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Use memmem for searching byte patterns

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topjohnwu
2021-02-28 14:36:48 -08:00
parent 0d42f937dd
commit 55fdee4d65
3 changed files with 80 additions and 71 deletions
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80
native/jni/magiskboot/dtb.cpp
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@@ -103,22 +103,23 @@ static void dtb_print(const char *file, bool fstab) {
mmap_ro(file, dtb, size);
// Loop through all the dtbs
int dtb_num = 0;
for (int i = 0; i < size; ++i) {
if (memcmp(dtb + i, FDT_MAGIC_STR, 4) == 0) {
auto fdt = dtb + i;
if (fstab) {
int node = find_fstab(fdt);
if (node >= 0) {
fprintf(stderr, "Found fstab in dtb.%04d\n", dtb_num);
print_node(fdt, node);
}
} else {
fprintf(stderr, "Printing dtb.%04d\n", dtb_num);
print_node(fdt);
uint8_t * const end = dtb + size;
for (uint8_t *fdt = dtb; fdt < end;) {
fdt = static_cast<uint8_t*>(memmem(fdt, end - fdt, FDT_MAGIC_STR, sizeof(fdt32_t)));
if (fdt == nullptr)
break;
if (fstab) {
int node = find_fstab(fdt);
if (node >= 0) {
fprintf(stderr, "Found fstab in dtb.%04d\n", dtb_num);
print_node(fdt, node);
}
++dtb_num;
i += fdt_totalsize(fdt) - 1;
} else {
fprintf(stderr, "Printing dtb.%04d\n", dtb_num);
print_node(fdt);
}
++dtb_num;
fdt += fdt_totalsize(fdt);
}
fprintf(stderr, "\n");
munmap(dtb, size);
@@ -136,21 +137,22 @@ static bool dtb_patch(const char *file) {
mmap_rw(file, dtb, size);
bool patched = false;
for (int i = 0; i < size; ++i) {
if (memcmp(dtb + i, FDT_MAGIC_STR, 4) == 0) {
auto fdt = dtb + i;
if (int fstab = find_fstab(fdt); fstab >= 0) {
int node;
fdt_for_each_subnode(node, fdt, fstab) {
if (!keep_verity) {
int len;
char *value = (char *) fdt_getprop(fdt, node, "fsmgr_flags", &len);
patched |= patch_verity(value, len) != len;
}
uint8_t * const end = dtb + size;
for (uint8_t *fdt = dtb; fdt < end;) {
fdt = static_cast<uint8_t*>(memmem(fdt, end - fdt, FDT_MAGIC_STR, sizeof(fdt32_t)));
if (fdt == nullptr)
break;
if (int fstab = find_fstab(fdt); fstab >= 0) {
int node;
fdt_for_each_subnode(node, fdt, fstab) {
if (!keep_verity) {
int len;
char *value = (char *) fdt_getprop(fdt, node, "fsmgr_flags", &len);
patched |= patch_verity(value, len) != len;
}
}
i += fdt_totalsize(fdt) - 1;
}
fdt += fdt_totalsize(fdt);
}
munmap(dtb, size);
@@ -312,18 +314,20 @@ static bool blob_patch(uint8_t *dtb, size_t dtb_sz, const char *out) {
vector<uint8_t *> fdt_list;
vector<uint32_t> padding_list;
for (int i = 0; i < dtb_sz; ++i) {
if (memcmp(dtb + i, FDT_MAGIC_STR, 4) == 0) {
auto len = fdt_totalsize(dtb + i);
auto fdt = static_cast<uint8_t *>(xmalloc(len + MAX_FDT_GROWTH));
memcpy(fdt, dtb + i, len);
fdt_pack(fdt);
uint32_t padding = len - fdt_totalsize(fdt);
padding_list.push_back(padding);
fdt_open_into(fdt, fdt, len + MAX_FDT_GROWTH);
fdt_list.push_back(fdt);
i += len - 1;
}
uint8_t * const end = dtb + dtb_sz;
for (uint8_t *curr = dtb; curr < end;) {
curr = static_cast<uint8_t*>(memmem(curr, end - curr, FDT_MAGIC_STR, sizeof(fdt32_t)));
if (curr == nullptr)
break;
auto len = fdt_totalsize(curr);
auto fdt = static_cast<uint8_t *>(xmalloc(len + MAX_FDT_GROWTH));
memcpy(fdt, curr, len);
fdt_pack(fdt);
uint32_t padding = len - fdt_totalsize(fdt);
padding_list.push_back(padding);
fdt_open_into(fdt, fdt, len + MAX_FDT_GROWTH);
fdt_list.push_back(fdt);
curr += len;
}
bool modified = false;