// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2020 ARM Limited

#define _GNU_SOURCE

#include <sys/auxv.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <signal.h>
#include <setjmp.h>
#include <sched.h>

#include "../../kselftest_harness.h"
#include "helper.h"

#define PAC_COLLISION_ATTEMPTS 10
/*
 * The kernel sets TBID by default. So bits 55 and above should remain
 * untouched no matter what.
 * The VA space size is 48 bits. Bigger is opt-in.
 */
#define PAC_MASK (~0xff80ffffffffffff)
#define ARBITRARY_VALUE (0x1234)
#define ASSERT_PAUTH_ENABLED() \
do { \
        unsigned long hwcaps = getauxval(AT_HWCAP); \
        /* data key instructions are not in NOP space. This prevents a SIGILL */ \
        ASSERT_NE(0, hwcaps & HWCAP_PACA) TH_LOG("PAUTH not enabled"); \
} while (0)
#define ASSERT_GENERIC_PAUTH_ENABLED() \
do { \
        unsigned long hwcaps = getauxval(AT_HWCAP); \
        /* generic key instructions are not in NOP space. This prevents a SIGILL */ \
        ASSERT_NE(0, hwcaps & HWCAP_PACG) TH_LOG("Generic PAUTH not enabled"); \
} while (0)

void sign_specific(struct signatures *sign, size_t val)
{
        sign->keyia = keyia_sign(val);
        sign->keyib = keyib_sign(val);
        sign->keyda = keyda_sign(val);
        sign->keydb = keydb_sign(val);
}

void sign_all(struct signatures *sign, size_t val)
{
        sign->keyia = keyia_sign(val);
        sign->keyib = keyib_sign(val);
        sign->keyda = keyda_sign(val);
        sign->keydb = keydb_sign(val);
        sign->keyg  = keyg_sign(val);
}

int n_same(struct signatures *old, struct signatures *new, int nkeys)
{
        int res = 0;

        res += old->keyia == new->keyia;
        res += old->keyib == new->keyib;
        res += old->keyda == new->keyda;
        res += old->keydb == new->keydb;
        if (nkeys == NKEYS)
                res += old->keyg == new->keyg;

        return res;
}

int n_same_single_set(struct signatures *sign, int nkeys)
{
        size_t vals[nkeys];
        int same = 0;

        vals[0] = sign->keyia & PAC_MASK;
        vals[1] = sign->keyib & PAC_MASK;
        vals[2] = sign->keyda & PAC_MASK;
        vals[3] = sign->keydb & PAC_MASK;

        if (nkeys >= 4)
                vals[4] = sign->keyg & PAC_MASK;

        for (int i = 0; i < nkeys - 1; i++) {
                for (int j = i + 1; j < nkeys; j++) {
                        if (vals[i] == vals[j])
                                same += 1;
                }
        }
        return same;
}

int exec_sign_all(struct signatures *signed_vals, size_t val)
{
        int new_stdin[2];
        int new_stdout[2];
        int status;
        int i;
        ssize_t ret;
        pid_t pid;
        cpu_set_t mask;

        ret = pipe(new_stdin);
        if (ret == -1) {
                perror("pipe returned error");
                return -1;
        }

        ret = pipe(new_stdout);
        if (ret == -1) {
                perror("pipe returned error");
                return -1;
        }

        /*
         * pin this process and all its children to a single CPU, so it can also
         * guarantee a context switch with its child
         */
        sched_getaffinity(0, sizeof(mask), &mask);

        for (i = 0; i < sizeof(cpu_set_t); i++)
                if (CPU_ISSET(i, &mask))
                        break;

        CPU_ZERO(&mask);
        CPU_SET(i, &mask);
        sched_setaffinity(0, sizeof(mask), &mask);

        pid = fork();
        // child
        if (pid == 0) {
                dup2(new_stdin[0], STDIN_FILENO);
                if (ret == -1) {
                        perror("dup2 returned error");
                        exit(1);
                }

                dup2(new_stdout[1], STDOUT_FILENO);
                if (ret == -1) {
                        perror("dup2 returned error");
                        exit(1);
                }

                close(new_stdin[0]);
                close(new_stdin[1]);
                close(new_stdout[0]);
                close(new_stdout[1]);

                ret = execl("exec_target", "exec_target", (char *)NULL);
                if (ret == -1) {
                        perror("exec returned error");
                        exit(1);
                }
        }

        close(new_stdin[0]);
        close(new_stdout[1]);

        ret = write(new_stdin[1], &val, sizeof(size_t));
        if (ret == -1) {
                perror("write returned error");
                return -1;
        }

        /*
         * wait for the worker to finish, so that read() reads all data
         * will also context switch with worker so that this function can be used
         * for context switch tests
         */
        waitpid(pid, &status, 0);
        if (WIFEXITED(status) == 0) {
                fprintf(stderr, "worker exited unexpectedly\n");
                return -1;
        }
        if (WEXITSTATUS(status) != 0) {
                fprintf(stderr, "worker exited with error\n");
                return -1;
        }

        ret = read(new_stdout[0], signed_vals, sizeof(struct signatures));
        if (ret == -1) {
                perror("read returned error");
                return -1;
        }

        return 0;
}

sigjmp_buf jmpbuf;
void pac_signal_handler(int signum, siginfo_t *si, void *uc)
{
        if (signum == SIGSEGV || signum == SIGILL)
                siglongjmp(jmpbuf, 1);
}

/* check that a corrupted PAC results in SIGSEGV or SIGILL */
TEST(corrupt_pac)
{
        struct sigaction sa;

        ASSERT_PAUTH_ENABLED();
        if (sigsetjmp(jmpbuf, 1) == 0) {
                sa.sa_sigaction = pac_signal_handler;
                sa.sa_flags = SA_SIGINFO | SA_RESETHAND;
                sigemptyset(&sa.sa_mask);

                sigaction(SIGSEGV, &sa, NULL);
                sigaction(SIGILL, &sa, NULL);

                pac_corruptor();
                ASSERT_TRUE(0) TH_LOG("SIGSEGV/SIGILL signal did not occur");
        }
}

/*
 * There are no separate pac* and aut* controls so checking only the pac*
 * instructions is sufficient
 */
TEST(pac_instructions_not_nop)
{
        size_t keyia = 0;
        size_t keyib = 0;
        size_t keyda = 0;
        size_t keydb = 0;

        ASSERT_PAUTH_ENABLED();

        for (int i = 0; i < PAC_COLLISION_ATTEMPTS; i++) {
                keyia |= keyia_sign(i) & PAC_MASK;
                keyib |= keyib_sign(i) & PAC_MASK;
                keyda |= keyda_sign(i) & PAC_MASK;
                keydb |= keydb_sign(i) & PAC_MASK;
        }

        ASSERT_NE(0, keyia) TH_LOG("keyia instructions did nothing");
        ASSERT_NE(0, keyib) TH_LOG("keyib instructions did nothing");
        ASSERT_NE(0, keyda) TH_LOG("keyda instructions did nothing");
        ASSERT_NE(0, keydb) TH_LOG("keydb instructions did nothing");
}

TEST(pac_instructions_not_nop_generic)
{
        size_t keyg = 0;

        ASSERT_GENERIC_PAUTH_ENABLED();

        for (int i = 0; i < PAC_COLLISION_ATTEMPTS; i++)
                keyg |= keyg_sign(i) & PAC_MASK;

        ASSERT_NE(0, keyg)  TH_LOG("keyg instructions did nothing");
}

TEST(single_thread_different_keys)
{
        int same = 10;
        int nkeys = NKEYS;
        int tmp;
        struct signatures signed_vals;
        unsigned long hwcaps = getauxval(AT_HWCAP);

        /* generic and data key instructions are not in NOP space. This prevents a SIGILL */
        ASSERT_NE(0, hwcaps & HWCAP_PACA) TH_LOG("PAUTH not enabled");
        if (!(hwcaps & HWCAP_PACG)) {
                TH_LOG("WARNING: Generic PAUTH not enabled. Skipping generic key checks");
                nkeys = NKEYS - 1;
        }

        /*
         * In Linux the PAC field can be up to 7 bits wide. Even if keys are
         * different, there is about 5% chance for PACs to collide with
         * different addresses. This chance rapidly increases with fewer bits
         * allocated for the PAC (e.g. wider address). A comparison of the keys
         * directly will be more reliable.
         * All signed values need to be different at least once out of n
         * attempts to be certain that the keys are different
         */
        for (int i = 0; i < PAC_COLLISION_ATTEMPTS; i++) {
                if (nkeys == NKEYS)
                        sign_all(&signed_vals, i);
                else
                        sign_specific(&signed_vals, i);

                tmp = n_same_single_set(&signed_vals, nkeys);
                if (tmp < same)
                        same = tmp;
        }

        ASSERT_EQ(0, same) TH_LOG("%d keys clashed every time", same);
}

/*
 * fork() does not change keys. Only exec() does so call a worker program.
 * Its only job is to sign a value and report back the resutls
 */
TEST(exec_changed_keys)
{
        struct signatures new_keys;
        struct signatures old_keys;
        int ret;
        int same = 10;
        int nkeys = NKEYS;
        unsigned long hwcaps = getauxval(AT_HWCAP);

        /* generic and data key instructions are not in NOP space. This prevents a SIGILL */
        ASSERT_NE(0, hwcaps & HWCAP_PACA) TH_LOG("PAUTH not enabled");
        if (!(hwcaps & HWCAP_PACG)) {
                TH_LOG("WARNING: Generic PAUTH not enabled. Skipping generic key checks");
                nkeys = NKEYS - 1;
        }

        for (int i = 0; i < PAC_COLLISION_ATTEMPTS; i++) {
                ret = exec_sign_all(&new_keys, i);
                ASSERT_EQ(0, ret) TH_LOG("failed to run worker");

                if (nkeys == NKEYS)
                        sign_all(&old_keys, i);
                else
                        sign_specific(&old_keys, i);

                ret = n_same(&old_keys, &new_keys, nkeys);
                if (ret < same)
                        same = ret;
        }

        ASSERT_EQ(0, same) TH_LOG("exec() did not change %d keys", same);
}

TEST(context_switch_keep_keys)
{
        int ret;
        struct signatures trash;
        struct signatures before;
        struct signatures after;

        ASSERT_PAUTH_ENABLED();

        sign_specific(&before, ARBITRARY_VALUE);

        /* will context switch with a process with different keys at least once */
        ret = exec_sign_all(&trash, ARBITRARY_VALUE);
        ASSERT_EQ(0, ret) TH_LOG("failed to run worker");

        sign_specific(&after, ARBITRARY_VALUE);

        ASSERT_EQ(before.keyia, after.keyia) TH_LOG("keyia changed after context switching");
        ASSERT_EQ(before.keyib, after.keyib) TH_LOG("keyib changed after context switching");
        ASSERT_EQ(before.keyda, after.keyda) TH_LOG("keyda changed after context switching");
        ASSERT_EQ(before.keydb, after.keydb) TH_LOG("keydb changed after context switching");
}

TEST(context_switch_keep_keys_generic)
{
        int ret;
        struct signatures trash;
        size_t before;
        size_t after;

        ASSERT_GENERIC_PAUTH_ENABLED();

        before = keyg_sign(ARBITRARY_VALUE);

        /* will context switch with a process with different keys at least once */
        ret = exec_sign_all(&trash, ARBITRARY_VALUE);
        ASSERT_EQ(0, ret) TH_LOG("failed to run worker");

        after = keyg_sign(ARBITRARY_VALUE);

        ASSERT_EQ(before, after) TH_LOG("keyg changed after context switching");
}

TEST_HARNESS_MAIN