Magisk/native/jni/magiskpolicy/policydb.cpp

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#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <cil/cil.h>
#include <utils.h>
#include <logging.h>
#include <stream.h>
#include "magiskpolicy.h"
#include "sepolicy.h"
int load_policydb(const char *file) {
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if (magisk_policydb)
destroy_policydb();
struct policy_file pf;
policy_file_init(&pf);
pf.fp = xfopen(file, "re");
pf.type = PF_USE_STDIO;
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magisk_policydb = static_cast<policydb_t *>(xmalloc(sizeof(policydb_t)));
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if (policydb_init(magisk_policydb) || policydb_read(magisk_policydb, &pf, 0)) {
LOGE("Fail to load policy from %s\n", file);
return 1;
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}
fclose(pf.fp);
return 0;
}
#define SHALEN 64
static bool cmp_sha256(const char *a, const char *b) {
char id_a[SHALEN] = {0};
char id_b[SHALEN] = {0};
if (int fd = xopen(a, O_RDONLY | O_CLOEXEC); fd >= 0) {
xread(fd, id_a, SHALEN);
close(fd);
} else {
return false;
}
if (int fd = xopen(b, O_RDONLY | O_CLOEXEC); fd >= 0) {
xread(fd, id_b, SHALEN);
close(fd);
} else {
return false;
}
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LOGD("%s=[%.*s]\n", a, SHALEN, id_a);
LOGD("%s=[%.*s]\n", b, SHALEN, id_b);
return memcmp(id_a, id_b, SHALEN) == 0;
}
static bool check_precompiled(const char *precompiled) {
bool ok = false;
const char *actual_sha;
char compiled_sha[128];
actual_sha = PLAT_POLICY_DIR "plat_and_mapping_sepolicy.cil.sha256";
if (access(actual_sha, R_OK) == 0) {
ok = true;
sprintf(compiled_sha, "%s.plat_and_mapping.sha256", precompiled);
if (!cmp_sha256(actual_sha, compiled_sha))
return false;
}
actual_sha = PLAT_POLICY_DIR "plat_sepolicy_and_mapping.sha256";
if (access(actual_sha, R_OK) == 0) {
ok = true;
sprintf(compiled_sha, "%s.plat_sepolicy_and_mapping.sha256", precompiled);
if (!cmp_sha256(actual_sha, compiled_sha))
return false;
}
actual_sha = PROD_POLICY_DIR "product_sepolicy_and_mapping.sha256";
if (access(actual_sha, R_OK) == 0) {
ok = true;
sprintf(compiled_sha, "%s.product_sepolicy_and_mapping.sha256", precompiled);
if (!cmp_sha256(actual_sha, compiled_sha) != 0)
return false;
}
return ok;
}
int load_split_cil() {
const char *odm_pre = ODM_POLICY_DIR "precompiled_sepolicy";
const char *vend_pre = VEND_POLICY_DIR "precompiled_sepolicy";
if (access(odm_pre, R_OK) == 0 && check_precompiled(odm_pre))
return load_policydb(odm_pre);
else if (access(vend_pre, R_OK) == 0 && check_precompiled(vend_pre))
return load_policydb(vend_pre);
else
return compile_split_cil();
}
static void load_cil(struct cil_db *db, const char *file) {
char *addr;
size_t size;
mmap_ro(file, addr, size);
cil_add_file(db, (char *) file, addr, size);
LOGD("cil_add[%s]\n", file);
munmap(addr, size);
}
int compile_split_cil() {
char path[128], plat_ver[10];
struct cil_db *db = nullptr;
sepol_policydb_t *pdb = nullptr;
FILE *f;
int policy_ver;
const char *cil_file;
cil_db_init(&db);
cil_set_mls(db, 1);
cil_set_multiple_decls(db, 1);
cil_set_disable_neverallow(db, 1);
cil_set_target_platform(db, SEPOL_TARGET_SELINUX);
cil_set_attrs_expand_generated(db, 0);
f = xfopen(SELINUX_VERSION, "re");
fscanf(f, "%d", &policy_ver);
fclose(f);
cil_set_policy_version(db, policy_ver);
// Get mapping version
f = xfopen(VEND_POLICY_DIR "plat_sepolicy_vers.txt", "re");
fscanf(f, "%s", plat_ver);
fclose(f);
// plat
load_cil(db, SPLIT_PLAT_CIL);
sprintf(path, PLAT_POLICY_DIR "mapping/%s.cil", plat_ver);
load_cil(db, path);
// product
sprintf(path, PROD_POLICY_DIR "mapping/%s.cil", plat_ver);
if (access(path, R_OK) == 0)
load_cil(db, path);
cil_file = PROD_POLICY_DIR "product_sepolicy.cil";
if (access(cil_file, R_OK) == 0)
load_cil(db, cil_file);
// vendor
cil_file = VEND_POLICY_DIR "nonplat_sepolicy.cil";
if (access(cil_file, R_OK) == 0)
load_cil(db, cil_file);
cil_file = VEND_POLICY_DIR "plat_pub_versioned.cil";
if (access(cil_file, R_OK) == 0)
load_cil(db, cil_file);
cil_file = VEND_POLICY_DIR "vendor_sepolicy.cil";
if (access(cil_file, R_OK) == 0)
load_cil(db, cil_file);
// odm
cil_file = ODM_POLICY_DIR "odm_sepolicy.cil";
if (access(cil_file, R_OK) == 0)
load_cil(db, cil_file);
if (cil_compile(db))
return 1;
if (cil_build_policydb(db, &pdb))
return 1;
cil_db_destroy(&db);
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magisk_policydb = &pdb->p;
return 0;
}
int dump_policydb(const char *file) {
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uint8_t *data;
size_t len;
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{
auto fp = make_stream<byte_stream>(data, len);
struct policy_file pf;
policy_file_init(&pf);
pf.type = PF_USE_STDIO;
pf.fp = fp.get();
if (policydb_write(magisk_policydb, &pf)) {
LOGE("Fail to create policy image\n");
return 1;
}
}
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int fd = xopen(file, O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC, 0644);
if (fd < 0)
return 1;
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xwrite(fd, data, len);
close(fd);
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free(data);
return 0;
}
void destroy_policydb() {
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if (magisk_policydb) {
policydb_destroy(magisk_policydb);
free(magisk_policydb);
magisk_policydb = nullptr;
}
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}