[libc-commits] [libc] [libc] implement secure random buffer filling with vDSO (PR #109870)
Schrodinger ZHU Yifan via libc-commits
libc-commits at lists.llvm.org
Tue Sep 24 15:07:44 PDT 2024
https://github.com/SchrodingerZhu created https://github.com/llvm/llvm-project/pull/109870
None
>From 553925e8ed93fdf035cb1094c8018eb7ea36026f Mon Sep 17 00:00:00 2001
From: Schrodinger ZHU Yifan <yifanzhu at rochester.edu>
Date: Tue, 24 Sep 2024 18:01:46 -0400
Subject: [PATCH] [libc] implement secure random buffer filling with vDSO
---
.../src/__support/OSUtil/linux/CMakeLists.txt | 22 ++
.../src/__support/OSUtil/linux/aarch64/vdso.h | 2 +
libc/src/__support/OSUtil/linux/random.cpp | 323 ++++++++++++++++++
libc/src/__support/OSUtil/linux/random.h | 20 ++
libc/src/__support/OSUtil/linux/vdso_sym.h | 9 +-
libc/src/__support/OSUtil/linux/x86_64/vdso.h | 2 +
libc/src/__support/threads/thread.cpp | 2 +-
.../integration/src/__support/CMakeLists.txt | 1 +
.../src/__support/OSUtil/CMakeLists.txt | 5 +
.../src/__support/OSUtil/linux/CMakeLists.txt | 10 +
.../OSUtil/linux/random_fill_test.cpp | 22 ++
11 files changed, 414 insertions(+), 4 deletions(-)
create mode 100644 libc/src/__support/OSUtil/linux/random.cpp
create mode 100644 libc/src/__support/OSUtil/linux/random.h
create mode 100644 libc/test/integration/src/__support/OSUtil/CMakeLists.txt
create mode 100644 libc/test/integration/src/__support/OSUtil/linux/CMakeLists.txt
create mode 100644 libc/test/integration/src/__support/OSUtil/linux/random_fill_test.cpp
diff --git a/libc/src/__support/OSUtil/linux/CMakeLists.txt b/libc/src/__support/OSUtil/linux/CMakeLists.txt
index 6c7014940407d8..4752e326cc153e 100644
--- a/libc/src/__support/OSUtil/linux/CMakeLists.txt
+++ b/libc/src/__support/OSUtil/linux/CMakeLists.txt
@@ -53,3 +53,25 @@ add_object_library(
libc.src.errno.errno
libc.src.sys.auxv.getauxval
)
+
+add_object_library(
+ random
+ HDRS
+ random.h
+ SRCS
+ random.cpp
+ DEPENDS
+ libc.src.sys.random.getrandom
+ libc.src.sys.mman.mmap
+ libc.src.sys.mman.munmap
+ libc.src.unistd.sysconf
+ libc.src.errno.errno
+ libc.src.__support.common
+ libc.src.__support.OSUtil.linux.vdso
+ libc.src.__support.threads.callonce
+ libc.src.__support.threads.linux.raw_mutex
+ libc.src.__support.threads.thread
+ libc.src.sched.sched_getaffinity
+ libc.src.sched.__sched_getcpucount
+)
+
diff --git a/libc/src/__support/OSUtil/linux/aarch64/vdso.h b/libc/src/__support/OSUtil/linux/aarch64/vdso.h
index 3c4c6205071da2..ee5777ad67f6dd 100644
--- a/libc/src/__support/OSUtil/linux/aarch64/vdso.h
+++ b/libc/src/__support/OSUtil/linux/aarch64/vdso.h
@@ -23,6 +23,8 @@ LIBC_INLINE constexpr cpp::string_view symbol_name(VDSOSym sym) {
return "__kernel_clock_gettime";
case VDSOSym::ClockGetRes:
return "__kernel_clock_getres";
+ case VDSOSym::GetRandom:
+ return "__kernel_getrandom";
default:
return "";
}
diff --git a/libc/src/__support/OSUtil/linux/random.cpp b/libc/src/__support/OSUtil/linux/random.cpp
new file mode 100644
index 00000000000000..612a184bda8455
--- /dev/null
+++ b/libc/src/__support/OSUtil/linux/random.cpp
@@ -0,0 +1,323 @@
+#include "src/__support/OSUtil/linux/random.h"
+#include "src/__support/CPP/mutex.h"
+#include "src/__support/CPP/new.h"
+#include "src/__support/OSUtil/linux/syscall.h"
+#include "src/__support/OSUtil/linux/vdso.h"
+#include "src/__support/OSUtil/linux/x86_64/vdso.h"
+#include "src/__support/libc_assert.h"
+#include "src/__support/memory_size.h"
+#include "src/__support/threads/callonce.h"
+#include "src/__support/threads/linux/callonce.h"
+#include "src/__support/threads/linux/raw_mutex.h"
+#include "src/errno/libc_errno.h"
+#include "src/sched/sched_getaffinity.h"
+#include "src/sched/sched_getcpucount.h"
+#include "src/stdlib/atexit.h"
+#include "src/sys/mman/mmap.h"
+#include "src/sys/mman/munmap.h"
+#include "src/sys/random/getrandom.h"
+#include "src/unistd/sysconf.h"
+#include <asm/param.h>
+
+namespace LIBC_NAMESPACE_DECL {
+namespace {
+// errno protection
+struct ErrnoProtect {
+ int backup;
+ ErrnoProtect() : backup(libc_errno) { libc_errno = 0; }
+ ~ErrnoProtect() { libc_errno = backup; }
+};
+
+// parameters for allocating per-thread random state
+struct Params {
+ unsigned size_of_opaque_state;
+ unsigned mmap_prot;
+ unsigned mmap_flags;
+ unsigned reserved[13];
+};
+
+// for registering thread-specific atexit callbacks
+using Destructor = void(void *);
+extern "C" int __cxa_thread_atexit_impl(Destructor *, void *, void *);
+extern "C" [[gnu::weak, gnu::visibility("hidden")]] void *__dso_handle =
+ nullptr;
+
+class MMapContainer {
+ void **ptr = nullptr;
+ void **usage = nullptr;
+ void **boundary = nullptr;
+
+ internal::SafeMemSize capacity() const {
+ return internal::SafeMemSize{
+ static_cast<size_t>(reinterpret_cast<ptrdiff_t>(boundary) -
+ reinterpret_cast<ptrdiff_t>(ptr))};
+ }
+
+ internal::SafeMemSize bytes() const {
+ return capacity() * internal::SafeMemSize{sizeof(void *)};
+ }
+
+ bool initialize() {
+ internal::SafeMemSize page_size{static_cast<size_t>(sysconf(_SC_PAGESIZE))};
+ if (!page_size.valid())
+ return false;
+ ptr = reinterpret_cast<void **>(mmap(nullptr, page_size,
+ PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS, -1, 0));
+ if (ptr == MAP_FAILED)
+ return false;
+ usage = ptr;
+ boundary = ptr + page_size / sizeof(void *);
+ return true;
+ }
+
+ bool grow(size_t additional) {
+ if (ptr == nullptr)
+ return initialize();
+
+ size_t old_capacity = capacity();
+
+ internal::SafeMemSize target_bytes{additional};
+ internal::SafeMemSize new_bytes = bytes();
+ target_bytes = target_bytes + size();
+ target_bytes = target_bytes * internal::SafeMemSize{sizeof(void *)};
+
+ if (!target_bytes.valid())
+ return false;
+ while (new_bytes < target_bytes) {
+ new_bytes = new_bytes * internal::SafeMemSize{static_cast<size_t>(2)};
+ if (!new_bytes.valid())
+ return false;
+ }
+
+ // TODO: migrate to syscall wrapper once it's available
+ auto result = syscall_impl<intptr_t>(
+ SYS_mremap, bytes(), static_cast<size_t>(new_bytes), MREMAP_MAYMOVE);
+
+ if (result < 0 && result > -EXEC_PAGESIZE)
+ return false;
+ ptr = reinterpret_cast<void **>(result);
+ usage = ptr + old_capacity;
+ boundary = ptr + new_bytes / sizeof(void *);
+ return true;
+ }
+
+public:
+ MMapContainer() = default;
+ ~MMapContainer() {
+ if (!ptr)
+ return;
+ munmap(ptr, bytes());
+ }
+
+ bool ensure_space(size_t additional) {
+ if (usage + additional >= boundary && !grow(additional))
+ return false;
+ return true;
+ }
+
+ void push_unchecked(void *value) {
+ LIBC_ASSERT(usage != boundary && "pushing into full container");
+ *usage++ = value;
+ }
+
+ using iterator = void **;
+ using value_type = void *;
+ iterator begin() const { return ptr; }
+ iterator end() const { return usage; }
+
+ bool empty() const { return begin() == end(); }
+ void *pop() {
+ LIBC_ASSERT(!empty() && "popping from empty container");
+ return *--usage;
+ }
+ internal::SafeMemSize size() const {
+ return internal::SafeMemSize{static_cast<size_t>(
+ reinterpret_cast<ptrdiff_t>(usage) - reinterpret_cast<ptrdiff_t>(ptr))};
+ }
+};
+
+class StateFactory {
+ RawMutex mutex{};
+ MMapContainer allocations{};
+ MMapContainer freelist{};
+ Params params{};
+ size_t states_per_page = 0;
+ size_t pages_per_allocation = 0;
+ size_t page_size = 0;
+
+ bool prepare() {
+ vdso::TypedSymbol<vdso::VDSOSym::GetRandom> vgetrandom;
+
+ if (!vgetrandom)
+ return false;
+
+ // get the allocation configuration suggested by the kernel
+ if (vgetrandom(nullptr, 0, 0, ¶ms, ~0UL))
+ return false;
+
+ cpu_set_t cs{};
+
+ if (LIBC_NAMESPACE::sched_getaffinity(0, sizeof(cs), &cs))
+ return false;
+
+ internal::SafeMemSize count{static_cast<size_t>(
+ LIBC_NAMESPACE::__sched_getcpucount(sizeof(cs), &cs))};
+
+ internal::SafeMemSize allocation_size =
+ internal::SafeMemSize{
+ static_cast<size_t>(params.size_of_opaque_state)} *
+ count;
+
+ page_size = static_cast<size_t>(sysconf(_SC_PAGESIZE));
+ allocation_size = allocation_size.align_up(page_size);
+ if (!allocation_size.valid())
+ return false;
+
+ states_per_page = page_size / params.size_of_opaque_state;
+ pages_per_allocation = allocation_size / page_size;
+
+ return true;
+ }
+
+ bool allocate_new_states() {
+ if (!allocations.ensure_space(1))
+ return false;
+
+ // we always ensure the freelist can contain all the allocated states
+ internal::SafeMemSize total_size =
+ internal::SafeMemSize{page_size} *
+ internal::SafeMemSize{pages_per_allocation} *
+ (internal::SafeMemSize{static_cast<size_t>(1)} + allocations.size());
+
+ if (!total_size.valid() ||
+ !freelist.ensure_space(total_size - freelist.size()))
+ return false;
+
+ auto *new_allocation =
+ static_cast<char *>(mmap(nullptr, page_size * pages_per_allocation,
+ params.mmap_prot, params.mmap_flags, -1, 0));
+ if (new_allocation == MAP_FAILED)
+ return false;
+
+ for (size_t i = 0; i < pages_per_allocation; ++i) {
+ auto *page = new_allocation + i * page_size;
+ for (size_t j = 0; j < states_per_page; ++j)
+ freelist.push_unchecked(page + j * params.size_of_opaque_state);
+ }
+ return true;
+ }
+
+ static StateFactory *instance() {
+ alignas(StateFactory) static char storage[sizeof(StateFactory)]{};
+ static CallOnceFlag flag = callonce_impl::NOT_CALLED;
+ static bool valid = false;
+ callonce(&flag, []() {
+ auto *factory = new (storage) StateFactory();
+ valid = factory->prepare();
+ if (valid)
+ atexit([]() {
+ auto factory = reinterpret_cast<StateFactory *>(storage);
+ factory->~StateFactory();
+ valid = false;
+ });
+ });
+ return valid ? reinterpret_cast<StateFactory *>(storage) : nullptr;
+ }
+
+ void *acquire() {
+ cpp::lock_guard guard{mutex};
+ if (freelist.empty() && !allocate_new_states())
+ return nullptr;
+ return freelist.pop();
+ }
+ void release(void *state) {
+ cpp::lock_guard guard{mutex};
+ // there should be no need to check this pushing
+ freelist.push_unchecked(state);
+ }
+ ~StateFactory() {
+ for (auto *allocation : allocations)
+ munmap(allocation, page_size * pages_per_allocation);
+ }
+
+public:
+ static void *acquire_global() {
+ auto *factory = instance();
+ if (!factory)
+ return nullptr;
+ return factory->acquire();
+ }
+ static void release_global(void *state) {
+ auto *factory = instance();
+ if (!factory)
+ return;
+ factory->release(state);
+ }
+ static size_t size_of_opaque_state() {
+ return instance()->params.size_of_opaque_state;
+ }
+};
+
+void *acquire_tls() {
+ static thread_local void *state = nullptr;
+ // previous acquire failed, do not try again
+ if (state == MAP_FAILED)
+ return nullptr;
+ // first acquirement
+ if (state == nullptr) {
+ state = StateFactory::acquire_global();
+ // if still fails, remember the failure
+ if (state == nullptr) {
+ state = MAP_FAILED;
+ return nullptr;
+ } else {
+ // register the release callback.
+ if (__cxa_thread_atexit_impl(
+ [](void *s) { StateFactory::release_global(s); }, state,
+ __dso_handle)) {
+ StateFactory::release_global(state);
+ state = MAP_FAILED;
+ return nullptr;
+ }
+ }
+ }
+ return state;
+}
+
+template <class F> void random_fill_impl(F gen, void *buf, size_t size) {
+ auto *buffer = reinterpret_cast<uint8_t *>(buf);
+ while (size > 0) {
+ ssize_t len = gen(buffer, size);
+ if (len == -1) {
+ if (libc_errno == EINTR)
+ continue;
+ break;
+ }
+ size -= len;
+ buffer += len;
+ }
+}
+} // namespace
+
+void random_fill(void *buf, size_t size) {
+ ErrnoProtect protect;
+ void *state = acquire_tls();
+ if (state) {
+ random_fill_impl(
+ [state](void *buf, size_t size) {
+ vdso::TypedSymbol<vdso::VDSOSym::GetRandom> vgetrandom;
+ return vgetrandom(buf, size, 0, state,
+ StateFactory::size_of_opaque_state());
+ },
+ buf, size);
+ } else {
+ random_fill_impl(
+ [](void *buf, size_t size) {
+ return LIBC_NAMESPACE::getrandom(buf, size, 0);
+ },
+ buf, size);
+ }
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/__support/OSUtil/linux/random.h b/libc/src/__support/OSUtil/linux/random.h
new file mode 100644
index 00000000000000..0e2d51391ec31c
--- /dev/null
+++ b/libc/src/__support/OSUtil/linux/random.h
@@ -0,0 +1,20 @@
+//===-- Utilities for getting secure randomness -----------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_RANDOMNESS_H
+#define LLVM_LIBC_SRC___SUPPORT_RANDOMNESS_H
+
+#include "src/__support/common.h"
+
+#define __need_size_t
+#include <stddef.h>
+
+namespace LIBC_NAMESPACE_DECL {
+void random_fill(void *buf, unsigned long size);
+} // namespace LIBC_NAMESPACE_DECL
+#endif // LLVM_LIBC_SRC___SUPPORT_RANDOMNESS_H
diff --git a/libc/src/__support/OSUtil/linux/vdso_sym.h b/libc/src/__support/OSUtil/linux/vdso_sym.h
index 968e1536c4d270..2b1cf398369de2 100644
--- a/libc/src/__support/OSUtil/linux/vdso_sym.h
+++ b/libc/src/__support/OSUtil/linux/vdso_sym.h
@@ -19,7 +19,6 @@ struct __kernel_timespec;
struct timezone;
struct riscv_hwprobe;
struct getcpu_cache;
-struct cpu_set_t;
// NOLINTEND(llvmlibc-implementation-in-namespace)
namespace LIBC_NAMESPACE_DECL {
@@ -35,7 +34,8 @@ enum class VDSOSym {
RTSigReturn,
FlushICache,
RiscvHwProbe,
- VDSOSymCount
+ GetRandom,
+ VDSOSymCount,
};
template <VDSOSym sym> LIBC_INLINE constexpr auto dispatcher() {
@@ -58,8 +58,11 @@ template <VDSOSym sym> LIBC_INLINE constexpr auto dispatcher() {
else if constexpr (sym == VDSOSym::FlushICache)
return static_cast<void (*)(void *, void *, unsigned int)>(nullptr);
else if constexpr (sym == VDSOSym::RiscvHwProbe)
- return static_cast<int (*)(riscv_hwprobe *, size_t, size_t, cpu_set_t *,
+ return static_cast<int (*)(riscv_hwprobe *, size_t, size_t, void *,
unsigned)>(nullptr);
+ else if constexpr (sym == VDSOSym::GetRandom)
+ return static_cast<int (*)(void *, size_t, unsigned int, void *, size_t)>(
+ nullptr);
else
return static_cast<void *>(nullptr);
}
diff --git a/libc/src/__support/OSUtil/linux/x86_64/vdso.h b/libc/src/__support/OSUtil/linux/x86_64/vdso.h
index abe7c33e07cfab..f46fcb038f2e60 100644
--- a/libc/src/__support/OSUtil/linux/x86_64/vdso.h
+++ b/libc/src/__support/OSUtil/linux/x86_64/vdso.h
@@ -29,6 +29,8 @@ LIBC_INLINE constexpr cpp::string_view symbol_name(VDSOSym sym) {
return "__vdso_time";
case VDSOSym::ClockGetRes:
return "__vdso_clock_getres";
+ case VDSOSym::GetRandom:
+ return "__vdso_getrandom";
default:
return "";
}
diff --git a/libc/src/__support/threads/thread.cpp b/libc/src/__support/threads/thread.cpp
index dad4f75f092ede..04668dbfcbb63a 100644
--- a/libc/src/__support/threads/thread.cpp
+++ b/libc/src/__support/threads/thread.cpp
@@ -117,7 +117,7 @@ class ThreadAtExitCallbackMgr {
int add_callback(AtExitCallback *callback, void *obj) {
cpp::lock_guard lock(mtx);
- return callback_list.push_back({callback, obj});
+ return callback_list.push_back({callback, obj}) ? 0 : -1;
}
void call() {
diff --git a/libc/test/integration/src/__support/CMakeLists.txt b/libc/test/integration/src/__support/CMakeLists.txt
index b5b6557e8d6899..d2dae7e02a9c57 100644
--- a/libc/test/integration/src/__support/CMakeLists.txt
+++ b/libc/test/integration/src/__support/CMakeLists.txt
@@ -1,4 +1,5 @@
add_subdirectory(threads)
+add_subdirectory(OSUtil)
if(LIBC_TARGET_OS_IS_GPU)
add_subdirectory(GPU)
endif()
diff --git a/libc/test/integration/src/__support/OSUtil/CMakeLists.txt b/libc/test/integration/src/__support/OSUtil/CMakeLists.txt
new file mode 100644
index 00000000000000..5ff1a11aff5c9d
--- /dev/null
+++ b/libc/test/integration/src/__support/OSUtil/CMakeLists.txt
@@ -0,0 +1,5 @@
+add_custom_target(libc-osutil-integration-tests)
+
+if(EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/${LIBC_TARGET_OS})
+ add_subdirectory(${LIBC_TARGET_OS})
+endif()
diff --git a/libc/test/integration/src/__support/OSUtil/linux/CMakeLists.txt b/libc/test/integration/src/__support/OSUtil/linux/CMakeLists.txt
new file mode 100644
index 00000000000000..a4f15ad8370352
--- /dev/null
+++ b/libc/test/integration/src/__support/OSUtil/linux/CMakeLists.txt
@@ -0,0 +1,10 @@
+add_integration_test(
+ random_fill_test
+ SUITE
+ libc-osutil-integration-tests
+ SRCS
+ random_fill_test.cpp
+ DEPENDS
+ libc.include.pthread
+ libc.src.__support.OSUtil.linux.random
+)
diff --git a/libc/test/integration/src/__support/OSUtil/linux/random_fill_test.cpp b/libc/test/integration/src/__support/OSUtil/linux/random_fill_test.cpp
new file mode 100644
index 00000000000000..bde24a1e0d5521
--- /dev/null
+++ b/libc/test/integration/src/__support/OSUtil/linux/random_fill_test.cpp
@@ -0,0 +1,22 @@
+//===-- Tests for pthread_equal -------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/__support/OSUtil/linux/random.h"
+
+#include "test/IntegrationTest/test.h"
+
+void smoke_test() {
+ using namespace LIBC_NAMESPACE;
+ uint32_t buffer;
+ random_fill(&buffer, sizeof(buffer));
+}
+
+TEST_MAIN() {
+ smoke_test();
+ return 0;
+}
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