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platform_system_core
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Add support for esdfs mounting 

If sdcardfs is turned off, try mounting esdfs.

Test: Override ro.sys.sdcardfs to be false, or run
      sm set-sdcardfs off. If the kernel contains
      esdfs, it will use it.
Bug: 63876697
Change-Id: I4db8bf336743edf62edfae41d753b1e3af163950
This commit is contained in:
Daniel Rosenberg 2018-01-17 18:11:20 -08:00
parent 334d2187e4
commit c336f86284
1 changed files with 68 additions and 13 deletions
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81
sdcard/sdcard.cpp
View File

@ -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;
}