From 31525f5cb659a51194a7e4710528e54ff91444d8 Mon Sep 17 00:00:00 2001
From: Tom Cherry <tomcherry@google.com>
Date: Wed, 9 May 2018 18:33:31 -0700
Subject: [PATCH] init: implement getpwnam for host init verifier

Bug: 36970783
Test: test bullhead successfully at TOT
Test: create errors and check that they're caught
Test: create uid in passwd and check that it's successful
Change-Id: I237fb8df16a294757fe898bdbbd42e850bcb8301
---
 init/Android.bp             |  5 ++-
 init/host_init_verifier.cpp | 80 ++++++++++++++++++++++++++++++++-----
 2 files changed, 74 insertions(+), 11 deletions(-)

diff --git a/init/Android.bp b/init/Android.bp
index f579647a8..25877c083 100644
--- a/init/Android.bp
+++ b/init/Android.bp
@@ -250,7 +250,10 @@ cc_binary {
     proto: {
         type: "lite",
     },
-    generated_headers: ["generated_stub_builtin_function_map"],
+    generated_headers: [
+        "generated_stub_builtin_function_map",
+        "generated_android_ids"
+    ],
     target: {
         android: {
             enabled: false,
diff --git a/init/host_init_verifier.cpp b/init/host_init_verifier.cpp
index c6ec078df..d6884af91 100644
--- a/init/host_init_verifier.cpp
+++ b/init/host_init_verifier.cpp
@@ -14,12 +14,17 @@
 // limitations under the License.
 //
 
+#include <errno.h>
 #include <pwd.h>
+#include <stdio.h>
 
 #include <iostream>
 #include <string>
+#include <vector>
 
+#include <android-base/file.h>
 #include <android-base/logging.h>
+#include <android-base/parseint.h>
 #include <android-base/strings.h>
 
 #include "action.h"
@@ -31,21 +36,74 @@
 #include "result.h"
 #include "service.h"
 
+#define EXCLUDE_FS_CONFIG_STRUCTURES
+#include "generated_android_ids.h"
+
 using namespace std::literals;
 
+using android::base::ParseInt;
+using android::base::ReadFileToString;
 using android::base::Split;
 
-// The host passwd file won't have the Android entries, so we fake success here.
+static std::string out_dir;
+
+static std::vector<std::pair<std::string, int>> GetVendorPasswd() {
+    std::string passwd;
+    if (!ReadFileToString(out_dir + "/vendor/etc/passwd", &passwd)) {
+        return {};
+    }
+
+    std::vector<std::pair<std::string, int>> result;
+    auto passwd_lines = Split(passwd, "\n");
+    for (const auto& line : passwd_lines) {
+        auto split_line = Split(line, ":");
+        if (split_line.size() < 3) {
+            continue;
+        }
+        int uid = 0;
+        if (!ParseInt(split_line[2], &uid)) {
+            continue;
+        }
+        result.emplace_back(split_line[0], uid);
+    }
+    return result;
+}
+
 passwd* getpwnam(const char* login) {  // NOLINT: implementing bad function.
-    char dummy_buf[] = "dummy";
-    static passwd dummy_passwd = {
-        .pw_name = dummy_buf,
-        .pw_dir = dummy_buf,
-        .pw_shell = dummy_buf,
-        .pw_uid = 123,
-        .pw_gid = 123,
+    // This isn't thread safe, but that's okay for our purposes.
+    static char static_name[32] = "";
+    static char static_dir[32] = "/";
+    static char static_shell[32] = "/system/bin/sh";
+    static passwd static_passwd = {
+        .pw_name = static_name,
+        .pw_dir = static_dir,
+        .pw_shell = static_shell,
+        .pw_uid = 0,
+        .pw_gid = 0,
     };
-    return &dummy_passwd;
+
+    for (size_t n = 0; n < android_id_count; ++n) {
+        if (!strcmp(android_ids[n].name, login)) {
+            snprintf(static_name, sizeof(static_name), "%s", android_ids[n].name);
+            static_passwd.pw_uid = android_ids[n].aid;
+            static_passwd.pw_gid = android_ids[n].aid;
+            return &static_passwd;
+        }
+    }
+
+    static const auto vendor_passwd = GetVendorPasswd();
+
+    for (const auto& [name, uid] : vendor_passwd) {
+        if (name == login) {
+            snprintf(static_name, sizeof(static_name), "%s", name.c_str());
+            static_passwd.pw_uid = uid;
+            static_passwd.pw_gid = uid;
+            return &static_passwd;
+        }
+    }
+
+    errno = ENOENT;
+    return nullptr;
 }
 
 namespace android {
@@ -65,6 +123,8 @@ int main(int argc, char** argv) {
         return -1;
     }
 
+    out_dir = argv[1];
+
     auto properties = Split(argv[2], ",");
     for (const auto& property : properties) {
         auto split_property = Split(property, "=");
@@ -81,7 +141,7 @@ int main(int argc, char** argv) {
     Parser parser;
     parser.AddSectionParser("service", std::make_unique<ServiceParser>(&sl, nullptr));
     parser.AddSectionParser("on", std::make_unique<ActionParser>(&am, nullptr));
-    parser.AddSectionParser("import", std::make_unique<HostImportParser>(argv[1], &parser));
+    parser.AddSectionParser("import", std::make_unique<HostImportParser>(out_dir, &parser));
 
     if (!parser.ParseConfig(argv[1] + "/root/init.rc"s)) {
         LOG(ERROR) << "Failed to find root init.rc script";