// 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);
        else
                info->iamr &= ~(1ul << pkeyshift(pkey1));

        info->iamr &= ~(1ul << pkeyshift(pkey2) | 1ul << pkeyshift(pkey3));

        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");
        SKIP_IF_MSG(!f, "Try with root privileges");

        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");
}