forked from MarcoBuster/Magisk
02dc1172be
Since we no longer need to add new properties in the device tree, and all the patches we do removes strings, we can just directly patch the flat device tree in-place, ignoring basically all the higher level DTB structure and format to accomplish 100% compatibility.
455 lines
12 KiB
C++
455 lines
12 KiB
C++
#include <unistd.h>
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#include <sys/mman.h>
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#include <bitset>
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#include <vector>
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#include <map>
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#include <utils.hpp>
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#include "magiskboot.hpp"
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#include "dtb.hpp"
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extern "C" {
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#include <libfdt.h>
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}
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using namespace std;
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constexpr int MAX_DEPTH = 32;
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static bitset<MAX_DEPTH> depth_set;
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static void pretty_node(int depth) {
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if (depth == 0)
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return;
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for (int i = 0; i < depth - 1; ++i)
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printf(depth_set[i] ? "│ " : " ");
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printf(depth_set[depth - 1] ? "├── " : "└── ");
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}
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static void pretty_prop(int depth) {
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for (int i = 0; i < depth; ++i)
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printf(depth_set[i] ? "│ " : " ");
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printf(depth_set[depth] ? "│ " : " ");
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}
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static void print_node(const void *fdt, int node = 0, int depth = 0) {
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// Print node itself
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pretty_node(depth);
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printf("#%d: %s\n", node, fdt_get_name(fdt, node, nullptr));
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// Print properties
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depth_set[depth] = fdt_first_subnode(fdt, node) >= 0;
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int prop;
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fdt_for_each_property_offset(prop, fdt, node) {
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pretty_prop(depth);
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int size;
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const char *name;
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auto value = static_cast<const char *>(fdt_getprop_by_offset(fdt, prop, &name, &size));
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bool is_str = !(size > 1 && value[0] == 0);
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if (is_str) {
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// Scan through value to see if printable
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for (int i = 0; i < size; ++i) {
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char c = value[i];
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if (i == size - 1) {
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// Make sure null terminate
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is_str = c == '\0';
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} else if ((c > 0 && c < 32) || c >= 127) {
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is_str = false;
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break;
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}
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}
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}
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if (is_str) {
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printf("[%s]: [%s]\n", name, value);
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} else {
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printf("[%s]: <bytes>(%d)\n", name, size);
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}
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}
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// Recursive
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if (depth_set[depth]) {
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int child;
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int prev = -1;
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fdt_for_each_subnode(child, fdt, node) {
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if (prev >= 0)
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print_node(fdt, prev, depth + 1);
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prev = child;
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}
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depth_set[depth] = false;
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print_node(fdt, prev, depth + 1);
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}
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}
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static int find_fstab(const void *fdt, int node = 0) {
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if (fdt_get_name(fdt, node, nullptr) == "fstab"sv)
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return node;
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int child;
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fdt_for_each_subnode(child, fdt, node) {
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int fstab = find_fstab(fdt, child);
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if (fstab >= 0)
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return fstab;
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}
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return -1;
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}
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static void dtb_print(const char *file, bool fstab) {
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size_t size;
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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
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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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}
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++dtb_num;
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i += fdt_totalsize(fdt) - 1;
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}
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}
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fprintf(stderr, "\n");
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munmap(dtb, size);
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}
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static bool dtb_patch(const char *file) {
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bool keepverity = check_env("KEEPVERITY");
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bool patched = false;
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size_t size;
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uint8_t *dtb;
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fprintf(stderr, "Loading dtbs from [%s]\n", file);
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mmap_rw(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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fprintf(stderr, "Loading dtb.%04d\n", dtb_num);
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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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const char *name = fdt_get_name(fdt, node, nullptr);
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fprintf(stderr, "Found fstab entry [%s]\n", name);
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if (!keepverity) {
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int len;
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auto value = fdt_getprop(fdt, node, "fsmgr_flags", &len);
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patched |= patch_verity(const_cast<void *>(value), len) != len;
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}
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}
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}
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++dtb_num;
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i += fdt_totalsize(fdt) - 1;
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}
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}
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fprintf(stderr, "\n");
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munmap(dtb, size);
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return patched;
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}
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int dtb_commands(int argc, char *argv[]) {
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char *dtb = argv[0];
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++argv;
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--argc;
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if (argv[0] == "print"sv) {
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dtb_print(dtb, argc > 1 && argv[1] == "-f"sv);
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return 0;
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} else if (argv[0] == "patch"sv) {
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if (!dtb_patch(dtb))
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exit(1);
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return 0;
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} else {
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return 1;
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}
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}
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namespace {
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// Unused, but keep these precious code as they took TONs of effort to write
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struct fdt_blob {
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void *fdt;
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uint32_t offset;
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uint32_t len;
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};
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template <class Iter>
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class fdt_map_iter {
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public:
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typedef decltype(std::declval<typename Iter::value_type::second_type>().fdt) value_type;
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typedef value_type* pointer;
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typedef value_type& reference;
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explicit fdt_map_iter(Iter j) : i(j) {}
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fdt_map_iter& operator++() { ++i; return *this; }
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fdt_map_iter operator++(int) { auto tmp = *this; ++(*this); return tmp; }
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fdt_map_iter& operator--() { --i; return *this; }
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fdt_map_iter operator--(int) { auto tmp = *this; --(*this); return tmp; }
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bool operator==(fdt_map_iter j) const { return i == j.i; }
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bool operator!=(fdt_map_iter j) const { return !(*this == j); }
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reference operator*() { return i->second.fdt; }
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pointer operator->() { return &i->second.fdt; }
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private:
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Iter i;
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};
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template<class Iter>
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inline fdt_map_iter<Iter> make_iter(Iter j) { return fdt_map_iter<Iter>(j); }
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template <typename Iter>
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static bool fdt_patch(Iter first, Iter last) {
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bool keepverity = check_env("KEEPVERITY");
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bool redirect = check_env("TWOSTAGEINIT");
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bool modified = false;
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int idx = 0;
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for (auto it = first; it != last; ++it) {
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++idx;
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auto fdt = *it;
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int fstab = find_fstab(fdt);
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if (fstab < 0)
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continue;
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fprintf(stderr, "Found fstab in dtb.%04d\n", idx - 1);
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int block;
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fdt_for_each_subnode(block, fdt, fstab) {
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const char *name = fdt_get_name(fdt, block, nullptr);
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fprintf(stderr, "Found entry [%s] in fstab\n", name);
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if (!keepverity) {
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int size;
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auto value = fdt_getprop(fdt, block, "fsmgr_flags", &size);
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char *copy = static_cast<char *>(memcpy(malloc(size), value, size));
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if (patch_verity(copy, size) != size) {
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modified = true;
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fdt_setprop_string(fdt, block, "fsmgr_flags", copy);
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}
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free(copy);
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}
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if (redirect && name == "system"sv) {
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modified = true;
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fprintf(stderr, "Changing mnt_point to /system_root\n");
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fdt_setprop_string(fdt, block, "mnt_point", "/system_root");
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}
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}
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}
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return modified;
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}
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#define MAX_FDT_GROWTH 256
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template <class Table, class Header>
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static int dt_table_patch(const Header *hdr, const char *out) {
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map<uint32_t, fdt_blob> dtb_map;
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auto buf = reinterpret_cast<const uint8_t *>(hdr);
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auto tables = reinterpret_cast<const Table *>(hdr + 1);
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constexpr bool is_dt_table = std::is_same_v<Header, dt_table_header>;
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using endian_conv = uint32_t (*)(uint32_t);
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endian_conv be_to_le;
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endian_conv le_to_be;
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if constexpr (is_dt_table) {
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be_to_le = fdt32_to_cpu;
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le_to_be = cpu_to_fdt32;
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} else {
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be_to_le = le_to_be = [](uint32_t x) -> auto { return x; };
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}
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// Collect all dtbs
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auto num_dtb = be_to_le(hdr->num_dtbs);
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for (int i = 0; i < num_dtb; ++i) {
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auto offset = be_to_le(tables[i].offset);
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if (dtb_map.count(offset) == 0) {
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auto blob = buf + offset;
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uint32_t size = fdt_totalsize(blob);
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auto fdt = xmalloc(size + MAX_FDT_GROWTH);
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memcpy(fdt, blob, size);
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fdt_open_into(fdt, fdt, size + MAX_FDT_GROWTH);
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dtb_map[offset] = { fdt, offset };
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}
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}
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if (dtb_map.empty())
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return 1;
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// Patch fdt
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if (!fdt_patch(make_iter(dtb_map.begin()), make_iter(dtb_map.end())))
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return 1;
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unlink(out);
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int fd = xopen(out, O_RDWR | O_CREAT | O_CLOEXEC, 0644);
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uint32_t total_size = 0;
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// Copy headers and tables
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total_size += xwrite(fd, buf, dtb_map.begin()->first);
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// mmap rw to patch table values retroactively
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auto mmap_sz = lseek(fd, 0, SEEK_CUR);
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auto addr = (uint8_t *) xmmap(nullptr, mmap_sz, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
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// Guess alignment using gcd
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uint32_t align = 1;
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if constexpr (!is_dt_table) {
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auto it = dtb_map.begin();
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align = (it++)->first;
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for (; it != dtb_map.end(); ++it)
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align = binary_gcd(align, it->first);
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}
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// Write dtbs
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for (auto &val : dtb_map) {
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val.second.offset = lseek(fd, 0, SEEK_CUR);
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auto fdt = val.second.fdt;
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fdt_pack(fdt);
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auto size = fdt_totalsize(fdt);
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total_size += xwrite(fd, fdt, size);
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val.second.len = do_align(size, align);
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write_zero(fd, align_off(lseek(fd, 0, SEEK_CUR), align));
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// total_size += align_off(lseek(fd, 0, SEEK_CUR), align); /* Not needed */
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free(fdt);
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}
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// Patch headers
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if constexpr (is_dt_table) {
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auto hdr_rw = reinterpret_cast<Header *>(addr);
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hdr_rw->total_size = le_to_be(total_size);
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}
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auto tables_rw = reinterpret_cast<Table *>(addr + sizeof(Header));
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for (int i = 0; i < num_dtb; ++i) {
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auto &blob = dtb_map[be_to_le(tables_rw[i].offset)];
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tables_rw[i].offset = le_to_be(blob.offset);
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tables_rw[i].len = le_to_be(blob.len);
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}
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munmap(addr, mmap_sz);
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close(fd);
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return 0;
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}
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static int 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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}
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if (!fdt_patch(fdt_list.begin(), fdt_list.end()))
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return 1;
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unlink(out);
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int fd = xopen(out, O_WRONLY | O_CREAT | O_CLOEXEC, 0644);
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for (int i = 0; i < fdt_list.size(); ++i) {
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auto fdt = fdt_list[i];
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fdt_pack(fdt);
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// Only add padding back if it is anything meaningful
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if (padding_list[i] > 4) {
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auto len = fdt_totalsize(fdt);
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fdt_set_totalsize(fdt, len + padding_list[i]);
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}
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xwrite(fd, fdt, fdt_totalsize(fdt));
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free(fdt);
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}
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close(fd);
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return 0;
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}
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#define MATCH(s) (memcmp(dtb, s, sizeof(s) - 1) == 0)
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[[maybe_unused]] static int dtb_patch(const char *in, const char *out) {
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if (!out)
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out = in;
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size_t dtb_sz ;
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uint8_t *dtb;
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fprintf(stderr, "Loading dtbs from [%s]\n", in);
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mmap_ro(in, dtb, dtb_sz);
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run_finally f([&]{ munmap(dtb, dtb_sz); });
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if (MATCH(QCDT_MAGIC)) {
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auto hdr = reinterpret_cast<qcdt_hdr*>(dtb);
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switch (hdr->version) {
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case 1:
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fprintf(stderr, "QCDT v1\n");
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return dt_table_patch<qctable_v1>(hdr, out);
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case 2:
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fprintf(stderr, "QCDT v2\n");
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return dt_table_patch<qctable_v2>(hdr, out);
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case 3:
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fprintf(stderr, "QCDT v3\n");
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return dt_table_patch<qctable_v3>(hdr, out);
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default:
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return 1;
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}
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} else if (MATCH(DTBH_MAGIC)) {
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auto hdr = reinterpret_cast<dtbh_hdr *>(dtb);
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switch (hdr->version) {
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case 2:
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fprintf(stderr, "DTBH v2\n");
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return dt_table_patch<bhtable_v2>(hdr, out);
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default:
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return 1;
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}
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} else if (MATCH(PXADT_MAGIC)) {
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auto hdr = reinterpret_cast<pxadt_hdr *>(dtb);
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switch (hdr->version) {
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case 1:
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fprintf(stderr, "PXA-DT v1\n");
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return dt_table_patch<pxatable_v1>(hdr, out);
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default:
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return 1;
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}
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} else if (MATCH(PXA19xx_MAGIC)) {
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auto hdr = reinterpret_cast<pxa19xx_hdr *>(dtb);
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switch (hdr->version) {
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case 1:
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fprintf(stderr, "PXA-19xx v1\n");
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return dt_table_patch<pxatable_v1>(hdr, out);
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default:
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return 1;
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}
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} else if (MATCH(SPRD_MAGIC)) {
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auto hdr = reinterpret_cast<sprd_hdr *>(dtb);
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switch (hdr->version) {
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case 1:
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fprintf(stderr, "SPRD v1\n");
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return dt_table_patch<sprdtable_v1>(hdr, out);
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default:
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return 1;
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}
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} else if (MATCH(DT_TABLE_MAGIC)) {
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auto hdr = reinterpret_cast<dt_table_header *>(dtb);
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switch (hdr->version) {
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case 0:
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fprintf(stderr, "DT_TABLE v0\n");
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return dt_table_patch<dt_table_entry>(hdr, out);
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default:
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return 1;
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}
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} else {
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return blob_patch(dtb, dtb_sz, out);
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}
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}
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}
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