| // Copyright 2014 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef THIRD_PARTY_BASE_ALLOCATOR_PARTITION_ALLOCATOR_ADDRESS_SPACE_RANDOMIZATION_H_ |
| #define THIRD_PARTY_BASE_ALLOCATOR_PARTITION_ALLOCATOR_ADDRESS_SPACE_RANDOMIZATION_H_ |
| |
| #include "build/build_config.h" |
| #include "third_party/base/allocator/partition_allocator/page_allocator.h" |
| #include "third_party/base/base_export.h" |
| |
| namespace pdfium { |
| namespace base { |
| |
| // Sets the seed for the random number generator used by GetRandomPageBase in |
| // order to generate a predictable sequence of addresses. May be called multiple |
| // times. |
| BASE_EXPORT void SetRandomPageBaseSeed(int64_t seed); |
| |
| // Calculates a random preferred mapping address. In calculating an address, we |
| // balance good ASLR against not fragmenting the address space too badly. |
| BASE_EXPORT void* GetRandomPageBase(); |
| |
| namespace internal { |
| |
| constexpr uintptr_t AslrAddress(uintptr_t mask) { |
| return mask & kPageAllocationGranularityBaseMask; |
| } |
| constexpr uintptr_t AslrMask(uintptr_t bits) { |
| return AslrAddress((1ULL << bits) - 1ULL); |
| } |
| |
| // Turn off formatting, because the thicket of nested ifdefs below is |
| // incomprehensible without indentation. It is also incomprehensible with |
| // indentation, but the only other option is a combinatorial explosion of |
| // *_{win,linux,mac,foo}_{32,64}.h files. |
| // |
| // clang-format off |
| |
| #if defined(ARCH_CPU_64_BITS) |
| |
| #if defined(MEMORY_TOOL_REPLACES_ALLOCATOR) |
| |
| // We shouldn't allocate system pages at all for sanitizer builds. However, |
| // we do, and if random hint addresses interfere with address ranges |
| // hard-coded in those tools, bad things happen. This address range is |
| // copied from TSAN source but works with all tools. See |
| // https://crbug.com/539863. |
| constexpr uintptr_t kASLRMask = AslrAddress(0x007fffffffffULL); |
| constexpr uintptr_t kASLROffset = AslrAddress(0x7e8000000000ULL); |
| |
| #elif defined(OS_WIN) |
| |
| // Windows 8.10 and newer support the full 48 bit address range. Older |
| // versions of Windows only support 44 bits. Since kASLROffset is non-zero |
| // and may cause a carry, use 47 and 43 bit masks. See |
| // http://www.alex-ionescu.com/?p=246 |
| constexpr uintptr_t kASLRMask = AslrMask(47); |
| constexpr uintptr_t kASLRMaskBefore8_10 = AslrMask(43); |
| // Try not to map pages into the range where Windows loads DLLs by default. |
| constexpr uintptr_t kASLROffset = 0x80000000ULL; |
| |
| #elif defined(OS_MACOSX) |
| |
| // macOS as of 10.12.5 does not clean up entries in page map levels 3/4 |
| // [PDP/PML4] created from mmap or mach_vm_allocate, even after the region |
| // is destroyed. Using a virtual address space that is too large causes a |
| // leak of about 1 wired [can never be paged out] page per call to mmap. The |
| // page is only reclaimed when the process is killed. Confine the hint to a |
| // 39-bit section of the virtual address space. |
| // |
| // This implementation adapted from |
| // https://chromium-review.googlesource.com/c/v8/v8/+/557958. The difference |
| // is that here we clamp to 39 bits, not 32. |
| // |
| // TODO(crbug.com/738925): Remove this limitation if/when the macOS behavior |
| // changes. |
| constexpr uintptr_t kASLRMask = AslrMask(38); |
| constexpr uintptr_t kASLROffset = AslrAddress(0x1000000000ULL); |
| |
| #elif defined(OS_POSIX) || defined(OS_FUCHSIA) |
| |
| #if defined(ARCH_CPU_X86_64) |
| |
| // Linux (and macOS) support the full 47-bit user space of x64 processors. |
| // Use only 46 to allow the kernel a chance to fulfill the request. |
| constexpr uintptr_t kASLRMask = AslrMask(46); |
| constexpr uintptr_t kASLROffset = AslrAddress(0); |
| |
| #elif defined(ARCH_CPU_ARM64) |
| |
| #if defined(OS_ANDROID) |
| |
| // Restrict the address range on Android to avoid a large performance |
| // regression in single-process WebViews. See https://crbug.com/837640. |
| constexpr uintptr_t kASLRMask = AslrMask(30); |
| constexpr uintptr_t kASLROffset = AslrAddress(0x20000000ULL); |
| |
| #else |
| |
| // ARM64 on Linux has 39-bit user space. Use 38 bits since kASLROffset |
| // could cause a carry. |
| constexpr uintptr_t kASLRMask = AslrMask(38); |
| constexpr uintptr_t kASLROffset = AslrAddress(0x1000000000ULL); |
| |
| #endif |
| |
| #elif defined(ARCH_CPU_PPC64) |
| |
| #if defined(OS_AIX) |
| |
| // AIX has 64 bits of virtual addressing, but we limit the address range |
| // to (a) minimize segment lookaside buffer (SLB) misses; and (b) use |
| // extra address space to isolate the mmap regions. |
| constexpr uintptr_t kASLRMask = AslrMask(30); |
| constexpr uintptr_t kASLROffset = AslrAddress(0x400000000000ULL); |
| |
| #elif defined(ARCH_CPU_BIG_ENDIAN) |
| |
| // Big-endian Linux PPC has 44 bits of virtual addressing. Use 42. |
| constexpr uintptr_t kASLRMask = AslrMask(42); |
| constexpr uintptr_t kASLROffset = AslrAddress(0); |
| |
| #else // !defined(OS_AIX) && !defined(ARCH_CPU_BIG_ENDIAN) |
| |
| // Little-endian Linux PPC has 48 bits of virtual addressing. Use 46. |
| constexpr uintptr_t kASLRMask = AslrMask(46); |
| constexpr uintptr_t kASLROffset = AslrAddress(0); |
| |
| #endif // !defined(OS_AIX) && !defined(ARCH_CPU_BIG_ENDIAN) |
| |
| #elif defined(ARCH_CPU_S390X) |
| |
| // Linux on Z uses bits 22 - 32 for Region Indexing, which translates to |
| // 42 bits of virtual addressing. Truncate to 40 bits to allow kernel a |
| // chance to fulfill the request. |
| constexpr uintptr_t kASLRMask = AslrMask(40); |
| constexpr uintptr_t kASLROffset = AslrAddress(0); |
| |
| #elif defined(ARCH_CPU_S390) |
| |
| // 31 bits of virtual addressing. Truncate to 29 bits to allow the kernel |
| // a chance to fulfill the request. |
| constexpr uintptr_t kASLRMask = AslrMask(29); |
| constexpr uintptr_t kASLROffset = AslrAddress(0); |
| |
| #else // !defined(ARCH_CPU_X86_64) && !defined(ARCH_CPU_PPC64) && |
| // !defined(ARCH_CPU_S390X) && !defined(ARCH_CPU_S390) |
| |
| // For all other POSIX variants, use 30 bits. |
| constexpr uintptr_t kASLRMask = AslrMask(30); |
| |
| #if defined(OS_SOLARIS) |
| |
| // For our Solaris/illumos mmap hint, we pick a random address in the |
| // bottom half of the top half of the address space (that is, the third |
| // quarter). Because we do not MAP_FIXED, this will be treated only as a |
| // hint -- the system will not fail to mmap because something else |
| // happens to already be mapped at our random address. We deliberately |
| // set the hint high enough to get well above the system's break (that |
| // is, the heap); Solaris and illumos will try the hint and if that |
| // fails allocate as if there were no hint at all. The high hint |
| // prevents the break from getting hemmed in at low values, ceding half |
| // of the address space to the system heap. |
| constexpr uintptr_t kASLROffset = AslrAddress(0x80000000ULL); |
| |
| #elif defined(OS_AIX) |
| |
| // The range 0x30000000 - 0xD0000000 is available on AIX; choose the |
| // upper range. |
| constexpr uintptr_t kASLROffset = AslrAddress(0x90000000ULL); |
| |
| #else // !defined(OS_SOLARIS) && !defined(OS_AIX) |
| |
| // The range 0x20000000 - 0x60000000 is relatively unpopulated across a |
| // variety of ASLR modes (PAE kernel, NX compat mode, etc) and on macOS |
| // 10.6 and 10.7. |
| constexpr uintptr_t kASLROffset = AslrAddress(0x20000000ULL); |
| |
| #endif // !defined(OS_SOLARIS) && !defined(OS_AIX) |
| |
| #endif // !defined(ARCH_CPU_X86_64) && !defined(ARCH_CPU_PPC64) && |
| // !defined(ARCH_CPU_S390X) && !defined(ARCH_CPU_S390) |
| |
| #endif // defined(OS_POSIX) |
| |
| #elif defined(ARCH_CPU_32_BITS) |
| |
| // This is a good range on 32-bit Windows and Android (the only platforms on |
| // which we support 32-bitness). Allocates in the 0.5 - 1.5 GiB region. There |
| // is no issue with carries here. |
| constexpr uintptr_t kASLRMask = AslrMask(30); |
| constexpr uintptr_t kASLROffset = AslrAddress(0x20000000ULL); |
| |
| #else |
| |
| #error Please tell us about your exotic hardware! Sounds interesting. |
| |
| #endif // defined(ARCH_CPU_32_BITS) |
| |
| // clang-format on |
| |
| } // namespace internal |
| |
| } // namespace base |
| } // namespace pdfium |
| |
| #endif // THIRD_PARTY_BASE_ALLOCATOR_PARTITION_ALLOCATOR_ADDRESS_SPACE_RANDOMIZATION_H_ |