mirror of
https://github.com/topjohnwu/Magisk.git
synced 2024-12-04 23:45:23 +00:00
223 lines
5.3 KiB
C++
223 lines
5.3 KiB
C++
#include <dlfcn.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <string.h>
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#include <syscall.h>
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#include <sys/xattr.h>
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#include <magisk.h>
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#include <utils.h>
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#include <selinux.h>
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#define UNLABEL_CON "u:object_r:unlabeled:s0"
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#define SYSTEM_CON "u:object_r:system_file:s0"
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#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 implementation
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static int stub(const char *) { return 0; }
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static int stub(const char *, const char *) { return 0; }
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static int stub(const char *, char **ctx) {
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*ctx = strdup("");
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return 0;
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}
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static int stub(int, const char *) { return 0; }
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static int stub(int, char **ctx) {
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*ctx = strdup("");
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return 0;
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}
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// Builtin implementation
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static void __freecon(char *s) {
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free(s);
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}
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static int __setcon(const char *ctx) {
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int fd = open("/proc/self/attr/current", O_WRONLY | O_CLOEXEC);
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if (fd < 0)
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return fd;
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size_t len = strlen(ctx) + 1;
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int rc = write(fd, ctx, len);
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close(fd);
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return rc != len;
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}
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static int __getfilecon(const char *path, char **ctx) {
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char buf[1024];
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int rc = syscall(__NR_getxattr, path, XATTR_NAME_SELINUX, buf, sizeof(buf) - 1);
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if (rc < 0) {
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errno = -rc;
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return -1;
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}
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*ctx = strdup(buf);
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return rc;
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}
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static int __lgetfilecon(const char *path, char **ctx) {
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char buf[1024];
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int rc = syscall(__NR_lgetxattr, path, XATTR_NAME_SELINUX, buf, sizeof(buf) - 1);
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if (rc < 0) {
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errno = -rc;
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return -1;
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}
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*ctx = strdup(buf);
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return rc;
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}
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static int __fgetfilecon(int fd, char **ctx) {
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char buf[1024];
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int rc = syscall(__NR_fgetxattr, fd, XATTR_NAME_SELINUX, buf, sizeof(buf) - 1);
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if (rc < 0) {
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errno = -rc;
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return -1;
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}
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*ctx = strdup(buf);
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return rc;
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}
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static int __setfilecon(const char *path, const char *ctx) {
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int rc = syscall(__NR_setxattr, path, XATTR_NAME_SELINUX, ctx, strlen(ctx) + 1, 0);
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if (rc) {
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errno = -rc;
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return -1;
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}
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return 0;
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}
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static int __lsetfilecon(const char *path, const char *ctx) {
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int rc = syscall(__NR_lsetxattr, path, XATTR_NAME_SELINUX, ctx, strlen(ctx) + 1, 0);
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if (rc) {
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errno = -rc;
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return -1;
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}
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return 0;
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}
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static int __fsetfilecon(int fd, const char *ctx) {
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int rc = syscall(__NR_fsetxattr, fd, XATTR_NAME_SELINUX, ctx, strlen(ctx) + 1, 0);
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if (rc) {
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errno = -rc;
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return -1;
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}
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return 0;
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}
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// Function pointers
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void (*freecon)(char *) = __freecon;
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int (*setcon)(const char *) = stub;
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int (*getfilecon)(const char *, char **) = stub;
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int (*lgetfilecon)(const char *, char **) = stub;
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int (*fgetfilecon)(int, char **) = stub;
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int (*setfilecon)(const char *, const char *) = stub;
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int (*lsetfilecon)(const char *, const char *) = stub;
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int (*fsetfilecon)(int, const char *) = stub;
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void getfilecon_at(int dirfd, const char *name, char **con) {
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char path[4096];
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fd_pathat(dirfd, name, path, sizeof(path));
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if (lgetfilecon(path, con))
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*con = strdup("");
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}
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void setfilecon_at(int dirfd, const char *name, const char *con) {
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char path[4096];
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fd_pathat(dirfd, name, path, sizeof(path));
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lsetfilecon(path, con);
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}
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void selinux_builtin_impl() {
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setcon = __setcon;
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getfilecon = __getfilecon;
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lgetfilecon = __lgetfilecon;
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fgetfilecon = __fgetfilecon;
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setfilecon = __setfilecon;
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lsetfilecon = __lsetfilecon;
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fsetfilecon = __fsetfilecon;
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}
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void dload_selinux() {
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if (access("/system/lib/libselinux.so", F_OK))
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return;
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/* We only check whether libselinux.so exists but don't dlopen.
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* For some reason calling symbols returned from dlsym
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* will result to SEGV_ACCERR on some devices.
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* Always use builtin implementations for SELinux stuffs. */
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selinux_builtin_impl();
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}
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static void restore_syscon(int dirfd) {
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struct dirent *entry;
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DIR *dir;
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char *con;
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fgetfilecon(dirfd, &con);
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if (strlen(con) == 0 || strcmp(con, UNLABEL_CON) == 0)
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fsetfilecon(dirfd, SYSTEM_CON);
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freecon(con);
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dir = xfdopendir(dirfd);
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while ((entry = xreaddir(dir))) {
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if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0)
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continue;
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int fd = openat(dirfd, entry->d_name, O_RDONLY | O_CLOEXEC);
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if (entry->d_type == DT_DIR) {
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restore_syscon(fd);
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} else if (entry->d_type == DT_REG) {
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fgetfilecon(fd, &con);
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if (con[0] == '\0' || strcmp(con, UNLABEL_CON) == 0)
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fsetfilecon(fd, SYSTEM_CON);
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freecon(con);
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} else if (entry->d_type == DT_LNK) {
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getfilecon_at(dirfd, entry->d_name, &con);
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if (con[0] == '\0' || strcmp(con, UNLABEL_CON) == 0)
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setfilecon_at(dirfd, entry->d_name, con);
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freecon(con);
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}
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close(fd);
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}
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}
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static void restore_magiskcon(int dirfd) {
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struct dirent *entry;
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DIR *dir;
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fsetfilecon(dirfd, MAGISK_CON);
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fchown(dirfd, 0, 0);
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dir = xfdopendir(dirfd);
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while ((entry = xreaddir(dir))) {
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if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0)
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continue;
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int fd = xopenat(dirfd, entry->d_name, O_RDONLY | O_CLOEXEC);
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if (entry->d_type == DT_DIR) {
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restore_magiskcon(fd);
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} else if (entry->d_type) {
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fsetfilecon(fd, MAGISK_CON);
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fchown(fd, 0, 0);
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}
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close(fd);
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}
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}
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void restorecon() {
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int fd;
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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);
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close(fd);
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lsetfilecon(MODULEROOT, SYSTEM_CON);
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fd = xopen(MODULEROOT, O_RDONLY | O_CLOEXEC);
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restore_syscon(fd);
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close(fd);
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fd = xopen(DATABIN, O_RDONLY | O_CLOEXEC);
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restore_magiskcon(fd);
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close(fd);
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}
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