1 //===-- dfsan_interface.h -------------------------------------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This file is a part of DataFlowSanitizer. 10 // 11 // Public interface header. 12 //===----------------------------------------------------------------------===// 13 #ifndef DFSAN_INTERFACE_H 14 #define DFSAN_INTERFACE_H 15 16 #include <stddef.h> 17 #include <stdint.h> 18 #include <sanitizer/common_interface_defs.h> 19 20 #ifdef __cplusplus 21 extern "C" { 22 #endif 23 24 typedef uint8_t dfsan_label; 25 typedef uint32_t dfsan_origin; 26 27 /// Signature of the callback argument to dfsan_set_write_callback(). 28 typedef void (*dfsan_write_callback_t)(int fd, const void *buf, size_t count); 29 30 /// Signature of the callback argument to dfsan_set_conditional_callback(). 31 typedef void (*dfsan_conditional_callback_t)(dfsan_label label, 32 dfsan_origin origin); 33 34 /// Signature of the callback argument to dfsan_set_reaches_function_callback(). 35 /// The description is intended to hold the name of the variable. 36 typedef void (*dfsan_reaches_function_callback_t)(dfsan_label label, 37 dfsan_origin origin, 38 const char *file, 39 unsigned int line, 40 const char *function); 41 42 /// Computes the union of \c l1 and \c l2, resulting in a union label. 43 dfsan_label dfsan_union(dfsan_label l1, dfsan_label l2); 44 45 /// Sets the label for each address in [addr,addr+size) to \c label. 46 void dfsan_set_label(dfsan_label label, void *addr, size_t size); 47 48 /// Sets the label for each address in [addr,addr+size) to the union of the 49 /// current label for that address and \c label. 50 void dfsan_add_label(dfsan_label label, void *addr, size_t size); 51 52 /// Retrieves the label associated with the given data. 53 /// 54 /// The type of 'data' is arbitrary. The function accepts a value of any type, 55 /// which can be truncated or extended (implicitly or explicitly) as necessary. 56 /// The truncation/extension operations will preserve the label of the original 57 /// value. 58 dfsan_label dfsan_get_label(long data); 59 60 /// Retrieves the immediate origin associated with the given data. The returned 61 /// origin may point to another origin. 62 /// 63 /// The type of 'data' is arbitrary. 64 dfsan_origin dfsan_get_origin(long data); 65 66 /// Retrieves the label associated with the data at the given address. 67 dfsan_label dfsan_read_label(const void *addr, size_t size); 68 69 /// Return the origin associated with the first taint byte in the size bytes 70 /// from the address addr. 71 dfsan_origin dfsan_read_origin_of_first_taint(const void *addr, size_t size); 72 73 /// Returns whether the given label label contains the label elem. 74 int dfsan_has_label(dfsan_label label, dfsan_label elem); 75 76 /// Flushes the DFSan shadow, i.e. forgets about all labels currently associated 77 /// with the application memory. Use this call to start over the taint tracking 78 /// within the same process. 79 /// 80 /// Note: If another thread is working with tainted data during the flush, that 81 /// taint could still be written to shadow after the flush. 82 void dfsan_flush(void); 83 84 /// Sets a callback to be invoked on calls to write(). The callback is invoked 85 /// before the write is done. The write is not guaranteed to succeed when the 86 /// callback executes. Pass in NULL to remove any callback. 87 void dfsan_set_write_callback(dfsan_write_callback_t labeled_write_callback); 88 89 /// Sets a callback to be invoked on any conditional expressions which have a 90 /// taint label set. This can be used to find where tainted data influences 91 /// the behavior of the program. 92 /// These callbacks will only be added when -dfsan-conditional-callbacks=true. 93 void dfsan_set_conditional_callback(dfsan_conditional_callback_t callback); 94 95 /// Conditional expressions occur during signal handlers. 96 /// Making callbacks that handle signals well is tricky, so when 97 /// -dfsan-conditional-callbacks=true, conditional expressions used in signal 98 /// handlers will add the labels they see into a global (bitwise-or together). 99 /// This function returns all label bits seen in signal handler conditions. 100 dfsan_label dfsan_get_labels_in_signal_conditional(); 101 102 /// Sets a callback to be invoked when tainted data reaches a function. 103 /// This could occur at function entry, or at a load instruction. 104 /// These callbacks will only be added if -dfsan-reaches-function-callbacks=1. 105 void dfsan_set_reaches_function_callback( 106 dfsan_reaches_function_callback_t callback); 107 108 /// Making callbacks that handle signals well is tricky, so when 109 /// -dfsan-reaches-function-callbacks=true, functions reached in signal 110 /// handlers will add the labels they see into a global (bitwise-or together). 111 /// This function returns all label bits seen during signal handlers. 112 dfsan_label dfsan_get_labels_in_signal_reaches_function(); 113 114 /// Interceptor hooks. 115 /// Whenever a dfsan's custom function is called the corresponding 116 /// hook is called it non-zero. The hooks should be defined by the user. 117 /// The primary use case is taint-guided fuzzing, where the fuzzer 118 /// needs to see the parameters of the function and the labels. 119 /// FIXME: implement more hooks. 120 void dfsan_weak_hook_memcmp(void *caller_pc, const void *s1, const void *s2, 121 size_t n, dfsan_label s1_label, 122 dfsan_label s2_label, dfsan_label n_label); 123 void dfsan_weak_hook_strncmp(void *caller_pc, const char *s1, const char *s2, 124 size_t n, dfsan_label s1_label, 125 dfsan_label s2_label, dfsan_label n_label); 126 127 /// Prints the origin trace of the label at the address addr to stderr. It also 128 /// prints description at the beginning of the trace. If origin tracking is not 129 /// on, or the address is not labeled, it prints nothing. 130 void dfsan_print_origin_trace(const void *addr, const char *description); 131 /// As above, but use an origin id from dfsan_get_origin() instead of address. 132 /// Does not include header line with taint label and address information. 133 void dfsan_print_origin_id_trace(dfsan_origin origin); 134 135 /// Prints the origin trace of the label at the address \p addr to a 136 /// pre-allocated output buffer. If origin tracking is not on, or the address is 137 /// not labeled, it prints nothing. 138 /// 139 /// Typical usage: 140 /// \code 141 /// char kDescription[] = "..."; 142 /// char buf[1024]; 143 /// dfsan_sprint_origin_trace(&tainted_var, kDescription, buf, sizeof(buf)); 144 /// \endcode 145 /// 146 /// Typical usage that handles truncation: 147 /// \code 148 /// char buf[1024]; 149 /// int len = dfsan_sprint_origin_trace(&var, nullptr, buf, sizeof(buf)); 150 /// 151 /// if (len < sizeof(buf)) { 152 /// ProcessOriginTrace(buf); 153 /// } else { 154 /// char *tmpbuf = new char[len + 1]; 155 /// dfsan_sprint_origin_trace(&var, nullptr, tmpbuf, len + 1); 156 /// ProcessOriginTrace(tmpbuf); 157 /// delete[] tmpbuf; 158 /// } 159 /// \endcode 160 /// 161 /// \param addr The tainted memory address whose origin we are printing. 162 /// \param description A description printed at the beginning of the trace. 163 /// \param [out] out_buf The output buffer to write the results to. 164 /// \param out_buf_size The size of \p out_buf. 165 /// 166 /// \returns The number of symbols that should have been written to \p out_buf 167 /// (not including trailing null byte '\0'). Thus, the string is truncated iff 168 /// return value is not less than \p out_buf_size. 169 size_t dfsan_sprint_origin_trace(const void *addr, const char *description, 170 char *out_buf, size_t out_buf_size); 171 /// As above, but use an origin id from dfsan_get_origin() instead of address. 172 /// Does not include header line with taint label and address information. 173 size_t dfsan_sprint_origin_id_trace(dfsan_origin origin, char *out_buf, 174 size_t out_buf_size); 175 176 /// Prints the stack trace leading to this call to a pre-allocated output 177 /// buffer. 178 /// 179 /// For usage examples, see dfsan_sprint_origin_trace. 180 /// 181 /// \param [out] out_buf The output buffer to write the results to. 182 /// \param out_buf_size The size of \p out_buf. 183 /// 184 /// \returns The number of symbols that should have been written to \p out_buf 185 /// (not including trailing null byte '\0'). Thus, the string is truncated iff 186 /// return value is not less than \p out_buf_size. 187 size_t dfsan_sprint_stack_trace(char *out_buf, size_t out_buf_size); 188 189 /// Retrieves the very first origin associated with the data at the given 190 /// address. 191 dfsan_origin dfsan_get_init_origin(const void *addr); 192 193 /// Returns the value of -dfsan-track-origins. 194 /// * 0: do not track origins. 195 /// * 1: track origins at memory store operations. 196 /// * 2: track origins at memory load and store operations. 197 int dfsan_get_track_origins(void); 198 #ifdef __cplusplus 199 } // extern "C" 200 201 template <typename T> void dfsan_set_label(dfsan_label label, T &data) { 202 dfsan_set_label(label, (void *)&data, sizeof(T)); 203 } 204 205 #endif 206 207 #endif // DFSAN_INTERFACE_H 208