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Magisk
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Cleanup zImage parsing code

This commit is contained in:
topjohnwu 2021-11-23 13:39:15 -08:00
parent 95fb230b8c
commit 01ebe5724a
2 changed files with 53 additions and 43 deletions
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84
native/jni/magiskboot/bootimg.cpp
View File

@ -327,15 +327,15 @@ void boot_img::parse_image(uint8_t *addr, format_t type) {
get_ignore(vendor_ramdisk_table)
get_ignore(bootconfig)
if (int dtb_off = find_dtb_offset(kernel, hdr->kernel_size()); dtb_off > 0) {
kernel_dtb = kernel + dtb_off;
hdr->kernel_dt_size = hdr->kernel_size() - dtb_off;
hdr->kernel_size() = dtb_off;
fprintf(stderr, "%-*s [%u]\n", PADDING, "KERNEL_DTB_SZ", hdr->kernel_dt_size);
}
if (auto size = hdr->kernel_size()) {
k_fmt = check_fmt_lg(kernel, size);
if (int dtb_off = find_dtb_offset(kernel, size); dtb_off > 0) {
kernel_dtb = kernel + dtb_off;
hdr->kernel_dt_size = size - dtb_off;
hdr->kernel_size() = dtb_off;
fprintf(stderr, "%-*s [%u]\n", PADDING, "KERNEL_DTB_SZ", hdr->kernel_dt_size);
}
k_fmt = check_fmt_lg(kernel, hdr->kernel_size());
if (k_fmt == MTK) {
fprintf(stderr, "MTK_KERNEL_HDR\n");
flags[MTK_KERNEL] = true;
@ -348,30 +348,34 @@ void boot_img::parse_image(uint8_t *addr, format_t type) {
}
if (k_fmt == ZIMAGE) {
z_hdr = reinterpret_cast<zimage_hdr *>(kernel);
uint32_t end = z_hdr->end_offset;
if (void *gzip_offset = memmem(kernel, hdr->kernel_size(), GZIP1_MAGIC "\x08\x00", 4)) {
fprintf(stderr, "ZIMAGE_KERNEL\n");
z_info.hdr_sz = (uint8_t *) gzip_offset - kernel;
uint8_t *end_addr = kernel + z_hdr->end_offset;
for (uint8_t *end_ptr = end_addr - 4; end_ptr >= end_addr - 64; end_ptr -= 4) {
uint32_t val;
memcpy(&val, end_ptr, sizeof(val));
if (z_hdr->end_offset - val < 0xFF && val < end) {
end = val;
// Find end of piggy
uint32_t zImage_size = z_hdr->end - z_hdr->start;
uint32_t piggy_end = zImage_size;
uint32_t offsets[16];
memcpy(offsets, kernel + zImage_size - sizeof(offsets), sizeof(offsets));
for (int i = 15; i >= 0; --i) {
if (offsets[i] > (zImage_size - 0xFF) && offsets[i] < zImage_size) {
piggy_end = offsets[i];
break;
}
}
if (end == z_hdr->end_offset) {
fprintf(stderr, "Could not find end of zImage gzip data, keeping raw kernel\n");
if (piggy_end == zImage_size) {
fprintf(stderr, "! Could not find end of zImage piggy, keeping raw kernel\n");
} else {
flags[ZIMAGE_KERNEL] = true;
z_info.tail = kernel + end;
z_info.tail_sz = hdr->kernel_size() - end;
z_info.tail = kernel + piggy_end;
z_info.tail_sz = hdr->kernel_size() - piggy_end;
kernel += z_info.hdr_sz;
hdr->kernel_size() = end - z_info.hdr_sz;
hdr->kernel_size() = piggy_end - z_info.hdr_sz;
k_fmt = check_fmt_lg(kernel, hdr->kernel_size());
}
} else {
fprintf(stderr, "Could not find zImage gzip data, keeping raw kernel\n");
fprintf(stderr, "! Could not find zImage gzip piggy, keeping raw kernel\n");
}
}
fprintf(stderr, "%-*s [%s]\n", PADDING, "KERNEL_FMT", fmt2name[k_fmt]);
@ -561,8 +565,8 @@ void repack(const char *src_img, const char *out_img, bool skip_comp) {
// Copy zImage headers
xwrite(fd, boot.z_hdr, boot.z_info.hdr_sz);
}
size_t raw_size;
if (access(KERNEL_FILE, R_OK) == 0) {
size_t raw_size;
void *raw_buf;
mmap_ro(KERNEL_FILE, raw_buf, raw_size);
if (!COMPRESSED_ANY(check_fmt(raw_buf, raw_size)) && COMPRESSED(boot.k_fmt)) {
@ -571,26 +575,32 @@ void repack(const char *src_img, const char *out_img, bool skip_comp) {
hdr->kernel_size() = xwrite(fd, raw_buf, raw_size);
}
if (boot.flags[ZIMAGE_KERNEL] &&
boot.k_fmt == GZIP && hdr->kernel_size() > boot.hdr->kernel_size()) {
// Revert and try zipfoli
ftruncate64(fd, lseek64(fd, -(off64_t)hdr->kernel_size(), SEEK_CUR));
hdr->kernel_size() = compress(ZOPFLI, fd, raw_buf, raw_size);
if (boot.flags[ZIMAGE_KERNEL]) {
if (boot.k_fmt == GZIP && hdr->kernel_size() > boot.hdr->kernel_size()) {
// Revert and try zopfli
ftruncate64(fd, lseek64(fd, -(off64_t)hdr->kernel_size(), SEEK_CUR));
hdr->kernel_size() = compress(ZOPFLI, fd, raw_buf, raw_size);
}
if (hdr->kernel_size() > boot.hdr->kernel_size()) {
LOGW("! Recompressed kernel is too large, using original kernel\n");
ftruncate64(fd, lseek64(fd, -(off64_t)hdr->kernel_size(), SEEK_CUR));
xwrite(fd, boot.kernel, boot.hdr->kernel_size());
} else {
// Pad zeros to make sure the zImage file size does not change
// Also ensure the last 4 bytes are the uncompressed vmlinux size
uint32_t sz = raw_size;
write_zero(fd, boot.hdr->kernel_size() - hdr->kernel_size() - sizeof(sz));
xwrite(fd, &sz, sizeof(sz));
}
// zImage size shall remain the same
hdr->kernel_size() = boot.hdr->kernel_size();
}
munmap(raw_buf, raw_size);
}
if (boot.flags[ZIMAGE_KERNEL]) {
if (hdr->kernel_size() > boot.hdr->kernel_size()) {
LOGW("Recompressed kernel is too large, using original kernel\n");
ftruncate64(fd, lseek64(fd, -(off64_t)hdr->kernel_size(), SEEK_CUR));
hdr->kernel_size() = xwrite(fd, boot.z_info.tail - boot.hdr->kernel_size(), boot.hdr->kernel_size());
} else {
write_zero(fd, boot.hdr->kernel_size() - hdr->kernel_size() - 4);
uint32_t sz = raw_size;
xwrite(fd, &sz, sizeof(sz));
hdr->kernel_size() = boot.hdr->kernel_size();
}
// Copy zImage tail and adjust size accordingly
hdr->kernel_size() += boot.z_info.hdr_sz;
hdr->kernel_size() += xwrite(fd, boot.z_info.tail, boot.z_info.tail_sz);
}

12
native/jni/magiskboot/bootimg.hpp
View File

@ -42,12 +42,12 @@ struct blob_hdr {
} __attribute__((packed));
struct zimage_hdr {
uint8_t head[36];
uint32_t magic; /* zImage magic */
uint32_t load_addr; /* absolute load/run zImage address */
uint32_t end_offset; /* zImage end offset */
uint32_t endianess; /* endianess flag */
uint8_t code[];
uint32_t code[9];
uint32_t magic; /* zImage magic */
uint32_t start; /* absolute load/run zImage address */
uint32_t end; /* zImage end address */
uint32_t endian; /* endianess flag */
// There could be more fields, but we don't care
} __attribute__((packed));
/**************