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Fix a few problems with darling.c
* Check for the kernel module being already loaded before trying to load it
* Correctly set UID/GID so that the shell doesn't drop them
* Remove module unloading functionality
* Fix droppping GID in prelaunchd
* Change prelaunchd name in "ps a" output to be "darling-init"
+35
-39
+34
-36
src/dyld/darling.c
+34
-36
src/dyld/darling.c
···
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const char* DARLING_INIT_COMM = "darling-init";
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char *prefix;
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uid_t g_originalUid, g_originalGid;
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+
char **g_argv, **g_envp;
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-
int main(int argc, char const ** argv)
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int main(int argc, char ** argv, char ** envp)
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{
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pid_t pidInit, pidChild;
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int wstatus;
···
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return 1;
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}
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g_argv = argv;
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g_envp = envp;
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+
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if (geteuid() != 0)
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{
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missingSetuidRoot();
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return 1;
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}
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-
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if (loadKernelModule())
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return 1;
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g_originalUid = getuid();
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g_originalGid = getgid();
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setuid(0);
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setgid(0);
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if (!isModuleLoaded())
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loadKernelModule();
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+
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prefix = getenv("DPREFIX");
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if (!prefix)
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prefix = defaultPrefixPath();
···
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};
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int option_index = 0;
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c = getopt_long(argc, (char *const *)argv, "", long_options, &option_index);
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c = getopt_long(argc, argv, "", long_options, &option_index);
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if (c == -1)
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{
···
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waitpid(pidChild, &wstatus, 0);
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// Should we unloadKernelModule() here? Others may be still using it
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if (WIFEXITED(wstatus))
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return WEXITSTATUS(wstatus);
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if (WIFSIGNALED(wstatus))
···
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exit(1);
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}
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*/
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-
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setresuid(g_originalUid, g_originalUid, g_originalUid);
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// Drop the privileges. It's important to drop GID first, because
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// non-root users can't change their GID.
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setresgid(g_originalGid, g_originalGid, g_originalGid);
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setresuid(g_originalUid, g_originalUid, g_originalUid);
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/*
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if (setns(fdNS, CLONE_NEWUSER) != 0)
···
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char *opts;
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char putOld[4096];
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char *p;
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close(pipefd[0]);
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···
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exit(1);
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}
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// Drop the privileges
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setresuid(g_originalUid, g_originalUid, g_originalUid);
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// Drop the privileges. It's important to drop GID first, because
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// non-root users can't change their GID.
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setresgid(g_originalGid, g_originalGid, g_originalGid);
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setresuid(g_originalUid, g_originalUid, g_originalUid);
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prctl(PR_SET_DUMPABLE, 1, 0, 0, 0);
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// Set name to darling-init
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prctl(PR_SET_NAME, DARLING_INIT_COMM, 0, 0);
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p = stpcpy(g_argv[0], DARLING_INIT_COMM);
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memset(p, 0, g_envp[0] - p);
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/*
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if (unshare(CLONE_NEWUSER) != 0)
···
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return 0;
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}
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int loadKernelModule()
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void loadKernelModule()
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{
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FILE* fp;
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char output[1024];
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int status;
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FILE *fp = popen("/sbin/modprobe darling-mach", "w");
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if ((fp = popen("/sbin/modprobe darling-mach", "r")) == NULL)
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if (fp == NULL)
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{
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fprintf(stderr, "Failed to run modprobe\n");
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return 1;
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fprintf(stderr, "Failed to run modprobe: %s\n", strerror(errno));
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exit(1);
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}
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while (fgets(output, sizeof(output), fp) != NULL)
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status = pclose(fp);
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if (WIFEXITED(status) && WEXITSTATUS(status) == 0)
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{
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printf("%s", output);
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}
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if (WEXITSTATUS(pclose(fp)) == 0)
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{
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fprintf(stderr, "Loaded kernel module successfully\n");
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return 0;
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fprintf(stderr, "Loaded the kernel module\n");
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return;
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}
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else
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{
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fprintf(stderr, "Failed to load the kernel module\n");
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return 1;
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exit(1);
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}
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}
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int unloadKernelModule()
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{
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if(syscall(SYS_delete_module, "darling_mach", 0))
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{
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fprintf(stderr, "Cannot unload kernel module: %s\n", strerror(errno));
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return 1;
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}
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return 0;
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}