wolfssl/linuxkm/module_hooks.c

/* module_hooks.c -- module load/unload hooks for libwolfssl.ko
 *
 * Copyright (C) 2006-2021 wolfSSL Inc.
 *
 * This file is part of wolfSSL.
 *
 * wolfSSL is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * wolfSSL is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335, USA
 */

#ifndef WOLFSSL_LICENSE
#define WOLFSSL_LICENSE "GPL v2"
#endif

#define FIPS_NO_WRAPPERS

#ifdef HAVE_CONFIG_H
    #include <config.h>
#endif

#include <wolfssl/wolfcrypt/settings.h>
#include <wolfssl/wolfcrypt/error-crypt.h>
#include <wolfssl/ssl.h>
#ifdef HAVE_FIPS
#include <wolfssl/wolfcrypt/fips_test.h>
#endif
#ifndef NO_CRYPT_TEST
#include <wolfcrypt/test/test.h>
#include <linux/delay.h>
#endif

static int libwolfssl_cleanup(void) {
    int ret;
#ifdef WOLFCRYPT_ONLY
    ret = wolfCrypt_Cleanup();
    if (ret != 0)
        pr_err("wolfCrypt_Cleanup() failed: %s\n", wc_GetErrorString(ret));
    else
        pr_info("wolfCrypt " LIBWOLFSSL_VERSION_STRING " cleanup complete.\n");
#else
    ret = wolfSSL_Cleanup();
    if (ret != WOLFSSL_SUCCESS)
        pr_err("wolfSSL_Cleanup() failed: %s\n", wc_GetErrorString(ret));
    else
        pr_info("wolfSSL " LIBWOLFSSL_VERSION_STRING " cleanup complete.\n");
#endif

    return ret;
}

#ifdef HAVE_LINUXKM_PIE_SUPPORT

extern int wolfCrypt_PIE_first_function(void);
extern int wolfCrypt_PIE_last_function(void);
extern const unsigned int wolfCrypt_PIE_rodata_start[];
extern const unsigned int wolfCrypt_PIE_rodata_end[];

/* cheap portable ad-hoc hash function to confirm bitwise stability of the PIE
 * binary image.
 */
static unsigned int hash_span(char *start, char *end) {
    unsigned int sum = 1;
    while (start < end) {
        unsigned int rotate_by;
        sum ^= *start++;
        rotate_by = (sum ^ (sum >> 5)) & 31;
        sum = (sum << rotate_by) | (sum >> (32 - rotate_by));
    }
    return sum;
}

#ifdef USE_WOLFSSL_LINUXKM_PIE_REDIRECT_TABLE
extern struct wolfssl_linuxkm_pie_redirect_table wolfssl_linuxkm_pie_redirect_table;
static int set_up_wolfssl_linuxkm_pie_redirect_table(void);
#endif /* USE_WOLFSSL_LINUXKM_PIE_REDIRECT_TABLE */

#endif /* HAVE_LINUXKM_PIE_SUPPORT */

#ifdef HAVE_FIPS
static void lkmFipsCb(int ok, int err, const char* hash)
{
    if ((! ok) || (err != 0))
        pr_err("libwolfssl FIPS error: %s\n", wc_GetErrorString(err));
    if (err == IN_CORE_FIPS_E) {
        pr_err("In-core integrity hash check failure.\n"
               "Update verifyCore[] in fips_test.c with new hash \"%s\" and rebuild.\n",
               hash ? hash : "<null>");
    }
}
#endif

#if defined(WOLFCRYPT_FIPS_CORE_DYNAMIC_HASH_VALUE) && !defined(CONFIG_MODULE_SIG)
#error WOLFCRYPT_FIPS_CORE_DYNAMIC_HASH_VALUE requires a CONFIG_MODULE_SIG kernel.
#endif

#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 0, 0)
static int __init wolfssl_init(void)
#else
static int wolfssl_init(void)
#endif
{
    int ret;

#if defined(CONFIG_MODULE_SIG_FORCE) || defined(WOLFCRYPT_FIPS_CORE_DYNAMIC_HASH_VALUE)
    if (THIS_MODULE->sig_ok == false) {
        pr_err("wolfSSL module load aborted -- bad or missing module signature with "
#ifdef CONFIG_MODULE_SIG_FORCE
               "CONFIG_MODULE_SIG_FORCE kernel"
#else
               "FIPS dynamic hash"
#endif
	".\n");
        return -ECANCELED;
    }
#endif

#ifdef USE_WOLFSSL_LINUXKM_PIE_REDIRECT_TABLE
    ret = set_up_wolfssl_linuxkm_pie_redirect_table();
    if (ret < 0)
        return ret;
#endif

#ifdef HAVE_LINUXKM_PIE_SUPPORT

#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 5, 0)
    #define THIS_MODULE_BASE (THIS_MODULE->core_layout.base)
    #define THIS_MODULE_TEXT_SIZE (THIS_MODULE->core_layout.text_size)
    #define THIS_MODULE_RO_SIZE (THIS_MODULE->core_layout.ro_size)
#else
    #define THIS_MODULE_BASE (THIS_MODULE->module_core)
    #define THIS_MODULE_TEXT_SIZE (THIS_MODULE->core_text_size)
    #define THIS_MODULE_RO_SIZE (THIS_MODULE->core_ro_size)
#endif

    {
        char *pie_text_start = (char *)wolfCrypt_PIE_first_function;
        char *pie_text_end = (char *)wolfCrypt_PIE_last_function;
        char *pie_rodata_start = (char *)wolfCrypt_PIE_rodata_start;
        char *pie_rodata_end = (char *)wolfCrypt_PIE_rodata_end;
        unsigned int text_hash, rodata_hash;

        if ((pie_text_start < pie_text_end) &&
            (pie_text_start >= (char *)THIS_MODULE_BASE) &&
            (pie_text_end - (char *)THIS_MODULE_BASE <= THIS_MODULE_TEXT_SIZE))
        {
            text_hash = hash_span(pie_text_start, pie_text_end);
        } else {
            pr_info("out-of-bounds PIE fenceposts! pie_text_start=%px pie_text_end=%px (span=%lu)"
                    " core_layout.base=%px text_end=%px\n",
                    pie_text_start,
                    pie_text_end,
                    pie_text_end-pie_text_start,
                    THIS_MODULE_BASE,
                    (char *)THIS_MODULE_BASE + THIS_MODULE_TEXT_SIZE);
            text_hash = 0;
        }

        if ((pie_rodata_start < pie_rodata_end) &&
            (pie_rodata_start >= (char *)THIS_MODULE_BASE + THIS_MODULE_TEXT_SIZE) &&
            (pie_rodata_end - (char *)THIS_MODULE_BASE <= THIS_MODULE_RO_SIZE))
        {
            rodata_hash = hash_span(pie_rodata_start, pie_rodata_end);
        } else {
            pr_info("out-of-bounds PIE fenceposts! pie_rodata_start=%px pie_rodata_end=%px (span=%lu)"
                    " core_layout.base+core_layout.text_size=%px rodata_end=%px\n",
                    pie_rodata_start,
                    pie_rodata_end,
                    pie_rodata_end-pie_rodata_start,
                    (char *)THIS_MODULE_BASE + THIS_MODULE_TEXT_SIZE,
                    (char *)THIS_MODULE_BASE + THIS_MODULE_RO_SIZE);
            rodata_hash = 0;
        }

        /* note, "%pK" conceals the actual layout information.  "%px" exposes
         * the true module start address, which is potentially useful to an
         * attacker.
         */
        pr_info("wolfCrypt container hashes (spans): %x (%lu) %x (%lu), module base %pK\n",
                text_hash, pie_text_end-pie_text_start,
                rodata_hash, pie_rodata_end-pie_rodata_start,
                THIS_MODULE_BASE);
    }
#endif /* HAVE_LINUXKM_PIE_SUPPORT */

#ifdef HAVE_FIPS
    ret = wolfCrypt_SetCb_fips(lkmFipsCb);
    if (ret != 0) {
        pr_err("wolfCrypt_SetCb_fips() failed: %s\n", wc_GetErrorString(ret));
        return -ECANCELED;
    }
    fipsEntry();
    ret = wolfCrypt_GetStatus_fips();
    if (ret != 0) {
        pr_err("wolfCrypt_GetStatus_fips() failed: %s\n", wc_GetErrorString(ret));
        if (ret == IN_CORE_FIPS_E) {
            const char *newhash = wolfCrypt_GetCoreHash_fips();
            pr_err("Update verifyCore[] in fips_test.c with new hash \"%s\" and rebuild.\n",
                   newhash ? newhash : "<null>");
        }
        return -ECANCELED;
    }

    pr_info("wolfCrypt FIPS ["

#if defined(HAVE_FIPS_VERSION) && (HAVE_FIPS_VERSION == 3)
            "ready"
#elif defined(HAVE_FIPS_VERSION) && (HAVE_FIPS_VERSION == 2) \
    && defined(WOLFCRYPT_FIPS_RAND)
            "140-2 rand"
#elif defined(HAVE_FIPS_VERSION) && (HAVE_FIPS_VERSION == 2)
            "140-2"
#else
            "140"
#endif
            "] POST succeeded.\n");
#endif /* HAVE_FIPS */

#ifdef WOLFCRYPT_ONLY
    ret = wolfCrypt_Init();
    if (ret != 0) {
        pr_err("wolfCrypt_Init() failed: %s\n", wc_GetErrorString(ret));
        return -ECANCELED;
    }
#else
    ret = wolfSSL_Init();
    if (ret != WOLFSSL_SUCCESS) {
        pr_err("wolfSSL_Init() failed: %s\n", wc_GetErrorString(ret));
        return -ECANCELED;
    }
#endif

#ifndef NO_CRYPT_TEST

#ifdef WC_RNG_SEED_CB
    ret = wc_SetSeed_Cb(wc_GenerateSeed);
    if (ret == 0)
#endif
    {
        ret = wolfcrypt_test(NULL);
    }
    if (ret < 0) {
        pr_err("wolfcrypt self-test failed with return code %d.\n", ret);
        (void)libwolfssl_cleanup();
        msleep(10);
        return -ECANCELED;
    }
    pr_info("wolfCrypt self-test passed.\n");
#endif

#ifdef WOLFCRYPT_ONLY
    pr_info("wolfCrypt " LIBWOLFSSL_VERSION_STRING " loaded%s"
            ".\nSee https://www.wolfssl.com/ for more information.\n"
            "wolfCrypt Copyright (C) 2006-present wolfSSL Inc.  Licensed under " WOLFSSL_LICENSE ".\n",
#ifdef CONFIG_MODULE_SIG
            THIS_MODULE->sig_ok ? " with valid module signature" : " without valid module signature"
#else
            ""
#endif
	);
#else
    pr_info("wolfSSL " LIBWOLFSSL_VERSION_STRING " loaded%s"
            ".\nSee https://www.wolfssl.com/ for more information.\n"
            "wolfSSL Copyright (C) 2006-present wolfSSL Inc.  Licensed under " WOLFSSL_LICENSE ".\n",
#ifdef CONFIG_MODULE_SIG
            THIS_MODULE->sig_ok ? " with valid module signature" : " without valid module signature"
#else
            ""
#endif
        );
#endif

    return 0;
}

module_init(wolfssl_init);

#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 0, 0)
static void __exit wolfssl_exit(void)
#else
static void wolfssl_exit(void)
#endif
{
    (void)libwolfssl_cleanup();

    return;
}

module_exit(wolfssl_exit);

MODULE_LICENSE(WOLFSSL_LICENSE);
MODULE_AUTHOR("https://www.wolfssl.com/");
MODULE_DESCRIPTION("libwolfssl cryptographic and protocol facilities");
MODULE_VERSION(LIBWOLFSSL_VERSION_STRING);

#ifdef USE_WOLFSSL_LINUXKM_PIE_REDIRECT_TABLE

/* get_current() is an inline or macro, depending on the target -- sidestep the whole issue with a wrapper func. */
static struct task_struct *my_get_current_thread(void) {
    return get_current();
}

/* ditto for preempt_count(). */
static int my_preempt_count(void) {
    return preempt_count();
}

#if defined(WOLFSSL_LINUXKM_SIMD_X86_IRQ_ALLOWED) && (LINUX_VERSION_CODE < KERNEL_VERSION(5, 14, 0))
static int my_copy_fpregs_to_fpstate(struct fpu *fpu) {
    return copy_fpregs_to_fpstate(fpu);
}
static void my_copy_kernel_to_fpregs(union fpregs_state *fpstate) {
    copy_kernel_to_fpregs(fpstate);
}
#endif

static int set_up_wolfssl_linuxkm_pie_redirect_table(void) {
    memset(
        &wolfssl_linuxkm_pie_redirect_table,
        0,
        sizeof wolfssl_linuxkm_pie_redirect_table);

#ifndef __ARCH_MEMCMP_NO_REDIRECT
    wolfssl_linuxkm_pie_redirect_table.memcmp = memcmp;
#endif
#ifndef __ARCH_MEMCPY_NO_REDIRECT
    wolfssl_linuxkm_pie_redirect_table.memcpy = memcpy;
#endif
#ifndef __ARCH_MEMSET_NO_REDIRECT
    wolfssl_linuxkm_pie_redirect_table.memset = memset;
#endif
#ifndef __ARCH_MEMMOVE_NO_REDIRECT
    wolfssl_linuxkm_pie_redirect_table.memmove = memmove;
#endif
#ifndef __ARCH_STRNCMP_NO_REDIRECT
    wolfssl_linuxkm_pie_redirect_table.strncmp = strncmp;
#endif
#ifndef __ARCH_STRLEN_NO_REDIRECT
    wolfssl_linuxkm_pie_redirect_table.strlen = strlen;
#endif
#ifndef __ARCH_STRSTR_NO_REDIRECT
    wolfssl_linuxkm_pie_redirect_table.strstr = strstr;
#endif
#ifndef __ARCH_STRNCPY_NO_REDIRECT
    wolfssl_linuxkm_pie_redirect_table.strncpy = strncpy;
#endif
#ifndef __ARCH_STRNCAT_NO_REDIRECT
    wolfssl_linuxkm_pie_redirect_table.strncat = strncat;
#endif
#ifndef __ARCH_STRNCASECMP_NO_REDIRECT
    wolfssl_linuxkm_pie_redirect_table.strncasecmp = strncasecmp;
#endif
    wolfssl_linuxkm_pie_redirect_table.kstrtoll = kstrtoll;

    wolfssl_linuxkm_pie_redirect_table.printk = printk;
    wolfssl_linuxkm_pie_redirect_table.snprintf = snprintf;

    wolfssl_linuxkm_pie_redirect_table._ctype = _ctype;

    wolfssl_linuxkm_pie_redirect_table.kmalloc = kmalloc;
    wolfssl_linuxkm_pie_redirect_table.kfree = kfree;
    wolfssl_linuxkm_pie_redirect_table.ksize = ksize;
    wolfssl_linuxkm_pie_redirect_table.krealloc = krealloc;
#ifdef HAVE_KVMALLOC
    wolfssl_linuxkm_pie_redirect_table.kvmalloc_node = kvmalloc_node;
    wolfssl_linuxkm_pie_redirect_table.kvfree = kvfree;
#endif
    wolfssl_linuxkm_pie_redirect_table.is_vmalloc_addr = is_vmalloc_addr;
    wolfssl_linuxkm_pie_redirect_table.kmem_cache_alloc_trace =
        kmem_cache_alloc_trace;
    wolfssl_linuxkm_pie_redirect_table.kmalloc_order_trace =
        kmalloc_order_trace;

    wolfssl_linuxkm_pie_redirect_table.get_random_bytes = get_random_bytes;
    #if LINUX_VERSION_CODE < KERNEL_VERSION(4, 0, 0)
        wolfssl_linuxkm_pie_redirect_table.getnstimeofday =
            getnstimeofday;
    #elif LINUX_VERSION_CODE < KERNEL_VERSION(5, 0, 0)
        wolfssl_linuxkm_pie_redirect_table.current_kernel_time64 =
            current_kernel_time64;
    #else
        wolfssl_linuxkm_pie_redirect_table.ktime_get_coarse_real_ts64 =
            ktime_get_coarse_real_ts64;
    #endif

    wolfssl_linuxkm_pie_redirect_table.get_current = my_get_current_thread;
    wolfssl_linuxkm_pie_redirect_table.preempt_count = my_preempt_count;

#ifdef WOLFSSL_LINUXKM_SIMD_X86
    wolfssl_linuxkm_pie_redirect_table.irq_fpu_usable = irq_fpu_usable;
    #ifdef kernel_fpu_begin
    wolfssl_linuxkm_pie_redirect_table.kernel_fpu_begin_mask =
        kernel_fpu_begin_mask;
    #else
    wolfssl_linuxkm_pie_redirect_table.kernel_fpu_begin =
        kernel_fpu_begin;
    #endif
    wolfssl_linuxkm_pie_redirect_table.kernel_fpu_end = kernel_fpu_end;
    #ifdef WOLFSSL_LINUXKM_SIMD_X86_IRQ_ALLOWED
        #if LINUX_VERSION_CODE < KERNEL_VERSION(5, 14, 0)
            wolfssl_linuxkm_pie_redirect_table.copy_fpregs_to_fpstate = my_copy_fpregs_to_fpstate;
            wolfssl_linuxkm_pie_redirect_table.copy_kernel_to_fpregs = my_copy_kernel_to_fpregs;
        #else
            wolfssl_linuxkm_pie_redirect_table.save_fpregs_to_fpstate = save_fpregs_to_fpstate;
            wolfssl_linuxkm_pie_redirect_table.__restore_fpregs_from_fpstate = __restore_fpregs_from_fpstate;
            wolfssl_linuxkm_pie_redirect_table.xfeatures_mask_all = &xfeatures_mask_all;
        #endif
        wolfssl_linuxkm_pie_redirect_table.cpu_number = &cpu_number;
        wolfssl_linuxkm_pie_redirect_table.nr_cpu_ids = &nr_cpu_ids;
#endif /* WOLFSSL_LINUXKM_SIMD_X86_IRQ_ALLOWED */
#endif

    wolfssl_linuxkm_pie_redirect_table.__mutex_init = __mutex_init;
    #if LINUX_VERSION_CODE < KERNEL_VERSION(4, 0, 0)
        wolfssl_linuxkm_pie_redirect_table.mutex_lock_nested = mutex_lock_nested;
    #else
        wolfssl_linuxkm_pie_redirect_table.mutex_lock = mutex_lock;
    #endif
    wolfssl_linuxkm_pie_redirect_table.mutex_unlock = mutex_unlock;
    #if LINUX_VERSION_CODE < KERNEL_VERSION(4, 0, 0)
        wolfssl_linuxkm_pie_redirect_table.mutex_destroy = mutex_destroy;
    #endif

#ifdef HAVE_FIPS
    wolfssl_linuxkm_pie_redirect_table.wolfCrypt_FIPS_first =
        wolfCrypt_FIPS_first;
    wolfssl_linuxkm_pie_redirect_table.wolfCrypt_FIPS_last =
        wolfCrypt_FIPS_last;
#endif

#if !defined(WOLFCRYPT_ONLY) && !defined(NO_CERTS)
    wolfssl_linuxkm_pie_redirect_table.GetCA = GetCA;
#ifndef NO_SKID
    wolfssl_linuxkm_pie_redirect_table.GetCAByName = GetCAByName;
#endif
#endif

    /* runtime assert that the table has no null slots after initialization. */
    {
        unsigned long *i;
        for (i = (unsigned long *)&wolfssl_linuxkm_pie_redirect_table;
             i < (unsigned long *)&wolfssl_linuxkm_pie_redirect_table._last_slot;
             ++i)
            if (*i == 0) {
                pr_err("wolfCrypt container redirect table initialization was incomplete.\n");
                return -EFAULT;
            }
    }

    return 0;
}

#endif /* USE_WOLFSSL_LINUXKM_PIE_REDIRECT_TABLE */