285 lines
7.1 KiB
C
285 lines
7.1 KiB
C
/*
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* Copyright 2017, John Wu (@topjohnwu)
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* Copyright 2015, Pierre-Hugues Husson <phh@phh.me>
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* Copyright 2010, Adam Shanks (@ChainsDD)
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* Copyright 2008, Zinx Verituse (@zinxv)
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*/
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/* su.c - The main function running in the daemon
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*/
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#define _GNU_SOURCE
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <getopt.h>
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#include <fcntl.h>
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#include <pwd.h>
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#include <errno.h>
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#include <signal.h>
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#include <sched.h>
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#include <libgen.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <selinux/selinux.h>
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#include "magisk.h"
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#include "utils.h"
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#include "su.h"
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struct su_context *su_ctx;
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static void usage(int status) {
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FILE *stream = (status == EXIT_SUCCESS) ? stdout : stderr;
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fprintf(stream,
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"MagiskSU v" xstr(MAGISK_VERSION) "(" xstr(MAGISK_VER_CODE) ")\n\n"
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"Usage: su [options] [-] [user [argument...]]\n\n"
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"Options:\n"
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" -c, --command COMMAND pass COMMAND to the invoked shell\n"
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" -h, --help display this help message and exit\n"
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" -, -l, --login pretend the shell to be a login shell\n"
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" -m, -p,\n"
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" --preserve-environment preserve the entire environment\n"
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" -s, --shell SHELL use SHELL instead of the default " DEFAULT_SHELL "\n"
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" -v, --version display version number and exit\n"
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" -V display version code and exit,\n"
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" this is used almost exclusively by Superuser.apk\n"
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" -mm, -M,\n"
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" --mount-master run in the global mount namespace,\n"
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" use if you need to publicly apply mounts\n");
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exit2(status);
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}
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static char *concat_commands(int argc, char *argv[]) {
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char command[ARG_MAX];
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command[0] = '\0';
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for (int i = optind - 1; i < argc; ++i) {
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if (command[0])
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sprintf(command, "%s %s", command, argv[i]);
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else
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strcpy(command, argv[i]);
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}
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return strdup(command);
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}
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static void populate_environment(const struct su_context *ctx) {
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struct passwd *pw;
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if (ctx->to.keepenv)
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return;
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pw = getpwuid(ctx->to.uid);
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if (pw) {
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setenv("HOME", pw->pw_dir, 1);
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if (ctx->to.shell)
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setenv("SHELL", ctx->to.shell, 1);
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else
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setenv("SHELL", DEFAULT_SHELL, 1);
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if (ctx->to.login || ctx->to.uid) {
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setenv("USER", pw->pw_name, 1);
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setenv("LOGNAME", pw->pw_name, 1);
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}
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}
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}
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void set_identity(unsigned uid) {
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/*
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* Set effective uid back to root, otherwise setres[ug]id will fail
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* if uid isn't root.
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*/
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if (seteuid(0)) {
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PLOGE("seteuid (root)");
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}
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if (setresgid(uid, uid, uid)) {
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PLOGE("setresgid (%u)", uid);
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}
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if (setresuid(uid, uid, uid)) {
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PLOGE("setresuid (%u)", uid);
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}
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}
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static __attribute__ ((noreturn)) void allow() {
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char* argv[] = { NULL, NULL, NULL, NULL };
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if (su_ctx->info->access.notify || su_ctx->info->access.log)
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app_send_result(su_ctx, ALLOW);
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if (su_ctx->to.login)
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argv[0] = "-";
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else
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argv[0] = basename(su_ctx->to.shell);
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if (su_ctx->to.command) {
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argv[1] = "-c";
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argv[2] = su_ctx->to.command;
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}
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// Setup shell
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umask(022);
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populate_environment(su_ctx);
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set_identity(su_ctx->to.uid);
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execvp(su_ctx->to.shell, argv);
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fprintf(stderr, "Cannot execute %s: %s\n", su_ctx->to.shell, strerror(errno));
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PLOGE("exec");
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exit(EXIT_FAILURE);
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}
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static __attribute__ ((noreturn)) void deny() {
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if (su_ctx->info->access.notify || su_ctx->info->access.log)
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app_send_result(su_ctx, DENY);
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LOGW("su: request rejected (%u->%u)", su_ctx->info->uid, su_ctx->to.uid);
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fprintf(stderr, "%s\n", strerror(EACCES));
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exit(EXIT_FAILURE);
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}
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static void socket_cleanup() {
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if (su_ctx && su_ctx->sock_path[0]) {
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unlink(su_ctx->sock_path);
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su_ctx->sock_path[0] = '\0';
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}
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}
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static void cleanup_signal(int sig) {
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socket_cleanup();
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exit2(EXIT_FAILURE);
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}
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__attribute__ ((noreturn)) void exit2(int status) {
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// Handle the pipe, or the daemon will get stuck
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if (su_ctx->pipefd[0] >= 0) {
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xwrite(su_ctx->pipefd[1], &su_ctx->info->access.policy, sizeof(policy_t));
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close(su_ctx->pipefd[0]);
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close(su_ctx->pipefd[1]);
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}
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exit(status);
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}
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int su_daemon_main(int argc, char **argv) {
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int c, socket_serv_fd, fd;
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char result[64];
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struct option long_opts[] = {
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{ "command", required_argument, NULL, 'c' },
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{ "help", no_argument, NULL, 'h' },
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{ "login", no_argument, NULL, 'l' },
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{ "preserve-environment", no_argument, NULL, 'p' },
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{ "shell", required_argument, NULL, 's' },
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{ "version", no_argument, NULL, 'v' },
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{ "context", required_argument, NULL, 'z' },
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{ "mount-master", no_argument, NULL, 'M' },
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{ NULL, 0, NULL, 0 },
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};
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while ((c = getopt_long(argc, argv, "c:hlmps:Vvuz:M", long_opts, NULL)) != -1) {
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switch (c) {
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case 'c':
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su_ctx->to.command = concat_commands(argc, argv);
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optind = argc;
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break;
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case 'h':
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usage(EXIT_SUCCESS);
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break;
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case 'l':
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su_ctx->to.login = 1;
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break;
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case 'm':
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case 'p':
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su_ctx->to.keepenv = 1;
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break;
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case 's':
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su_ctx->to.shell = optarg;
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break;
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case 'V':
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printf("%d\n", MAGISK_VER_CODE);
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exit2(EXIT_SUCCESS);
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case 'v':
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printf("%s\n", MAGISKSU_VER_STR);
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exit2(EXIT_SUCCESS);
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case 'z':
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// Do nothing, placed here for legacy support :)
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break;
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case 'M':
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su_ctx->info->dbs.v[SU_MNT_NS] = NAMESPACE_MODE_GLOBAL;
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break;
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default:
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/* Bionic getopt_long doesn't terminate its error output by newline */
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fprintf(stderr, "\n");
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usage(2);
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}
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}
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if (optind < argc && strcmp(argv[optind], "-") == 0) {
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su_ctx->to.login = 1;
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optind++;
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}
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/* username or uid */
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if (optind < argc) {
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struct passwd *pw;
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pw = getpwnam(argv[optind]);
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if (pw)
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su_ctx->to.uid = pw->pw_uid;
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else
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su_ctx->to.uid = atoi(argv[optind]);
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optind++;
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}
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// Handle namespaces
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switch (su_ctx->info->dbs.v[SU_MNT_NS]) {
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case NAMESPACE_MODE_GLOBAL:
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LOGD("su: use global namespace\n");
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break;
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case NAMESPACE_MODE_REQUESTER:
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LOGD("su: use namespace of pid=[%d]\n", su_ctx->pid);
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if (switch_mnt_ns(su_ctx->pid)) {
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LOGD("su: setns failed, fallback to isolated\n");
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unshare(CLONE_NEWNS);
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}
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break;
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case NAMESPACE_MODE_ISOLATE:
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LOGD("su: use new isolated namespace\n");
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unshare(CLONE_NEWNS);
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break;
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}
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// Change directory to cwd
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chdir(su_ctx->cwd);
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// New request or no db exist, notify user for response
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if (su_ctx->pipefd[0] >= 0) {
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socket_serv_fd = socket_create_temp(su_ctx->sock_path, sizeof(su_ctx->sock_path));
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setup_sighandlers(cleanup_signal);
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// Start activity
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app_send_request(su_ctx);
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atexit(socket_cleanup);
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fd = socket_accept(socket_serv_fd);
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socket_send_request(fd, su_ctx);
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socket_receive_result(fd, result, sizeof(result));
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close(fd);
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close(socket_serv_fd);
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socket_cleanup();
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if (strcmp(result, "socket:ALLOW") == 0)
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su_ctx->info->access.policy = ALLOW;
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else
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su_ctx->info->access.policy = DENY;
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// Report the policy to main daemon
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xwrite(su_ctx->pipefd[1], &su_ctx->info->access.policy, sizeof(policy_t));
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close(su_ctx->pipefd[0]);
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close(su_ctx->pipefd[1]);
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}
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if (su_ctx->info->access.policy == ALLOW)
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allow();
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else
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deny();
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}
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