Merge "Add support for esdfs mounting" (6de4e7ef) · Commits · e / os / android_system_core

sdcard/sdcard.cpp

+68 −13

Original line number	Diff line number	Diff line
		@@ -43,6 +43,44 @@

		#include <private/android_filesystem_config.h>

		#define PROP_SDCARDFS_DEVICE "ro.sys.sdcardfs"
		#define PROP_SDCARDFS_USER "persist.sys.sdcardfs"

		static bool supports_esdfs(void) {
		std::string filesystems;
		if (!android::base::ReadFileToString("/proc/filesystems", &filesystems)) {
		PLOG(ERROR) << "Could not read /proc/filesystems";
		return false;
		}
		for (const auto& fs : android::base::Split(filesystems, "\n")) {
		if (fs.find("esdfs") != std::string::npos) return true;
		}
		return false;
		}

		static bool should_use_sdcardfs(void) {
		char property[PROPERTY_VALUE_MAX];

		// Allow user to have a strong opinion about state
		property_get(PROP_SDCARDFS_USER, property, "");
		if (!strcmp(property, "force_on")) {
		LOG(WARNING) << "User explicitly enabled sdcardfs";
		return true;
		} else if (!strcmp(property, "force_off")) {
		LOG(WARNING) << "User explicitly disabled sdcardfs";
		return !supports_esdfs();
		}

		// Fall back to device opinion about state
		if (property_get_bool(PROP_SDCARDFS_DEVICE, true)) {
		LOG(WARNING) << "Device explicitly enabled sdcardfs";
		return true;
		} else {
		LOG(WARNING) << "Device explicitly disabled sdcardfs";
		return !supports_esdfs();
		}
		}

		// NOTE: This is a vestigial program that simply exists to mount the in-kernel
		// sdcardfs filesystem. The older FUSE-based design that used to live here has
		// been completely removed to avoid confusion.
		@@ -61,7 +99,7 @@ static void drop_privs(uid_t uid, gid_t gid) {

		static bool sdcardfs_setup(const std::string& source_path, const std::string& dest_path,
		uid_t fsuid, gid_t fsgid, bool multi_user, userid_t userid, gid_t gid,
		mode_t mask, bool derive_gid, bool default_normal) {
		mode_t mask, bool derive_gid, bool default_normal, bool use_esdfs) {
		// Try several attempts, each time with one less option, to gracefully
		// handle older kernels that aren't updated yet.
		for (int i = 0; i < 4; i++) {
		@@ -72,7 +110,7 @@ static bool sdcardfs_setup(const std::string& source_path, const std::string& de

		auto opts = android::base::StringPrintf("fsuid=%d,fsgid=%d,%smask=%d,userid=%d,gid=%d",
		fsuid, fsgid, new_opts.c_str(), mask, userid, gid);
		if (mount(source_path.c_str(), dest_path.c_str(), "sdcardfs",
		if (mount(source_path.c_str(), dest_path.c_str(), use_esdfs ? "esdfs" : "sdcardfs",
		MS_NOSUID \| MS_NODEV \| MS_NOEXEC \| MS_NOATIME, opts.c_str()) == -1) {
		PLOG(WARNING) << "Failed to mount sdcardfs with options " << opts;
		} else {
		@@ -104,9 +142,21 @@ static bool sdcardfs_setup_bind_remount(const std::string& source_path, const st
		return true;
		}

		static bool sdcardfs_setup_secondary(const std::string& default_path, const std::string& source_path,
		const std::string& dest_path, uid_t fsuid, gid_t fsgid,
		bool multi_user, userid_t userid, gid_t gid, mode_t mask,
		bool derive_gid, bool default_normal, bool use_esdfs) {
		if (use_esdfs) {
		return sdcardfs_setup(source_path, dest_path, fsuid, fsgid, multi_user, userid, gid, mask,
		derive_gid, default_normal, use_esdfs);
		} else {
		return sdcardfs_setup_bind_remount(default_path, dest_path, gid, mask);
		}
		}

		static void run_sdcardfs(const std::string& source_path, const std::string& label, uid_t uid,
		gid_t gid, userid_t userid, bool multi_user, bool full_write,
		bool derive_gid, bool default_normal) {
		bool derive_gid, bool default_normal, bool use_esdfs) {
		std::string dest_path_default = "/mnt/runtime/default/" + label;
		std::string dest_path_read = "/mnt/runtime/read/" + label;
		std::string dest_path_write = "/mnt/runtime/write/" + label;
		@@ -116,10 +166,13 @@ static void run_sdcardfs(const std::string& source_path, const std::string& labe
		// Multi-user storage is fully isolated per user, so "other"
		// permissions are completely masked off.
		if (!sdcardfs_setup(source_path, dest_path_default, uid, gid, multi_user, userid,
		AID_SDCARD_RW, 0006, derive_gid, default_normal) \|\|
		!sdcardfs_setup_bind_remount(dest_path_default, dest_path_read, AID_EVERYBODY, 0027) \|\|
		!sdcardfs_setup_bind_remount(dest_path_default, dest_path_write, AID_EVERYBODY,
		full_write ? 0007 : 0027)) {
		AID_SDCARD_RW, 0006, derive_gid, default_normal, use_esdfs) \|\|
		!sdcardfs_setup_secondary(dest_path_default, source_path, dest_path_read, uid, gid,
		multi_user, userid, AID_EVERYBODY, 0027, derive_gid,
		default_normal, use_esdfs) \|\|
		!sdcardfs_setup_secondary(dest_path_default, source_path, dest_path_write, uid, gid,
		multi_user, userid, AID_EVERYBODY, full_write ? 0007 : 0027,
		derive_gid, default_normal, use_esdfs)) {
		LOG(FATAL) << "failed to sdcardfs_setup";
		}
		} else {
		@@ -127,11 +180,13 @@ static void run_sdcardfs(const std::string& source_path, const std::string& labe
		// the Android directories are masked off to a single user
		// deep inside attr_from_stat().
		if (!sdcardfs_setup(source_path, dest_path_default, uid, gid, multi_user, userid,
		AID_SDCARD_RW, 0006, derive_gid, default_normal) \|\|
		!sdcardfs_setup_bind_remount(dest_path_default, dest_path_read, AID_EVERYBODY,
		full_write ? 0027 : 0022) \|\|
		!sdcardfs_setup_bind_remount(dest_path_default, dest_path_write, AID_EVERYBODY,
		full_write ? 0007 : 0022)) {
		AID_SDCARD_RW, 0006, derive_gid, default_normal, use_esdfs) \|\|
		!sdcardfs_setup_secondary(dest_path_default, source_path, dest_path_read, uid, gid,
		multi_user, userid, AID_EVERYBODY, full_write ? 0027 : 0022,
		derive_gid, default_normal, use_esdfs) \|\|
		!sdcardfs_setup_secondary(dest_path_default, source_path, dest_path_write, uid, gid,
		multi_user, userid, AID_EVERYBODY, full_write ? 0007 : 0022,
		derive_gid, default_normal, use_esdfs)) {
		LOG(FATAL) << "failed to sdcardfs_setup";
		}
		}
		@@ -242,6 +297,6 @@ int main(int argc, char **argv) {
		}

		run_sdcardfs(source_path, label, uid, gid, userid, multi_user, full_write, derive_gid,
		default_normal);
		default_normal, !should_use_sdcardfs());
		return 1;
		}