Magisk/native/jni/magiskboot/dtb.cpp

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#include <unistd.h>
#include <sys/mman.h>
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extern "C" {
#include <libfdt.h>
}
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#include <utils.h>
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#include <bitset>
#include <vector>
#include <map>
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#include "magiskboot.h"
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using namespace std;
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#define DTB_MAGIC "\xd0\x0d\xfe\xed"
#define QCDT_MAGIC "QCDT"
#define DTBH_MAGIC "DTBH"
#define PXADT_MAGIC "PXA-DT"
#define PXA_19xx_MAGIC "PXA-19xx"
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struct qcdt_hdr {
char magic[4]; /* "QCDT" */
uint32_t version; /* QCDT version */
uint32_t num_dtbs; /* Number of DTBs */
} __attribute__((packed));
struct qctable_v1 {
uint32_t cpu_info[3]; /* Some CPU info */
uint32_t offset; /* DTB offset in QCDT */
uint32_t len; /* DTB size */
} __attribute__((packed));
struct qctable_v2 {
uint32_t cpu_info[4]; /* Some CPU info */
uint32_t offset; /* DTB offset in QCDT */
uint32_t len; /* DTB size */
} __attribute__((packed));
struct qctable_v3 {
uint32_t cpu_info[8]; /* Some CPU info */
uint32_t offset; /* DTB offset in QCDT */
uint32_t len; /* DTB size */
} __attribute__((packed));
struct dtbh_hdr {
char magic[4]; /* "DTBH" */
uint32_t version; /* DTBH version */
uint32_t num_dtbs; /* Number of DTBs */
} __attribute__((packed));
struct bhtable_v2 {
uint32_t cpu_info[5]; /* Some CPU info */
uint32_t offset; /* DTB offset in DTBH */
uint32_t len; /* DTB size */
uint32_t space; /* 0x00000020 */
} __attribute__((packed));
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struct pxadt_hdr {
char magic[6]; /* "PXA-DT" */
uint32_t version; /* PXA-DT version */
uint32_t num_dtbs; /* Number of DTBs */
} __attribute__((packed));
struct pxa_19xx_hdr {
char magic[8]; /* "PXA-19xx" */
uint32_t version; /* PXA-DT version */
uint32_t num_dtbs; /* Number of DTBs */
} __attribute__((packed));
struct pxa_table_v1 {
uint32_t cpu_info[2]; /* Some CPU info */
uint32_t offset; /* DTB offset in PXA-DT */
uint32_t len; /* DTB size */
} __attribute__((packed));
struct dtb_blob {
void *fdt;
uint32_t offset;
uint32_t len;
};
template <class Iter>
class fdt_map_iter {
public:
typedef decltype(std::declval<typename Iter::value_type::second_type>().fdt) value_type;
typedef value_type* pointer;
typedef value_type& reference;
explicit fdt_map_iter(Iter j) : i(j) {}
fdt_map_iter& operator++() { ++i; return *this; }
fdt_map_iter operator++(int) { auto tmp = *this; ++(*this); return tmp; }
fdt_map_iter& operator--() { --i; return *this; }
fdt_map_iter operator--(int) { auto tmp = *this; --(*this); return tmp; }
bool operator==(fdt_map_iter j) const { return i == j.i; }
bool operator!=(fdt_map_iter j) const { return !(*this == j); }
reference operator*() { return i->second.fdt; }
pointer operator->() { return &i->second.fdt; }
private:
Iter i;
};
template<class Iter>
inline fdt_map_iter<Iter> make_iter(Iter j) { return fdt_map_iter<Iter>(j); }
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constexpr int MAX_DEPTH = 32;
static bitset<MAX_DEPTH> depth_set;
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static void pretty_node(int depth) {
if (depth == 0)
return;
for (int i = 0; i < depth - 1; ++i)
printf(depth_set[i] ? "│ " : " ");
printf(depth_set[depth - 1] ? "├── " : "└── ");
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}
static void pretty_prop(int depth) {
for (int i = 0; i < depth; ++i)
printf(depth_set[i] ? "│ " : " ");
printf(depth_set[depth] ? "│ " : " ");
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}
static void print_node(const void *fdt, int node = 0, int depth = 0) {
// Print node itself
pretty_node(depth);
printf("#%d: %s\n", node, fdt_get_name(fdt, node, nullptr));
// Print properties
depth_set[depth] = fdt_first_subnode(fdt, node) >= 0;
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int prop;
fdt_for_each_property_offset(prop, fdt, node) {
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pretty_prop(depth);
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int size;
const char *name;
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auto value = static_cast<const char *>(fdt_getprop_by_offset(fdt, prop, &name, &size));
bool is_str = !(size > 1 && value[0] == 0);
if (is_str) {
// Scan through value to see if printable
for (int i = 0; i < size; ++i) {
char c = value[i];
if (i == size - 1) {
// Make sure null terminate
is_str = c == '\0';
} else if ((c > 0 && c < 32) || c >= 127) {
is_str = false;
break;
}
}
}
if (is_str) {
printf("[%s]: [%s]\n", name, value);
} else {
printf("[%s]: <bytes>(%d)\n", name, size);
}
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}
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// Recursive
if (depth_set[depth]) {
int child;
int prev = -1;
fdt_for_each_subnode(child, fdt, node) {
if (prev >= 0)
print_node(fdt, prev, depth + 1);
prev = child;
}
depth_set[depth] = false;
print_node(fdt, prev, depth + 1);
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}
}
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static int find_fstab(const void *fdt, int node = 0) {
if (fdt_get_name(fdt, node, nullptr) == "fstab"sv)
return node;
int child;
fdt_for_each_subnode(child, fdt, node) {
int fstab = find_fstab(fdt, child);
if (fstab >= 0)
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return fstab;
}
return -1;
}
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static void dtb_print(const char *file, bool fstab) {
size_t size;
uint8_t *dtb;
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fprintf(stderr, "Loading dtbs from [%s]\n", file);
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mmap_ro(file, dtb, size);
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// Loop through all the dtbs
int dtb_num = 0;
for (int i = 0; i < size; ++i) {
if (memcmp(dtb + i, DTB_MAGIC, 4) == 0) {
auto fdt = dtb + i;
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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);
}
++dtb_num;
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i += fdt_totalsize(fdt) - 1;
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}
}
fprintf(stderr, "\n");
munmap(dtb, size);
}
template <typename Iter>
static bool fdt_patch(Iter first, Iter last) {
bool keepverity = check_env("KEEPVERITY");
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bool redirect = check_env("TWOSTAGEINIT");
bool modified = false;
int idx = 0;
for (auto it = first; it != last; ++it) {
++idx;
auto fdt = *it;
int fstab = find_fstab(fdt);
if (fstab < 0)
continue;
fprintf(stderr, "Found fstab in dtb.%04d\n", idx - 1);
int block;
fdt_for_each_subnode(block, fdt, fstab) {
const char *name = fdt_get_name(fdt, block, nullptr);
fprintf(stderr, "Found entry [%s] in fstab\n", name);
if (!keepverity) {
uint32_t size;
auto value = static_cast<const char *>(
fdt_getprop(fdt, block, "fsmgr_flags", reinterpret_cast<int *>(&size)));
char *pval = patch_verity(value, size);
if (pval) {
modified = true;
fdt_setprop_string(fdt, block, "fsmgr_flags", pval);
}
}
if (redirect && name == "system"sv) {
modified = true;
fprintf(stderr, "Changing mnt_point to /system_root\n");
fdt_setprop_string(fdt, block, "mnt_point", "/system_root");
}
}
}
return modified;
}
template <class Table, class Header>
static int dtb_patch(const Header *hdr, const char *in, const char *out) {
map<uint32_t, dtb_blob> dtb_map;
auto buf = reinterpret_cast<const uint8_t *>(hdr);
auto tables = reinterpret_cast<const Table *>(hdr + 1);
// Collect all dtbs
for (int i = 0; i < hdr->num_dtbs; ++i) {
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if (dtb_map.find(tables[i].offset) == dtb_map.end()) {
auto blob = buf + tables[i].offset;
int size = fdt_totalsize(blob);
auto fdt = xmalloc(size + 256);
memcpy(fdt, blob, size);
fdt_open_into(fdt, fdt, size + 256);
dtb_map[tables[i].offset] = { fdt, tables[i].offset };
}
}
if (dtb_map.empty())
return 1;
// Patch fdt
if (!fdt_patch(make_iter(dtb_map.begin()), make_iter(dtb_map.end())))
return 1;
if (out == in)
unlink(in);
int fd = xopen(out, O_RDWR | O_CREAT | O_TRUNC | O_CLOEXEC, 0644);
// Copy headers and tables
xwrite(fd, buf, dtb_map.begin()->first);
// mmap rw to patch table values retroactively
auto mmap_sz = lseek(fd, 0, SEEK_CUR);
auto addr = (uint8_t *) xmmap(nullptr, mmap_sz, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
// Guess page size using gcd
auto it = dtb_map.begin();
uint32_t page_size = (it++)->first;
for (; it != dtb_map.end(); ++it)
page_size = binary_gcd(page_size, it->first);
// Write dtbs
for (auto &val : dtb_map) {
val.second.offset = lseek(fd, 0, SEEK_CUR);
auto fdt = val.second.fdt;
fdt_pack(fdt);
int size = fdt_totalsize(fdt);
xwrite(fd, fdt, size);
val.second.len = do_align(size, page_size);
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write_zero(fd, align_off(lseek(fd, 0, SEEK_CUR), page_size));
free(fdt);
}
// Patch tables
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auto tables_rw = reinterpret_cast<Table *>(addr + sizeof(Header));
for (int i = 0; i < hdr->num_dtbs; ++i) {
auto &blob = dtb_map[tables_rw[i].offset];
tables_rw[i].offset = blob.offset;
tables_rw[i].len = blob.len;
}
munmap(addr, mmap_sz);
close(fd);
return 0;
}
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#define MATCH(s) (memcmp(dtb, s, sizeof(s) - 1) == 0)
static int dtb_patch(const char *in, const char *out) {
if (!out)
out = in;
size_t dtb_sz ;
uint8_t *dtb;
fprintf(stderr, "Loading dtbs from [%s]\n", in);
mmap_ro(in, dtb, dtb_sz);
run_finally f([&]{ munmap(dtb, dtb_sz); });
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if (MATCH(QCDT_MAGIC)) {
auto hdr = reinterpret_cast<qcdt_hdr*>(dtb);
switch (hdr->version) {
case 1:
fprintf(stderr, "QCDT v1\n");
return dtb_patch<qctable_v1>(hdr, in, out);
case 2:
fprintf(stderr, "QCDT v2\n");
return dtb_patch<qctable_v2>(hdr, in, out);
case 3:
fprintf(stderr, "QCDT v3\n");
return dtb_patch<qctable_v3>(hdr, in, out);
default:
return 1;
}
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} else if (MATCH(DTBH_MAGIC)) {
auto hdr = reinterpret_cast<dtbh_hdr *>(dtb);
switch (hdr->version) {
case 2:
fprintf(stderr, "DTBH v2\n");
return dtb_patch<bhtable_v2>(hdr, in, out);
default:
return 1;
}
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} else if (MATCH(PXADT_MAGIC)) {
auto hdr = reinterpret_cast<pxadt_hdr *>(dtb);
switch (hdr->version) {
case 1:
fprintf(stderr, "PXA-DT v1\n");
return dtb_patch<pxa_table_v1>(hdr, in, out);
default:
return 1;
}
} else if (MATCH(PXA_19xx_MAGIC)) {
auto hdr = reinterpret_cast<pxa_19xx_hdr *>(dtb);
switch (hdr->version) {
case 1:
fprintf(stderr, "PXA-19xx v1\n");
return dtb_patch<pxa_table_v1>(hdr, in, out);
default:
return 1;
}
} else {
vector<uint8_t *> fdt_list;
for (int i = 0; i < dtb_sz; ++i) {
if (memcmp(dtb + i, DTB_MAGIC, 4) == 0) {
int len = fdt_totalsize(dtb + i);
auto fdt = static_cast<uint8_t *>(xmalloc(len + 256));
memcpy(fdt, dtb + i, len);
fdt_open_into(fdt, fdt, len + 256);
fdt_list.push_back(fdt);
i += len - 1;
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}
}
if (!fdt_patch(fdt_list.begin(), fdt_list.end()))
return 1;
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int fd = xopen(out, O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC, 0644);
for (auto fdt : fdt_list) {
fdt_pack(fdt);
xwrite(fd, fdt, fdt_totalsize(fdt));
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free(fdt);
}
close(fd);
}
return 0;
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}
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int dtb_commands(int argc, char *argv[]) {
char *dtb = argv[0];
++argv;
--argc;
if (argv[0] == "print"sv) {
dtb_print(dtb, argc > 1 && argv[1] == "-f"sv);
return 0;
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} else if (argv[0] == "patch"sv) {
if (dtb_patch(dtb, argv[1]))
exit(1);
return 0;
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} else {
return 1;
}
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}