Le 17/08/2022 à 07:06, Russell Currey a écrit :
> From: Nicholas Miehlbradt <nicho...@linux.ibm.com>
>
> This selftest is designed to cover execute-only protections
> on the Radix MMU but will also work with Hash.
>
> The tests are based on those found in pkey_exec_test with modifications
> to use the generic mprotect() instead of the pkey variants.
>
> Signed-off-by: Nicholas Miehlbradt <nicho...@linux.ibm.com>
> Signed-off-by: Russell Currey <rus...@russell.cc>
> ---
> v4: new
>
> tools/testing/selftests/powerpc/mm/Makefile | 3 +-
> .../testing/selftests/powerpc/mm/exec_prot.c | 231 ++++++++++++++++++
There is a lot of code in common with pkey_exec_prot.c
Isn't there a way to refactor ?
> 2 files changed, 233 insertions(+), 1 deletion(-)
> create mode 100644 tools/testing/selftests/powerpc/mm/exec_prot.c
>
> diff --git a/tools/testing/selftests/powerpc/mm/Makefile
> b/tools/testing/selftests/powerpc/mm/Makefile
> index 27dc09d0bfee..19dd0b2ea397 100644
> --- a/tools/testing/selftests/powerpc/mm/Makefile
> +++ b/tools/testing/selftests/powerpc/mm/Makefile
> @@ -3,7 +3,7 @@ noarg:
> $(MAKE) -C ../
>
> TEST_GEN_PROGS := hugetlb_vs_thp_test subpage_prot prot_sao segv_errors
> wild_bctr \
> - large_vm_fork_separation bad_accesses pkey_exec_prot \
> + large_vm_fork_separation bad_accesses exec_prot
> pkey_exec_prot \
> pkey_siginfo stack_expansion_signal stack_expansion_ldst \
> large_vm_gpr_corruption
> TEST_PROGS := stress_code_patching.sh
> @@ -22,6 +22,7 @@ $(OUTPUT)/wild_bctr: CFLAGS += -m64
> $(OUTPUT)/large_vm_fork_separation: CFLAGS += -m64
> $(OUTPUT)/large_vm_gpr_corruption: CFLAGS += -m64
> $(OUTPUT)/bad_accesses: CFLAGS += -m64
> +$(OUTPUT)/exec_prot: CFLAGS += -m64
> $(OUTPUT)/pkey_exec_prot: CFLAGS += -m64
> $(OUTPUT)/pkey_siginfo: CFLAGS += -m64
>
> diff --git a/tools/testing/selftests/powerpc/mm/exec_prot.c
> b/tools/testing/selftests/powerpc/mm/exec_prot.c
> new file mode 100644
> index 000000000000..db75b2225de1
> --- /dev/null
> +++ b/tools/testing/selftests/powerpc/mm/exec_prot.c
> @@ -0,0 +1,231 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +/*
> + * Copyright 2022, Nicholas Miehlbradt, IBM Corporation
> + * based on pkey_exec_prot.c
> + *
> + * Test if applying execute protection on pages works as expected.
> + */
> +
> +#define _GNU_SOURCE
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <signal.h>
> +
> +#include <unistd.h>
> +#include <sys/mman.h>
> +
> +#include "pkeys.h"
> +
> +
> +#define PPC_INST_NOP 0x60000000
> +#define PPC_INST_TRAP 0x7fe00008
> +#define PPC_INST_BLR 0x4e800020
> +
> +static volatile sig_atomic_t fault_code;
> +static volatile sig_atomic_t remaining_faults;
> +static volatile unsigned int *fault_addr;
> +static unsigned long pgsize, numinsns;
> +static unsigned int *insns;
> +static bool pkeys_supported;
> +
> +static bool is_fault_expected(int fault_code)
> +{
> + if (fault_code == SEGV_ACCERR)
> + return true;
> +
> + /* Assume any pkey error is fine since pkey_exec_prot test covers them
> */
> + if (fault_code == SEGV_PKUERR && pkeys_supported)
> + return true;
> +
> + return false;
> +}
> +
> +static void trap_handler(int signum, siginfo_t *sinfo, void *ctx)
> +{
> + /* Check if this fault originated from the expected address */
> + if (sinfo->si_addr != (void *)fault_addr)
> + sigsafe_err("got a fault for an unexpected address\n");
> +
> + _exit(1);
> +}
> +
> +static void segv_handler(int signum, siginfo_t *sinfo, void *ctx)
> +{
> + fault_code = sinfo->si_code;
> +
> + /* Check if this fault originated from the expected address */
> + if (sinfo->si_addr != (void *)fault_addr) {
> + sigsafe_err("got a fault for an unexpected address\n");
> + _exit(1);
> + }
> +
> + /* Check if too many faults have occurred for a single test case */
> + if (!remaining_faults) {
> + sigsafe_err("got too many faults for the same address\n");
> + _exit(1);
> + }
> +
> +
> + /* Restore permissions in order to continue */
> + if (is_fault_expected(fault_code)) {
> + if (mprotect(insns, pgsize, PROT_READ | PROT_WRITE |
> PROT_EXEC)) {
> + sigsafe_err("failed to set access permissions\n");
> + _exit(1);
> + }
> + } else {
> + sigsafe_err("got a fault with an unexpected code\n");
> + _exit(1);
> + }
> +
> + remaining_faults--;
> +}
> +
> +static int check_exec_fault(int rights)
> +{
> + /*
> + * Jump to the executable region.
> + *
> + * The first iteration also checks if the overwrite of the
> + * first instruction word from a trap to a no-op succeeded.
> + */
> + fault_code = -1;
> + remaining_faults = 0;
> + if (!(rights & PROT_EXEC))
> + remaining_faults = 1;
> +
> + FAIL_IF(mprotect(insns, pgsize, rights) != 0);
> + asm volatile("mtctr %0; bctrl" : : "r"(insns));
> +
> + FAIL_IF(remaining_faults != 0);
> + if (!(rights & PROT_EXEC))
> + FAIL_IF(!is_fault_expected(fault_code));
> +
> + return 0;
> +}
> +
> +static int test(void)
> +{
> + struct sigaction segv_act, trap_act;
> + int i;
> +
> + /* Skip the test if the CPU doesn't support Radix */
> + SKIP_IF(!have_hwcap2(PPC_FEATURE2_ARCH_3_00));
> +
> + /* Check if pkeys are supported */
> + pkeys_supported = pkeys_unsupported() == 0;
> +
> + /* Setup SIGSEGV handler */
> + segv_act.sa_handler = 0;
> + segv_act.sa_sigaction = segv_handler;
> + FAIL_IF(sigprocmask(SIG_SETMASK, 0, &segv_act.sa_mask) != 0);
> + segv_act.sa_flags = SA_SIGINFO;
> + segv_act.sa_restorer = 0;
> + FAIL_IF(sigaction(SIGSEGV, &segv_act, NULL) != 0);
> +
> + /* Setup SIGTRAP handler */
> + trap_act.sa_handler = 0;
> + trap_act.sa_sigaction = trap_handler;
> + FAIL_IF(sigprocmask(SIG_SETMASK, 0, &trap_act.sa_mask) != 0);
> + trap_act.sa_flags = SA_SIGINFO;
> + trap_act.sa_restorer = 0;
> + FAIL_IF(sigaction(SIGTRAP, &trap_act, NULL) != 0);
> +
> + /* Setup executable region */
> + pgsize = getpagesize();
> + numinsns = pgsize / sizeof(unsigned int);
> + insns = (unsigned int *)mmap(NULL, pgsize, PROT_READ | PROT_WRITE,
> + MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
> + FAIL_IF(insns == MAP_FAILED);
> +
> + /* Write the instruction words */
> + for (i = 1; i < numinsns - 1; i++)
> + insns[i] = PPC_INST_NOP;
> +
> + /*
> + * Set the first instruction as an unconditional trap. If
> + * the last write to this address succeeds, this should
> + * get overwritten by a no-op.
> + */
> + insns[0] = PPC_INST_TRAP;
> +
> + /*
> + * Later, to jump to the executable region, we use a branch
> + * and link instruction (bctrl) which sets the return address
> + * automatically in LR. Use that to return back.
> + */
> + insns[numinsns - 1] = PPC_INST_BLR;
> +
> + /*
> + * Pick the first instruction's address from the executable
> + * region.
> + */
> + fault_addr = insns;
> +
> + /*
> + * Read an instruction word from the address when the page
> + * is execute only. This should generate an access fault.
> + */
> + fault_code = -1;
> + remaining_faults = 1;
> + printf("Testing read on --x, should fault...");
> + FAIL_IF(mprotect(insns, pgsize, PROT_EXEC) != 0);
> + i = *fault_addr;
> + FAIL_IF(remaining_faults != 0 || !is_fault_expected(fault_code));
> + printf("ok!\n");
> +
> + /*
> + * Write an instruction word to the address when the page
> + * execute only. This should also generate an access fault.
> + */
> + fault_code = -1;
> + remaining_faults = 1;
> + printf("Testing write on --x, should fault...");
> + FAIL_IF(mprotect(insns, pgsize, PROT_EXEC) != 0);
> + *fault_addr = PPC_INST_NOP;
> + FAIL_IF(remaining_faults != 0 || !is_fault_expected(fault_code));
> + printf("ok!\n");
> +
> + printf("Testing exec on ---, should fault...");
> + FAIL_IF(check_exec_fault(PROT_NONE));
> + printf("ok!\n");
> +
> + printf("Testing exec on r--, should fault...");
> + FAIL_IF(check_exec_fault(PROT_READ));
> + printf("ok!\n");
> +
> + printf("Testing exec on -w-, should fault...");
> + FAIL_IF(check_exec_fault(PROT_WRITE));
> + printf("ok!\n");
> +
> + printf("Testing exec on rw-, should fault...");
> + FAIL_IF(check_exec_fault(PROT_READ | PROT_WRITE));
> + printf("ok!\n");
> +
> + printf("Testing exec on --x, should succeed...");
> + FAIL_IF(check_exec_fault(PROT_EXEC));
> + printf("ok!\n");
> +
> + printf("Testing exec on r-x, should succeed...");
> + FAIL_IF(check_exec_fault(PROT_READ | PROT_EXEC));
> + printf("ok!\n");
> +
> + printf("Testing exec on -wx, should succeed...");
> + FAIL_IF(check_exec_fault(PROT_WRITE | PROT_EXEC));
> + printf("ok!\n");
> +
> + printf("Testing exec on rwx, should succeed...");
> + FAIL_IF(check_exec_fault(PROT_READ | PROT_WRITE | PROT_EXEC));
> + printf("ok!\n");
> +
> + /* Cleanup */
> + FAIL_IF(munmap((void *)insns, pgsize));
> +
> + return 0;
> +}
> +
> +int main(void)
> +{
> + return test_harness(test, "exec_prot");
> +}
