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