trace.c revision f13505251e6402460f6cc7ec84e0d8ca91607b4f
1#include <stdio.h> 2#include <stdlib.h> 3#include <string.h> 4#include <errno.h> 5#include <unistd.h> 6#include <sys/types.h> 7#include <sys/wait.h> 8#include "ptrace.h" 9#include <asm/unistd.h> 10 11#include "ltrace.h" 12#include "options.h" 13#include "sysdep.h" 14#include "debug.h" 15 16/* If the system headers did not provide the constants, hard-code the normal 17 values. */ 18#ifndef PTRACE_EVENT_FORK 19 20#define PTRACE_OLDSETOPTIONS 21 21#define PTRACE_SETOPTIONS 0x4200 22#define PTRACE_GETEVENTMSG 0x4201 23 24/* options set using PTRACE_SETOPTIONS */ 25#define PTRACE_O_TRACESYSGOOD 0x00000001 26#define PTRACE_O_TRACEFORK 0x00000002 27#define PTRACE_O_TRACEVFORK 0x00000004 28#define PTRACE_O_TRACECLONE 0x00000008 29#define PTRACE_O_TRACEEXEC 0x00000010 30#define PTRACE_O_TRACEVFORKDONE 0x00000020 31#define PTRACE_O_TRACEEXIT 0x00000040 32 33/* Wait extended result codes for the above trace options. */ 34#define PTRACE_EVENT_FORK 1 35#define PTRACE_EVENT_VFORK 2 36#define PTRACE_EVENT_CLONE 3 37#define PTRACE_EVENT_EXEC 4 38#define PTRACE_EVENT_VFORK_DONE 5 39#define PTRACE_EVENT_EXIT 6 40 41#endif /* PTRACE_EVENT_FORK */ 42 43static int fork_exec_syscalls[][5] = { 44 { 45#ifdef __NR_fork 46 __NR_fork, 47#else 48 -1, 49#endif 50#ifdef __NR_clone 51 __NR_clone, 52#else 53 -1, 54#endif 55#ifdef __NR_clone2 56 __NR_clone2, 57#else 58 -1, 59#endif 60#ifdef __NR_vfork 61 __NR_vfork, 62#else 63 -1, 64#endif 65#ifdef __NR_execve 66 __NR_execve, 67#else 68 -1, 69#endif 70 } 71#ifdef FORK_EXEC_SYSCALLS 72 FORK_EXEC_SYSCALLS 73#endif 74}; 75 76#ifdef ARCH_HAVE_UMOVELONG 77extern int arch_umovelong (struct process *, void *, long *, arg_type_info *); 78int 79umovelong (struct process *proc, void *addr, long *result, arg_type_info *info) { 80 return arch_umovelong (proc, addr, result, info); 81} 82#else 83/* Read a single long from the process's memory address 'addr' */ 84int 85umovelong (struct process *proc, void *addr, long *result, arg_type_info *info) { 86 long pointed_to; 87 88 errno = 0; 89 pointed_to = ptrace (PTRACE_PEEKTEXT, proc->pid, addr, 0); 90 if (pointed_to == -1 && errno) 91 return -errno; 92 93 *result = pointed_to; 94 return 0; 95} 96#endif 97 98 99/* Returns 1 if the sysnum may make a new child to be created 100 * (ie, with fork() or clone()) 101 * Returns 0 otherwise. 102 */ 103int 104fork_p(struct process *proc, int sysnum) { 105 unsigned int i; 106 if (proc->personality 107 >= sizeof fork_exec_syscalls / sizeof(fork_exec_syscalls[0])) 108 return 0; 109 for (i = 0; i < sizeof(fork_exec_syscalls[0]) / sizeof(int) - 1; ++i) 110 if (sysnum == fork_exec_syscalls[proc->personality][i]) 111 return 1; 112 return 0; 113} 114 115/* Returns 1 if the sysnum may make the process exec other program 116 */ 117int 118exec_p(struct process *proc, int sysnum) { 119 int i; 120 if (proc->personality 121 >= sizeof fork_exec_syscalls / sizeof(fork_exec_syscalls[0])) 122 return 0; 123 i = sizeof(fork_exec_syscalls[0]) / sizeof(int) - 1; 124 if (sysnum == fork_exec_syscalls[proc->personality][i]) 125 return 1; 126 return 0; 127} 128 129/* Check that we just hit an exec. 130 */ 131int 132was_exec(struct process *proc, int status) { 133 if (!WIFSTOPPED (status)) 134 return 0; 135 136 if (WSTOPSIG (status) == SIGTRAP 137 && (status >> 16) == PTRACE_EVENT_EXEC) { 138 debug (1, "detected exec (PTRACE_EVENT_EXEC)"); 139 return 1; 140 } 141 142 if (WSTOPSIG (status) == SIGTRAP 143 && proc->callstack_depth > 0) { 144 /* Check whether this SIGTRAP is received just after 145 execve is called for this process. Ideally we'd 146 like to check that the exec succeeded, but e.g. on 147 s390 we have no way of knowing, because return 148 value is not set to -1 (as it should). Never mind, 149 reseting breakpoints for current process doesn't 150 hurt. */ 151 struct callstack_element *elem; 152 elem = &proc->callstack[proc->callstack_depth - 1]; 153 if (elem && elem->is_syscall && exec_p(proc, elem->c_un.syscall)) { 154 debug (1, "detected exec (callstack)"); 155 return 1; 156 } 157 } 158 159 return 0; 160} 161 162void 163trace_me(void) { 164 if (ptrace(PTRACE_TRACEME, 0, 1, 0) < 0) { 165 perror("PTRACE_TRACEME"); 166 exit(1); 167 } 168} 169 170int 171trace_pid(pid_t pid) { 172 if (ptrace(PTRACE_ATTACH, pid, 1, 0) < 0) { 173 return -1; 174 } 175 176 return 0; 177} 178 179void 180trace_set_options(struct process *proc, pid_t pid) { 181 if (proc->tracesysgood & 0x80) 182 return; 183 184 long options = PTRACE_O_TRACESYSGOOD | PTRACE_O_TRACEEXEC; 185 if (ptrace(PTRACE_SETOPTIONS, pid, 0, options) < 0 && 186 ptrace(PTRACE_OLDSETOPTIONS, pid, 0, options) < 0) { 187 perror("PTRACE_SETOPTIONS"); 188 return; 189 } 190 proc->tracesysgood |= 0x80; 191} 192 193void 194untrace_pid(pid_t pid) { 195 ptrace(PTRACE_DETACH, pid, 1, 0); 196} 197 198void 199continue_after_signal(pid_t pid, int signum) { 200 /* We should always trace syscalls to be able to control fork(), clone(), execve()... */ 201 ptrace(PTRACE_SYSCALL, pid, 0, signum); 202} 203 204void 205continue_process(pid_t pid) { 206 continue_after_signal(pid, 0); 207} 208 209void 210continue_enabling_breakpoint(pid_t pid, struct breakpoint *sbp) { 211 enable_breakpoint(pid, sbp); 212 continue_process(pid); 213} 214 215void 216continue_after_breakpoint(struct process *proc, struct breakpoint *sbp) { 217 if (sbp->enabled) 218 disable_breakpoint(proc->pid, sbp); 219 set_instruction_pointer(proc, sbp->addr); 220 if (sbp->enabled == 0) { 221 continue_process(proc->pid); 222 } else { 223 proc->breakpoint_being_enabled = sbp; 224#if defined __sparc__ || defined __ia64___ 225 /* we don't want to singlestep here */ 226 continue_process(proc->pid); 227#else 228 ptrace(PTRACE_SINGLESTEP, proc->pid, 0, 0); 229#endif 230 } 231} 232 233/* Read a series of bytes starting at the process's memory address 234 'addr' and continuing until a NUL ('\0') is seen or 'len' bytes 235 have been read. 236*/ 237int 238umovestr(struct process *proc, void *addr, int len, void *laddr) { 239 union { 240 long a; 241 char c[sizeof(long)]; 242 } a; 243 int i; 244 int offset = 0; 245 246 while (offset < len) { 247 a.a = ptrace(PTRACE_PEEKTEXT, proc->pid, addr + offset, 0); 248 for (i = 0; i < sizeof(long); i++) { 249 if (a.c[i] && offset + (signed)i < len) { 250 *(char *)(laddr + offset + i) = a.c[i]; 251 } else { 252 *(char *)(laddr + offset + i) = '\0'; 253 return 0; 254 } 255 } 256 offset += sizeof(long); 257 } 258 *(char *)(laddr + offset) = '\0'; 259 return 0; 260} 261