[PATCH v2 2/2] selftests/powerpc: Add core file test for Protection Key registers

Thiago Jung Bauermann
2018-05-25T02:12:36Z

This test verifies that the AMR, IAMR and UAMOR are being written to a
process' core file.

Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
---
tools/testing/selftests/powerpc/ptrace/Makefile | 5 +-
tools/testing/selftests/powerpc/ptrace/core-pkey.c | 461 +++++++++++++++++++++
2 files changed, 465 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/powerpc/ptrace/core-pkey.c

Changes in v2:
- Use PARENT_SKIP_IF_UNSUPPORTED macro in first call to
ptrace_read_regs(NT_PPC_PKEY). (Suggested by Michael Ellerman)

diff --git a/tools/testing/selftests/powerpc/ptrace/Makefile b/tools/testing/selftests/powerpc/ptrace/Makefile
index 707ba734faf2..a10916c3f3e1 100644
--- a/tools/testing/selftests/powerpc/ptrace/Makefile
+++ b/tools/testing/selftests/powerpc/ptrace/Makefile
@@ -1,7 +1,7 @@
# SPDX-License-Identifier: GPL-2.0
TEST_PROGS := ptrace-gpr ptrace-tm-gpr ptrace-tm-spd-gpr \
ptrace-tar ptrace-tm-tar ptrace-tm-spd-tar ptrace-vsx ptrace-tm-vsx \
- ptrace-tm-spd-vsx ptrace-tm-spr ptrace-pkey
+ ptrace-tm-spd-vsx ptrace-tm-spr ptrace-pkey core-pkey

include ../../lib.mk

@@ -12,6 +12,9 @@ CFLAGS += -m64 -I../../../../../usr/include -I../tm -mhtm -fno-pie
ptrace-pkey: ../harness.c ../utils.c ../lib/reg.S ptrace.h child.h ptrace-pkey.c
$(LINK.c) $^ $(LDLIBS) -pthread -o $@

+core-pkey: ../harness.c ../utils.c ../lib/reg.S ptrace.h child.h core-pkey.c
+ $(LINK.c) $^ $(LDLIBS) -pthread -o $@
+
$(TEST_PROGS): ../harness.c ../utils.c ../lib/reg.S ptrace.h

clean:
diff --git a/tools/testing/selftests/powerpc/ptrace/core-pkey.c b/tools/testing/selftests/powerpc/ptrace/core-pkey.c
new file mode 100644
index 000000000000..36bc312b1f5c
--- /dev/null
+++ b/tools/testing/selftests/powerpc/ptrace/core-pkey.c
@@ -0,0 +1,461 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Ptrace test for Memory Protection Key registers
+ *
+ * Copyright (C) 2015 Anshuman Khandual, IBM Corporation.
+ * Copyright (C) 2018 IBM Corporation.
+ */
+#include <limits.h>
+#include <linux/kernel.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/time.h>
+#include <sys/resource.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include "ptrace.h"
+#include "child.h"
+
+#ifndef __NR_pkey_alloc
+#define __NR_pkey_alloc 384
+#endif
+
+#ifndef __NR_pkey_free
+#define __NR_pkey_free 385
+#endif
+
+#ifndef NT_PPC_PKEY
+#define NT_PPC_PKEY 0x110
+#endif
+
+#ifndef PKEY_DISABLE_EXECUTE
+#define PKEY_DISABLE_EXECUTE 0x4
+#endif
+
+#define AMR_BITS_PER_PKEY 2
+#define PKEY_REG_BITS (sizeof(u64) * 8)
+#define pkeyshift(pkey) (PKEY_REG_BITS - ((pkey + 1) * AMR_BITS_PER_PKEY))
+
+#define CORE_FILE_LIMIT (5 * 1024 * 1024) /* 5 MB should be enough */
+
+static const char core_pattern_file[] = "/proc/sys/kernel/core_pattern";
+
+static const char user_write[] = "[User Write (Running)]";
+static const char core_read_running[] = "[Core Read (Running)]";
+
+/* Information shared between the parent and the child. */
+struct shared_info {
+ struct child_sync child_sync;
+
+ /* AMR value the parent expects to read in the core file. */
+ unsigned long amr;
+
+ /* IAMR value the parent expects to read in the core file. */
+ unsigned long iamr;
+
+ /* UAMOR value the parent expects to read in the core file. */
+ unsigned long uamor;
+
+ /* When the child crashed. */
+ time_t core_time;
+};
+
+static int sys_pkey_alloc(unsigned long flags, unsigned long init_access_rights)
+{
+ return syscall(__NR_pkey_alloc, flags, init_access_rights);
+}
+
+static int sys_pkey_free(int pkey)
+{
+ return syscall(__NR_pkey_free, pkey);
+}
+
+static int increase_core_file_limit(void)
+{
+ struct rlimit rlim;
+ int ret;
+
+ ret = getrlimit(RLIMIT_CORE, &rlim);
+ FAIL_IF(ret);
+
+ if (rlim.rlim_cur != RLIM_INFINITY && rlim.rlim_cur < CORE_FILE_LIMIT) {
+ rlim.rlim_cur = CORE_FILE_LIMIT;
+
+ if (rlim.rlim_max != RLIM_INFINITY &&
+ rlim.rlim_max < CORE_FILE_LIMIT)
+ rlim.rlim_max = CORE_FILE_LIMIT;
+
+ ret = setrlimit(RLIMIT_CORE, &rlim);
+ FAIL_IF(ret);
+ }
+
+ ret = getrlimit(RLIMIT_FSIZE, &rlim);
+ FAIL_IF(ret);
+
+ if (rlim.rlim_cur != RLIM_INFINITY && rlim.rlim_cur < CORE_FILE_LIMIT) {
+ rlim.rlim_cur = CORE_FILE_LIMIT;
+
+ if (rlim.rlim_max != RLIM_INFINITY &&
+ rlim.rlim_max < CORE_FILE_LIMIT)
+ rlim.rlim_max = CORE_FILE_LIMIT;
+
+ ret = setrlimit(RLIMIT_FSIZE, &rlim);
+ FAIL_IF(ret);
+ }
+
+ return TEST_PASS;
+}
+
+static int child(struct shared_info *info)
+{
+ bool disable_execute = true;
+ int pkey1, pkey2, pkey3;
+ int *ptr, ret;
+
+ /* Wait until parent fills out the initial register values. */
+ ret = wait_parent(&info->child_sync);
+ if (ret)
+ return ret;
+
+ ret = increase_core_file_limit();
+ FAIL_IF(ret);
+
+ /* Get some pkeys so that we can change their bits in the AMR. */
+ pkey1 = sys_pkey_alloc(0, PKEY_DISABLE_EXECUTE);
+ if (pkey1 < 0) {
+ pkey1 = sys_pkey_alloc(0, 0);
+ FAIL_IF(pkey1 < 0);
+
+ disable_execute = false;
+ }
+
+ pkey2 = sys_pkey_alloc(0, 0);
+ FAIL_IF(pkey2 < 0);
+
+ pkey3 = sys_pkey_alloc(0, 0);
+ FAIL_IF(pkey3 < 0);
+
+ info->amr |= 3ul << pkeyshift(pkey1) | 2ul << pkeyshift(pkey2);
+
+ if (disable_execute)
+ info->iamr |= 1ul << pkeyshift(pkey1);
+
+ info->uamor |= 3ul << pkeyshift(pkey1) | 3ul << pkeyshift(pkey2);
+
+ printf("%-30s AMR: %016lx pkey1: %d pkey2: %d pkey3: %d\n",
+ user_write, info->amr, pkey1, pkey2, pkey3);
+
+ mtspr(SPRN_AMR, info->amr);
+
+ /*
+ * We won't use pkey3. This tests whether the kernel restores the UAMOR
+ * permissions after a key is freed.
+ */
+ sys_pkey_free(pkey3);
+
+ info->core_time = time(NULL);
+
+ /* Crash. */
+ ptr = 0;
+ *ptr = 1;
+
+ /* Shouldn't get here. */
+ FAIL_IF(true);
+
+ return TEST_FAIL;
+}
+
+/* Return file size if filename exists and pass sanity check, or zero if not. */
+static off_t try_core_file(const char *filename, struct shared_info *info,
+ pid_t pid)
+{
+ struct stat buf;
+ int ret;
+
+ ret = stat(filename, &buf);
+ if (ret == -1)
+ return TEST_FAIL;
+
+ /* Make sure we're not using a stale core file. */
+ return buf.st_mtime >= info->core_time ? buf.st_size : TEST_FAIL;
+}
+
+static Elf64_Nhdr *next_note(Elf64_Nhdr *nhdr)
+{
+ return (void *) nhdr + sizeof(*nhdr) +
+ __ALIGN_KERNEL(nhdr->n_namesz, 4) +
+ __ALIGN_KERNEL(nhdr->n_descsz, 4);
+}
+
+static int check_core_file(struct shared_info *info, Elf64_Ehdr *ehdr,
+ off_t core_size)
+{
+ unsigned long *regs;
+ Elf64_Phdr *phdr;
+ Elf64_Nhdr *nhdr;
+ size_t phdr_size;
+ void *p = ehdr, *note;
+ int ret;
+
+ ret = memcmp(ehdr->e_ident, ELFMAG, SELFMAG);
+ FAIL_IF(ret);
+
+ FAIL_IF(ehdr->e_type != ET_CORE);
+ FAIL_IF(ehdr->e_machine != EM_PPC64);
+ FAIL_IF(ehdr->e_phoff == 0 || ehdr->e_phnum == 0);
+
+ /*
+ * e_phnum is at most 65535 so calculating the size of the
+ * program header cannot overflow.
+ */
+ phdr_size = sizeof(*phdr) * ehdr->e_phnum;
+
+ /* Sanity check the program header table location. */
+ FAIL_IF(ehdr->e_phoff + phdr_size < ehdr->e_phoff);
+ FAIL_IF(ehdr->e_phoff + phdr_size > core_size);
+
+ /* Find the PT_NOTE segment. */
+ for (phdr = p + ehdr->e_phoff;
+ (void *) phdr < p + ehdr->e_phoff + phdr_size;
+ phdr += ehdr->e_phentsize)
+ if (phdr->p_type == PT_NOTE)
+ break;
+
+ FAIL_IF((void *) phdr >= p + ehdr->e_phoff + phdr_size);
+
+ /* Find the NT_PPC_PKEY note. */
+ for (nhdr = p + phdr->p_offset;
+ (void *) nhdr < p + phdr->p_offset + phdr->p_filesz;
+ nhdr = next_note(nhdr))
+ if (nhdr->n_type == NT_PPC_PKEY)
+ break;
+
+ FAIL_IF((void *) nhdr >= p + phdr->p_offset + phdr->p_filesz);
+ FAIL_IF(nhdr->n_descsz == 0);
+
+ p = nhdr;
+ note = p + sizeof(*nhdr) + __ALIGN_KERNEL(nhdr->n_namesz, 4);
+
+ regs = (unsigned long *) note;
+
+ printf("%-30s AMR: %016lx IAMR: %016lx UAMOR: %016lx\n",
+ core_read_running, regs[0], regs[1], regs[2]);
+
+ FAIL_IF(regs[0] != info->amr);
+ FAIL_IF(regs[1] != info->iamr);
+ FAIL_IF(regs[2] != info->uamor);
+
+ return TEST_PASS;
+}
+
+static int parent(struct shared_info *info, pid_t pid)
+{
+ char *filenames, *filename[3];
+ int fd, i, ret, status;
+ unsigned long regs[3];
+ off_t core_size;
+ void *core;
+
+ /*
+ * Get the initial values for AMR, IAMR and UAMOR and communicate them
+ * to the child.
+ */
+ ret = ptrace_read_regs(pid, NT_PPC_PKEY, regs, 3);
+ PARENT_SKIP_IF_UNSUPPORTED(ret, &info->child_sync);
+ PARENT_FAIL_IF(ret, &info->child_sync);
+
+ info->amr = regs[0];
+ info->iamr = regs[1];
+ info->uamor = regs[2];
+
+ /* Wake up child so that it can set itself up. */
+ ret = prod_child(&info->child_sync);
+ PARENT_FAIL_IF(ret, &info->child_sync);
+
+ ret = wait(&status);
+ if (ret != pid) {
+ printf("Child's exit status not captured\n");
+ return TEST_FAIL;
+ } else if (!WIFSIGNALED(status) || !WCOREDUMP(status)) {
+ printf("Child didn't dump core\n");
+ return TEST_FAIL;
+ }
+
+ /* Construct array of core file names to try. */
+
+ filename[0] = filenames = malloc(PATH_MAX);
+ if (!filenames) {
+ perror("Error allocating memory");
+ return TEST_FAIL;
+ }
+
+ ret = snprintf(filename[0], PATH_MAX, "core-pkey.%d", pid);
+ if (ret < 0 || ret >= PATH_MAX) {
+ ret = TEST_FAIL;
+ goto out;
+ }
+
+ filename[1] = filename[0] + ret + 1;
+ ret = snprintf(filename[1], PATH_MAX - ret - 1, "core.%d", pid);
+ if (ret < 0 || ret >= PATH_MAX - ret - 1) {
+ ret = TEST_FAIL;
+ goto out;
+ }
+ filename[2] = "core";
+
+ for (i = 0; i < 3; i++) {
+ core_size = try_core_file(filename[i], info, pid);
+ if (core_size != TEST_FAIL)
+ break;
+ }
+
+ if (i == 3) {
+ printf("Couldn't find core file\n");
+ ret = TEST_FAIL;
+ goto out;
+ }
+
+ fd = open(filename[i], O_RDONLY);
+ if (fd == -1) {
+ perror("Error opening core file");
+ ret = TEST_FAIL;
+ goto out;
+ }
+
+ core = mmap(NULL, core_size, PROT_READ, MAP_PRIVATE, fd, 0);
+ if (core == (void *) -1) {
+ perror("Error mmaping core file");
+ ret = TEST_FAIL;
+ goto out;
+ }
+
+ ret = check_core_file(info, core, core_size);
+
+ munmap(core, core_size);
+ close(fd);
+ unlink(filename[i]);
+
+ out:
+ free(filenames);
+
+ return ret;
+}
+
+static int write_core_pattern(const char *core_pattern)
+{
+ size_t len = strlen(core_pattern), ret;
+ FILE *f;
+
+ f = fopen(core_pattern_file, "w");
+ if (!f) {
+ perror("Error writing to core_pattern file");
+ return TEST_FAIL;
+ }
+
+ ret = fwrite(core_pattern, 1, len, f);
+ fclose(f);
+ if (ret != len) {
+ perror("Error writing to core_pattern file");
+ return TEST_FAIL;
+ }
+
+ return TEST_PASS;
+}
+
+static int setup_core_pattern(char **core_pattern_, bool *changed_)
+{
+ FILE *f;
+ char *core_pattern;
+ int ret;
+
+ core_pattern = malloc(PATH_MAX);
+ if (!core_pattern) {
+ perror("Error allocating memory");
+ return TEST_FAIL;
+ }
+
+ f = fopen(core_pattern_file, "r");
+ if (!f) {
+ perror("Error opening core_pattern file");
+ ret = TEST_FAIL;
+ goto out;
+ }
+
+ ret = fread(core_pattern, 1, PATH_MAX, f);
+ fclose(f);
+ if (!ret) {
+ perror("Error reading core_pattern file");
+ ret = TEST_FAIL;
+ goto out;
+ }
+
+ /* Check whether we can predict the name of the core file. */
+ if (!strcmp(core_pattern, "core") || !strcmp(core_pattern, "core.%p"))
+ *changed_ = false;
+ else {
+ ret = write_core_pattern("core-pkey.%p");
+ if (ret)
+ goto out;
+
+ *changed_ = true;
+ }
+
+ *core_pattern_ = core_pattern;
+ ret = TEST_PASS;
+
+ out:
+ if (ret)
+ free(core_pattern);
+
+ return ret;
+}
+
+static int core_pkey(void)
+{
+ char *core_pattern;
+ bool changed_core_pattern;
+ struct shared_info *info;
+ int shm_id;
+ int ret;
+ pid_t pid;
+
+ ret = setup_core_pattern(&core_pattern, &changed_core_pattern);
+ if (ret)
+ return ret;
+
+ shm_id = shmget(IPC_PRIVATE, sizeof(*info), 0777 | IPC_CREAT);
+ info = shmat(shm_id, NULL, 0);
+
+ ret = init_child_sync(&info->child_sync);
+ if (ret)
+ return ret;
+
+ pid = fork();
+ if (pid < 0) {
+ perror("fork() failed");
+ ret = TEST_FAIL;
+ } else if (pid == 0)
+ ret = child(info);
+ else
+ ret = parent(info, pid);
+
+ shmdt(info);
+
+ if (pid) {
+ destroy_child_sync(&info->child_sync);
+ shmctl(shm_id, IPC_RMID, NULL);
+
+ if (changed_core_pattern)
+ write_core_pattern(core_pattern);
+ }
+
+ free(core_pattern);
+
+ return ret;
+}
+
+int main(int argc, char *argv[])
+{
+ return test_harness(core_pkey, "core_pkey");
+}