Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit e35fef3e authored by Steven Moreland's avatar Steven Moreland
Browse files

libbinder: allow stability downgrade 

For instance, use a VINTF interface inside the system image without
adding it to the VINTF manifest (e.g. for testing, in this case, the
interface can't be used between system and vendor).

Bug: 183154648
Test: binderStabilityTest
Change-Id: I38019e226547b2437b920e79c252c7e55c17f7e4
parent a647f2bc

libs/binder/Stability.cpp

+30 −7
Original line number Diff line number Diff line
@@ -38,6 +38,18 @@ Stability::Category Stability::Category::currentFromLevel(Level level) { 
    };

}



void Stability::forceDowngradeCompilationUnit(const sp<IBinder>& binder) {

    // Downgrading a remote binder would require also copying the version from

    // the binder sent here. In practice though, we don't need to downgrade the

    // stability of a remote binder, since this would as an effect only restrict

    // what we can do to it.

    LOG_ALWAYS_FATAL_IF(!binder || !binder->localBinder(), "Can only downgrade local binder");



    auto stability = Category::currentFromLevel(getLocalLevel());

    status_t result = setRepr(binder.get(), stability.repr(), REPR_LOG | REPR_ALLOW_DOWNGRADE);

    LOG_ALWAYS_FATAL_IF(result != OK, "Should only mark known object.");

}



std::string Stability::Category::debugString() {

    return levelString(level) + " wire protocol version "

        + std::to_string(version);
@@ -45,13 +57,13 @@ std::string Stability::Category::debugString() { 


void Stability::markCompilationUnit(IBinder* binder) {

    auto stability = Category::currentFromLevel(getLocalLevel());

    status_t result = setRepr(binder, stability.repr(), true /*log*/);

    status_t result = setRepr(binder, stability.repr(), REPR_LOG);

    LOG_ALWAYS_FATAL_IF(result != OK, "Should only mark known object.");

}



void Stability::markVintf(IBinder* binder) {

    auto stability = Category::currentFromLevel(Level::VINTF);

    status_t result = setRepr(binder, stability.repr(), true /*log*/);

    status_t result = setRepr(binder, stability.repr(), REPR_LOG);

    LOG_ALWAYS_FATAL_IF(result != OK, "Should only mark known object.");

}
@@ -62,7 +74,7 @@ void Stability::debugLogStability(const std::string& tag, const sp<IBinder>& bin 


void Stability::markVndk(IBinder* binder) {

    auto stability = Category::currentFromLevel(Level::VENDOR);

    status_t result = setRepr(binder, stability.repr(), true /*log*/);

    status_t result = setRepr(binder, stability.repr(), REPR_LOG);

    LOG_ALWAYS_FATAL_IF(result != OK, "Should only mark known object.");

}
@@ -72,7 +84,7 @@ bool Stability::requiresVintfDeclaration(const sp<IBinder>& binder) { 


void Stability::tryMarkCompilationUnit(IBinder* binder) {

    auto stability = Category::currentFromLevel(getLocalLevel());

    (void) setRepr(binder, stability.repr(), false /*log*/);

    (void) setRepr(binder, stability.repr(), REPR_NONE);

}



Stability::Level Stability::getLocalLevel() {
@@ -94,7 +106,10 @@ Stability::Level Stability::getLocalLevel() { 
#endif

}



status_t Stability::setRepr(IBinder* binder, int32_t representation, bool log) {

status_t Stability::setRepr(IBinder* binder, int32_t representation, uint32_t flags) {

    bool log = flags & REPR_LOG;

    bool allowDowngrade = flags & REPR_ALLOW_DOWNGRADE;



    auto current = getCategory(binder);

    auto setting = Category::fromRepr(representation);
@@ -129,7 +144,11 @@ status_t Stability::setRepr(IBinder* binder, int32_t representation, bool log) { 
        return BAD_TYPE;

    }



    if (current.repr() != 0 && current != setting) {

    if (current == setting) return OK;



    bool hasAlreadyBeenSet = current.repr() != 0;

    bool isAllowedDowngrade = allowDowngrade && check(current, setting.level);

    if (hasAlreadyBeenSet && !isAllowedDowngrade) {

        if (log) {

            ALOGE("Interface being set with %s but it is already marked as %s",

                  setting.debugString().c_str(),
@@ -138,7 +157,11 @@ status_t Stability::setRepr(IBinder* binder, int32_t representation, bool log) { 
        return BAD_TYPE;

    }



    if (current == setting) return OK;

    if (isAllowedDowngrade) {

        ALOGI("Interface set with %s downgraded to %s stability",

              current.debugString().c_str(),

              setting.debugString().c_str());

    }



    BBinder* local = binder->localBinder();

    if (local != nullptr) {

libs/binder/include/binder/Stability.h

+15 −3
Original line number Diff line number Diff line
@@ -49,10 +49,17 @@ namespace internal { 
// that it knows how to process. The summary of stability of a binder is

// represented by a Stability::Category object.



// WARNING: These APIs are only ever expected to be called by auto-generated code.

//     Instead of calling them, you should set the stability of a .aidl interface

class Stability final {

public:

    // Given a binder interface at a certain stability, there may be some

    // requirements associated with that higher stability level. For instance, a

    // VINTF stability binder is required to be in the VINTF manifest. This API

    // can be called to use that same interface within a partition.

    static void forceDowngradeCompilationUnit(const sp<IBinder>& binder);



    // WARNING: Below APIs are only ever expected to be called by auto-generated code.

    //     Instead of calling them, you should set the stability of a .aidl interface



    // WARNING: This is only ever expected to be called by auto-generated code. You likely want to

    // change or modify the stability class of the interface you are using.

    // This must be called as soon as the binder in question is constructed. No thread safety
@@ -139,9 +146,14 @@ private: 
    // returns the stability according to how this was built

    static Level getLocalLevel();



    enum {

      REPR_NONE = 0,

      REPR_LOG = 1,

      REPR_ALLOW_DOWNGRADE = 2,

    };

    // applies stability to binder if stability level is known

    __attribute__((warn_unused_result))

    static status_t setRepr(IBinder* binder, int32_t representation, bool log);

    static status_t setRepr(IBinder* binder, int32_t representation, uint32_t flags);



    // get stability information as encoded on the wire

    static Category getCategory(IBinder* binder);

libs/binder/tests/binderStabilityTest.cpp

+11 −0
Original line number Diff line number Diff line
@@ -131,6 +131,17 @@ TEST(BinderStability, OnlyVintfStabilityBinderNeedsVintfDeclaration) { 
    EXPECT_TRUE(Stability::requiresVintfDeclaration(BadStableBinder::vintf()));

}



TEST(BinderStability, ForceDowngradeStability) {

    sp<IBinder> someBinder = BadStableBinder::vintf();



    EXPECT_TRUE(Stability::requiresVintfDeclaration(someBinder));



    // silly to do this after already using the binder, but it's for the test

    Stability::forceDowngradeCompilationUnit(someBinder);



    EXPECT_FALSE(Stability::requiresVintfDeclaration(someBinder));

}



TEST(BinderStability, VintfStabilityServerMustBeDeclaredInManifest) {

    sp<IBinder> vintfServer = BadStableBinder::vintf();