trigger function above; this is mandatory + */ + int (*run)(struct tdescr *td, siginfo_t *si, ucontext_t *uc); + + /* an optional function for custom results' processing */ + void (*check_result)(struct tdescr *td); + + void *priv; +}; + +extern struct tdescr tde; +#endif diff --git a/tools/testing/selftests/arm64/signal/test_signals_utils.c b/tools/testing/selftests/arm64/signal/test_signals_utils.c new file mode 100644 index 000000000000..e2a5f37e6ad3 --- /dev/null +++ b/tools/testing/selftests/arm64/signal/test_signals_utils.c @@ -0,0 +1,269 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (C) 2019 ARM Limited */ + +#include <stdio.h> +#include <stdlib.h> +#include <signal.h> +#include <string.h> +#include <unistd.h> +#include <assert.h> +#include <sys/auxv.h> +#include <linux/auxvec.h> +#include <ucontext.h> + +#include "test_signals.h" +#include "test_signals_utils.h" +#include "testcases/testcases.h" + +extern struct tdescr *current; + +static char *feats_store[FMAX_END] = { + " SSBS ", + " PAN ", + " UAO ", +}; + +#define MAX_FEATS_SZ 128 +static char feats_string[MAX_FEATS_SZ]; + +static inline char *feats_to_string(unsigned long feats) +{ + size_t flen = MAX_FEATS_SZ - 1; + + for (int i = 0; i < FMAX_END; i++) { + if (feats & 1UL << i) { + size_t tlen = strlen(feats_store[i]); + + assert(flen > tlen); + flen -= tlen; + strncat(feats_string, feats_store[i], flen); + } + } + + return feats_string; +} + +static void unblock_signal(int signum) +{ + sigset_t sset; + + sigemptyset(&sset); + sigaddset(&sset, signum); + sigprocmask(SIG_UNBLOCK, &sset, NULL); +} + +static void default_result(struct tdescr *td, bool force_exit) +{ + if (td->pass) + fprintf(stderr, "==>> completed. PASS(1)\n"); + else + fprintf(stdout, "==>> completed. FAIL(0)\n"); + if (force_exit) + exit(td->pass ? EXIT_SUCCESS : EXIT_FAILURE); +} + +static inline bool are_feats_ok(struct tdescr *td) +{ + return (td->feats_required & td->feats_supported) == td->feats_required; +} + +static void default_handler(int signum, siginfo_t *si, void *uc) +{ + if (current->sig_trig && signum == current->sig_trig) { + fprintf(stderr, "Handling SIG_TRIG\n"); + current->triggered = 1; + /* ->run was asserted NON-NULL in test_setup() already */ + current->run(current, si, uc); + } else if (signum == SIGILL && !current->initialized) { + /* + * A SIGILL here while still not initialized means we failed + * even to asses the existence of features during init + */ + fprintf(stdout, + "Got SIGILL test_init. Marking ALL features UNSUPPORTED.\n"); + current->feats_supported = 0; + } else if (current->sig_ok && signum == current->sig_ok) { + /* + * it's a bug in the test code when this assert fail: + * if a sig_trig was defined, it must have been used before + * arriving here. + */ + assert(!current->sig_trig || current->triggered); + fprintf(stderr, + "SIG_OK -- SP:0x%llX si_addr@:%p si_code:%d token@:%p offset:%ld\n", + ((ucontext_t *)uc)->uc_mcontext.sp, + si->si_addr, si->si_code, current->token, + current->token - si->si_addr); + /* + * fake_sigreturn tests, which have sanity_enabled=1, set, at + * the very last time, the token field to the SP address used + * to place the fake sigframe: so token==0 means we never made + * it to the end, segfaulting well-before, and the test is + * possibly broken. + */ + if (!current->sanity_disabled && !current->token) { + fprintf(stdout, + "current->token ZEROED...test is probably broken!\n"); + abort(); + } + /* + * Trying to narrow down the SEGV to the ones generated by + * Kernel itself via arm64_notify_segfault(). + * This is a best-effort check anyway, and the si_code check may + * need to change if this aspect of the kernel ABI changes. + */ + if (current->sig_ok == SIGSEGV && si->si_code != SEGV_ACCERR) { + fprintf(stdout, + "si_code != SEGV_ACCERR...test is probably broken!\n"); + abort(); + } + fprintf(stderr, "Handling SIG_OK\n"); + current->pass = 1; + /* + * Some tests can lead to SEGV loops: in such a case we want + * to terminate immediately exiting straight away + */ + default_result(current, 1); + } else { + if (signum == current->sig_unsupp && !are_feats_ok(current)) { + fprintf(stderr, + "-- RX SIG_UNSUPP on unsupported feat...OK\n"); + current->pass = 1; + } else if (signum == SIGALRM && current->timeout) { + fprintf(stderr, "-- Timeout !\n"); + } else { + fprintf(stderr, + "-- RX UNEXPECTED SIGNAL: %d\n", signum); + } + default_result(current, 1); + } +} + +static int default_setup(struct tdescr *td) +{ + struct sigaction sa; + + sa.sa_sigaction = default_handler; + sa.sa_flags = SA_SIGINFO | SA_RESTART; + sa.sa_flags |= td->sa_flags; + sigemptyset(&sa.sa_mask); + /* uncatchable signals naturally skipped ... */ + for (int sig = 1; sig < 32; sig++) + sigaction(sig, &sa, NULL); + /* + * RT Signals default disposition is Term but they cannot be + * generated by the Kernel in response to our tests; so just catch + * them all and report them as UNEXPECTED signals. + */ + for (int sig = SIGRTMIN; sig <= SIGRTMAX; sig++) + sigaction(sig, &sa, NULL); + + /* just in case...unblock explicitly all we need */ + if (td->sig_trig) + unblock_signal(td->sig_trig); + if (td->sig_ok) + unblock_signal(td->sig_ok); + if (td->sig_unsupp) + unblock_signal(td->sig_unsupp); + + if (td->timeout) { + unblock_signal(SIGALRM); + alarm(td->timeout); + } + fprintf(stderr, "Registered handlers for all signals.\n"); + + return 1; +} + +static inline int default_trigger(struct tdescr *td) +{ + return !raise(td->sig_trig); +} + +static int test_init(struct tdescr *td) +{ + td->minsigstksz = getauxval(AT_MINSIGSTKSZ); + if (!td->minsigstksz) + td->minsigstksz = MINSIGSTKSZ; + fprintf(stderr, "Detected MINSTKSIGSZ:%d\n", td->minsigstksz); + + if (td->feats_required) { + bool feats_ok = false; + + td->feats_supported = 0; + /* + * Checking for CPU required features using both the + * auxval and the arm64 MRS Emulation to read sysregs. + */ + if (getauxval(AT_HWCAP) & HWCAP_CPUID) { + uint64_t val = 0; + + /* Uses HWCAP to check capability */ + if (getauxval(AT_HWCAP) & HWCAP_SSBS) + td->feats_supported |= FEAT_SSBS; + /* Uses MRS emulation to check capability */ + get_regval(SYS_ID_AA64MMFR1_EL1, val); + if (ID_AA64MMFR1_EL1_PAN_SUPPORTED(val)) + td->feats_supported |= FEAT_PAN; + /* Uses MRS emulation to check capability */ + get_regval(SYS_ID_AA64MMFR2_EL1, val); + if (ID_AA64MMFR2_EL1_UAO_SUPPORTED(val)) + td->feats_supported |= FEAT_UAO; + } else { + fprintf(stderr, + "HWCAP_CPUID NOT available. Mark ALL feats UNSUPPORTED.\n"); + } + feats_ok = are_feats_ok(td); + fprintf(stderr, + "Required Features: [%s] %ssupported\n", + feats_ok ? feats_to_string(td->feats_supported) : + feats_to_string(td->feats_required ^ + td->feats_supported), + !feats_ok ? "NOT " : ""); + } + + td->initialized = 1; + return 1; +} + +int test_setup(struct tdescr *td) +{ + /* assert core invariants symptom of a rotten testcase */ + assert(current); + assert(td); + assert(td->name); + assert(td->run); + + if (!test_init(td)) + return 0; + + if (td->setup) + return td->setup(td); + else + return default_setup(td); +} + +int test_run(struct tdescr *td) +{ + if (td->sig_trig) { + if (td->trigger) + return td->trigger(td); + else + return default_trigger(td); + } else { + return td->run(td, NULL, NULL); + } +} + +void test_result(struct tdescr *td) +{ + if (td->check_result) + td->check_result(td); + default_result(td, 0); +} + +void test_cleanup(struct tdescr *td) +{ + if (td->cleanup) + td->cleanup(td); +} diff --git a/tools/testing/selftests/arm64/signal/test_signals_utils.h b/tools/testing/selftests/arm64/signal/test_signals_utils.h new file mode 100644 index 000000000000..8658d1a7d4b9 --- /dev/null +++ b/tools/testing/selftests/arm64/signal/test_signals_utils.h @@ -0,0 +1,13 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* Copyright (C) 2019 ARM Limited */ + +#ifndef __TEST_SIGNALS_UTILS_H__ +#define __TEST_SIGNALS_UTILS_H__ + +#include "test_signals.h" + +int test_setup(struct tdescr *td); +void test_cleanup(struct tdescr *td); +int test_run(struct tdescr *td); +void test_result(struct tdescr *td); +#endif diff --git a/tools/testing/selftests/arm64/signal/testcases/.gitignore b/tools/testing/selftests/arm64/signal/testcases/.gitignore new file mode 100644 index 000000000000..e5aeae45febb --- /dev/null +++ b/tools/testing/selftests/arm64/signal/testcases/.gitignore @@ -0,0 +1,3 @@ +!*.[ch] +mangle_* +fake_sigreturn_* diff --git a/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_compat_toggle.c b/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_compat_toggle.c new file mode 100644 index 000000000000..2cb118b0ba05 --- /dev/null +++ b/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_compat_toggle.c @@ -0,0 +1,31 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2019 ARM Limited + * + * Try to mangle the ucontext from inside a signal handler, toggling + * the execution state bit: this attempt must be spotted by Kernel and + * the test case is expected to be terminated via SEGV. + */ + +#include "test_signals_utils.h" +#include "testcases.h" + +static int mangle_invalid_pstate_run(struct tdescr *td, siginfo_t *si, + ucontext_t *uc) +{ + ASSERT_GOOD_CONTEXT(uc); + + /* This config should trigger a SIGSEGV by Kernel */ + uc->uc_mcontext.pstate ^= PSR_MODE32_BIT; + + return 1; +} + +struct tdescr tde = { + .sanity_disabled = true, + .name = "MANGLE_PSTATE_INVALID_STATE_TOGGLE", + .descr = "Mangling uc_mcontext with INVALID STATE_TOGGLE", + .sig_trig = SIGUSR1, + .sig_ok = SIGSEGV, + .run = mangle_invalid_pstate_run, +}; diff --git a/tools/testing/selftests/arm64/signal/testcases/testcases.c b/tools/testing/selftests/arm64/signal/testcases/testcases.c new file mode 100644 index 000000000000..72e3f482b177 --- /dev/null +++ b/tools/testing/selftests/arm64/signal/testcases/testcases.c @@ -0,0 +1,151 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (C) 2019 ARM Limited */ +#include "testcases.h" + +struct _aarch64_ctx *get_header(struct _aarch64_ctx *head, uint32_t magic, + size_t resv_sz, size_t *offset) +{ + size_t offs = 0; + struct _aarch64_ctx *found = NULL; + + if (!head) + return found; + + while (offs <= resv_sz - HDR_SZ && + head->magic != magic && head->magic) { + offs += head->size; + head = GET_RESV_NEXT_HEAD(head); + } + if (head->magic == magic) { + found = head; + if (offset) + *offset = offs; + } + + return found; +} + +bool validate_extra_context(struct extra_context *extra, char **err) +{ + struct _aarch64_ctx *term; + + if (!extra || !err) + return false; + + fprintf(stderr, "Validating EXTRA...\n"); + term = GET_RESV_NEXT_HEAD(extra); + if (!term || term->magic || term->size) { + *err = "Missing terminator after EXTRA context"; + return false; + } + if (extra->datap & 0x0fUL) + *err = "Extra DATAP misaligned"; + else if (extra->size & 0x0fUL) + *err = "Extra SIZE misaligned"; + else if (extra->datap != (uint64_t)term + sizeof(*term)) + *err = "Extra DATAP misplaced (not contiguos)"; + if (*err) + return false; + + return true; +} + +bool validate_reserved(ucontext_t *uc, size_t resv_sz, char **err) +{ + bool terminated = false; + size_t offs = 0; + int flags = 0; + struct extra_context *extra = NULL; + struct _aarch64_ctx *head = + (struct _aarch64_ctx *)uc->uc_mcontext.__reserved; + + if (!err) + return false; + /* Walk till the end terminator verifying __reserved contents */ + while (head && !terminated && offs < resv_sz) { + if ((uint64_t)head & 0x0fUL) { + *err = "Misaligned HEAD"; + return false; + } + + switch (head->magic) { + case 0: + if (head->size) + *err = "Bad size for terminator"; + else + terminated = true; + break; + case FPSIMD_MAGIC: + if (flags & FPSIMD_CTX) + *err = "Multiple FPSIMD_MAGIC"; + else if (head->size != + sizeof(struct fpsimd_context)) + *err = "Bad size for fpsimd_context"; + flags |= FPSIMD_CTX; + break; + case ESR_MAGIC: + if (head->size != sizeof(struct esr_context)) + fprintf(stderr, + "Bad size for esr_context is not an error...just ignore.\n"); + break; + case SVE_MAGIC: + if (flags & SVE_CTX) + *err = "Multiple SVE_MAGIC"; + else if (head->size != + sizeof(struct sve_context)) + *err = "Bad size for sve_context"; + flags |= SVE_CTX; + break; + case EXTRA_MAGIC: + if (flags & EXTRA_CTX) + *err = "Multiple EXTRA_MAGIC"; + else if (head->size != + sizeof(struct extra_context)) + *err = "Bad size for extra_context"; + flags |= EXTRA_CTX; + extra = (struct extra_context *)head; + break; + case KSFT_BAD_MAGIC: + /* + * This is a BAD magic header defined + * artificially by a testcase and surely + * unknown to the Kernel parse_user_sigframe(). + * It MUST cause a Kernel induced SEGV + */ + *err = "BAD MAGIC !"; + break; + default: + /* + * A still unknown Magic: potentially freshly added + * to the Kernel code and still unknown to the + * tests. + */ + fprintf(stdout, + "SKIP Unknown MAGIC: 0x%X - Is KSFT arm64/signal up to date ?\n", + head->magic); + break; + } + + if (*err) + return false; + + offs += head->size; + if (resv_sz < offs + sizeof(*head)) { + *err = "HEAD Overrun"; + return false; + } + + if (flags & EXTRA_CTX) + if (!validate_extra_context(extra, err)) + return false; + + head = GET_RESV_NEXT_HEAD(head); + } + + if (terminated && !(flags & FPSIMD_CTX)) { + *err = "Missing FPSIMD"; + return false; + } + + return true; +} diff --git a/tools/testing/selftests/arm64/signal/testcases/testcases.h b/tools/testing/selftests/arm64/signal/testcases/testcases.h new file mode 100644 index 000000000000..00618c3202bb --- /dev/null +++ b/tools/testing/selftests/arm64/signal/testcases/testcases.h @@ -0,0 +1,86 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* Copyright (C) 2019 ARM Limited */ +#ifndef __TESTCASES_H__ +#define __TESTCASES_H__ + +#include <stddef.h> +#include <stdio.h> +#include <stdbool.h> +#include <stdint.h> +#include <ucontext.h> +#include <assert.h> +#include <signal.h> + +/* Architecture specific sigframe definitions */ +#include <asm/sigcontext.h> + +#define FPSIMD_CTX (1 << 0) +#define SVE_CTX (1 << 1) +#define EXTRA_CTX (1 << 2) + +#define KSFT_BAD_MAGIC 0xdeadbeef + +#define HDR_SZ \ + sizeof(struct _aarch64_ctx) + +#define GET_SF_RESV_HEAD(sf) \ + (struct _aarch64_ctx *)(&(sf).uc.uc_mcontext.__reserved) + +#define GET_SF_RESV_SIZE(sf) \ + sizeof((sf).uc.uc_mcontext.__reserved) + +#define GET_UCP_RESV_SIZE(ucp) \ + sizeof((ucp)->uc_mcontext.__reserved) + +#define ASSERT_BAD_CONTEXT(uc) do { \ + char *err = NULL; \ + assert(!validate_reserved((uc), GET_UCP_RESV_SIZE((uc)), &err));\ + if (err) \ + fprintf(stderr, \ + "Using badly built context - ERR: %s\n", err); \ +} while (0) + +#define ASSERT_GOOD_CONTEXT(uc) do { \ + char *err = NULL; \ + if (!validate_reserved((uc), GET_UCP_RESV_SIZE((uc)), &err)) { \ + if (err) \ + fprintf(stderr, \ + "Detected BAD context - ERR: %s\n", err);\ + assert(0); \ + } else { \ + fprintf(stderr, "uc context validated.\n"); \ + } \ +} while (0) + +/* head->size accounts both for payload and header _aarch64_ctx size ! */ +#define GET_RESV_NEXT_HEAD(h) \ + (struct _aarch64_ctx *)((char *)(h) + (h)->size) + +struct fake_sigframe { + siginfo_t info; + ucontext_t uc; +}; + + +bool validate_reserved(ucontext_t *uc, size_t resv_sz, char **err); + +bool validate_extra_context(struct extra_context *extra, char **err); + +struct _aarch64_ctx *get_header(struct _aarch64_ctx *head, uint32_t magic, + size_t resv_sz, size_t *offset); + +static inline struct _aarch64_ctx *get_terminator(struct _aarch64_ctx *head, + size_t resv_sz, + size_t *offset) +{ + return get_header(head, 0, resv_sz, offset); +} + +static inline void write_terminator_record(struct _aarch64_ctx *tail) +{ + if (tail) { + tail->magic = 0; + tail->size = 0; + } +} +#endif

Add 6 simple mangle testcases that mess with the ucontext_t from within the signal handler, trying to toggle PSTATE mode bits to trick the system into switching to EL1/EL2/EL3 using both SP_EL0(t) and SP_ELx(h). Expects SIGSEGV on test PASS.

Signed-off-by: Cristian Marussi cristian.marussi@arm.com --- v3 --> v4 - fixed commit message - macroization - splitted into 6 macro-ised testcases to address t/h SP selection modes - added test description --- .../mangle_pstate_invalid_mode_el1h.c | 15 ++++++++++ .../mangle_pstate_invalid_mode_el1t.c | 15 ++++++++++ .../mangle_pstate_invalid_mode_el2h.c | 15 ++++++++++ .../mangle_pstate_invalid_mode_el2t.c | 15 ++++++++++ .../mangle_pstate_invalid_mode_el3h.c | 15 ++++++++++ .../mangle_pstate_invalid_mode_el3t.c | 15 ++++++++++ .../mangle_pstate_invalid_mode_template.h | 28 +++++++++++++++++++ 7 files changed, 118 insertions(+) create mode 100644 tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_mode_el1h.c create mode 100644 tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_mode_el1t.c create mode 100644 tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_mode_el2h.c create mode 100644 tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_mode_el2t.c create mode 100644 tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_mode_el3h.c create mode 100644 tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_mode_el3t.c create mode 100644 tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_mode_template.h

diff --git a/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_mode_el1h.c b/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_mode_el1h.c new file mode 100644 index 000000000000..95f821abdf46 --- /dev/null +++ b/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_mode_el1h.c @@ -0,0 +1,15 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2019 ARM Limited + * + * Try to mangle the ucontext from inside a signal handler, toggling + * the mode bit to escalate exception level: this attempt must be spotted + * by Kernel and the test case is expected to be termninated via SEGV. + */ + +#include "test_signals_utils.h" +#include "testcases.h" + +#include "mangle_pstate_invalid_mode_template.h" + +DEFINE_TESTCASE_MANGLE_PSTATE_INVALID_MODE(1h); diff --git a/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_mode_el1t.c b/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_mode_el1t.c new file mode 100644 index 000000000000..cc222d8a618a --- /dev/null +++ b/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_mode_el1t.c @@ -0,0 +1,15 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2019 ARM Limited + * + * Try to mangle the ucontext from inside a signal handler, toggling + * the mode bit to escalate exception level: this attempt must be spotted + * by Kernel and the test case is expected to be termninated via SEGV. + */ + +#include "test_signals_utils.h" +#include "testcases.h" + +#include "mangle_pstate_invalid_mode_template.h" + +DEFINE_TESTCASE_MANGLE_PSTATE_INVALID_MODE(1t); diff --git a/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_mode_el2h.c b/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_mode_el2h.c new file mode 100644 index 000000000000..2188add7d28c --- /dev/null +++ b/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_mode_el2h.c @@ -0,0 +1,15 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2019 ARM Limited + * + * Try to mangle the ucontext from inside a signal handler, toggling + * the mode bit to escalate exception level: this attempt must be spotted + * by Kernel and the test case is expected to be termninated via SEGV. + */ + +#include "test_signals_utils.h" +#include "testcases.h" + +#include "mangle_pstate_invalid_mode_template.h" + +DEFINE_TESTCASE_MANGLE_PSTATE_INVALID_MODE(2h); diff --git a/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_mode_el2t.c b/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_mode_el2t.c new file mode 100644 index 000000000000..df32dd5a479c --- /dev/null +++ b/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_mode_el2t.c @@ -0,0 +1,15 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2019 ARM Limited + * + * Try to mangle the ucontext from inside a signal handler, toggling + * the mode bit to escalate exception level: this attempt must be spotted + * by Kernel and the test case is expected to be termninated via SEGV. + */ + +#include "test_signals_utils.h" +#include "testcases.h" + +#include "mangle_pstate_invalid_mode_template.h" + +DEFINE_TESTCASE_MANGLE_PSTATE_INVALID_MODE(2t); diff --git a/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_mode_el3h.c b/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_mode_el3h.c new file mode 100644 index 000000000000..9e6829b7e5db --- /dev/null +++ b/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_mode_el3h.c @@ -0,0 +1,15 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2019 ARM Limited + * + * Try to mangle the ucontext from inside a signal handler, toggling + * the mode bit to escalate exception level: this attempt must be spotted + * by Kernel and the test case is expected to be termninated via SEGV. + */ + +#include "test_signals_utils.h" +#include "testcases.h" + +#include "mangle_pstate_invalid_mode_template.h" + +DEFINE_TESTCASE_MANGLE_PSTATE_INVALID_MODE(3h); diff --git a/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_mode_el3t.c b/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_mode_el3t.c new file mode 100644 index 000000000000..5685a4f10d06 --- /dev/null +++ b/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_mode_el3t.c @@ -0,0 +1,15 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2019 ARM Limited + * + * Try to mangle the ucontext from inside a signal handler, toggling + * the mode bit to escalate exception level: this attempt must be spotted + * by Kernel and the test case is expected to be termninated via SEGV. + */ + +#include "test_signals_utils.h" +#include "testcases.h" + +#include "mangle_pstate_invalid_mode_template.h" + +DEFINE_TESTCASE_MANGLE_PSTATE_INVALID_MODE(3t); diff --git a/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_mode_template.h b/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_mode_template.h new file mode 100644 index 000000000000..f5bf1804d858 --- /dev/null +++ b/tools/testing/selftests/arm64/signal/testcases/mangle_pstate_invalid_mode_template.h @@ -0,0 +1,28 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (C) 2019 ARM Limited + * + * Utility macro to ease definition of testcases toggling mode EL + */ + +#define DEFINE_TESTCASE_MANGLE_PSTATE_INVALID_MODE(_mode) \ + \ +static int mangle_invalid_pstate_run(struct tdescr *td, siginfo_t *si, \ + ucontext_t *uc) \ +{ \ + ASSERT_GOOD_CONTEXT(uc); \ + \ + uc->uc_mcontext.pstate &= ~PSR_MODE_MASK; \ + uc->uc_mcontext.pstate |= PSR_MODE_EL ## _mode; \ + \ + return 1; \ +} \ + \ +struct tdescr tde = { \ + .sanity_disabled = true, \ + .name = "MANGLE_PSTATE_INVALID_MODE_EL"#_mode, \ + .descr = "Mangling uc_mcontext INVALID MODE EL"#_mode, \ + .sig_trig = SIGUSR1, \ + .sig_ok = SIGSEGV, \ + .run = mangle_invalid_pstate_run, \ +}

Add a simple fake_sigreturn testcase which builds a ucontext_t with a bad magic header and place it onto the stack. Expects a SIGSEGV on test PASS.

Introduce a common utility assembly trampoline function to invoke a sigreturn while placing the provided sigframe at wanted alignment and also an helper to make space when needed inside the sigframe reserved area.

Signed-off-by: Cristian Marussi cristian.marussi@arm.com --- v3 --> v4 - fix commit - fix signal.S, handle misalign requests too - remove unneeded comments - add signal.h include - added get_starting_head() helper - added test description --- tools/testing/selftests/arm64/signal/Makefile | 2 +- .../testing/selftests/arm64/signal/signals.S | 62 +++++++++++++++++++ .../arm64/signal/test_signals_utils.h | 1 + .../testcases/fake_sigreturn_bad_magic.c | 54 ++++++++++++++++ .../arm64/signal/testcases/testcases.c | 28 +++++++++ .../arm64/signal/testcases/testcases.h | 4 ++ 6 files changed, 150 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/arm64/signal/signals.S create mode 100644 tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c

diff --git a/tools/testing/selftests/arm64/signal/Makefile b/tools/testing/selftests/arm64/signal/Makefile index 852f0a73ca00..11af7b843d8e 100644 --- a/tools/testing/selftests/arm64/signal/Makefile +++ b/tools/testing/selftests/arm64/signal/Makefile @@ -42,7 +42,7 @@ clean: # Common test-unit targets to build common-layout test-cases executables # Needs secondary expansion to properly include the testcase c-file in pre-reqs .SECONDEXPANSION: -$(PROGS): test_signals.c test_signals_utils.c testcases/testcases.c $$@.c test_signals.h test_signals_utils.h testcases/testcases.h +$(PROGS): test_signals.c test_signals_utils.c testcases/testcases.c signals.S $$@.c test_signals.h test_signals_utils.h testcases/testcases.h @if [ ! -d $(khdr_dir) ]; then \ echo -n "\n!!! WARNING: $(khdr_dir) NOT FOUND."; \ echo "===> Are you sure Kernel Headers have been installed properly ?\n"; \ diff --git a/tools/testing/selftests/arm64/signal/signals.S b/tools/testing/selftests/arm64/signal/signals.S new file mode 100644 index 000000000000..b89fec0d5ba0 --- /dev/null +++ b/tools/testing/selftests/arm64/signal/signals.S @@ -0,0 +1,62 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* Copyright (C) 2019 ARM Limited */ + +#include <asm/unistd.h> + +.section .rodata, "a" +call_fmt: + .asciz "Calling sigreturn with fake sigframe sized:%zd at SP @%08lX\n" + +.text + +.globl fake_sigreturn + +/* fake_sigreturn x0:&sigframe, x1:sigframe_size, x2:misalign_bytes */ +fake_sigreturn: + mov x20, x0 + mov x21, x1 + mov x22, x2 + mov x23, sp + + /* create space on the stack for fake sigframe 16 bytes-aligned */ + add x0, x21, #16 + bic x0, x0, #15 + sub x23, x23, x0 + /* any misalignment requested ? */ + add x23, x23, x22 + + ldr x0, =call_fmt + mov x1, x21 + mov x2, x23 + bl printf + + mov sp, x23 + + /* now fill it with the provided content... */ + mov x0, sp + mov x1, x20 + mov x2, x21 + bl memcpy + + /* + * Here saving a last minute SP to current->token acts as a marker: + * if we got here, we are successfully faking a sigreturn; in other + * words we are sure no bad fatal signal has been raised till now + * for unrelated reasons, so we should consider the possibly observed + * fatal signal like SEGV coming from Kernel restore_sigframe() and + * triggered as expected from our test-case. + * For simplicity this assumes that current field 'token' is laid out + * as first in struct tdescr + */ + ldr x0, current + str x23, [x0] + /* SP is already pointing back to the just built fake sigframe here */ + mov x8, #__NR_rt_sigreturn + svc #0 + + /* + * Above sigreturn should not return...looping here leads to a timeout + * and ensure proper and clean test failure, instead of jumping around + * on a potentially corrupted stack. + */ + b . diff --git a/tools/testing/selftests/arm64/signal/test_signals_utils.h b/tools/testing/selftests/arm64/signal/test_signals_utils.h index ce35be8ebc8e..68930f1e46e5 100644 --- a/tools/testing/selftests/arm64/signal/test_signals_utils.h +++ b/tools/testing/selftests/arm64/signal/test_signals_utils.h @@ -12,4 +12,5 @@ int test_run(struct tdescr *td); void test_result(struct tdescr *td);

bool get_current_context(struct tdescr *td, ucontext_t *dest_uc); +int fake_sigreturn(void *sigframe, size_t sz, int misalign_bytes); #endif diff --git a/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c new file mode 100644 index 000000000000..7fb700b9801b --- /dev/null +++ b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_magic.c @@ -0,0 +1,54 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2019 ARM Limited + * + * Place a fake sigframe on the stack including a BAD Unknown magic + * record: on sigreturn Kernel must spot this attempt and the test + * case is expected to be terminated via SEGV. + */ + +#include <signal.h> +#include <ucontext.h> + +#include "test_signals_utils.h" +#include "testcases.h" + +struct fake_sigframe sf; + +static int fake_sigreturn_bad_magic_run(struct tdescr *td, + siginfo_t *si, ucontext_t *uc) +{ + size_t resv_sz, need_sz; + struct _aarch64_ctx *shead = GET_SF_RESV_HEAD(sf), *head; + + /* just to fill the ucontext_t with something real */ + if (!get_current_context(td, &sf.uc)) + return 1; + + resv_sz = GET_SF_RESV_SIZE(sf); + /* need at least 2*HDR_SZ space: KSFT_BAD_MAGIC + terminator. */ + need_sz = HDR_SZ * 2; + head = get_starting_head(shead, need_sz, resv_sz, NULL); + if (head) { + /* + * use a well known NON existent bad magic...something + * we should pretty sure won't be ever defined in Kernel + */ + head->magic = KSFT_BAD_MAGIC; + head->size = HDR_SZ; + write_terminator_record(GET_RESV_NEXT_HEAD(head)); + + ASSERT_BAD_CONTEXT(&sf.uc); + fake_sigreturn(&sf, sizeof(sf), 0); + } + + return 1; +} + +struct tdescr tde = { + .name = "FAKE_SIGRETURN_BAD_MAGIC", + .descr = "Trigger a sigreturn with a sigframe with a bad magic", + .sig_ok = SIGSEGV, + .timeout = 3, + .run = fake_sigreturn_bad_magic_run, +}; diff --git a/tools/testing/selftests/arm64/signal/testcases/testcases.c b/tools/testing/selftests/arm64/signal/testcases/testcases.c index 72e3f482b177..2effb8ded935 100644 --- a/tools/testing/selftests/arm64/signal/testcases/testcases.c +++ b/tools/testing/selftests/arm64/signal/testcases/testcases.c @@ -149,3 +149,31 @@ bool validate_reserved(ucontext_t *uc, size_t resv_sz, char **err)

return true; } + +struct _aarch64_ctx *get_starting_head(struct _aarch64_ctx *shead, + size_t need_sz, size_t resv_sz, + size_t *offset) +{ + size_t offs = 0; + struct _aarch64_ctx *head; + + head = get_terminator(shead, resv_sz, &offs); + /* not found a terminator...no need to update offset if any */ + if (!head) + return head; + if (resv_sz - offs < need_sz) { + fprintf(stderr, "Low on space:%zd. Discarding extra_context.\n", + resv_sz - offs); + head = get_header(shead, EXTRA_MAGIC, resv_sz, &offs); + if (!head || resv_sz - offs < need_sz) { + fprintf(stderr, + "Failed to reclaim space on sigframe.\n"); + return NULL; + } + } + + fprintf(stderr, "Available space:%zd\n", resv_sz - offs); + if (offset) + *offset = offs; + return head; +} diff --git a/tools/testing/selftests/arm64/signal/testcases/testcases.h b/tools/testing/selftests/arm64/signal/testcases/testcases.h index 00618c3202bb..7653f8a64b3d 100644 --- a/tools/testing/selftests/arm64/signal/testcases/testcases.h +++ b/tools/testing/selftests/arm64/signal/testcases/testcases.h @@ -83,4 +83,8 @@ static inline void write_terminator_record(struct _aarch64_ctx *tail) tail->size = 0; } } + +struct _aarch64_ctx *get_starting_head(struct _aarch64_ctx *shead, + size_t need_sz, size_t resv_sz, + size_t *offset); #endif

Add a simple fake_sigreturn testcase which builds a ucontext_t without the required fpsimd_context and place it onto the stack. Expects a SIGSEGV on test PASS.

Signed-off-by: Cristian Marussi cristian.marussi@arm.com --- v3 --> v4 - fix commit - added signal.h - added test description --- .../testcases/fake_sigreturn_missing_fpsimd.c | 50 +++++++++++++++++++ 1 file changed, 50 insertions(+) create mode 100644 tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_missing_fpsimd.c

diff --git a/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_missing_fpsimd.c b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_missing_fpsimd.c new file mode 100644 index 000000000000..08ecd8073a1a --- /dev/null +++ b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_missing_fpsimd.c @@ -0,0 +1,50 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2019 ARM Limited + * + * Place a fake sigframe on the stack missing the mandatory FPSIMD + * record: on sigreturn Kernel must spot this attempt and the test + * case is expected to be terminated via SEGV. + */ + +#include <stdio.h> +#include <signal.h> +#include <ucontext.h> + +#include "test_signals_utils.h" +#include "testcases.h" + +struct fake_sigframe sf; + +static int fake_sigreturn_missing_fpsimd_run(struct tdescr *td, + siginfo_t *si, ucontext_t *uc) +{ + size_t resv_sz, offset; + struct _aarch64_ctx *head = GET_SF_RESV_HEAD(sf); + + /* just to fill the ucontext_t with something real */ + if (!get_current_context(td, &sf.uc)) + return 1; + + resv_sz = GET_SF_RESV_SIZE(sf); + head = get_header(head, FPSIMD_MAGIC, resv_sz, &offset); + if (head && resv_sz - offset >= HDR_SZ) { + fprintf(stderr, "Mangling template header. Spare space:%zd\n", + resv_sz - offset); + /* Just overwrite fpsmid_context */ + write_terminator_record(head); + + ASSERT_BAD_CONTEXT(&sf.uc); + fake_sigreturn(&sf, sizeof(sf), 0); + } + + return 1; +} + +struct tdescr tde = { + .name = "FAKE_SIGRETURN_MISSING_FPSIMD", + .descr = "Triggers a sigreturn with a missing fpsimd_context", + .sig_ok = SIGSEGV, + .timeout = 3, + .run = fake_sigreturn_missing_fpsimd_run, +};

Add a simple fake_sigreturn testcase which builds a ucontext_t with a badly sized header that causes a overrun in the __reserved area and place it onto the stack. Expects a SIGSEGV on test PASS.

Signed-off-by: Cristian Marussi cristian.marussi@arm.com --- v3 --> v4 - fix commit - missing include - using new get_starting_head() helper - added test description --- .../testcases/fake_sigreturn_bad_size.c | 77 +++++++++++++++++++ 1 file changed, 77 insertions(+) create mode 100644 tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_size.c

diff --git a/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_size.c b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_size.c new file mode 100644 index 000000000000..b1156afdb691 --- /dev/null +++ b/tools/testing/selftests/arm64/signal/testcases/fake_sigreturn_bad_size.c @@ -0,0 +1,77 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2019 ARM Limited + * + * Place a fake sigframe on the stack including a bad record overflowing + * the __reserved space: on sigreturn Kernel must spot this attempt and + * the test case is expected to be terminated via SEGV. + */ + +#include <signal.h> +#include <ucontext.h> + +#include "test_signals_utils.h" +#include "testcases.h" + +struct fake_sigframe sf; + +#define MIN_SZ_ALIGN 16 + +static int fake_sigreturn_bad_size_run(struct tdescr *td, + siginfo_t *si, ucontext_t *uc) +{ + size_t resv_sz, need_sz, offset; + struct _aarch64_ctx *shead = GET_SF_RESV_HEAD(sf), *head; + + /* just to fill the ucontext_t with something real */ + if (!get_current_context(td, &sf.uc)) + return 1; + + resv_sz = GET_SF_RESV_SIZE(sf); + /* at least HDR_SZ + bad sized esr_context needed */ + need_sz = HDR_SZ + sizeof(struct esr_context); + head = get_starting_head(shead, need_sz, resv_sz, &offset); + if (head) { + /* + * Use an esr_context to build a fake header with a + * size greater then the free __reserved area minus HDR_SZ; + * using ESR_MAGIC here since it is not checked for size nor + * is limited to one instance. + * + * At first inject an additional normal esr_context + */ + head->magic = ESR_MAGIC; + head->size = sizeof(struct esr_context); + /* and terminate properly */ + write_terminator_record(GET_RESV_NEXT_HEAD(head)); + ASSERT_GOOD_CONTEXT(&sf.uc); + + /* + * now mess with fake esr_context size: leaving less space than + * needed while keeping size value 16-aligned + * + * It must trigger a SEGV from Kernel on: + * + * resv_sz - offset < sizeof(*head) + */ + /* at first set the maximum good 16-aligned size */ + head->size = + (resv_sz - offset - need_sz + MIN_SZ_ALIGN) & ~0xfUL; + /* plus a bit more of 16-aligned sized stuff */ + head->size += MIN_SZ_ALIGN; + /* and terminate properly */ + write_terminator_record(GET_RESV_NEXT_HEAD(head)); + ASSERT_BAD_CONTEXT(&sf.uc); + fake_sigreturn(&sf, sizeof(sf), 0); + } + + return 1; +} + +struct tdescr tde = { + .name = "FAKE_SIGRETURN_BAD_SIZE", + .descr = "Triggers a sigreturn with a overrun __reserved area", + .sig_ok = SIGSEGV, + .timeout = 3, + .run = fake_sigreturn_bad_size_run, +};