Magisk/core/jni/magiskboot/dtb.c

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#include <libfdt.h>
#include <unistd.h>
#include <sys/mman.h>
#include "magiskboot.h"
#include "utils.h"
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extern int check_verity_pattern(const char *s);
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static void print_props(const void *fdt, int node, int depth) {
int prop;
fdt_for_each_property_offset(prop, fdt, node) {
for (int i = 0; i < depth; ++i) printf(" ");
printf(" ");
int size;
const char *name;
const char *value = fdt_getprop_by_offset(fdt, prop, &name, &size);
printf("[%s]: [%s]\n", name, value);
}
}
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static void print_subnode(const void *fdt, int parent, int depth) {
int node;
fdt_for_each_subnode(node, fdt, parent) {
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for (int i = 0; i < depth; ++i) printf(" ");
printf("#%d: %s\n", node, fdt_get_name(fdt, node, NULL));
print_props(fdt, node, depth);
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print_subnode(fdt, node, depth + 1);
}
}
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static int find_fstab(const void *fdt, int parent) {
int node, fstab;
fdt_for_each_subnode(node, fdt, parent) {
if (strcmp(fdt_get_name(fdt, node, NULL), "fstab") == 0)
return node;
fstab = find_fstab(fdt, node);
if (fstab != -1)
return fstab;
}
return -1;
}
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static void dtb_dump(const char *file) {
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size_t size ;
void *dtb, *fdt;
fprintf(stderr, "Loading dtbs from [%s]\n", file);
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, DTB_MAGIC, 4) == 0) {
fdt = dtb + i;
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fprintf(stderr, "Dumping dtb.%04d\n\n", dtb_num++);
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print_subnode(fdt, 0, 0);
}
}
fprintf(stderr, "\n");
munmap(dtb, size);
exit(0);
}
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static void dtb_patch(const char *file, int patch) {
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size_t size ;
void *dtb, *fdt;
fprintf(stderr, "Loading dtbs from [%s]\n\n", file);
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if (patch)
mmap_rw(file, &dtb, &size);
else
mmap_ro(file, &dtb, &size);
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// Loop through all the dtbs
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int dtb_num = 0, found = 0;
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for (int i = 0; i < size; ++i) {
if (memcmp(dtb + i, DTB_MAGIC, 4) == 0) {
fdt = dtb + i;
int fstab = find_fstab(fdt, 0);
if (fstab > 0) {
fprintf(stderr, "Found fstab in dtb.%04d\n", dtb_num++);
int block;
fdt_for_each_subnode(block, fdt, fstab) {
fprintf(stderr, "Found block [%s] in fstab\n", fdt_get_name(fdt, block, NULL));
int skip, value_size;
char *value = (char *) fdt_getprop(fdt, block, "fsmgr_flags", &value_size);
for (int i = 0; i < value_size; ++i) {
if ((skip = check_verity_pattern(value + i)) > 0) {
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if (patch) {
fprintf(stderr, "Remove pattern [%.*s] in [fsmgr_flags]\n", skip, value + i);
memcpy(value + i, value + i + skip, value_size - i - skip);
memset(value + value_size - skip, '\0', skip);
} else {
fprintf(stderr, "Found pattern [%.*s] in [fsmgr_flags]\n", skip, value + i);
i += skip - 1;
}
found = 1;
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}
}
}
}
}
}
fprintf(stderr, "\n");
munmap(dtb, size);
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exit(!found);
}
int dtb_commands(const char *cmd, int argc, char *argv[]) {
if (argc == 0) return 1;
if (strcmp(cmd, "dump") == 0)
dtb_dump(argv[0]);
else if (strcmp(cmd, "patch") == 0)
dtb_patch(argv[0], 1);
else if (strcmp(cmd, "test") == 0)
dtb_patch(argv[0], 0);
return 0;
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}