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Added root companion and logging macros

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snake-4
2024-04-16 17:49:25 +02:00
parent 2962997439
commit f200aa4561
6 changed files with 97 additions and 38 deletions
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80
module/jni/main.cpp
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@@ -1,6 +1,10 @@
#include <unistd.h>
#include <sched.h>
#include <sys/mount.h>
#include <grp.h>
#include <cstdint>
#include <functional>
#include "zygisk.hpp"
#include "logging.hpp"
@@ -13,6 +17,8 @@ using zygisk::ServerSpecializeArgs;
void doUnmount();
void doRemount();
static std::function<void()> callbackFunction = []() {};
/*
* [What's the purpose of this hook?]
* Calling unshare twice invalidates existing FD links, which fails Zygote sanity checks.
@@ -28,9 +34,7 @@ void doRemount();
*/
DCL_HOOK_FUNC(static int, unshare, int flags)
{
doUnmount();
doRemount();
callbackFunction();
// Do not allow CLONE_NEWNS.
flags &= ~(CLONE_NEWNS);
if (!flags)
@@ -68,27 +72,41 @@ public:
/*
* Read the comment above unshare hook.
*/
if (unshare(CLONE_NEWNS) == -1)
{
LOGE("unshare(CLONE_NEWNS) returned -1: %d (%s)", errno, strerror(errno));
return;
}
ASSERT_EXIT("preAppSpecialize", unshare(CLONE_NEWNS) != -1, return);
/*
* Mount the app mount namespace's root as MS_SLAVE, so every mount/umount from
* Zygote shared pre-specialization namespace is propagated to this one.
*/
if (mount("rootfs", "/", NULL, (MS_SLAVE | MS_REC), NULL) == -1)
{
LOGE("mount(\"rootfs\", \"/\", NULL, (MS_SLAVE | MS_REC), NULL) returned -1: %d (%s)", errno, strerror(errno));
return;
}
ASSERT_EXIT("preAppSpecialize", mount("rootfs", "/", NULL, (MS_SLAVE | MS_REC), NULL) != -1, return);
if (!hookPLTByName("libandroid_runtime.so", "unshare", new_unshare, &old_unshare))
ASSERT_EXIT("preAppSpecialize", hookPLTByName("libandroid_runtime.so", "unshare", new_unshare, &old_unshare), return);
ASSERT_LOG("preAppSpecialize", (companionFd = api->connectCompanion()) != -1);
callbackFunction = [fd = companionFd]()
{
LOGE("plt_hook_wrapper(\"libandroid_runtime.so\", \"unshare\", new_unshare, old_unshare) returned false");
return;
}
bool result = false;
if (fd != -1)
{
do
{
pid_t pid = getpid();
ASSERT_EXIT("invokeZygiskCompanion", write(fd, &pid, sizeof(pid)) == sizeof(pid), break);
ASSERT_EXIT("invokeZygiskCompanion", read(fd, &result, sizeof(result)) == sizeof(result), break);
} while (false);
close(fd);
}
if (result)
LOGD("Invoking the companion was successful.");
else
{
LOGW("Invoking the companion failed. Performing operations in Zygote context!");
doUnmount();
doRemount();
}
};
}
void preServerSpecialize(ServerSpecializeArgs *args) override
@@ -98,10 +116,8 @@ public:
void postAppSpecialize(const AppSpecializeArgs *args) override
{
if (old_unshare != nullptr && !hookPLTByName("libandroid_runtime.so", "unshare", old_unshare))
{
LOGE("plt_hook_wrapper(\"libandroid_runtime.so\", \"unshare\", old_unshare) returned false");
}
if (old_unshare != nullptr)
ASSERT_LOG("postAppSpecialize", hookPLTByName("libandroid_runtime.so", "unshare", old_unshare));
}
template <typename T>
@@ -111,8 +127,30 @@ public:
}
private:
int companionFd = -1;
Api *api;
JNIEnv *env;
};
void zygisk_companion_handler(int fd)
{
bool result = [&]() -> bool
{
pid_t pid;
ASSERT_EXIT("zygisk_companion_handler", read(fd, &pid, sizeof(pid)) == sizeof(pid), return false);
LOGD("zygisk_companion_handler received pid=%d", pid);
ASSERT_EXIT("zygisk_companion_handler", unshare(CLONE_NEWNS) != -1, return false);
ASSERT_EXIT("zygisk_companion_handler", switchMountNS(pid), return false);
doUnmount();
doRemount();
return true;
}();
ASSERT_LOG("zygisk_companion_handler", write(fd, &result, sizeof(result)) == sizeof(result));
}
REGISTER_ZYGISK_MODULE(ZygiskModule)
REGISTER_ZYGISK_COMPANION(zygisk_companion_handler)