| //===-- dfsan.cpp ---------------------------------------------------------===// |
| // |
| // 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 |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file is a part of DataFlowSanitizer. |
| // |
| // DataFlowSanitizer runtime. This file defines the public interface to |
| // DataFlowSanitizer as well as the definition of certain runtime functions |
| // called automatically by the compiler (specifically the instrumentation pass |
| // in llvm/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp). |
| // |
| // The public interface is defined in include/sanitizer/dfsan_interface.h whose |
| // functions are prefixed dfsan_ while the compiler interface functions are |
| // prefixed __dfsan_. |
| //===----------------------------------------------------------------------===// |
| |
| #include "dfsan/dfsan.h" |
| |
| #include "dfsan/dfsan_chained_origin_depot.h" |
| #include "dfsan/dfsan_flags.h" |
| #include "dfsan/dfsan_origin.h" |
| #include "dfsan/dfsan_thread.h" |
| #include "sanitizer_common/sanitizer_atomic.h" |
| #include "sanitizer_common/sanitizer_common.h" |
| #include "sanitizer_common/sanitizer_file.h" |
| #include "sanitizer_common/sanitizer_flag_parser.h" |
| #include "sanitizer_common/sanitizer_flags.h" |
| #include "sanitizer_common/sanitizer_internal_defs.h" |
| #include "sanitizer_common/sanitizer_libc.h" |
| #include "sanitizer_common/sanitizer_report_decorator.h" |
| #include "sanitizer_common/sanitizer_stacktrace.h" |
| |
| using namespace __dfsan; |
| |
| typedef atomic_uint16_t atomic_dfsan_label; |
| static const dfsan_label kInitializingLabel = -1; |
| |
| static const uptr kNumLabels = 1 << (sizeof(dfsan_label) * 8); |
| |
| static atomic_dfsan_label __dfsan_last_label; |
| static dfsan_label_info __dfsan_label_info[kNumLabels]; |
| |
| Flags __dfsan::flags_data; |
| |
| // The size of TLS variables. These constants must be kept in sync with the ones |
| // in DataFlowSanitizer.cpp. |
| static const int kDFsanArgTlsSize = 800; |
| static const int kDFsanRetvalTlsSize = 800; |
| static const int kDFsanArgOriginTlsSize = 800; |
| |
| SANITIZER_INTERFACE_ATTRIBUTE THREADLOCAL u64 |
| __dfsan_retval_tls[kDFsanRetvalTlsSize / sizeof(u64)]; |
| SANITIZER_INTERFACE_ATTRIBUTE THREADLOCAL u32 __dfsan_retval_origin_tls; |
| SANITIZER_INTERFACE_ATTRIBUTE THREADLOCAL u64 |
| __dfsan_arg_tls[kDFsanArgTlsSize / sizeof(u64)]; |
| SANITIZER_INTERFACE_ATTRIBUTE THREADLOCAL u32 |
| __dfsan_arg_origin_tls[kDFsanArgOriginTlsSize / sizeof(u32)]; |
| |
| SANITIZER_INTERFACE_ATTRIBUTE uptr __dfsan_shadow_ptr_mask; |
| |
| // Instrumented code may set this value in terms of -dfsan-track-origins. |
| // * undefined or 0: do not track origins. |
| // * 1: track origins at memory store operations. |
| // * 2: TODO: track origins at memory store operations and callsites. |
| extern "C" SANITIZER_WEAK_ATTRIBUTE const int __dfsan_track_origins; |
| |
| int __dfsan_get_track_origins() { |
| return &__dfsan_track_origins ? __dfsan_track_origins : 0; |
| } |
| |
| // On Linux/x86_64, memory is laid out as follows: |
| // |
| // +--------------------+ 0x800000000000 (top of memory) |
| // | application memory | |
| // +--------------------+ 0x700000008000 (kAppAddr) |
| // | | |
| // | unused | |
| // | | |
| // +--------------------+ 0x300200000000 (kUnusedAddr) |
| // | union table | |
| // +--------------------+ 0x300000000000 (kUnionTableAddr) |
| // | origin | |
| // +--------------------+ 0x200000000000 (kOriginAddr) |
| // | shadow memory | |
| // +--------------------+ 0x000000010000 (kShadowAddr) |
| // | reserved by kernel | |
| // +--------------------+ 0x000000000000 |
| // |
| // To derive a shadow memory address from an application memory address, |
| // bits 44-46 are cleared to bring the address into the range |
| // [0x000000008000,0x100000000000). Then the address is shifted left by 1 to |
| // account for the double byte representation of shadow labels and move the |
| // address into the shadow memory range. See the function shadow_for below. |
| |
| // On Linux/MIPS64, memory is laid out as follows: |
| // |
| // +--------------------+ 0x10000000000 (top of memory) |
| // | application memory | |
| // +--------------------+ 0xF000008000 (kAppAddr) |
| // | | |
| // | unused | |
| // | | |
| // +--------------------+ 0x2200000000 (kUnusedAddr) |
| // | union table | |
| // +--------------------+ 0x2000000000 (kUnionTableAddr) |
| // | shadow memory | |
| // +--------------------+ 0x0000010000 (kShadowAddr) |
| // | reserved by kernel | |
| // +--------------------+ 0x0000000000 |
| |
| // On Linux/AArch64 (39-bit VMA), memory is laid out as follow: |
| // |
| // +--------------------+ 0x8000000000 (top of memory) |
| // | application memory | |
| // +--------------------+ 0x7000008000 (kAppAddr) |
| // | | |
| // | unused | |
| // | | |
| // +--------------------+ 0x1200000000 (kUnusedAddr) |
| // | union table | |
| // +--------------------+ 0x1000000000 (kUnionTableAddr) |
| // | shadow memory | |
| // +--------------------+ 0x0000010000 (kShadowAddr) |
| // | reserved by kernel | |
| // +--------------------+ 0x0000000000 |
| |
| // On Linux/AArch64 (42-bit VMA), memory is laid out as follow: |
| // |
| // +--------------------+ 0x40000000000 (top of memory) |
| // | application memory | |
| // +--------------------+ 0x3ff00008000 (kAppAddr) |
| // | | |
| // | unused | |
| // | | |
| // +--------------------+ 0x1200000000 (kUnusedAddr) |
| // | union table | |
| // +--------------------+ 0x8000000000 (kUnionTableAddr) |
| // | shadow memory | |
| // +--------------------+ 0x0000010000 (kShadowAddr) |
| // | reserved by kernel | |
| // +--------------------+ 0x0000000000 |
| |
| // On Linux/AArch64 (48-bit VMA), memory is laid out as follow: |
| // |
| // +--------------------+ 0x1000000000000 (top of memory) |
| // | application memory | |
| // +--------------------+ 0xffff00008000 (kAppAddr) |
| // | unused | |
| // +--------------------+ 0xaaaab0000000 (top of PIE address) |
| // | application PIE | |
| // +--------------------+ 0xaaaaa0000000 (top of PIE address) |
| // | | |
| // | unused | |
| // | | |
| // +--------------------+ 0x1200000000 (kUnusedAddr) |
| // | union table | |
| // +--------------------+ 0x8000000000 (kUnionTableAddr) |
| // | shadow memory | |
| // +--------------------+ 0x0000010000 (kShadowAddr) |
| // | reserved by kernel | |
| // +--------------------+ 0x0000000000 |
| |
| typedef atomic_dfsan_label dfsan_union_table_t[kNumLabels][kNumLabels]; |
| |
| #ifdef DFSAN_RUNTIME_VMA |
| // Runtime detected VMA size. |
| int __dfsan::vmaSize; |
| #endif |
| |
| static uptr UnusedAddr() { |
| return UnionTableAddr() + sizeof(dfsan_union_table_t); |
| } |
| |
| static atomic_dfsan_label *union_table(dfsan_label l1, dfsan_label l2) { |
| return &(*(dfsan_union_table_t *) UnionTableAddr())[l1][l2]; |
| } |
| |
| // Checks we do not run out of labels. |
| static void dfsan_check_label(dfsan_label label) { |
| if (label == kInitializingLabel) { |
| Report("FATAL: DataFlowSanitizer: out of labels\n"); |
| Die(); |
| } |
| } |
| |
| // Resolves the union of two unequal labels. Nonequality is a precondition for |
| // this function (the instrumentation pass inlines the equality test). |
| extern "C" SANITIZER_INTERFACE_ATTRIBUTE |
| dfsan_label __dfsan_union(dfsan_label l1, dfsan_label l2) { |
| DCHECK_NE(l1, l2); |
| |
| if (l1 == 0) |
| return l2; |
| if (l2 == 0) |
| return l1; |
| |
| // If no labels have been created, yet l1 and l2 are non-zero, we are using |
| // fast16labels mode. |
| if (atomic_load(&__dfsan_last_label, memory_order_relaxed) == 0) |
| return l1 | l2; |
| |
| if (l1 > l2) |
| Swap(l1, l2); |
| |
| atomic_dfsan_label *table_ent = union_table(l1, l2); |
| // We need to deal with the case where two threads concurrently request |
| // a union of the same pair of labels. If the table entry is uninitialized, |
| // (i.e. 0) use a compare-exchange to set the entry to kInitializingLabel |
| // (i.e. -1) to mark that we are initializing it. |
| dfsan_label label = 0; |
| if (atomic_compare_exchange_strong(table_ent, &label, kInitializingLabel, |
| memory_order_acquire)) { |
| // Check whether l2 subsumes l1. We don't need to check whether l1 |
| // subsumes l2 because we are guaranteed here that l1 < l2, and (at least |
| // in the cases we are interested in) a label may only subsume labels |
| // created earlier (i.e. with a lower numerical value). |
| if (__dfsan_label_info[l2].l1 == l1 || |
| __dfsan_label_info[l2].l2 == l1) { |
| label = l2; |
| } else { |
| label = |
| atomic_fetch_add(&__dfsan_last_label, 1, memory_order_relaxed) + 1; |
| dfsan_check_label(label); |
| __dfsan_label_info[label].l1 = l1; |
| __dfsan_label_info[label].l2 = l2; |
| } |
| atomic_store(table_ent, label, memory_order_release); |
| } else if (label == kInitializingLabel) { |
| // Another thread is initializing the entry. Wait until it is finished. |
| do { |
| internal_sched_yield(); |
| label = atomic_load(table_ent, memory_order_acquire); |
| } while (label == kInitializingLabel); |
| } |
| return label; |
| } |
| |
| extern "C" SANITIZER_INTERFACE_ATTRIBUTE |
| dfsan_label __dfsan_union_load(const dfsan_label *ls, uptr n) { |
| dfsan_label label = ls[0]; |
| for (uptr i = 1; i != n; ++i) { |
| dfsan_label next_label = ls[i]; |
| if (label != next_label) |
| label = __dfsan_union(label, next_label); |
| } |
| return label; |
| } |
| |
| extern "C" SANITIZER_INTERFACE_ATTRIBUTE |
| dfsan_label __dfsan_union_load_fast16labels(const dfsan_label *ls, uptr n) { |
| dfsan_label label = ls[0]; |
| for (uptr i = 1; i != n; ++i) |
| label |= ls[i]; |
| return label; |
| } |
| |
| // Return the union of all the n labels from addr at the high 32 bit, and the |
| // origin of the first taint byte at the low 32 bit. |
| extern "C" SANITIZER_INTERFACE_ATTRIBUTE u64 |
| __dfsan_load_label_and_origin(const void *addr, uptr n) { |
| dfsan_label label = 0; |
| u64 ret = 0; |
| uptr p = (uptr)addr; |
| dfsan_label *s = shadow_for((void *)p); |
| for (uptr i = 0; i < n; ++i) { |
| dfsan_label l = s[i]; |
| if (!l) |
| continue; |
| label |= l; |
| if (!ret) |
| ret = *(dfsan_origin *)origin_for((void *)(p + i)); |
| } |
| return ret | (u64)label << 32; |
| } |
| |
| extern "C" SANITIZER_INTERFACE_ATTRIBUTE |
| void __dfsan_unimplemented(char *fname) { |
| if (flags().warn_unimplemented) |
| Report("WARNING: DataFlowSanitizer: call to uninstrumented function %s\n", |
| fname); |
| } |
| |
| // Use '-mllvm -dfsan-debug-nonzero-labels' and break on this function |
| // to try to figure out where labels are being introduced in a nominally |
| // label-free program. |
| extern "C" SANITIZER_INTERFACE_ATTRIBUTE void __dfsan_nonzero_label() { |
| if (flags().warn_nonzero_labels) |
| Report("WARNING: DataFlowSanitizer: saw nonzero label\n"); |
| } |
| |
| // Indirect call to an uninstrumented vararg function. We don't have a way of |
| // handling these at the moment. |
| extern "C" SANITIZER_INTERFACE_ATTRIBUTE void |
| __dfsan_vararg_wrapper(const char *fname) { |
| Report("FATAL: DataFlowSanitizer: unsupported indirect call to vararg " |
| "function %s\n", fname); |
| Die(); |
| } |
| |
| // Like __dfsan_union, but for use from the client or custom functions. Hence |
| // the equality comparison is done here before calling __dfsan_union. |
| SANITIZER_INTERFACE_ATTRIBUTE dfsan_label |
| dfsan_union(dfsan_label l1, dfsan_label l2) { |
| if (l1 == l2) |
| return l1; |
| return __dfsan_union(l1, l2); |
| } |
| |
| extern "C" SANITIZER_INTERFACE_ATTRIBUTE |
| dfsan_label dfsan_create_label(const char *desc, void *userdata) { |
| dfsan_label label = |
| atomic_fetch_add(&__dfsan_last_label, 1, memory_order_relaxed) + 1; |
| dfsan_check_label(label); |
| __dfsan_label_info[label].l1 = __dfsan_label_info[label].l2 = 0; |
| __dfsan_label_info[label].desc = desc; |
| __dfsan_label_info[label].userdata = userdata; |
| return label; |
| } |
| |
| // Return the origin of the first taint byte in the size bytes from the address |
| // addr. |
| static dfsan_origin GetOriginIfTainted(uptr addr, uptr size) { |
| for (uptr i = 0; i < size; ++i, ++addr) { |
| dfsan_label *s = shadow_for((void *)addr); |
| if (!is_shadow_addr_valid((uptr)s)) { |
| // The current DFSan memory layout is not always correct. For example, |
| // addresses (0, 0x10000) are mapped to (0, 0x10000). Before fixing the |
| // issue, we ignore such addresses. |
| continue; |
| } |
| if (*s) |
| return *(dfsan_origin *)origin_for((void *)addr); |
| } |
| return 0; |
| } |
| |
| // For platforms which support slow unwinder only, we need to restrict the store |
| // context size to 1, basically only storing the current pc, because the slow |
| // unwinder which is based on libunwind is not async signal safe and causes |
| // random freezes in forking applications as well as in signal handlers. |
| // DFSan supports only Linux. So we do not restrict the store context size. |
| #define GET_STORE_STACK_TRACE_PC_BP(pc, bp) \ |
| BufferedStackTrace stack; \ |
| stack.Unwind(pc, bp, nullptr, true, flags().store_context_size); |
| |
| #define PRINT_CALLER_STACK_TRACE \ |
| { \ |
| GET_CALLER_PC_BP_SP; \ |
| (void)sp; \ |
| GET_STORE_STACK_TRACE_PC_BP(pc, bp) \ |
| stack.Print(); \ |
| } |
| |
| // Return a chain with the previous ID id and the current stack. |
| // from_init = true if this is the first chain of an origin tracking path. |
| static u32 ChainOrigin(u32 id, StackTrace *stack, bool from_init = false) { |
| // StackDepot is not async signal safe. Do not create new chains in a signal |
| // handler. |
| DFsanThread *t = GetCurrentThread(); |
| if (t && t->InSignalHandler()) |
| return id; |
| |
| // As an optimization the origin of an application byte is updated only when |
| // its shadow is non-zero. Because we are only interested in the origins of |
| // taint labels, it does not matter what origin a zero label has. This reduces |
| // memory write cost. MSan does similar optimization. The following invariant |
| // may not hold because of some bugs. We check the invariant to help debug. |
| if (!from_init && id == 0 && flags().check_origin_invariant) { |
| Printf(" DFSan found invalid origin invariant\n"); |
| PRINT_CALLER_STACK_TRACE |
| } |
| |
| Origin o = Origin::FromRawId(id); |
| stack->tag = StackTrace::TAG_UNKNOWN; |
| Origin chained = Origin::CreateChainedOrigin(o, stack); |
| return chained.raw_id(); |
| } |
| |
| static const uptr kOriginAlign = sizeof(dfsan_origin); |
| static const uptr kOriginAlignMask = ~(kOriginAlign - 1UL); |
| |
| static uptr AlignUp(uptr u) { |
| return (u + kOriginAlign - 1) & kOriginAlignMask; |
| } |
| |
| static uptr AlignDown(uptr u) { return u & kOriginAlignMask; } |
| |
| static void ChainAndWriteOriginIfTainted(uptr src, uptr size, uptr dst, |
| StackTrace *stack) { |
| dfsan_origin o = GetOriginIfTainted(src, size); |
| if (o) { |
| o = ChainOrigin(o, stack); |
| *(dfsan_origin *)origin_for((void *)dst) = o; |
| } |
| } |
| |
| // Copy the origins of the size bytes from src to dst. The source and target |
| // memory ranges cannot be overlapped. This is used by memcpy. stack records the |
| // stack trace of the memcpy. When dst and src are not 4-byte aligned properly, |
| // origins at the unaligned address boundaries may be overwritten because four |
| // contiguous bytes share the same origin. |
| static void CopyOrigin(const void *dst, const void *src, uptr size, |
| StackTrace *stack) { |
| uptr d = (uptr)dst; |
| uptr beg = AlignDown(d); |
| // Copy left unaligned origin if that memory is tainted. |
| if (beg < d) { |
| ChainAndWriteOriginIfTainted((uptr)src, beg + kOriginAlign - d, beg, stack); |
| beg += kOriginAlign; |
| } |
| |
| uptr end = AlignDown(d + size); |
| // If both ends fall into the same 4-byte slot, we are done. |
| if (end < beg) |
| return; |
| |
| // Copy right unaligned origin if that memory is tainted. |
| if (end < d + size) |
| ChainAndWriteOriginIfTainted((uptr)src + (end - d), (d + size) - end, end, |
| stack); |
| |
| if (beg >= end) |
| return; |
| |
| // Align src up. |
| uptr s = AlignUp((uptr)src); |
| dfsan_origin *src_o = (dfsan_origin *)origin_for((void *)s); |
| u64 *src_s = (u64 *)shadow_for((void *)s); |
| dfsan_origin *src_end = (dfsan_origin *)origin_for((void *)(s + (end - beg))); |
| dfsan_origin *dst_o = (dfsan_origin *)origin_for((void *)beg); |
| dfsan_origin last_src_o = 0; |
| dfsan_origin last_dst_o = 0; |
| for (; src_o < src_end; ++src_o, ++src_s, ++dst_o) { |
| if (!*src_s) |
| continue; |
| if (*src_o != last_src_o) { |
| last_src_o = *src_o; |
| last_dst_o = ChainOrigin(last_src_o, stack); |
| } |
| *dst_o = last_dst_o; |
| } |
| } |
| |
| // Copy the origins of the size bytes from src to dst. The source and target |
| // memory ranges may be overlapped. So the copy is done in a reverse order. |
| // This is used by memmove. stack records the stack trace of the memmove. |
| static void ReverseCopyOrigin(const void *dst, const void *src, uptr size, |
| StackTrace *stack) { |
| uptr d = (uptr)dst; |
| uptr end = AlignDown(d + size); |
| |
| // Copy right unaligned origin if that memory is tainted. |
| if (end < d + size) |
| ChainAndWriteOriginIfTainted((uptr)src + (end - d), (d + size) - end, end, |
| stack); |
| |
| uptr beg = AlignDown(d); |
| |
| if (beg + kOriginAlign < end) { |
| // Align src up. |
| uptr s = AlignUp((uptr)src); |
| dfsan_origin *src = |
| (dfsan_origin *)origin_for((void *)(s + end - beg - kOriginAlign)); |
| u64 *src_s = (u64 *)shadow_for((void *)(s + end - beg - kOriginAlign)); |
| dfsan_origin *src_begin = (dfsan_origin *)origin_for((void *)s); |
| dfsan_origin *dst = |
| (dfsan_origin *)origin_for((void *)(end - kOriginAlign)); |
| dfsan_origin src_o = 0; |
| dfsan_origin dst_o = 0; |
| for (; src >= src_begin; --src, --src_s, --dst) { |
| if (!*src_s) |
| continue; |
| if (*src != src_o) { |
| src_o = *src; |
| dst_o = ChainOrigin(src_o, stack); |
| } |
| *dst = dst_o; |
| } |
| } |
| |
| // Copy left unaligned origin if that memory is tainted. |
| if (beg < d) |
| ChainAndWriteOriginIfTainted((uptr)src, beg + kOriginAlign - d, beg, stack); |
| } |
| |
| // Copy or move the origins of the len bytes from src to dst. The source and |
| // target memory ranges may or may not be overlapped. This is used by memory |
| // transfer operations. stack records the stack trace of the memory transfer |
| // operation. |
| static void MoveOrigin(const void *dst, const void *src, uptr size, |
| StackTrace *stack) { |
| if (!has_valid_shadow_addr(dst) || |
| !has_valid_shadow_addr((void *)((uptr)dst + size)) || |
| !has_valid_shadow_addr(src) || |
| !has_valid_shadow_addr((void *)((uptr)src + size))) { |
| return; |
| } |
| // If destination origin range overlaps with source origin range, move |
| // origins by copying origins in a reverse order; otherwise, copy origins in |
| // a normal order. The orders of origin transfer are consistent with the |
| // orders of how memcpy and memmove transfer user data. |
| uptr src_aligned_beg = reinterpret_cast<uptr>(src) & ~3UL; |
| uptr src_aligned_end = (reinterpret_cast<uptr>(src) + size) & ~3UL; |
| uptr dst_aligned_beg = reinterpret_cast<uptr>(dst) & ~3UL; |
| if (dst_aligned_beg < src_aligned_end && dst_aligned_beg >= src_aligned_beg) |
| return ReverseCopyOrigin(dst, src, size, stack); |
| return CopyOrigin(dst, src, size, stack); |
| } |
| |
| // Set the size bytes from the addres dst to be the origin value. |
| static void SetOrigin(const void *dst, uptr size, u32 origin) { |
| if (size == 0) |
| return; |
| |
| // Origin mapping is 4 bytes per 4 bytes of application memory. |
| // Here we extend the range such that its left and right bounds are both |
| // 4 byte aligned. |
| uptr x = unaligned_origin_for((uptr)dst); |
| uptr beg = AlignDown(x); |
| uptr end = AlignUp(x + size); // align up. |
| u64 origin64 = ((u64)origin << 32) | origin; |
| // This is like memset, but the value is 32-bit. We unroll by 2 to write |
| // 64 bits at once. May want to unroll further to get 128-bit stores. |
| if (beg & 7ULL) { |
| if (*(u32 *)beg != origin) |
| *(u32 *)beg = origin; |
| beg += 4; |
| } |
| for (uptr addr = beg; addr < (end & ~7UL); addr += 8) { |
| if (*(u64 *)addr == origin64) |
| continue; |
| *(u64 *)addr = origin64; |
| } |
| if (end & 7ULL) |
| if (*(u32 *)(end - kOriginAlign) != origin) |
| *(u32 *)(end - kOriginAlign) = origin; |
| } |
| |
| static void WriteShadowInRange(dfsan_label label, uptr beg_shadow_addr, |
| uptr end_shadow_addr) { |
| // TODO: After changing dfsan_label to 8bit, use internal_memset when label |
| // is not 0. |
| dfsan_label *labelp = (dfsan_label *)beg_shadow_addr; |
| if (label) { |
| for (; (uptr)labelp < end_shadow_addr; ++labelp) *labelp = label; |
| return; |
| } |
| |
| for (; (uptr)labelp < end_shadow_addr; ++labelp) { |
| // Don't write the label if it is already the value we need it to be. |
| // In a program where most addresses are not labeled, it is common that |
| // a page of shadow memory is entirely zeroed. The Linux copy-on-write |
| // implementation will share all of the zeroed pages, making a copy of a |
| // page when any value is written. The un-sharing will happen even if |
| // the value written does not change the value in memory. Avoiding the |
| // write when both |label| and |*labelp| are zero dramatically reduces |
| // the amount of real memory used by large programs. |
| if (!*labelp) |
| continue; |
| |
| *labelp = 0; |
| } |
| } |
| |
| static void WriteShadowWithSize(dfsan_label label, uptr shadow_addr, |
| uptr size) { |
| WriteShadowInRange(label, shadow_addr, shadow_addr + size * sizeof(label)); |
| } |
| |
| #define RET_CHAIN_ORIGIN(id) \ |
| GET_CALLER_PC_BP_SP; \ |
| (void)sp; \ |
| GET_STORE_STACK_TRACE_PC_BP(pc, bp); \ |
| return ChainOrigin(id, &stack); |
| |
| // Return a new origin chain with the previous ID id and the current stack |
| // trace. |
| extern "C" SANITIZER_INTERFACE_ATTRIBUTE dfsan_origin |
| __dfsan_chain_origin(dfsan_origin id) { |
| RET_CHAIN_ORIGIN(id) |
| } |
| |
| // Return a new origin chain with the previous ID id and the current stack |
| // trace if the label is tainted. |
| extern "C" SANITIZER_INTERFACE_ATTRIBUTE dfsan_origin |
| __dfsan_chain_origin_if_tainted(dfsan_label label, dfsan_origin id) { |
| if (!label) |
| return id; |
| RET_CHAIN_ORIGIN(id) |
| } |
| |
| // Copy or move the origins of the len bytes from src to dst. |
| extern "C" SANITIZER_INTERFACE_ATTRIBUTE void __dfsan_mem_origin_transfer( |
| const void *dst, const void *src, uptr len) { |
| if (src == dst) |
| return; |
| GET_CALLER_PC_BP; |
| GET_STORE_STACK_TRACE_PC_BP(pc, bp); |
| MoveOrigin(dst, src, len, &stack); |
| } |
| |
| SANITIZER_INTERFACE_ATTRIBUTE void dfsan_mem_origin_transfer(const void *dst, |
| const void *src, |
| uptr len) { |
| __dfsan_mem_origin_transfer(dst, src, len); |
| } |
| |
| namespace __dfsan { |
| |
| bool dfsan_inited = false; |
| bool dfsan_init_is_running = false; |
| |
| void dfsan_copy_memory(void *dst, const void *src, uptr size) { |
| internal_memcpy(dst, src, size); |
| internal_memcpy((void *)shadow_for(dst), (const void *)shadow_for(src), |
| size * sizeof(dfsan_label)); |
| if (__dfsan_get_track_origins()) |
| dfsan_mem_origin_transfer(dst, src, size); |
| } |
| |
| } // namespace __dfsan |
| |
| // If the label s is tainted, set the size bytes from the address p to be a new |
| // origin chain with the previous ID o and the current stack trace. This is |
| // used by instrumentation to reduce code size when too much code is inserted. |
| extern "C" SANITIZER_INTERFACE_ATTRIBUTE void __dfsan_maybe_store_origin( |
| u16 s, void *p, uptr size, dfsan_origin o) { |
| if (UNLIKELY(s)) { |
| GET_CALLER_PC_BP_SP; |
| (void)sp; |
| GET_STORE_STACK_TRACE_PC_BP(pc, bp); |
| SetOrigin(p, size, ChainOrigin(o, &stack)); |
| } |
| } |
| |
| // Releases the pages within the origin address range. |
| static void ReleaseOrigins(void *addr, uptr size) { |
| const uptr beg_origin_addr = (uptr)__dfsan::origin_for(addr); |
| const void *end_addr = (void *)((uptr)addr + size); |
| const uptr end_origin_addr = (uptr)__dfsan::origin_for(end_addr); |
| |
| if (end_origin_addr - beg_origin_addr < |
| common_flags()->clear_shadow_mmap_threshold) |
| return; |
| |
| const uptr page_size = GetPageSizeCached(); |
| const uptr beg_aligned = RoundUpTo(beg_origin_addr, page_size); |
| const uptr end_aligned = RoundDownTo(end_origin_addr, page_size); |
| |
| if (!MmapFixedSuperNoReserve(beg_aligned, end_aligned - beg_aligned)) |
| Die(); |
| } |
| |
| // Releases the pages within the shadow address range, and sets |
| // the shadow addresses not on the pages to be 0. |
| static void ReleaseOrClearShadows(void *addr, uptr size) { |
| const uptr beg_shadow_addr = (uptr)__dfsan::shadow_for(addr); |
| const void *end_addr = (void *)((uptr)addr + size); |
| const uptr end_shadow_addr = (uptr)__dfsan::shadow_for(end_addr); |
| |
| if (end_shadow_addr - beg_shadow_addr < |
| common_flags()->clear_shadow_mmap_threshold) |
| return WriteShadowWithSize(0, beg_shadow_addr, size); |
| |
| const uptr page_size = GetPageSizeCached(); |
| const uptr beg_aligned = RoundUpTo(beg_shadow_addr, page_size); |
| const uptr end_aligned = RoundDownTo(end_shadow_addr, page_size); |
| |
| if (beg_aligned >= end_aligned) { |
| WriteShadowWithSize(0, beg_shadow_addr, size); |
| } else { |
| if (beg_aligned != beg_shadow_addr) |
| WriteShadowInRange(0, beg_shadow_addr, beg_aligned); |
| if (end_aligned != end_shadow_addr) |
| WriteShadowInRange(0, end_aligned, end_shadow_addr); |
| if (!MmapFixedSuperNoReserve(beg_aligned, end_aligned - beg_aligned)) |
| Die(); |
| } |
| } |
| |
| void SetShadow(dfsan_label label, void *addr, uptr size, dfsan_origin origin) { |
| if (0 != label) { |
| const uptr beg_shadow_addr = (uptr)__dfsan::shadow_for(addr); |
| WriteShadowWithSize(label, beg_shadow_addr, size); |
| if (__dfsan_get_track_origins()) |
| SetOrigin(addr, size, origin); |
| return; |
| } |
| |
| if (__dfsan_get_track_origins()) |
| ReleaseOrigins(addr, size); |
| |
| ReleaseOrClearShadows(addr, size); |
| } |
| |
| extern "C" SANITIZER_INTERFACE_ATTRIBUTE void __dfsan_set_label( |
| dfsan_label label, dfsan_origin origin, void *addr, uptr size) { |
| SetShadow(label, addr, size, origin); |
| } |
| |
| SANITIZER_INTERFACE_ATTRIBUTE |
| void dfsan_set_label(dfsan_label label, void *addr, uptr size) { |
| dfsan_origin init_origin = 0; |
| if (label && __dfsan_get_track_origins()) { |
| GET_CALLER_PC_BP; |
| GET_STORE_STACK_TRACE_PC_BP(pc, bp); |
| init_origin = ChainOrigin(0, &stack, true); |
| } |
| SetShadow(label, addr, size, init_origin); |
| } |
| |
| SANITIZER_INTERFACE_ATTRIBUTE |
| void dfsan_add_label(dfsan_label label, void *addr, uptr size) { |
| if (0 == label) |
| return; |
| |
| if (__dfsan_get_track_origins()) { |
| GET_CALLER_PC_BP; |
| GET_STORE_STACK_TRACE_PC_BP(pc, bp); |
| dfsan_origin init_origin = ChainOrigin(0, &stack, true); |
| SetOrigin(addr, size, init_origin); |
| } |
| |
| for (dfsan_label *labelp = shadow_for(addr); size != 0; --size, ++labelp) |
| if (*labelp != label) |
| *labelp = __dfsan_union(*labelp, label); |
| } |
| |
| // Unlike the other dfsan interface functions the behavior of this function |
| // depends on the label of one of its arguments. Hence it is implemented as a |
| // custom function. |
| extern "C" SANITIZER_INTERFACE_ATTRIBUTE dfsan_label |
| __dfsw_dfsan_get_label(long data, dfsan_label data_label, |
| dfsan_label *ret_label) { |
| *ret_label = 0; |
| return data_label; |
| } |
| |
| extern "C" SANITIZER_INTERFACE_ATTRIBUTE dfsan_label __dfso_dfsan_get_label( |
| long data, dfsan_label data_label, dfsan_label *ret_label, |
| dfsan_origin data_origin, dfsan_origin *ret_origin) { |
| *ret_label = 0; |
| *ret_origin = 0; |
| return data_label; |
| } |
| |
| // This function is used if dfsan_get_origin is called when origin tracking is |
| // off. |
| extern "C" SANITIZER_INTERFACE_ATTRIBUTE dfsan_origin __dfsw_dfsan_get_origin( |
| long data, dfsan_label data_label, dfsan_label *ret_label) { |
| *ret_label = 0; |
| return 0; |
| } |
| |
| extern "C" SANITIZER_INTERFACE_ATTRIBUTE dfsan_origin __dfso_dfsan_get_origin( |
| long data, dfsan_label data_label, dfsan_label *ret_label, |
| dfsan_origin data_origin, dfsan_origin *ret_origin) { |
| *ret_label = 0; |
| *ret_origin = 0; |
| return data_origin; |
| } |
| |
| SANITIZER_INTERFACE_ATTRIBUTE dfsan_label |
| dfsan_read_label(const void *addr, uptr size) { |
| if (size == 0) |
| return 0; |
| return __dfsan_union_load(shadow_for(addr), size); |
| } |
| |
| SANITIZER_INTERFACE_ATTRIBUTE dfsan_origin |
| dfsan_read_origin_of_first_taint(const void *addr, uptr size) { |
| return GetOriginIfTainted((uptr)addr, size); |
| } |
| |
| SANITIZER_INTERFACE_ATTRIBUTE void dfsan_set_label_origin(dfsan_label label, |
| dfsan_origin origin, |
| void *addr, |
| uptr size) { |
| __dfsan_set_label(label, origin, addr, size); |
| } |
| |
| extern "C" SANITIZER_INTERFACE_ATTRIBUTE |
| const struct dfsan_label_info *dfsan_get_label_info(dfsan_label label) { |
| return &__dfsan_label_info[label]; |
| } |
| |
| extern "C" SANITIZER_INTERFACE_ATTRIBUTE int |
| dfsan_has_label(dfsan_label label, dfsan_label elem) { |
| if (label == elem) |
| return true; |
| const dfsan_label_info *info = dfsan_get_label_info(label); |
| if (info->l1 != 0) { |
| return dfsan_has_label(info->l1, elem) || dfsan_has_label(info->l2, elem); |
| } else { |
| return false; |
| } |
| } |
| |
| extern "C" SANITIZER_INTERFACE_ATTRIBUTE dfsan_label |
| dfsan_has_label_with_desc(dfsan_label label, const char *desc) { |
| const dfsan_label_info *info = dfsan_get_label_info(label); |
| if (info->l1 != 0) { |
| return dfsan_has_label_with_desc(info->l1, desc) || |
| dfsan_has_label_with_desc(info->l2, desc); |
| } else { |
| return internal_strcmp(desc, info->desc) == 0; |
| } |
| } |
| |
| extern "C" SANITIZER_INTERFACE_ATTRIBUTE uptr |
| dfsan_get_label_count(void) { |
| dfsan_label max_label_allocated = |
| atomic_load(&__dfsan_last_label, memory_order_relaxed); |
| |
| return static_cast<uptr>(max_label_allocated); |
| } |
| |
| extern "C" SANITIZER_INTERFACE_ATTRIBUTE void |
| dfsan_dump_labels(int fd) { |
| dfsan_label last_label = |
| atomic_load(&__dfsan_last_label, memory_order_relaxed); |
| for (uptr l = 1; l <= last_label; ++l) { |
| char buf[64]; |
| internal_snprintf(buf, sizeof(buf), "%u %u %u ", l, |
| __dfsan_label_info[l].l1, __dfsan_label_info[l].l2); |
| WriteToFile(fd, buf, internal_strlen(buf)); |
| if (__dfsan_label_info[l].l1 == 0 && __dfsan_label_info[l].desc) { |
| WriteToFile(fd, __dfsan_label_info[l].desc, |
| internal_strlen(__dfsan_label_info[l].desc)); |
| } |
| WriteToFile(fd, "\n", 1); |
| } |
| } |
| |
| class Decorator : public __sanitizer::SanitizerCommonDecorator { |
| public: |
| Decorator() : SanitizerCommonDecorator() {} |
| const char *Origin() const { return Magenta(); } |
| }; |
| |
| extern "C" SANITIZER_INTERFACE_ATTRIBUTE void dfsan_print_origin_trace( |
| const void *addr, const char *description) { |
| Decorator d; |
| |
| if (!__dfsan_get_track_origins()) { |
| Printf( |
| " %sDFSan: origin tracking is not enabled. Did you specify the " |
| "-dfsan-track-origins=1 option?%s\n", |
| d.Warning(), d.Default()); |
| return; |
| } |
| |
| const dfsan_label label = *__dfsan::shadow_for(addr); |
| if (!label) { |
| Printf(" %sDFSan: no tainted value at %x%s\n", d.Warning(), addr, |
| d.Default()); |
| return; |
| } |
| |
| const dfsan_origin origin = *__dfsan::origin_for(addr); |
| |
| Printf(" %sTaint value 0x%x (at %p) origin tracking (%s)%s\n", d.Origin(), |
| label, addr, description ? description : "", d.Default()); |
| Origin o = Origin::FromRawId(origin); |
| bool found = false; |
| while (o.isChainedOrigin()) { |
| StackTrace stack; |
| dfsan_origin origin_id = o.raw_id(); |
| o = o.getNextChainedOrigin(&stack); |
| if (o.isChainedOrigin()) |
| Printf(" %sOrigin value: 0x%x, Taint value was stored to memory at%s\n", |
| d.Origin(), origin_id, d.Default()); |
| else |
| Printf(" %sOrigin value: 0x%x, Taint value was created at%s\n", |
| d.Origin(), origin_id, d.Default()); |
| stack.Print(); |
| found = true; |
| } |
| if (!found) |
| Printf( |
| " %sTaint value 0x%x (at %p) has invalid origin tracking. This can " |
| "be a DFSan bug.%s\n", |
| d.Warning(), label, addr, d.Default()); |
| } |
| |
| extern "C" SANITIZER_INTERFACE_ATTRIBUTE dfsan_origin |
| dfsan_get_init_origin(const void *addr) { |
| if (!__dfsan_get_track_origins()) |
| return 0; |
| |
| const dfsan_label label = *__dfsan::shadow_for(addr); |
| if (!label) |
| return 0; |
| |
| const dfsan_origin origin = *__dfsan::origin_for(addr); |
| |
| Origin o = Origin::FromRawId(origin); |
| dfsan_origin origin_id = o.raw_id(); |
| while (o.isChainedOrigin()) { |
| StackTrace stack; |
| origin_id = o.raw_id(); |
| o = o.getNextChainedOrigin(&stack); |
| } |
| return origin_id; |
| } |
| |
| #define GET_FATAL_STACK_TRACE_PC_BP(pc, bp) \ |
| BufferedStackTrace stack; \ |
| stack.Unwind(pc, bp, nullptr, common_flags()->fast_unwind_on_fatal); |
| |
| void __sanitizer::BufferedStackTrace::UnwindImpl(uptr pc, uptr bp, |
| void *context, |
| bool request_fast, |
| u32 max_depth) { |
| using namespace __dfsan; |
| DFsanThread *t = GetCurrentThread(); |
| if (!t || !StackTrace::WillUseFastUnwind(request_fast)) { |
| return Unwind(max_depth, pc, bp, context, 0, 0, false); |
| } |
| Unwind(max_depth, pc, bp, nullptr, t->stack_top(), t->stack_bottom(), true); |
| } |
| |
| extern "C" SANITIZER_INTERFACE_ATTRIBUTE void __sanitizer_print_stack_trace() { |
| GET_FATAL_STACK_TRACE_PC_BP(StackTrace::GetCurrentPc(), GET_CURRENT_FRAME()); |
| stack.Print(); |
| } |
| |
| void Flags::SetDefaults() { |
| #define DFSAN_FLAG(Type, Name, DefaultValue, Description) Name = DefaultValue; |
| #include "dfsan_flags.inc" |
| #undef DFSAN_FLAG |
| } |
| |
| static void RegisterDfsanFlags(FlagParser *parser, Flags *f) { |
| #define DFSAN_FLAG(Type, Name, DefaultValue, Description) \ |
| RegisterFlag(parser, #Name, Description, &f->Name); |
| #include "dfsan_flags.inc" |
| #undef DFSAN_FLAG |
| } |
| |
| static void InitializeFlags() { |
| SetCommonFlagsDefaults(); |
| { |
| CommonFlags cf; |
| cf.CopyFrom(*common_flags()); |
| cf.intercept_tls_get_addr = true; |
| OverrideCommonFlags(cf); |
| } |
| flags().SetDefaults(); |
| |
| FlagParser parser; |
| RegisterCommonFlags(&parser); |
| RegisterDfsanFlags(&parser, &flags()); |
| parser.ParseStringFromEnv("DFSAN_OPTIONS"); |
| InitializeCommonFlags(); |
| if (Verbosity()) ReportUnrecognizedFlags(); |
| if (common_flags()->help) parser.PrintFlagDescriptions(); |
| } |
| |
| SANITIZER_INTERFACE_ATTRIBUTE |
| void dfsan_clear_arg_tls(uptr offset, uptr size) { |
| internal_memset((void *)((uptr)__dfsan_arg_tls + offset), 0, size); |
| } |
| |
| SANITIZER_INTERFACE_ATTRIBUTE |
| void dfsan_clear_thread_local_state() { |
| internal_memset(__dfsan_arg_tls, 0, sizeof(__dfsan_arg_tls)); |
| internal_memset(__dfsan_retval_tls, 0, sizeof(__dfsan_retval_tls)); |
| |
| if (__dfsan_get_track_origins()) { |
| internal_memset(__dfsan_arg_origin_tls, 0, sizeof(__dfsan_arg_origin_tls)); |
| internal_memset(&__dfsan_retval_origin_tls, 0, |
| sizeof(__dfsan_retval_origin_tls)); |
| } |
| } |
| |
| static void InitializePlatformEarly() { |
| AvoidCVE_2016_2143(); |
| #ifdef DFSAN_RUNTIME_VMA |
| __dfsan::vmaSize = |
| (MostSignificantSetBitIndex(GET_CURRENT_FRAME()) + 1); |
| if (__dfsan::vmaSize == 39 || __dfsan::vmaSize == 42 || |
| __dfsan::vmaSize == 48) { |
| __dfsan_shadow_ptr_mask = ShadowMask(); |
| } else { |
| Printf("FATAL: DataFlowSanitizer: unsupported VMA range\n"); |
| Printf("FATAL: Found %d - Supported 39, 42, and 48\n", __dfsan::vmaSize); |
| Die(); |
| } |
| #endif |
| } |
| |
| static void dfsan_fini() { |
| if (internal_strcmp(flags().dump_labels_at_exit, "") != 0) { |
| fd_t fd = OpenFile(flags().dump_labels_at_exit, WrOnly); |
| if (fd == kInvalidFd) { |
| Report("WARNING: DataFlowSanitizer: unable to open output file %s\n", |
| flags().dump_labels_at_exit); |
| return; |
| } |
| |
| Report("INFO: DataFlowSanitizer: dumping labels to %s\n", |
| flags().dump_labels_at_exit); |
| dfsan_dump_labels(fd); |
| CloseFile(fd); |
| } |
| } |
| |
| extern "C" void dfsan_flush() { |
| if (!MmapFixedSuperNoReserve(ShadowAddr(), UnusedAddr() - ShadowAddr())) |
| Die(); |
| } |
| |
| static void DFsanInit(int argc, char **argv, char **envp) { |
| CHECK(!dfsan_init_is_running); |
| if (dfsan_inited) |
| return; |
| dfsan_init_is_running = true; |
| SanitizerToolName = "DataflowSanitizer"; |
| |
| InitializeFlags(); |
| |
| ::InitializePlatformEarly(); |
| |
| dfsan_flush(); |
| if (common_flags()->use_madv_dontdump) |
| DontDumpShadowMemory(ShadowAddr(), UnusedAddr() - ShadowAddr()); |
| |
| // Protect the region of memory we don't use, to preserve the one-to-one |
| // mapping from application to shadow memory. But if ASLR is disabled, Linux |
| // will load our executable in the middle of our unused region. This mostly |
| // works so long as the program doesn't use too much memory. We support this |
| // case by disabling memory protection when ASLR is disabled. |
| uptr init_addr = (uptr)&DFsanInit; |
| if (!(init_addr >= UnusedAddr() && init_addr < AppAddr())) |
| MmapFixedNoAccess(UnusedAddr(), AppAddr() - UnusedAddr()); |
| |
| InitializeInterceptors(); |
| |
| // Register the fini callback to run when the program terminates successfully |
| // or it is killed by the runtime. |
| Atexit(dfsan_fini); |
| AddDieCallback(dfsan_fini); |
| |
| // Set up threads |
| DFsanTSDInit(DFsanTSDDtor); |
| |
| dfsan_allocator_init(); |
| |
| DFsanThread *main_thread = DFsanThread::Create(nullptr, nullptr, nullptr); |
| SetCurrentThread(main_thread); |
| main_thread->ThreadStart(); |
| |
| __dfsan_label_info[kInitializingLabel].desc = "<init label>"; |
| |
| dfsan_init_is_running = false; |
| dfsan_inited = true; |
| } |
| |
| namespace __dfsan { |
| |
| void dfsan_init() { DFsanInit(0, nullptr, nullptr); } |
| |
| } // namespace __dfsan |
| |
| #if SANITIZER_CAN_USE_PREINIT_ARRAY |
| __attribute__((section(".preinit_array"), |
| used)) static void (*dfsan_init_ptr)(int, char **, |
| char **) = DFsanInit; |
| #endif |