ueventd: allow configuring SO_RCVBUF(FORCE) for the ueventd socket

Some configurations won't allow ueventd to have CAP_NET_ADMIN, so the
new default size of 16M is not possible for those.  Those
configurations also won't need such a large buffer size, so this
change allows devices to customize the SO_RCVBUF(FORCE) size for the
uevent socket.

This is done by adding the line 'uevent_socket_rcvbuf_size <size>' to
your device's ueventd.rc file.  <size> is specified as a byte count,
for example '16M' is 16MiB.

The last parsed uevent_socket_rcvbuf_size line is the one that is
used.

Bug: 120485624
Test: boot sailfish
Test: ueventd unit tests
Change-Id: If8123b92ca8a9b089ad50318caada2f21bc94707

init/first_stage_mount.cpp

@@ -132,7 +132,9 @@ static bool IsRecoveryMode() {
 // Class Definitions
 // -----------------
 FirstStageMount::FirstStageMount()
-    : need_dm_verity_(false), fstab_(fs_mgr_read_fstab_dt(), fs_mgr_free_fstab) {
+    : need_dm_verity_(false),
+      fstab_(fs_mgr_read_fstab_dt(), fs_mgr_free_fstab),
+      uevent_listener_(16 * 1024 * 1024) {
     // Stores fstab_->recs[] into mount_fstab_recs_ (vector<fstab_rec*>)
     // for easier manipulation later, e.g., range-base for loop.
     if (fstab_) {

init/uevent_listener.cpp

@@ -86,9 +86,8 @@ static void ParseEvent(const char* msg, Uevent* uevent) {
     }
 }
 
-UeventListener::UeventListener() {
-    // is 16MB enough? udev uses 128MB!
-    device_fd_.reset(uevent_open_socket(16 * 1024 * 1024, true));
+UeventListener::UeventListener(size_t uevent_socket_rcvbuf_size) {
+    device_fd_.reset(uevent_open_socket(uevent_socket_rcvbuf_size, true));
     if (device_fd_ == -1) {
         LOG(FATAL) << "Could not open uevent socket";
     }

init/uevent_listener.h

@@ -41,7 +41,7 @@ using ListenerCallback = std::function<ListenerAction(const Uevent&)>;
 
 class UeventListener {
   public:
-    UeventListener();
+    UeventListener(size_t uevent_socket_rcvbuf_size);
 
     void RegenerateUevents(const ListenerCallback& callback) const;
     ListenerAction RegenerateUeventsForPath(const std::string& path,

init/ueventd.cpp

@@ -233,29 +233,26 @@ int ueventd_main(int argc, char** argv) {
     SelabelInitialize();
 
     std::vector<std::unique_ptr<UeventHandler>> uevent_handlers;
-    UeventListener uevent_listener;
 
-    {
-        // Keep the current product name base configuration so we remain backwards compatible and
-        // allow it to override everything.
-        // TODO: cleanup platform ueventd.rc to remove vendor specific device node entries (b/34968103)
-        auto hardware = android::base::GetProperty("ro.hardware", "");
+    // Keep the current product name base configuration so we remain backwards compatible and
+    // allow it to override everything.
+    // TODO: cleanup platform ueventd.rc to remove vendor specific device node entries (b/34968103)
+    auto hardware = android::base::GetProperty("ro.hardware", "");
 
-        auto ueventd_configuration =
-                ParseConfig({"/ueventd.rc", "/vendor/ueventd.rc", "/odm/ueventd.rc",
-                             "/ueventd." + hardware + ".rc"});
+    auto ueventd_configuration = ParseConfig({"/ueventd.rc", "/vendor/ueventd.rc",
+                                              "/odm/ueventd.rc", "/ueventd." + hardware + ".rc"});
 
-        uevent_handlers.emplace_back(std::make_unique<DeviceHandler>(
-                std::move(ueventd_configuration.dev_permissions),
-                std::move(ueventd_configuration.sysfs_permissions),
-                std::move(ueventd_configuration.subsystems), fs_mgr_get_boot_devices(), true));
-        uevent_handlers.emplace_back(std::make_unique<FirmwareHandler>(
-                std::move(ueventd_configuration.firmware_directories)));
+    uevent_handlers.emplace_back(std::make_unique<DeviceHandler>(
+            std::move(ueventd_configuration.dev_permissions),
+            std::move(ueventd_configuration.sysfs_permissions),
+            std::move(ueventd_configuration.subsystems), fs_mgr_get_boot_devices(), true));
+    uevent_handlers.emplace_back(std::make_unique<FirmwareHandler>(
+            std::move(ueventd_configuration.firmware_directories)));
 
-        if (ueventd_configuration.enable_modalias_handling) {
-            uevent_handlers.emplace_back(std::make_unique<ModaliasHandler>());
-        }
+    if (ueventd_configuration.enable_modalias_handling) {
+        uevent_handlers.emplace_back(std::make_unique<ModaliasHandler>());
     }
+    UeventListener uevent_listener(ueventd_configuration.uevent_socket_rcvbuf_size);
 
     if (access(COLDBOOT_DONE, F_OK) != 0) {
         ColdBoot cold_boot(uevent_listener, uevent_handlers);

init/ueventd_parser.cpp

@@ -19,9 +19,13 @@
 #include <grp.h>
 #include <pwd.h>
 
+#include <android-base/parseint.h>
+
 #include "keyword_map.h"
 #include "parser.h"
 
+using android::base::ParseByteCount;
+
 namespace android {
 namespace init {
 
@@ -101,6 +105,22 @@ Result<Success> ParseModaliasHandlingLine(std::vector<std::string>&& args,
     return Success();
 }
 
+Result<Success> ParseUeventSocketRcvbufSizeLine(std::vector<std::string>&& args,
+                                                size_t* uevent_socket_rcvbuf_size) {
+    if (args.size() != 2) {
+        return Error() << "uevent_socket_rcvbuf_size lines take exactly one parameter";
+    }
+
+    size_t parsed_size;
+    if (!ParseByteCount(args[1], &parsed_size)) {
+        return Error() << "could not parse size '" << args[1] << "' for uevent_socket_rcvbuf_line";
+    }
+
+    *uevent_socket_rcvbuf_size = parsed_size;
+
+    return Success();
+}
+
 class SubsystemParser : public SectionParser {
   public:
     SubsystemParser(std::vector<Subsystem>* subsystems) : subsystems_(subsystems) {}
@@ -202,6 +222,9 @@ UeventdConfiguration ParseConfig(const std::vector<std::string>& configs) {
     parser.AddSingleLineParser("modalias_handling",
                                std::bind(ParseModaliasHandlingLine, _1,
                                          &ueventd_configuration.enable_modalias_handling));
+    parser.AddSingleLineParser("uevent_socket_rcvbuf_size",
+                               std::bind(ParseUeventSocketRcvbufSizeLine, _1,
+                                         &ueventd_configuration.uevent_socket_rcvbuf_size));
 
     for (const auto& config : configs) {
         parser.ParseConfig(config);

init/ueventd_parser.h

@@ -31,6 +31,7 @@ struct UeventdConfiguration {
     std::vector<Permissions> dev_permissions;
     std::vector<std::string> firmware_directories;
     bool enable_modalias_handling = false;
+    size_t uevent_socket_rcvbuf_size = 0;
 };
 
 UeventdConfiguration ParseConfig(const std::vector<std::string>& configs);

init/ueventd_parser_test.cpp

@@ -138,6 +138,15 @@ firmware_directories /more
     TestUeventdFile(ueventd_file, {{}, {}, {}, firmware_directories});
 }
 
+TEST(ueventd_parser, UeventSocketRcvbufSize) {
+    auto ueventd_file = R"(
+uevent_socket_rcvbuf_size 8k
+uevent_socket_rcvbuf_size 8M
+)";
+
+    TestUeventdFile(ueventd_file, {{}, {}, {}, {}, false, 8 * 1024 * 1024});
+}
+
 TEST(ueventd_parser, AllTogether) {
     auto ueventd_file = R"(
 
@@ -169,6 +178,8 @@ subsystem test_devpath_dirname
 /sys/devices/virtual/*/input   poll_delay  0660  root   input
 firmware_directories /more
 
+uevent_socket_rcvbuf_size 6M
+
 #ending comment
 )";
 
@@ -197,8 +208,10 @@ firmware_directories /more
             "/more",
     };
 
-    TestUeventdFile(ueventd_file,
-                    {subsystems, sysfs_permissions, permissions, firmware_directories});
+    size_t uevent_socket_rcvbuf_size = 6 * 1024 * 1024;
+
+    TestUeventdFile(ueventd_file, {subsystems, sysfs_permissions, permissions, firmware_directories,
+                                   false, uevent_socket_rcvbuf_size});
 }
 
 // All of these lines are ill-formed, so test that there is 0 output.
@@ -213,6 +226,8 @@ firmware_directories #no directory listed
 /sys/devices/platform/trusty.*      trusty_version        0440  baduidbad   log
 /sys/devices/platform/trusty.*      trusty_version        0440  root   baduidbad
 
+uevent_socket_rcvbuf_size blah
+
 subsystem #no name
 
 )";

rootdir/ueventd.rc

@@ -1,4 +1,5 @@
 firmware_directories /etc/firmware/ /odm/firmware/ /vendor/firmware/ /firmware/image/
+uevent_socket_rcvbuf_size 16M
 
 subsystem adf
     devname uevent_devname