Add runconuid command to xbin
Change-Id: Iebaabb316682acd4415673f1ef3727a25922225d
diff --git a/runconuid/Android.mk b/runconuid/Android.mk
new file mode 100644
index 0000000..c36baae
--- /dev/null
+++ b/runconuid/Android.mk
@@ -0,0 +1,15 @@
+LOCAL_PATH:= $(call my-dir)
+include $(CLEAR_VARS)
+
+LOCAL_CFLAGS := -std=c11 -Wall -Werror
+
+LOCAL_SRC_FILES:= runconuid.cpp
+
+LOCAL_MODULE:= runconuid
+
+LOCAL_MODULE_PATH := $(TARGET_OUT_OPTIONAL_EXECUTABLES)
+LOCAL_MODULE_TAGS := debug
+
+LOCAL_STATIC_LIBRARIES := libselinux
+
+include $(BUILD_EXECUTABLE)
diff --git a/runconuid/MODULE_LICENSE_APACHE2 b/runconuid/MODULE_LICENSE_APACHE2
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/runconuid/MODULE_LICENSE_APACHE2
diff --git a/runconuid/NOTICE b/runconuid/NOTICE
new file mode 100644
index 0000000..c5b1efa
--- /dev/null
+++ b/runconuid/NOTICE
@@ -0,0 +1,190 @@
+
+ Copyright (c) 2005-2008, The Android Open Source Project
+
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+
+ Unless required by applicable law or agreed to in writing, software
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+ form, that is based on (or derived from) the Work and for which the
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diff --git a/runconuid/runconuid.cpp b/runconuid/runconuid.cpp
new file mode 100644
index 0000000..496d51f
--- /dev/null
+++ b/runconuid/runconuid.cpp
@@ -0,0 +1,230 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+const char* optstr = "<1u:g:G:c:s";
+const char* usage =
+ R"(usage: runconuid [-s] [-u UID] [-g GID] [-G GROUPS] [-c CONTEXT] COMMAND ARGS
+
+Run a command in the specified security context, as the specified user,
+with the specified group membership.
+
+-c SELinux context
+-g Group ID by name or numeric value
+-G List of groups by name or numeric value
+-s Set enforcing mode
+-u User ID by name or numeric value
+)";
+
+#include <assert.h>
+#include <grp.h>
+#include <pwd.h>
+#include <selinux/selinux.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <sys/ptrace.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+static uid_t uid = -1;
+static gid_t gid = -1;
+static gid_t* groups = nullptr;
+static size_t ngroups = 0;
+static char* context = nullptr;
+static bool setenforce = false;
+static char** child_argv = nullptr;
+
+[[noreturn]] void perror_exit(const char* message) {
+ perror(message);
+ exit(1);
+}
+
+void do_child(void) {
+ if (context && setexeccon(context) < 0) {
+ perror_exit("Setting context to failed");
+ }
+
+ if (ngroups && setgroups(ngroups, groups) < 0) {
+ perror_exit("Setting supplementary groups failed.");
+ }
+
+ if (gid != (gid_t) -1 && setresgid(gid, gid, gid) < 0) {
+ perror_exit("Setting group failed.");
+ }
+
+ if (uid != (uid_t) -1 && setresuid(uid, uid, uid) < 0) {
+ perror_exit("Setting user failed.");
+ }
+
+ ptrace(PTRACE_TRACEME, 0, 0, 0);
+ raise(SIGSTOP);
+ execvp(child_argv[0], child_argv);
+ perror_exit("Failed to execve");
+}
+
+uid_t lookup_uid(char* c) {
+ struct passwd* pw;
+ uid_t u;
+
+ if (sscanf(c, "%d", &u) == 1) {
+ return u;
+ }
+
+ if ((pw = getpwnam(c)) != 0) {
+ return pw->pw_uid;
+ }
+
+ perror_exit("Could not resolve user ID by name");
+}
+
+gid_t lookup_gid(char* c) {
+ struct group* gr;
+ gid_t g;
+
+ if (sscanf(c, "%d", &g) == 1) {
+ return g;
+ }
+
+ if ((gr = getgrnam(c)) != 0) {
+ return gr->gr_gid;
+ }
+
+ perror_exit("Could not resolve group ID by name");
+}
+
+void lookup_groups(char* c) {
+ char* group;
+
+ // Count the number of groups
+ for (group = c; *group; group++) {
+ if (*group == ',') {
+ ngroups++;
+ *group = '\0';
+ }
+ }
+
+ // The last group is not followed by a comma.
+ ngroups++;
+
+ // Allocate enough space for all of them
+ groups = (gid_t*)calloc(ngroups, sizeof(gid_t));
+ group = c;
+
+ // Fill in the group IDs
+ for (size_t n = 0; n < ngroups; n++) {
+ groups[n] = lookup_gid(group);
+ group += strlen(group) + 1;
+ }
+}
+
+void parse_arguments(int argc, char** argv) {
+ int c;
+
+ while ((c = getopt(argc, argv, optstr)) != -1) {
+ switch (c) {
+ case 'u':
+ uid = lookup_uid(optarg);
+ break;
+ case 'g':
+ gid = lookup_gid(optarg);
+ break;
+ case 'G':
+ lookup_groups(optarg);
+ break;
+ case 's':
+ setenforce = true;
+ break;
+ case 'c':
+ context = optarg;
+ break;
+ default:
+ perror_exit(usage);
+ break;
+ }
+ }
+
+ child_argv = &argv[optind];
+
+ if (optind == argc) {
+ perror_exit(usage);
+ }
+}
+
+int main(int argc, char** argv) {
+ pid_t child;
+
+ parse_arguments(argc, argv);
+ child = fork();
+
+ if (child < 0) {
+ perror_exit("Could not fork.");
+ }
+
+ if (setenforce && is_selinux_enabled()) {
+ if (security_setenforce(0) < 0) {
+ perror("Couldn't set enforcing status to 0");
+ }
+ }
+
+ if (child == 0) {
+ do_child();
+ }
+
+ if (ptrace(PTRACE_ATTACH, child, 0, 0) < 0) {
+ int err = errno;
+ kill(SIGKILL, child);
+ errno = err;
+ perror_exit("Could not ptrace child.");
+ }
+
+ // Wait for the SIGSTOP
+ int status = 0;
+ if (-1 == wait(&status)) {
+ perror_exit("Could not wait for child SIGSTOP");
+ }
+
+ // Trace all syscalls.
+ ptrace(PTRACE_SETOPTIONS, child, 0, PTRACE_O_TRACESYSGOOD);
+
+ while (1) {
+ ptrace(PTRACE_SYSCALL, child, 0, 0);
+ waitpid(child, &status, 0);
+
+ // Child raises SIGINT after the execve, on the first instruction.
+ if (WIFSTOPPED(status) && WSTOPSIG(status) == SIGTRAP) {
+ break;
+ }
+
+ // Child did some other syscall.
+ if (WIFSTOPPED(status) && WSTOPSIG(status) & 0x80) {
+ continue;
+ }
+
+ // Child exited.
+ if (WIFEXITED(status)) {
+ exit(WEXITSTATUS(status));
+ }
+ }
+
+ if (setenforce && is_selinux_enabled()) {
+ if (security_setenforce(1) < 0) {
+ perror("Couldn't set enforcing status to 1");
+ }
+ }
+
+ ptrace(PTRACE_DETACH, child, 0, 0);
+ return 0;
+}
