util_hash.c

/*-
 * Copyright (c) 2008-2015 Juan Romero Pardines.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
#include <sys/mman.h>
#include <sys/stat.h>
 
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
 
#include <openssl/sha.h>
 
#include "xbps_api_impl.h"
 
/**
 * @file lib/util.c
 * @brief Utility routines
 * @defgroup util Utility functions
 */
static void
digest2string(const uint8_t *digest, char *string, size_t len)
{
        while (len--) {
                if (*digest / 16 < 10)
                        *string++ = '0' + *digest / 16;
                else
                        *string++ = 'a' + *digest / 16 - 10;
                if (*digest % 16 < 10)
                        *string++ = '0' + *digest % 16;
                else
                        *string++ = 'a' + *digest % 16 - 10;
                ++digest;
        }
        *string = '\0';
}
 
bool
xbps_mmap_file(const char *file, void **mmf, size_t *mmflen, size_t *filelen)
{
        struct stat st;
        size_t pgsize = (size_t)sysconf(_SC_PAGESIZE);
        size_t pgmask = pgsize - 1, mapsize;
        unsigned char *mf;
        bool need_guard = false;
        int fd;
 
        assert(file);
 
        if ((fd = open(file, O_RDONLY|O_CLOEXEC)) == -1)
                return false;
 
        if (fstat(fd, &st) == -1) {
                (void)close(fd);
                return false;
        }
        if (st.st_size > SSIZE_MAX - 1) {
                (void)close(fd);
                return false;
        }
        mapsize = ((size_t)st.st_size + pgmask) & ~pgmask;
        if (mapsize < (size_t)st.st_size) {
                (void)close(fd);
                return false;
        }
        /*
         * If the file length is an integral number of pages, then we
         * need to map a guard page at the end in order to provide the
         * necessary NUL-termination of the buffer.
         */
        if ((st.st_size & pgmask) == 0)
                need_guard = true;
 
        mf = mmap(NULL, need_guard ? mapsize + pgsize : mapsize,
            PROT_READ, MAP_PRIVATE, fd, 0);
        (void)close(fd);
        if (mf == MAP_FAILED) {
                (void)munmap(mf, mapsize);
                return false;
        }
 
        *mmf = mf;
        *mmflen = mapsize;
        *filelen = st.st_size;
 
        return true;
}
 
bool
xbps_file_sha256_raw(unsigned char *dst, size_t dstlen, const char *file)
{
        int fd;
        ssize_t len;
        char buf[65536];
        SHA256_CTX sha256;
 
        assert(dstlen >= XBPS_SHA256_DIGEST_SIZE);
        if (dstlen < XBPS_SHA256_DIGEST_SIZE) {
                errno = ENOBUFS;
                return false;
        }
 
        if ((fd = open(file, O_RDONLY)) < 0)
                return false;
 
        SHA256_Init(&sha256);
 
        while ((len = read(fd, buf, sizeof(buf))) > 0)
                SHA256_Update(&sha256, buf, len);
 
        (void)close(fd);
 
        if(len == -1)
                return false;
 
        SHA256_Final(dst, &sha256);
 
        return true;
}
 
bool
xbps_file_sha256(char *dst, size_t dstlen, const char *file)
{
        unsigned char digest[XBPS_SHA256_DIGEST_SIZE];
 
        assert(dstlen >= XBPS_SHA256_SIZE);
        if (dstlen < XBPS_SHA256_SIZE) {
                errno = ENOBUFS;
                return false;
        }
 
        if (!xbps_file_sha256_raw(digest, sizeof digest, file))
                return false;
 
        digest2string(digest, dst, XBPS_SHA256_DIGEST_SIZE);
 
        return true;
}
 
static bool
sha256_digest_compare(const char *sha256, size_t shalen,
                const unsigned char *digest, size_t digestlen)
{
 
        assert(shalen == XBPS_SHA256_SIZE - 1);
        if (shalen != XBPS_SHA256_SIZE -1)
                return false;
 
        assert(digestlen == XBPS_SHA256_DIGEST_SIZE);
        if (digestlen != XBPS_SHA256_DIGEST_SIZE)
                return false;
 
        for (; *sha256;) {
                if (*digest / 16 < 10) {
                        if (*sha256++ != '0' + *digest / 16)
                                return false;
                } else {
                        if (*sha256++ != 'a' + *digest / 16 - 10)
                                return false;
                }
                if (*digest % 16 < 10) {
                        if (*sha256++ != '0' + *digest % 16)
                                return false;
                } else {
                        if (*sha256++ != 'a' + *digest % 16 - 10)
                                return false;
                }
                digest++;
        }
 
        return true;
}
 
int
xbps_file_sha256_check(const char *file, const char *sha256)
{
        unsigned char digest[XBPS_SHA256_DIGEST_SIZE];
 
        assert(file != NULL);
        assert(sha256 != NULL);
 
        if (!xbps_file_sha256_raw(digest, sizeof digest, file))
                return errno;
 
        if (!sha256_digest_compare(sha256, strlen(sha256), digest, sizeof digest))
                return ERANGE;
 
        return 0;
}
 
static const char *
file_hash_dictionary(xbps_dictionary_t d, const char *key, const char *file)
{
        xbps_object_t obj;
        xbps_object_iterator_t iter;
        const char *curfile = NULL, *sha256 = NULL;
 
        assert(xbps_object_type(d) == XBPS_TYPE_DICTIONARY);
        assert(key != NULL);
        assert(file != NULL);
 
        iter = xbps_array_iter_from_dict(d, key);
        if (iter == NULL) {
                errno = ENOENT;
                return NULL;
        }
        while ((obj = xbps_object_iterator_next(iter)) != NULL) {
                xbps_dictionary_get_cstring_nocopy(obj,
                    "file", &curfile);
                if (strcmp(file, curfile) == 0) {
                        /* file matched */
                        xbps_dictionary_get_cstring_nocopy(obj,
                            "sha256", &sha256);
                        break;
                }
        }
        xbps_object_iterator_release(iter);
        if (sha256 == NULL)
                errno = ENOENT;
 
        return sha256;
}
 
int HIDDEN
xbps_file_hash_check_dictionary(struct xbps_handle *xhp,
                                xbps_dictionary_t d,
                                const char *key,
                                const char *file)
{
        const char *sha256d = NULL;
        char *buf;
        int rv;
 
        assert(xbps_object_type(d) == XBPS_TYPE_DICTIONARY);
        assert(key != NULL);
        assert(file != NULL);
 
        if ((sha256d = file_hash_dictionary(d, key, file)) == NULL) {
                if (errno == ENOENT)
                        return 1; /* no match, file not found */
 
                return -1; /* error */
        }
 
        if (strcmp(xhp->rootdir, "/") == 0) {
                rv = xbps_file_sha256_check(file, sha256d);
        } else {
                buf = xbps_xasprintf("%s/%s", xhp->rootdir, file);
                rv = xbps_file_sha256_check(buf, sha256d);
                free(buf);
        }
        if (rv == 0)
                return 0; /* matched */
        else if (rv == ERANGE || rv == ENOENT)
                return 1; /* no match */
        else
                return -1; /* error */
}