1 // SPDX-License-Identifier: GPL-2.0 2 // Copyright (c) 2019 Facebook 3 #include <linux/sched.h> 4 #include <linux/ptrace.h> 5 #include <stdint.h> 6 #include <stddef.h> 7 #include <stdbool.h> 8 #include <linux/bpf.h> 9 #include "bpf_helpers.h" 10 11 #define FUNCTION_NAME_LEN 64 12 #define FILE_NAME_LEN 128 13 #define TASK_COMM_LEN 16 14 15 typedef struct { 16 int PyThreadState_frame; 17 int PyThreadState_thread; 18 int PyFrameObject_back; 19 int PyFrameObject_code; 20 int PyFrameObject_lineno; 21 int PyCodeObject_filename; 22 int PyCodeObject_name; 23 int String_data; 24 int String_size; 25 } OffsetConfig; 26 27 typedef struct { 28 uintptr_t current_state_addr; 29 uintptr_t tls_key_addr; 30 OffsetConfig offsets; 31 bool use_tls; 32 } PidData; 33 34 typedef struct { 35 uint32_t success; 36 } Stats; 37 38 typedef struct { 39 char name[FUNCTION_NAME_LEN]; 40 char file[FILE_NAME_LEN]; 41 } Symbol; 42 43 typedef struct { 44 uint32_t pid; 45 uint32_t tid; 46 char comm[TASK_COMM_LEN]; 47 int32_t kernel_stack_id; 48 int32_t user_stack_id; 49 bool thread_current; 50 bool pthread_match; 51 bool stack_complete; 52 int16_t stack_len; 53 int32_t stack[STACK_MAX_LEN]; 54 55 int has_meta; 56 int metadata; 57 char dummy_safeguard; 58 } Event; 59 60 61 typedef int pid_t; 62 63 typedef struct { 64 void* f_back; // PyFrameObject.f_back, previous frame 65 void* f_code; // PyFrameObject.f_code, pointer to PyCodeObject 66 void* co_filename; // PyCodeObject.co_filename 67 void* co_name; // PyCodeObject.co_name 68 } FrameData; 69 70 static __always_inline void *get_thread_state(void *tls_base, PidData *pidData) 71 { 72 void* thread_state; 73 int key; 74 75 bpf_probe_read_user(&key, sizeof(key), (void*)(long)pidData->tls_key_addr); 76 bpf_probe_read_user(&thread_state, sizeof(thread_state), 77 tls_base + 0x310 + key * 0x10 + 0x08); 78 return thread_state; 79 } 80 81 static __always_inline bool get_frame_data(void *frame_ptr, PidData *pidData, 82 FrameData *frame, Symbol *symbol) 83 { 84 // read data from PyFrameObject 85 bpf_probe_read_user(&frame->f_back, 86 sizeof(frame->f_back), 87 frame_ptr + pidData->offsets.PyFrameObject_back); 88 bpf_probe_read_user(&frame->f_code, 89 sizeof(frame->f_code), 90 frame_ptr + pidData->offsets.PyFrameObject_code); 91 92 // read data from PyCodeObject 93 if (!frame->f_code) 94 return false; 95 bpf_probe_read_user(&frame->co_filename, 96 sizeof(frame->co_filename), 97 frame->f_code + pidData->offsets.PyCodeObject_filename); 98 bpf_probe_read_user(&frame->co_name, 99 sizeof(frame->co_name), 100 frame->f_code + pidData->offsets.PyCodeObject_name); 101 // read actual names into symbol 102 if (frame->co_filename) 103 bpf_probe_read_user_str(&symbol->file, 104 sizeof(symbol->file), 105 frame->co_filename + 106 pidData->offsets.String_data); 107 if (frame->co_name) 108 bpf_probe_read_user_str(&symbol->name, 109 sizeof(symbol->name), 110 frame->co_name + 111 pidData->offsets.String_data); 112 return true; 113 } 114 115 struct { 116 __uint(type, BPF_MAP_TYPE_HASH); 117 __uint(max_entries, 1); 118 __type(key, int); 119 __type(value, PidData); 120 } pidmap SEC(".maps"); 121 122 struct { 123 __uint(type, BPF_MAP_TYPE_HASH); 124 __uint(max_entries, 1); 125 __type(key, int); 126 __type(value, Event); 127 } eventmap SEC(".maps"); 128 129 struct { 130 __uint(type, BPF_MAP_TYPE_HASH); 131 __uint(max_entries, 1); 132 __type(key, Symbol); 133 __type(value, int); 134 } symbolmap SEC(".maps"); 135 136 struct { 137 __uint(type, BPF_MAP_TYPE_ARRAY); 138 __uint(max_entries, 1); 139 __type(key, int); 140 __type(value, Stats); 141 } statsmap SEC(".maps"); 142 143 struct { 144 __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY); 145 __uint(max_entries, 32); 146 __uint(key_size, sizeof(int)); 147 __uint(value_size, sizeof(int)); 148 } perfmap SEC(".maps"); 149 150 struct { 151 __uint(type, BPF_MAP_TYPE_STACK_TRACE); 152 __uint(max_entries, 1000); 153 __uint(key_size, sizeof(int)); 154 __uint(value_size, sizeof(long long) * 127); 155 } stackmap SEC(".maps"); 156 157 static __always_inline int __on_event(struct pt_regs *ctx) 158 { 159 uint64_t pid_tgid = bpf_get_current_pid_tgid(); 160 pid_t pid = (pid_t)(pid_tgid >> 32); 161 PidData* pidData = bpf_map_lookup_elem(&pidmap, &pid); 162 if (!pidData) 163 return 0; 164 165 int zero = 0; 166 Event* event = bpf_map_lookup_elem(&eventmap, &zero); 167 if (!event) 168 return 0; 169 170 event->pid = pid; 171 172 event->tid = (pid_t)pid_tgid; 173 bpf_get_current_comm(&event->comm, sizeof(event->comm)); 174 175 event->user_stack_id = bpf_get_stackid(ctx, &stackmap, BPF_F_USER_STACK); 176 event->kernel_stack_id = bpf_get_stackid(ctx, &stackmap, 0); 177 178 void* thread_state_current = (void*)0; 179 bpf_probe_read_user(&thread_state_current, 180 sizeof(thread_state_current), 181 (void*)(long)pidData->current_state_addr); 182 183 struct task_struct* task = (struct task_struct*)bpf_get_current_task(); 184 void* tls_base = (void*)task; 185 186 void* thread_state = pidData->use_tls ? get_thread_state(tls_base, pidData) 187 : thread_state_current; 188 event->thread_current = thread_state == thread_state_current; 189 190 if (pidData->use_tls) { 191 uint64_t pthread_created; 192 uint64_t pthread_self; 193 bpf_probe_read_user(&pthread_self, sizeof(pthread_self), 194 tls_base + 0x10); 195 196 bpf_probe_read_user(&pthread_created, 197 sizeof(pthread_created), 198 thread_state + 199 pidData->offsets.PyThreadState_thread); 200 event->pthread_match = pthread_created == pthread_self; 201 } else { 202 event->pthread_match = 1; 203 } 204 205 if (event->pthread_match || !pidData->use_tls) { 206 void* frame_ptr; 207 FrameData frame; 208 Symbol sym = {}; 209 int cur_cpu = bpf_get_smp_processor_id(); 210 211 bpf_probe_read_user(&frame_ptr, 212 sizeof(frame_ptr), 213 thread_state + 214 pidData->offsets.PyThreadState_frame); 215 216 int32_t* symbol_counter = bpf_map_lookup_elem(&symbolmap, &sym); 217 if (symbol_counter == NULL) 218 return 0; 219 #ifdef NO_UNROLL 220 #pragma clang loop unroll(disable) 221 #else 222 #pragma clang loop unroll(full) 223 #endif 224 /* Unwind python stack */ 225 for (int i = 0; i < STACK_MAX_LEN; ++i) { 226 if (frame_ptr && get_frame_data(frame_ptr, pidData, &frame, &sym)) { 227 int32_t new_symbol_id = *symbol_counter * 64 + cur_cpu; 228 int32_t *symbol_id = bpf_map_lookup_elem(&symbolmap, &sym); 229 if (!symbol_id) { 230 bpf_map_update_elem(&symbolmap, &sym, &zero, 0); 231 symbol_id = bpf_map_lookup_elem(&symbolmap, &sym); 232 if (!symbol_id) 233 return 0; 234 } 235 if (*symbol_id == new_symbol_id) 236 (*symbol_counter)++; 237 event->stack[i] = *symbol_id; 238 event->stack_len = i + 1; 239 frame_ptr = frame.f_back; 240 } 241 } 242 event->stack_complete = frame_ptr == NULL; 243 } else { 244 event->stack_complete = 1; 245 } 246 247 Stats* stats = bpf_map_lookup_elem(&statsmap, &zero); 248 if (stats) 249 stats->success++; 250 251 event->has_meta = 0; 252 bpf_perf_event_output(ctx, &perfmap, 0, event, offsetof(Event, metadata)); 253 return 0; 254 } 255 256 SEC("raw_tracepoint/kfree_skb") 257 int on_event(struct pt_regs* ctx) 258 { 259 int i, ret = 0; 260 ret |= __on_event(ctx); 261 ret |= __on_event(ctx); 262 ret |= __on_event(ctx); 263 ret |= __on_event(ctx); 264 ret |= __on_event(ctx); 265 return ret; 266 } 267 268 char _license[] SEC("license") = "GPL"; 269