diff options
Diffstat (limited to 'installer/fetcher/filelist.c')
| -rw-r--r-- | installer/fetcher/filelist.c | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/installer/fetcher/filelist.c b/installer/fetcher/filelist.c new file mode 100644 index 00000000..f938e324 --- /dev/null +++ b/installer/fetcher/filelist.c @@ -0,0 +1,168 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2020-2022 Jason A. Donenfeld. All Rights Reserved. + */ + +#include "constants.h" +#include "crypto.h" +#include "filelist.h" +#include <stdbool.h> +#include <string.h> +#include <stdio.h> +#include <stdlib.h> + +static inline int decode_base64(const char src[static 4]) +{ + int val = 0; + + for (unsigned int i = 0; i < 4; ++i) + val |= (-1 + + ((((('A' - 1) - src[i]) & (src[i] - ('Z' + 1))) >> 8) & (src[i] - 64)) + + ((((('a' - 1) - src[i]) & (src[i] - ('z' + 1))) >> 8) & (src[i] - 70)) + + ((((('0' - 1) - src[i]) & (src[i] - ('9' + 1))) >> 8) & (src[i] + 5)) + + ((((('+' - 1) - src[i]) & (src[i] - ('+' + 1))) >> 8) & 63) + + ((((('/' - 1) - src[i]) & (src[i] - ('/' + 1))) >> 8) & 64) + ) << (18 - 6 * i); + return val; +} + +bool signify_pubkey_from_base64(uint8_t key[static 42], const char base64[static 56]) +{ + unsigned int i; + volatile uint8_t ret = 0; + int val; + + for (i = 0; i < 42 / 3; ++i) { + val = decode_base64(&base64[i * 4]); + ret |= (uint32_t)val >> 31; + key[i * 3 + 0] = (val >> 16) & 0xff; + key[i * 3 + 1] = (val >> 8) & 0xff; + key[i * 3 + 2] = val & 0xff; + } + + return 1 & ((ret - 1) >> 8); +} + +bool signify_signature_from_base64(uint8_t sig[static 74], const char base64[static 100]) +{ + unsigned int i; + volatile uint8_t ret = 0; + int val; + + if (base64[99] != '=') + return false; + + for (i = 0; i < 74 / 3; ++i) { + val = decode_base64(&base64[i * 4]); + ret |= (uint32_t)val >> 31; + sig[i * 3 + 0] = (val >> 16) & 0xff; + sig[i * 3 + 1] = (val >> 8) & 0xff; + sig[i * 3 + 2] = val & 0xff; + } + val = decode_base64((const char[]){ base64[i * 4 + 0], base64[i * 4 + 1], base64[i * 4 + 2], 'A' }); + ret |= ((uint32_t)val >> 31) | (val & 0xff); + sig[i * 3 + 0] = (val >> 16) & 0xff; + sig[i * 3 + 1] = (val >> 8) & 0xff; + + return 1 & ((ret - 1) >> 8); +} + +bool hash_from_hex(uint8_t hash[static 32], const char hex[static 64]) +{ + uint8_t c, c_acc, c_alpha0, c_alpha, c_num0, c_num, c_val; + volatile uint8_t ret = 0; + + for (unsigned int i = 0; i < 64; i += 2) { + c = (uint8_t)hex[i]; + c_num = c ^ 48U; + c_num0 = (c_num - 10U) >> 8; + c_alpha = (c & ~32U) - 55U; + c_alpha0 = ((c_alpha - 10U) ^ (c_alpha - 16U)) >> 8; + ret |= ((c_num0 | c_alpha0) - 1) >> 8; + c_val = (c_num0 & c_num) | (c_alpha0 & c_alpha); + c_acc = c_val * 16U; + + c = (uint8_t)hex[i + 1]; + c_num = c ^ 48U; + c_num0 = (c_num - 10U) >> 8; + c_alpha = (c & ~32U) - 55U; + c_alpha0 = ((c_alpha - 10U) ^ (c_alpha - 16U)) >> 8; + ret |= ((c_num0 | c_alpha0) - 1) >> 8; + c_val = (c_num0 & c_num) | (c_alpha0 & c_alpha); + hash[i / 2] = c_acc | c_val; + } + + return 1 & ((ret - 1) >> 8); +} + +static uint64_t parse_version(const char *str, size_t len) +{ + uint64_t version = 0; + unsigned long nibble; + const char *limit = str + len; + char *end; + + for (int shift = 64 - 16; shift >= 0; shift -= 16, str = end + 1) { + if (str[0] == '-' || str[0] == '+') + return 0; + nibble = strtoul(str, &end, 10); + if (nibble > UINT16_MAX) + return 0; + version |= (uint64_t)nibble << shift; + if (end >= limit) + break; + if (end[0] != '.') + return 0; + } + return version; +} + +bool extract_newest_file(char filename[static MAX_FILENAME_LEN], uint8_t hash[static 32], const char *list, size_t len, const char *arch) +{ + const char *first_nl, *second_nl, *line_start, *line_end; + char msi_prefix[sizeof(msi_arch_prefix) + 10]; + int msi_prefix_len; + uint8_t pubkey[42], signature[74]; + uint64_t biggest_version = 0, version; + + if ((msi_prefix_len = _snprintf_s(msi_prefix, sizeof(msi_prefix), _TRUNCATE, msi_arch_prefix, arch)) < 0) + return false; + if (!signify_pubkey_from_base64(pubkey, release_public_key_base64)) + return false; + first_nl = memchr(list, '\n', len); + if (!first_nl) + return false; + second_nl = memchr(first_nl + 1, '\n', len - (first_nl + 1 - list)); + if (!second_nl) + return false; + if (len < 19 || memcmp(list, "untrusted comment: ", 19)) + return false; + if (second_nl - first_nl != 101) + return false; + if (!signify_signature_from_base64(signature, first_nl + 1)) + return false; + if (memcmp(pubkey, signature, 10)) + return false; + if (!ed25519_verify(signature + 10, pubkey + 10, second_nl + 1, len - (second_nl + 1 - list))) + return false; + for (line_start = second_nl + 1; line_start < list + len; line_start = line_end + 1) { + line_end = memchr(line_start + 1, '\n', len - (line_start + 1 - list)); + if (!line_end) + break; + if ((size_t)(line_end - line_start) < (64 + 2 + msi_prefix_len + strlen(msi_suffix) + 1) || line_start[64] != ' ' || line_start[65] != ' ') + continue; + if (memcmp(msi_prefix, line_start + 66, msi_prefix_len) || memcmp(msi_suffix, line_end - strlen(msi_suffix), strlen(msi_suffix))) + continue; + if (line_end - line_start - 66 > MAX_FILENAME_LEN - 1) + continue; + version = parse_version(line_start + 66 + msi_prefix_len, line_end - strlen(msi_suffix) - line_start - 66 - msi_prefix_len); + if (version < biggest_version) + continue; + if (!hash_from_hex(hash, line_start)) + continue; + memcpy(filename, line_start + 66, line_end - line_start - 66); + filename[line_end - line_start - 66] = '\0'; + biggest_version = version; + } + return biggest_version > 0; +} |