libfiemap_writer: Improve device unwrapping to support simple linear devices.
Normally we reject complex dm targets that would invalidate or shift the
block mappings returned via FIEMAP/FIBMAP. Currently the only targets
allowed are crypt, default-key, and bow. This patch adds support for
"linear" as long as there is only one linear target and it targets
sector 0 of the underlying block device.
This is useful for testing gsid, so we can simulate how a
metadata-encrypted device works without having to create a dm-crypt or
dm-default-key node.
Bug: 134536978
Test: manual test
Change-Id: I7c12bc20d95ff4c90402e66bafb4cf2fce7818e2
diff --git a/fs_mgr/libdm/dm.cpp b/fs_mgr/libdm/dm.cpp
index c2917a4..d3c0c1f 100644
--- a/fs_mgr/libdm/dm.cpp
+++ b/fs_mgr/libdm/dm.cpp
@@ -368,5 +368,13 @@
}
}
+std::string DeviceMapper::GetTargetType(const struct dm_target_spec& spec) {
+ if (const void* p = memchr(spec.target_type, '\0', sizeof(spec.target_type))) {
+ ptrdiff_t length = reinterpret_cast<const char*>(p) - spec.target_type;
+ return std::string{spec.target_type, static_cast<size_t>(length)};
+ }
+ return std::string{spec.target_type, sizeof(spec.target_type)};
+}
+
} // namespace dm
} // namespace android
diff --git a/fs_mgr/libdm/dm_test.cpp b/fs_mgr/libdm/dm_test.cpp
index dc47c33..2bf5643 100644
--- a/fs_mgr/libdm/dm_test.cpp
+++ b/fs_mgr/libdm/dm_test.cpp
@@ -170,6 +170,10 @@
EXPECT_EQ(targets[1].spec.sector_start, 1);
EXPECT_EQ(targets[1].spec.length, 1);
+ // Test GetTargetType().
+ EXPECT_EQ(DeviceMapper::GetTargetType(targets[0].spec), std::string{"linear"});
+ EXPECT_EQ(DeviceMapper::GetTargetType(targets[1].spec), std::string{"linear"});
+
// Normally the TestDevice destructor would delete this, but at least one
// test should ensure that device deletion works.
ASSERT_TRUE(dev.Destroy());
diff --git a/fs_mgr/libdm/include/libdm/dm.h b/fs_mgr/libdm/include/libdm/dm.h
index d7e8aa9..fe736a3 100644
--- a/fs_mgr/libdm/include/libdm/dm.h
+++ b/fs_mgr/libdm/include/libdm/dm.h
@@ -136,6 +136,8 @@
// mapper device from the kernel.
bool GetTableInfo(const std::string& name, std::vector<TargetInfo>* table);
+ static std::string GetTargetType(const struct dm_target_spec& spec);
+
private:
// Maximum possible device mapper targets registered in the kernel.
// This is only used to read the list of targets from kernel so we allocate
diff --git a/fs_mgr/libfiemap_writer/fiemap_writer.cpp b/fs_mgr/libfiemap_writer/fiemap_writer.cpp
index f064436..0a3ba6c 100644
--- a/fs_mgr/libfiemap_writer/fiemap_writer.cpp
+++ b/fs_mgr/libfiemap_writer/fiemap_writer.cpp
@@ -89,6 +89,31 @@
return true;
}
+static bool ValidateDmTarget(const DeviceMapper::TargetInfo& target) {
+ const auto& entry = target.spec;
+ if (entry.sector_start != 0) {
+ LOG(INFO) << "Stopping at target with non-zero starting sector";
+ return false;
+ }
+
+ auto target_type = DeviceMapper::GetTargetType(entry);
+ if (target_type == "bow" || target_type == "default-key" || target_type == "crypt") {
+ return true;
+ }
+ if (target_type == "linear") {
+ auto pieces = android::base::Split(target.data, " ");
+ if (pieces[1] != "0") {
+ LOG(INFO) << "Stopping at complex linear target with non-zero starting sector: "
+ << pieces[1];
+ return false;
+ }
+ return true;
+ }
+
+ LOG(INFO) << "Stopping at complex target type " << target_type;
+ return false;
+}
+
static bool DeviceMapperStackPop(const std::string& bdev, std::string* bdev_raw) {
*bdev_raw = bdev;
@@ -128,15 +153,7 @@
LOG(INFO) << "Stopping at complex table for " << dm_name << " at " << bdev;
return true;
}
- const auto& entry = table[0].spec;
- std::string target_type(std::string(entry.target_type, sizeof(entry.target_type)).c_str());
- if (target_type != "bow" && target_type != "default-key" && target_type != "crypt") {
- LOG(INFO) << "Stopping at complex target-type " << target_type << " for " << dm_name
- << " at " << bdev;
- return true;
- }
- if (entry.sector_start != 0) {
- LOG(INFO) << "Stopping at target-type with non-zero starting sector";
+ if (!ValidateDmTarget(table[0])) {
return true;
}