Magisk/native/jni/utils/selinux.cpp

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#include <dlfcn.h>
#include <unistd.h>
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#include <string.h>
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#include "magisk.h"
#include "utils.h"
#include "selinux.h"
#define UNLABEL_CON "u:object_r:unlabeled:s0"
#define SYSTEM_CON "u:object_r:system_file:s0"
#define ADB_CON "u:object_r:adb_data_file:s0"
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#define MAGISK_CON "u:object_r:" SEPOL_FILE_DOMAIN ":s0"
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// Stub implementations
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static void v_s(char *s) { delete[] s; }
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static int i_s(const char *) { return 0; }
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static int i_ss(const char *, const char *) { return 0; }
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static int i_ssp(const char *, char ** sp) {
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*sp = new char[1]();
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return 0;
}
// Function pointers
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void (*freecon)(char *) = v_s;
int (*setcon)(const char *) = i_s;
int (*getfilecon)(const char *, char **) = i_ssp;
int (*lgetfilecon)(const char *, char **) = i_ssp;
int (*setfilecon)(const char *, const char *) = i_ss;
int (*lsetfilecon)(const char *, const char *) = i_ss;
void dload_selinux() {
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void *handle = dlopen("libselinux.so", RTLD_LAZY);
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if (handle == nullptr)
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return;
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*(void **) &freecon = dlsym(handle, "freecon");
*(void **) &setcon = dlsym(handle, "setcon");
*(void **) &getfilecon = dlsym(handle, "getfilecon");
*(void **) &lgetfilecon = dlsym(handle, "lgetfilecon");
*(void **) &setfilecon = dlsym(handle, "setfilecon");
*(void **) &lsetfilecon = dlsym(handle, "lsetfilecon");
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}
static void restore_syscon(int dirfd) {
struct dirent *entry;
DIR *dir;
char path[PATH_MAX], *con;
fd_getpath(dirfd, path, sizeof(path));
size_t len = strlen(path);
getfilecon(path, &con);
if (strlen(con) == 0 || strcmp(con, UNLABEL_CON) == 0)
lsetfilecon(path, SYSTEM_CON);
freecon(con);
dir = xfdopendir(dirfd);
while ((entry = xreaddir(dir))) {
if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0)
continue;
if (entry->d_type == DT_DIR) {
int fd = xopenat(dirfd, entry->d_name, O_RDONLY | O_CLOEXEC);
restore_syscon(fd);
close(fd);
} else {
path[len] = '/';
strcpy(path + len + 1, entry->d_name);
lgetfilecon(path, &con);
if (strlen(con) == 0 || strcmp(con, UNLABEL_CON) == 0)
lsetfilecon(path, SYSTEM_CON);
freecon(con);
path[len] = '\0';
}
}
}
static void restore_magiskcon(int dirfd) {
struct dirent *entry;
DIR *dir;
char path[PATH_MAX];
fd_getpath(dirfd, path, sizeof(path));
size_t len = strlen(path);
lsetfilecon(path, MAGISK_CON);
lchown(path, 0, 0);
dir = xfdopendir(dirfd);
while ((entry = xreaddir(dir))) {
if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0)
continue;
if (entry->d_type == DT_DIR) {
int fd = xopenat(dirfd, entry->d_name, O_RDONLY | O_CLOEXEC);
restore_magiskcon(fd);
close(fd);
} else {
path[len] = '/';
strcpy(path + len + 1, entry->d_name);
lsetfilecon(path, MAGISK_CON);
lchown(path, 0, 0);
path[len] = '\0';
}
}
}
void restorecon() {
int fd;
fd = xopen(SELINUX_CONTEXT, O_WRONLY | O_CLOEXEC);
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if (write(fd, ADB_CON, sizeof(ADB_CON)) >= 0)
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lsetfilecon(SECURE_DIR, ADB_CON);
close(fd);
fd = xopen(MOUNTPOINT, O_RDONLY | O_CLOEXEC);
restore_syscon(fd);
close(fd);
fd = xopen(DATABIN, O_RDONLY | O_CLOEXEC);
restore_magiskcon(fd);
close(fd);
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}