diff options
Diffstat (limited to 'usr.sbin/uefisign/pe.c')
| -rw-r--r-- | usr.sbin/uefisign/pe.c | 564 |
1 files changed, 564 insertions, 0 deletions
diff --git a/usr.sbin/uefisign/pe.c b/usr.sbin/uefisign/pe.c new file mode 100644 index 0000000..768ba5a --- /dev/null +++ b/usr.sbin/uefisign/pe.c @@ -0,0 +1,564 @@ +/*- + * Copyright (c) 2014 The FreeBSD Foundation + * All rights reserved. + * + * This software was developed by Edward Tomasz Napierala under sponsorship + * from the FreeBSD Foundation. + * + * 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 AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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. + * + */ + +/* + * PE format reference: + * http://www.microsoft.com/whdc/system/platform/firmware/PECOFF.mspx + */ + +#include <sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +#include <assert.h> +#include <err.h> +#include <errno.h> +#include <stddef.h> +#include <stdio.h> +#include <stdint.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> + +#include "uefisign.h" + +#ifndef CTASSERT +#define CTASSERT(x) _CTASSERT(x, __LINE__) +#define _CTASSERT(x, y) __CTASSERT(x, y) +#define __CTASSERT(x, y) typedef char __assert_ ## y [(x) ? 1 : -1] +#endif + +struct mz_header { + uint8_t mz_signature[2]; + uint8_t mz_dont_care[58]; + uint16_t mz_lfanew; +} __attribute__((packed)); + +struct coff_header { + uint8_t coff_dont_care[2]; + uint16_t coff_number_of_sections; + uint8_t coff_dont_care_either[16]; +} __attribute__((packed)); + +#define PE_SIGNATURE 0x00004550 + +struct pe_header { + uint32_t pe_signature; + struct coff_header pe_coff; +} __attribute__((packed)); + +#define PE_OPTIONAL_MAGIC_32 0x010B +#define PE_OPTIONAL_MAGIC_32_PLUS 0x020B + +#define PE_OPTIONAL_SUBSYSTEM_EFI_APPLICATION 10 +#define PE_OPTIONAL_SUBSYSTEM_EFI_BOOT 11 +#define PE_OPTIONAL_SUBSYSTEM_EFI_RUNTIME 12 + +struct pe_optional_header_32 { + uint16_t po_magic; + uint8_t po_dont_care[58]; + uint32_t po_size_of_headers; + uint32_t po_checksum; + uint16_t po_subsystem; + uint8_t po_dont_care_either[22]; + uint32_t po_number_of_rva_and_sizes; +} __attribute__((packed)); + +CTASSERT(offsetof(struct pe_optional_header_32, po_size_of_headers) == 60); +CTASSERT(offsetof(struct pe_optional_header_32, po_checksum) == 64); +CTASSERT(offsetof(struct pe_optional_header_32, po_subsystem) == 68); +CTASSERT(offsetof(struct pe_optional_header_32, po_number_of_rva_and_sizes) == 92); + +struct pe_optional_header_32_plus { + uint16_t po_magic; + uint8_t po_dont_care[58]; + uint32_t po_size_of_headers; + uint32_t po_checksum; + uint16_t po_subsystem; + uint8_t po_dont_care_either[38]; + uint32_t po_number_of_rva_and_sizes; +} __attribute__((packed)); + +CTASSERT(offsetof(struct pe_optional_header_32_plus, po_size_of_headers) == 60); +CTASSERT(offsetof(struct pe_optional_header_32_plus, po_checksum) == 64); +CTASSERT(offsetof(struct pe_optional_header_32_plus, po_subsystem) == 68); +CTASSERT(offsetof(struct pe_optional_header_32_plus, po_number_of_rva_and_sizes) == 108); + +#define PE_DIRECTORY_ENTRY_CERTIFICATE 4 + +struct pe_directory_entry { + uint32_t pde_rva; + uint32_t pde_size; +} __attribute__((packed)); + +struct pe_section_header { + uint8_t psh_dont_care[16]; + uint32_t psh_size_of_raw_data; + uint32_t psh_pointer_to_raw_data; + uint8_t psh_dont_care_either[16]; +} __attribute__((packed)); + +CTASSERT(offsetof(struct pe_section_header, psh_size_of_raw_data) == 16); +CTASSERT(offsetof(struct pe_section_header, psh_pointer_to_raw_data) == 20); + +#define PE_CERTIFICATE_REVISION 0x0200 +#define PE_CERTIFICATE_TYPE 0x0002 + +struct pe_certificate { + uint32_t pc_len; + uint16_t pc_revision; + uint16_t pc_type; + char pc_signature[0]; +} __attribute__((packed)); + +void +range_check(const struct executable *x, off_t off, size_t len, + const char *name) +{ + + if (off < 0) { + errx(1, "%s starts at negative offset %jd", + name, (intmax_t)off); + } + if (off >= (off_t)x->x_len) { + errx(1, "%s starts at %jd, past the end of executable at %zd", + name, (intmax_t)off, x->x_len); + } + if (len >= x->x_len) { + errx(1, "%s size %zd is larger than the executable size %zd", + name, len, x->x_len); + } + if (off + len > x->x_len) { + errx(1, "%s extends to %jd, past the end of executable at %zd", + name, (intmax_t)(off + len), x->x_len); + } +} + +size_t +signature_size(const struct executable *x) +{ + const struct pe_directory_entry *pde; + + range_check(x, x->x_certificate_entry_off, + x->x_certificate_entry_len, "Certificate Directory"); + + pde = (struct pe_directory_entry *) + (x->x_buf + x->x_certificate_entry_off); + + if (pde->pde_rva != 0 && pde->pde_size == 0) + warnx("signature size is 0, but its RVA is %d", pde->pde_rva); + if (pde->pde_rva == 0 && pde->pde_size != 0) + warnx("signature RVA is 0, but its size is %d", pde->pde_size); + + return (pde->pde_size); +} + +void +show_certificate(const struct executable *x) +{ + struct pe_certificate *pc; + const struct pe_directory_entry *pde; + + range_check(x, x->x_certificate_entry_off, + x->x_certificate_entry_len, "Certificate Directory"); + + pde = (struct pe_directory_entry *) + (x->x_buf + x->x_certificate_entry_off); + + if (signature_size(x) == 0) { + printf("file not signed\n"); + return; + } + +#if 0 + printf("certificate chunk at offset %zd, size %zd\n", + pde->pde_rva, pde->pde_size); +#endif + + range_check(x, pde->pde_rva, pde->pde_size, "Certificate chunk"); + + pc = (struct pe_certificate *)(x->x_buf + pde->pde_rva); + if (pc->pc_revision != PE_CERTIFICATE_REVISION) { + errx(1, "wrong certificate chunk revision, is %d, should be %d", + pc->pc_revision, PE_CERTIFICATE_REVISION); + } + if (pc->pc_type != PE_CERTIFICATE_TYPE) { + errx(1, "wrong certificate chunk type, is %d, should be %d", + pc->pc_type, PE_CERTIFICATE_TYPE); + } + printf("to dump PKCS7:\n " + "dd if='%s' bs=1 skip=%zd | openssl pkcs7 -inform DER -print\n", + x->x_path, pde->pde_rva + offsetof(struct pe_certificate, pc_signature)); + printf("to dump raw ASN.1:\n " + "openssl asn1parse -i -inform DER -offset %zd -in '%s'\n", + pde->pde_rva + offsetof(struct pe_certificate, pc_signature), x->x_path); +} + +static void +parse_section_table(struct executable *x, off_t off, int number_of_sections) +{ + const struct pe_section_header *psh; + int i; + + range_check(x, off, sizeof(*psh) * number_of_sections, + "section table"); + + if (x->x_headers_len <= off + sizeof(*psh) * number_of_sections) + errx(1, "section table outside of headers"); + + psh = (const struct pe_section_header *)(x->x_buf + off); + + if (number_of_sections >= MAX_SECTIONS) { + errx(1, "too many sections: got %d, should be %d", + number_of_sections, MAX_SECTIONS); + } + x->x_nsections = number_of_sections; + + for (i = 0; i < number_of_sections; i++) { + if (psh->psh_pointer_to_raw_data < x->x_headers_len) + errx(1, "section points inside the headers"); + + range_check(x, psh->psh_pointer_to_raw_data, + psh->psh_size_of_raw_data, "section"); +#if 0 + printf("section %d: start %d, size %d\n", + i, psh->psh_pointer_to_raw_data, psh->psh_size_of_raw_data); +#endif + x->x_section_off[i] = psh->psh_pointer_to_raw_data; + x->x_section_len[i] = psh->psh_size_of_raw_data; + psh++; + } +} + +static void +parse_directory(struct executable *x, off_t off, + int number_of_rva_and_sizes, int number_of_sections) +{ + //int i; + const struct pe_directory_entry *pde; + + //printf("Data Directory at offset %zd\n", off); + + if (number_of_rva_and_sizes <= PE_DIRECTORY_ENTRY_CERTIFICATE) { + errx(1, "wrong NumberOfRvaAndSizes %d; should be at least %d", + number_of_rva_and_sizes, PE_DIRECTORY_ENTRY_CERTIFICATE); + } + + range_check(x, off, sizeof(*pde) * number_of_rva_and_sizes, + "PE Data Directory"); + if (x->x_headers_len <= off + sizeof(*pde) * number_of_rva_and_sizes) + errx(1, "PE Data Directory outside of headers"); + + x->x_certificate_entry_off = + off + sizeof(*pde) * PE_DIRECTORY_ENTRY_CERTIFICATE; + x->x_certificate_entry_len = sizeof(*pde); +#if 0 + printf("certificate directory entry at offset %zd, len %zd\n", + x->x_certificate_entry_off, x->x_certificate_entry_len); + + pde = (struct pe_directory_entry *)(x->x_buf + off); + for (i = 0; i < number_of_rva_and_sizes; i++) { + printf("rva %zd, size %zd\n", pde->pde_rva, pde->pde_size); + pde++; + } +#endif + + return (parse_section_table(x, + off + sizeof(*pde) * number_of_rva_and_sizes, number_of_sections)); +} + +/* + * The PE checksum algorithm is undocumented; this code is mostly based on + * http://forum.sysinternals.com/optional-header-checksum-calculation_topic24214.html + * + * "Sum the entire image file, excluding the CheckSum field in the optional + * header, as an array of USHORTs, allowing any carry above 16 bits to be added + * back onto the low 16 bits. Then add the file size to get a 32-bit value." + * + * Note that most software does not care about the checksum at all; perhaps + * we could just set it to 0 instead. + * + * XXX: Endianness? + */ +static uint32_t +compute_checksum(const struct executable *x) +{ + uint32_t cksum = 0; + uint16_t tmp; + int i; + + range_check(x, x->x_checksum_off, x->x_checksum_len, "PE checksum"); + + assert(x->x_checksum_off % 2 == 0); + + for (i = 0; i + sizeof(tmp) < x->x_len; i += 2) { + /* + * Don't checksum the checksum. The +2 is because the checksum + * is 4 bytes, and here we're iterating over 2 byte chunks. + */ + if (i == x->x_checksum_off || i == x->x_checksum_off + 2) { + tmp = 0; + } else { + assert(i + sizeof(tmp) <= x->x_len); + memcpy(&tmp, x->x_buf + i, sizeof(tmp)); + } + + cksum += tmp; + cksum += cksum >> 16; + cksum &= 0xffff; + } + + cksum += cksum >> 16; + cksum &= 0xffff; + + cksum += x->x_len; + + return (cksum); +} + +static void +parse_optional_32_plus(struct executable *x, off_t off, + int number_of_sections) +{ +#if 0 + uint32_t computed_checksum; +#endif + const struct pe_optional_header_32_plus *po; + + range_check(x, off, sizeof(*po), "PE Optional Header"); + + po = (struct pe_optional_header_32_plus *)(x->x_buf + off); + switch (po->po_subsystem) { + case PE_OPTIONAL_SUBSYSTEM_EFI_APPLICATION: + case PE_OPTIONAL_SUBSYSTEM_EFI_BOOT: + case PE_OPTIONAL_SUBSYSTEM_EFI_RUNTIME: + break; + default: + errx(1, "wrong PE Optional Header subsystem 0x%x", + po->po_subsystem); + } + +#if 0 + printf("subsystem %d, checksum 0x%x, %d data directories\n", + po->po_subsystem, po->po_checksum, po->po_number_of_rva_and_sizes); +#endif + + x->x_checksum_off = off + + offsetof(struct pe_optional_header_32_plus, po_checksum); + x->x_checksum_len = sizeof(po->po_checksum); +#if 0 + printf("checksum 0x%x at offset %zd, len %zd\n", + po->po_checksum, x->x_checksum_off, x->x_checksum_len); + + computed_checksum = compute_checksum(x); + if (computed_checksum != po->po_checksum) { + warnx("invalid PE+ checksum; is 0x%x, should be 0x%x", + po->po_checksum, computed_checksum); + } +#endif + + if (x->x_len < x->x_headers_len) + errx(1, "invalid SizeOfHeaders %d", po->po_size_of_headers); + x->x_headers_len = po->po_size_of_headers; + //printf("Size of Headers: %d\n", po->po_size_of_headers); + + return (parse_directory(x, off + sizeof(*po), + po->po_number_of_rva_and_sizes, number_of_sections)); +} + +static void +parse_optional_32(struct executable *x, off_t off, int number_of_sections) +{ +#if 0 + uint32_t computed_checksum; +#endif + const struct pe_optional_header_32 *po; + + range_check(x, off, sizeof(*po), "PE Optional Header"); + + po = (struct pe_optional_header_32 *)(x->x_buf + off); + switch (po->po_subsystem) { + case PE_OPTIONAL_SUBSYSTEM_EFI_APPLICATION: + case PE_OPTIONAL_SUBSYSTEM_EFI_BOOT: + case PE_OPTIONAL_SUBSYSTEM_EFI_RUNTIME: + break; + default: + errx(1, "wrong PE Optional Header subsystem 0x%x", + po->po_subsystem); + } + +#if 0 + printf("subsystem %d, checksum 0x%x, %d data directories\n", + po->po_subsystem, po->po_checksum, po->po_number_of_rva_and_sizes); +#endif + + x->x_checksum_off = off + + offsetof(struct pe_optional_header_32, po_checksum); + x->x_checksum_len = sizeof(po->po_checksum); +#if 0 + printf("checksum at offset %zd, len %zd\n", + x->x_checksum_off, x->x_checksum_len); + + computed_checksum = compute_checksum(x); + if (computed_checksum != po->po_checksum) { + warnx("invalid PE checksum; is 0x%x, should be 0x%x", + po->po_checksum, computed_checksum); + } +#endif + + if (x->x_len < x->x_headers_len) + errx(1, "invalid SizeOfHeaders %d", po->po_size_of_headers); + x->x_headers_len = po->po_size_of_headers; + //printf("Size of Headers: %d\n", po->po_size_of_headers); + + return (parse_directory(x, off + sizeof(*po), + po->po_number_of_rva_and_sizes, number_of_sections)); +} + +static void +parse_optional(struct executable *x, off_t off, int number_of_sections) +{ + const struct pe_optional_header_32 *po; + + //printf("Optional header offset %zd\n", off); + + range_check(x, off, sizeof(*po), "PE Optional Header"); + + po = (struct pe_optional_header_32 *)(x->x_buf + off); + + switch (po->po_magic) { + case PE_OPTIONAL_MAGIC_32: + return (parse_optional_32(x, off, number_of_sections)); + case PE_OPTIONAL_MAGIC_32_PLUS: + return (parse_optional_32_plus(x, off, number_of_sections)); + default: + errx(1, "wrong PE Optional Header magic 0x%x", po->po_magic); + } +} + +static void +parse_pe(struct executable *x, off_t off) +{ + const struct pe_header *pe; + + //printf("PE offset %zd, PE size %zd\n", off, sizeof(*pe)); + + range_check(x, off, sizeof(*pe), "PE header"); + + pe = (struct pe_header *)(x->x_buf + off); + if (pe->pe_signature != PE_SIGNATURE) + errx(1, "wrong PE signature 0x%x", pe->pe_signature); + + //printf("Number of sections: %d\n", pe->pe_coff.coff_number_of_sections); + + parse_optional(x, off + sizeof(*pe), + pe->pe_coff.coff_number_of_sections); +} + +void +parse(struct executable *x) +{ + const struct mz_header *mz; + + range_check(x, 0, sizeof(*mz), "MZ header"); + + mz = (struct mz_header *)x->x_buf; + if (mz->mz_signature[0] != 'M' || mz->mz_signature[1] != 'Z') + errx(1, "MZ header not found"); + + return (parse_pe(x, mz->mz_lfanew)); +} + +static off_t +append(struct executable *x, void *ptr, size_t len) +{ + off_t off; + + /* + * XXX: Alignment. + */ + off = x->x_len; + x->x_buf = realloc(x->x_buf, x->x_len + len); + if (x->x_buf == NULL) + err(1, "realloc"); + memcpy(x->x_buf + x->x_len, ptr, len); + x->x_len += len; + + return (off); +} + +void +update(struct executable *x) +{ + uint32_t checksum; + struct pe_certificate *pc; + struct pe_directory_entry pde; + size_t pc_len; + off_t pc_off; + + pc_len = sizeof(*pc) + x->x_signature_len; + pc = calloc(1, pc_len); + if (pc == NULL) + err(1, "calloc"); + +#if 0 + /* + * Note that pc_len is the length of pc_certificate, + * not the whole structure. + * + * XXX: That's what the spec says - but it breaks at least + * sbverify and "pesign -S", so the spec is probably wrong. + */ + pc->pc_len = x->x_signature_len; +#else + pc->pc_len = pc_len; +#endif + pc->pc_revision = PE_CERTIFICATE_REVISION; + pc->pc_type = PE_CERTIFICATE_TYPE; + memcpy(&pc->pc_signature, x->x_signature, x->x_signature_len); + + pc_off = append(x, pc, pc_len); +#if 0 + printf("added signature chunk at offset %zd, len %zd\n", + pc_off, pc_len); +#endif + + free(pc); + + pde.pde_rva = pc_off; + pde.pde_size = pc_len; + memcpy(x->x_buf + x->x_certificate_entry_off, &pde, sizeof(pde)); + + checksum = compute_checksum(x); + assert(sizeof(checksum) == x->x_checksum_len); + memcpy(x->x_buf + x->x_checksum_off, &checksum, sizeof(checksum)); +#if 0 + printf("new checksum 0x%x\n", checksum); +#endif +} |
