Use memmem for searching byte patterns
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topjohnwu
parent
0d42f937dd
commit
55fdee4d65
@ -198,27 +198,31 @@ boot_img::~boot_img() {
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}
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static int find_dtb_offset(uint8_t *buf, unsigned sz) {
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for (int off = 0; off + sizeof(fdt_header) < sz; ++off) {
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auto fdt_hdr = reinterpret_cast<fdt_header *>(buf + off);
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if (fdt32_to_cpu(fdt_hdr->magic) != FDT_MAGIC)
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continue;
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uint8_t * const end = buf + sz;
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for (uint8_t *curr = buf; curr < end; curr += sizeof(fdt_header)) {
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curr = static_cast<uint8_t*>(memmem(curr, end - curr, DTB_MAGIC, sizeof(fdt32_t)));
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if (curr == nullptr)
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return -1;
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auto fdt_hdr = reinterpret_cast<fdt_header *>(curr);
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// Check that fdt_header.totalsize does not overflow kernel image size
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uint32_t totalsize = fdt32_to_cpu(fdt_hdr->totalsize);
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if (totalsize + off > sz)
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if (curr + totalsize > end)
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continue;
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// Check that fdt_header.off_dt_struct does not overflow kernel image size
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uint32_t off_dt_struct = fdt32_to_cpu(fdt_hdr->off_dt_struct);
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if (off_dt_struct + off > sz)
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if (curr + off_dt_struct > end)
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continue;
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// Check that fdt_node_header.tag of first node is FDT_BEGIN_NODE
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auto fdt_node_hdr = reinterpret_cast<fdt_node_header *>(buf + off + off_dt_struct);
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auto fdt_node_hdr = reinterpret_cast<fdt_node_header *>(curr + off_dt_struct);
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if (fdt32_to_cpu(fdt_node_hdr->tag) != FDT_BEGIN_NODE)
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continue;
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return off;
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return curr - buf;
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}
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return -1;
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}
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@ -103,22 +103,23 @@ static void dtb_print(const char *file, bool fstab) {
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mmap_ro(file, dtb, size);
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// Loop through all the dtbs
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int dtb_num = 0;
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for (int i = 0; i < size; ++i) {
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if (memcmp(dtb + i, FDT_MAGIC_STR, 4) == 0) {
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auto fdt = dtb + i;
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if (fstab) {
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int node = find_fstab(fdt);
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if (node >= 0) {
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fprintf(stderr, "Found fstab in dtb.%04d\n", dtb_num);
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print_node(fdt, node);
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}
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} else {
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fprintf(stderr, "Printing dtb.%04d\n", dtb_num);
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print_node(fdt);
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uint8_t * const end = dtb + size;
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for (uint8_t *fdt = dtb; fdt < end;) {
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fdt = static_cast<uint8_t*>(memmem(fdt, end - fdt, FDT_MAGIC_STR, sizeof(fdt32_t)));
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if (fdt == nullptr)
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break;
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if (fstab) {
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int node = find_fstab(fdt);
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if (node >= 0) {
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fprintf(stderr, "Found fstab in dtb.%04d\n", dtb_num);
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print_node(fdt, node);
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}
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++dtb_num;
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i += fdt_totalsize(fdt) - 1;
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} else {
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fprintf(stderr, "Printing dtb.%04d\n", dtb_num);
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print_node(fdt);
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}
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++dtb_num;
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fdt += fdt_totalsize(fdt);
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}
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fprintf(stderr, "\n");
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munmap(dtb, size);
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@ -136,21 +137,22 @@ static bool dtb_patch(const char *file) {
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mmap_rw(file, dtb, size);
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bool patched = false;
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for (int i = 0; i < size; ++i) {
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if (memcmp(dtb + i, FDT_MAGIC_STR, 4) == 0) {
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auto fdt = dtb + i;
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if (int fstab = find_fstab(fdt); fstab >= 0) {
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int node;
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fdt_for_each_subnode(node, fdt, fstab) {
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if (!keep_verity) {
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int len;
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char *value = (char *) fdt_getprop(fdt, node, "fsmgr_flags", &len);
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patched |= patch_verity(value, len) != len;
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}
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uint8_t * const end = dtb + size;
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for (uint8_t *fdt = dtb; fdt < end;) {
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fdt = static_cast<uint8_t*>(memmem(fdt, end - fdt, FDT_MAGIC_STR, sizeof(fdt32_t)));
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if (fdt == nullptr)
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break;
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if (int fstab = find_fstab(fdt); fstab >= 0) {
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int node;
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fdt_for_each_subnode(node, fdt, fstab) {
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if (!keep_verity) {
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int len;
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char *value = (char *) fdt_getprop(fdt, node, "fsmgr_flags", &len);
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patched |= patch_verity(value, len) != len;
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}
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}
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i += fdt_totalsize(fdt) - 1;
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}
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fdt += fdt_totalsize(fdt);
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}
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munmap(dtb, size);
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@ -312,18 +314,20 @@ static bool blob_patch(uint8_t *dtb, size_t dtb_sz, const char *out) {
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vector<uint8_t *> fdt_list;
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vector<uint32_t> padding_list;
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for (int i = 0; i < dtb_sz; ++i) {
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if (memcmp(dtb + i, FDT_MAGIC_STR, 4) == 0) {
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auto len = fdt_totalsize(dtb + i);
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auto fdt = static_cast<uint8_t *>(xmalloc(len + MAX_FDT_GROWTH));
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memcpy(fdt, dtb + i, len);
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fdt_pack(fdt);
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uint32_t padding = len - fdt_totalsize(fdt);
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padding_list.push_back(padding);
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fdt_open_into(fdt, fdt, len + MAX_FDT_GROWTH);
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fdt_list.push_back(fdt);
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i += len - 1;
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}
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uint8_t * const end = dtb + dtb_sz;
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for (uint8_t *curr = dtb; curr < end;) {
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curr = static_cast<uint8_t*>(memmem(curr, end - curr, FDT_MAGIC_STR, sizeof(fdt32_t)));
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if (curr == nullptr)
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break;
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auto len = fdt_totalsize(curr);
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auto fdt = static_cast<uint8_t *>(xmalloc(len + MAX_FDT_GROWTH));
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memcpy(fdt, curr, len);
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fdt_pack(fdt);
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uint32_t padding = len - fdt_totalsize(fdt);
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padding_list.push_back(padding);
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fdt_open_into(fdt, fdt, len + MAX_FDT_GROWTH);
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fdt_list.push_back(fdt);
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curr += len;
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}
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bool modified = false;
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@ -1,43 +1,44 @@
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#include <stdlib.h>
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#include <ctype.h>
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#include <string.h>
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#include <sys/mman.h>
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#include <utils.hpp>
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#include "magiskboot.hpp"
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static void hex2byte(uint8_t *hex, uint8_t *str) {
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using namespace std;
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static void hex2byte(const char *hex, uint8_t *buf) {
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char high, low;
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for (int i = 0, length = strlen((char *) hex); i < length; i += 2) {
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for (int i = 0, length = strlen(hex); i < length; i += 2) {
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high = toupper(hex[i]) - '0';
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low = toupper(hex[i + 1]) - '0';
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str[i / 2] = ((high > 9 ? high - 7 : high) << 4) + (low > 9 ? low - 7 : low);
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buf[i / 2] = ((high > 9 ? high - 7 : high) << 4) + (low > 9 ? low - 7 : low);
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}
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}
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int hexpatch(const char *image, const char *from, const char *to) {
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int patternsize = strlen(from) / 2, patchsize = strlen(to) / 2;
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int patched = 1;
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size_t filesize;
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uint8_t *file, *pattern, *patch;
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mmap_rw(image, file, filesize);
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pattern = (uint8_t *) xmalloc(patternsize);
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patch = (uint8_t *) xmalloc(patchsize);
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hex2byte((uint8_t *) from, pattern);
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hex2byte((uint8_t *) to, patch);
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for (size_t i = 0; filesize > 0 && i < filesize - patternsize; ++i) {
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if (memcmp(file + i, pattern, patternsize) == 0) {
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fprintf(stderr, "Patch @ %08X [%s]->[%s]\n", (unsigned) i, from, to);
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memset(file + i, 0, patternsize);
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memcpy(file + i, patch, patchsize);
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i += patternsize - 1;
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patched = 0;
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}
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uint8_t *buf;
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size_t sz;
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mmap_rw(image, buf, sz);
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run_finally f([=]{ munmap(buf, sz); });
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vector<uint8_t> pattern(strlen(from) / 2);
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vector<uint8_t> patch(strlen(to) / 2);
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hex2byte(from, pattern.data());
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hex2byte(to, patch.data());
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uint8_t * const end = buf + sz;
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for (uint8_t *curr = buf; curr < end; curr += pattern.size()) {
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curr = static_cast<uint8_t*>(memmem(curr, end - curr, pattern.data(), pattern.size()));
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if (curr == nullptr)
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return patched;
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fprintf(stderr, "Patch @ %08X [%s] -> [%s]\n", curr - buf, from, to);
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memset(curr, 0, pattern.size());
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memcpy(curr, patch.data(), patch.size());
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patched = 0;
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}
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munmap(file, filesize);
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free(pattern);
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free(patch);
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return patched;
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}
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