selftests/powerpc: Add core file test for Protection Key registers

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>
[mpe: Simplify make rule]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

2 files changed, 464 insertions, 3 deletions

diff --git a/tools/testing/selftests/powerpc/ptrace/Makefile b/tools/testing/selftests/powerpc/ptrace/Makefile
index bd8959854aec..4f5957538908 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-hwbreak ptrace-pkey
+              ptrace-tm-spd-vsx ptrace-tm-spr ptrace-hwbreak ptrace-pkey core-pkey
 
 include ../../lib.mk
 
@@ -9,8 +9,8 @@ all: $(TEST_PROGS)
 
 CFLAGS += -m64 -I../../../../../usr/include -I../tm -mhtm -fno-pie
 
-ptrace-pkey: child.h
-ptrace-pkey: LDLIBS += -pthread
+ptrace-pkey core-pkey: child.h
+ptrace-pkey core-pkey: LDLIBS += -pthread
 
 $(TEST_PROGS): ../harness.c ../utils.c ../lib/reg.S ptrace.h
 
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");
+}