--- /dev/null
+// 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");
+}
projects / kernel.git / commitdiff