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Commit 87b2ef0e authored by Will McVicker's avatar Will McVicker
Browse files

libmodprobe: refactor blocklist functionality 

Remove the function EnableBlocklist() and add a constructor argument to
enable/disable the use of modules.blocklist. In all cases, the
enabling/disabling of the blocklist happens immediately after creating
the Modprobe object. So this simplies libmodprobe.

Additionally, the use of the blocklist by libmodprobe should be enabled
by default unless explicitly disabled during creation of the Modprobe
object. Currently, only modprobe(8) defaults to not using the blocklist
and includes the argument -b BLOCKLIST for enabling it. That
functionality remains.

This refactor allows us to use the blocklist during first stage init.
However, additional logic is needed to not return an error for the
blocked non-aliased modules during first stage init; otherwise, the
error would result in an init crash leading to a device reboot. So fixup
LoadListedModules() to allow blocking modules without returning an
error.

Bug: 182582036
Test: boot test on pixel 5 with a module in modules.blocklist
Change-Id: I394b5aa98fa98821011982cfe693749010c381f7
parent 007d7941

libmodprobe/include/modprobe/modprobe.h

+3 −2
Original line number Diff line number Diff line
@@ -24,7 +24,8 @@ 


class Modprobe {

  public:

    Modprobe(const std::vector<std::string>&, const std::string load_file = "modules.load");

    Modprobe(const std::vector<std::string>&, const std::string load_file = "modules.load",

             bool use_blocklist = true);



    bool LoadListedModules(bool strict = true);

    bool LoadWithAliases(const std::string& module_name, bool strict,
@@ -36,7 +37,6 @@ class Modprobe { 
                            std::vector<std::string>* post_dependencies);

    void ResetModuleCount() { module_count_ = 0; }

    int GetModuleCount() { return module_count_; }

    void EnableBlocklist(bool enable);



  private:

    std::string MakeCanonical(const std::string& module_path);
@@ -48,6 +48,7 @@ class Modprobe { 
    void AddOption(const std::string& module_name, const std::string& option_name,

                   const std::string& value);

    std::string GetKernelCmdline();

    bool IsBlocklisted(const std::string& module_name);



    bool ParseDepCallback(const std::string& base_path, const std::vector<std::string>& args);

    bool ParseAliasCallback(const std::vector<std::string>& args);

libmodprobe/libmodprobe.cpp

+18 −13
Original line number Diff line number Diff line
@@ -313,7 +313,9 @@ void Modprobe::ParseKernelCmdlineOptions(void) { 
    }

}



Modprobe::Modprobe(const std::vector<std::string>& base_paths, const std::string load_file) {

Modprobe::Modprobe(const std::vector<std::string>& base_paths, const std::string load_file,

                   bool use_blocklist)

    : blocklist_enabled(use_blocklist) {

    using namespace std::placeholders;



    for (const auto& base_path : base_paths) {
@@ -339,10 +341,6 @@ Modprobe::Modprobe(const std::vector<std::string>& base_paths, const std::string 
    ParseKernelCmdlineOptions();

}



void Modprobe::EnableBlocklist(bool enable) {

    blocklist_enabled = enable;

}



std::vector<std::string> Modprobe::GetDependencies(const std::string& module) {

    auto it = module_deps_.find(module);

    if (it == module_deps_.end()) {
@@ -427,10 +425,23 @@ bool Modprobe::LoadWithAliases(const std::string& module_name, bool strict, 
    return true;

}



bool Modprobe::IsBlocklisted(const std::string& module_name) {

    if (!blocklist_enabled) return false;



    auto canonical_name = MakeCanonical(module_name);

    auto dependencies = GetDependencies(canonical_name);

    for (auto dep = dependencies.begin(); dep != dependencies.end(); ++dep) {

        if (module_blocklist_.count(MakeCanonical(*dep))) return true;

    }



    return module_blocklist_.count(canonical_name) > 0;

}



bool Modprobe::LoadListedModules(bool strict) {

    auto ret = true;

    for (const auto& module : module_load_) {

        if (!LoadWithAliases(module, true)) {

            if (IsBlocklisted(module)) continue;

            ret = false;

            if (strict) break;

        }
@@ -440,16 +451,10 @@ bool Modprobe::LoadListedModules(bool strict) { 


bool Modprobe::Remove(const std::string& module_name) {

    auto dependencies = GetDependencies(MakeCanonical(module_name));

    if (dependencies.empty()) {

        LOG(ERROR) << "Empty dependencies for module " << module_name;

        return false;

    }

    if (!Rmmod(dependencies[0])) {

        return false;

    }

    for (auto dep = dependencies.begin() + 1; dep != dependencies.end(); ++dep) {

    for (auto dep = dependencies.begin(); dep != dependencies.end(); ++dep) {

        Rmmod(*dep);

    }

    Rmmod(module_name);

    return true;

}

libmodprobe/libmodprobe_test.cpp

+28 −2
Original line number Diff line number Diff line
@@ -78,6 +78,18 @@ TEST(libmodprobe, Test) { 
            "/test13.ko",

    };



    std::vector<std::string> expected_modules_blocklist_enabled = {

            "/test1.ko option1=50 option2=60",

            "/test6.ko",

            "/test2.ko",

            "/test5.ko option1=",

            "/test8.ko",

            "/test7.ko param1=4",

            "/test12.ko",

            "/test11.ko",

            "/test13.ko",

    };



    const std::string modules_dep =

            "test1.ko:\n"

            "test2.ko:\n"
@@ -146,7 +158,7 @@ TEST(libmodprobe, Test) { 
        *i = dir.path + *i;

    }



    Modprobe m({dir.path});

    Modprobe m({dir.path}, "modules.load", false);

    EXPECT_TRUE(m.LoadListedModules());



    GTEST_LOG_(INFO) << "Expected modules loaded (in order):";
@@ -176,8 +188,22 @@ TEST(libmodprobe, Test) { 


    EXPECT_TRUE(modules_loaded == expected_after_remove);



    m.EnableBlocklist(true);

    m = Modprobe({dir.path});

    EXPECT_FALSE(m.LoadWithAliases("test4", true));

    while (modules_loaded.size() > 0) EXPECT_TRUE(m.Remove(modules_loaded.front()));

    EXPECT_TRUE(m.LoadListedModules());



    GTEST_LOG_(INFO) << "Expected modules loaded after enabling blocklist (in order):";

    for (auto i = expected_modules_blocklist_enabled.begin();

         i != expected_modules_blocklist_enabled.end(); ++i) {

        *i = dir.path + *i;

        GTEST_LOG_(INFO) << "\"" << *i << "\"";

    }

    GTEST_LOG_(INFO) << "Actual modules loaded with blocklist enabled (in order):";

    for (auto i = modules_loaded.begin(); i != modules_loaded.end(); ++i) {

        GTEST_LOG_(INFO) << "\"" << *i << "\"";

    }

    EXPECT_TRUE(modules_loaded == expected_modules_blocklist_enabled);

}



TEST(libmodprobe, ModuleDepLineWithoutColonIsSkipped) {

toolbox/modprobe.cpp

+1 −4
Original line number Diff line number Diff line
@@ -215,10 +215,7 @@ extern "C" int modprobe_main(int argc, char** argv) { 
        return EXIT_FAILURE;

    }



    Modprobe m(mod_dirs);

    if (blocklist) {

        m.EnableBlocklist(true);

    }

    Modprobe m(mod_dirs, "modules.load", blocklist);



    for (const auto& module : modules) {

        switch (mode) {