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3960
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1 /*
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8058
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2 * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
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3960
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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20 * or visit www.oracle.com if you need additional information or have any
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21 * questions.
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22 *
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23 */
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24
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25 #include <limits.h>
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26 #include <stdio.h>
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27 #include <stdlib.h>
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28 #include <string.h>
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29 #include <errno.h>
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30 #include <sys/types.h>
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31 #include <sys/wait.h>
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32 #include <sys/ptrace.h>
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33 #include <sys/param.h>
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34 #include <sys/user.h>
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35 #include <elf.h>
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36 #include <sys/elf_common.h>
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37 #include <sys/link_elf.h>
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38 #include <libutil.h>
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39 #include "libproc_impl.h"
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40 #include "elfmacros.h"
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41
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42 // This file has the libproc implementation specific to live process
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43 // For core files, refer to ps_core.c
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44
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45 static inline uintptr_t align(uintptr_t ptr, size_t size) {
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46 return (ptr & ~(size - 1));
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47 }
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48
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49 // ---------------------------------------------
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50 // ptrace functions
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51 // ---------------------------------------------
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52
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53 // read "size" bytes of data from "addr" within the target process.
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54 // unlike the standard ptrace() function, process_read_data() can handle
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55 // unaligned address - alignment check, if required, should be done
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56 // before calling process_read_data.
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57
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58 static bool process_read_data(struct ps_prochandle* ph, uintptr_t addr, char *buf, size_t size) {
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59 int rslt;
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60 size_t i, words;
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61 uintptr_t end_addr = addr + size;
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62 uintptr_t aligned_addr = align(addr, sizeof(int));
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63
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64 if (aligned_addr != addr) {
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65 char *ptr = (char *)&rslt;
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66 errno = 0;
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67 rslt = ptrace(PT_READ_D, ph->pid, (caddr_t) aligned_addr, 0);
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68 if (errno) {
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69 print_debug("ptrace(PT_READ_D, ..) failed for %d bytes @ %lx\n", size, addr);
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70 return false;
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71 }
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72 for (; aligned_addr != addr; aligned_addr++, ptr++);
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73 for (; ((intptr_t)aligned_addr % sizeof(int)) && aligned_addr < end_addr;
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74 aligned_addr++)
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75 *(buf++) = *(ptr++);
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76 }
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77
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78 words = (end_addr - aligned_addr) / sizeof(int);
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79
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80 // assert((intptr_t)aligned_addr % sizeof(int) == 0);
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81 for (i = 0; i < words; i++) {
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82 errno = 0;
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83 rslt = ptrace(PT_READ_D, ph->pid, (caddr_t) aligned_addr, 0);
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84 if (errno) {
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85 print_debug("ptrace(PT_READ_D, ..) failed for %d bytes @ %lx\n", size, addr);
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86 return false;
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87 }
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88 *(int *)buf = rslt;
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89 buf += sizeof(int);
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90 aligned_addr += sizeof(int);
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91 }
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92
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93 if (aligned_addr != end_addr) {
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94 char *ptr = (char *)&rslt;
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95 errno = 0;
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96 rslt = ptrace(PT_READ_D, ph->pid, (caddr_t) aligned_addr, 0);
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97 if (errno) {
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98 print_debug("ptrace(PT_READ_D, ..) failed for %d bytes @ %lx\n", size, addr);
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99 return false;
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100 }
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101 for (; aligned_addr != end_addr; aligned_addr++)
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102 *(buf++) = *(ptr++);
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103 }
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104 return true;
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105 }
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106
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107 // null implementation for write
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108 static bool process_write_data(struct ps_prochandle* ph,
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109 uintptr_t addr, const char *buf , size_t size) {
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110 return false;
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111 }
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112
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113 // "user" should be a pointer to a reg
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114 static bool process_get_lwp_regs(struct ps_prochandle* ph, pid_t pid, struct reg *user) {
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115 // we have already attached to all thread 'pid's, just use ptrace call
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116 // to get regset now. Note that we don't cache regset upfront for processes.
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117 if (ptrace(PT_GETREGS, pid, (caddr_t) user, 0) < 0) {
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118 print_debug("ptrace(PTRACE_GETREGS, ...) failed for lwp %d\n", pid);
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119 return false;
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120 }
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121 return true;
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122 }
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123
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124 // fill in ptrace_lwpinfo for lid
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125 static bool process_get_lwp_info(struct ps_prochandle *ph, lwpid_t lwp_id, void *linfo) {
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126 errno = 0;
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127 ptrace(PT_LWPINFO, lwp_id, linfo, sizeof(struct ptrace_lwpinfo));
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128
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129 return (errno == 0)? true: false;
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130 }
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131
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8058
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132 static bool ptrace_continue(pid_t pid, int signal) {
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133 // pass the signal to the process so we don't swallow it
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134 if (ptrace(PTRACE_CONT, pid, NULL, signal) < 0) {
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135 print_debug("ptrace(PTRACE_CONT, ..) failed for %d\n", pid);
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136 return false;
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137 }
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138 return true;
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139 }
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140
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141 // waits until the ATTACH has stopped the process
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142 // by signal SIGSTOP
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143 static bool ptrace_waitpid(pid_t pid) {
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144 int ret;
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145 int status;
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146 do {
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147 // Wait for debuggee to stop.
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148 ret = waitpid(pid, &status, 0);
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149 if (ret >= 0) {
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150 if (WIFSTOPPED(status)) {
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151 // Any signal will stop the thread, make sure it is SIGSTOP. Otherwise SIGSTOP
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152 // will still be pending and delivered when the process is DETACHED and the process
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153 // will go to sleep.
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154 if (WSTOPSIG(status) == SIGSTOP) {
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155 // Debuggee stopped by SIGSTOP.
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156 return true;
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157 }
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158 if (!ptrace_continue(pid, WSTOPSIG(status))) {
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159 print_error("Failed to correctly attach to VM. VM might HANG! [PTRACE_CONT failed, stopped by %d]\n", WSTOPSIG(status));
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160 return false;
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161 }
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162 } else {
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163 print_debug("waitpid(): Child process exited/terminated (status = 0x%x)\n", status);
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164 return false;
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165 }
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166 } else {
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167 switch (errno) {
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168 case EINTR:
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169 continue;
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170 break;
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171 case ECHILD:
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172 print_debug("waitpid() failed. Child process pid (%d) does not exist \n", pid);
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173 break;
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174 case EINVAL:
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175 print_debug("waitpid() failed. Invalid options argument.\n");
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176 break;
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177 default:
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178 print_debug("waitpid() failed. Unexpected error %d\n",errno);
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179 }
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180 return false;
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181 }
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182 } while(true);
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183 }
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184
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3960
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185 // attach to a process/thread specified by "pid"
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186 static bool ptrace_attach(pid_t pid) {
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187 if (ptrace(PT_ATTACH, pid, NULL, 0) < 0) {
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188 print_debug("ptrace(PTRACE_ATTACH, ..) failed for %d\n", pid);
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189 return false;
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190 } else {
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8058
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191 return ptrace_waitpid(pid);
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3960
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192 }
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193 }
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194
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195 // -------------------------------------------------------
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196 // functions for obtaining library information
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197 // -------------------------------------------------------
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198
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199 // callback for read_thread_info
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200 static bool add_new_thread(struct ps_prochandle* ph, pthread_t pthread_id, lwpid_t lwp_id) {
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201 return add_thread_info(ph, pthread_id, lwp_id) != NULL;
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202 }
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203
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204 #if defined(__FreeBSD__) && __FreeBSD_version < 701000
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205 /*
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206 * TEXT_START_ADDR from binutils/ld/emulparams/<arch_spec>.sh
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207 * Not the most robust but good enough.
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208 */
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209
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210 #if defined(amd64) || defined(x86_64)
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211 #define TEXT_START_ADDR 0x400000
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212 #elif defined(i386)
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213 #define TEXT_START_ADDR 0x8048000
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214 #else
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215 #error TEXT_START_ADDR not defined
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216 #endif
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217
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218 #define BUF_SIZE (PATH_MAX + NAME_MAX + 1)
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219
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220 uintptr_t linkmap_addr(struct ps_prochandle *ph) {
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221 uintptr_t ehdr_addr, phdr_addr, dyn_addr, dmap_addr, lmap_addr;
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222 ELF_EHDR ehdr;
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223 ELF_PHDR *phdrs, *phdr;
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224 ELF_DYN *dyns, *dyn;
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225 struct r_debug dmap;
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226 unsigned long hdrs_size;
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227 unsigned int i;
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228
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229 /* read ELF_EHDR at TEXT_START_ADDR and validate */
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230
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231 ehdr_addr = (uintptr_t)TEXT_START_ADDR;
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232
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233 if (process_read_data(ph, ehdr_addr, (char *)&ehdr, sizeof(ehdr)) != true) {
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234 print_debug("process_read_data failed for ehdr_addr %p\n", ehdr_addr);
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235 return (0);
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236 }
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237
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238 if (!IS_ELF(ehdr) ||
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239 ehdr.e_ident[EI_CLASS] != ELF_TARG_CLASS ||
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240 ehdr.e_ident[EI_DATA] != ELF_TARG_DATA ||
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241 ehdr.e_ident[EI_VERSION] != EV_CURRENT ||
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242 ehdr.e_phentsize != sizeof(ELF_PHDR) ||
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243 ehdr.e_version != ELF_TARG_VER ||
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244 ehdr.e_machine != ELF_TARG_MACH) {
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245 print_debug("not an ELF_EHDR at %p\n", ehdr_addr);
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246 return (0);
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247 }
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248
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249 /* allocate space for all ELF_PHDR's and read */
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250
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251 phdr_addr = ehdr_addr + ehdr.e_phoff;
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252 hdrs_size = ehdr.e_phnum * sizeof(ELF_PHDR);
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253
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254 if ((phdrs = malloc(hdrs_size)) == NULL)
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255 return (0);
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256
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257 if (process_read_data(ph, phdr_addr, (char *)phdrs, hdrs_size) != true) {
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258 print_debug("process_read_data failed for phdr_addr %p\n", phdr_addr);
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259 return (0);
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260 }
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261
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262 /* find PT_DYNAMIC section */
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263
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264 for (i = 0, phdr = phdrs; i < ehdr.e_phnum; i++, phdr++) {
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265 if (phdr->p_type == PT_DYNAMIC)
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266 break;
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267 }
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268
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269 if (i >= ehdr.e_phnum) {
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270 print_debug("PT_DYNAMIC section not found!\n");
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271 free(phdrs);
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272 return (0);
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273 }
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274
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275 /* allocate space and read in ELF_DYN headers */
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276
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277 dyn_addr = phdr->p_vaddr;
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278 hdrs_size = phdr->p_memsz;
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279 free(phdrs);
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280
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281 if ((dyns = malloc(hdrs_size)) == NULL)
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282 return (0);
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283
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284 if (process_read_data(ph, dyn_addr, (char *)dyns, hdrs_size) != true) {
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285 print_debug("process_read_data failed for dyn_addr %p\n", dyn_addr);
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286 free(dyns);
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287 return (0);
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288 }
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289
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290 /* find DT_DEBUG */
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291
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292 dyn = dyns;
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293 while (dyn->d_tag != DT_DEBUG && dyn->d_tag != DT_NULL) {
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294 dyn++;
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295 }
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296
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297 if (dyn->d_tag != DT_DEBUG) {
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298 print_debug("failed to find DT_DEBUG\n");
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299 free(dyns);
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300 return (0);
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301 }
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302
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303 /* read struct r_debug into dmap */
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304
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305 dmap_addr = (uintptr_t)dyn->d_un.d_ptr;
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306 free(dyns);
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307
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308 if (process_read_data(ph, dmap_addr, (char *)&dmap, sizeof(dmap)) != true) {
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309 print_debug("process_read_data failed for dmap_addr %p\n", dmap_addr);
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310 return (0);
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311 }
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312
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313 lmap_addr = (uintptr_t)dmap.r_map;
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314
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315 return (lmap_addr);
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316 }
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317 #endif // __FreeBSD__ && __FreeBSD_version < 701000
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318
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319 static bool read_lib_info(struct ps_prochandle* ph) {
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320 #if defined(__FreeBSD__) && __FreeBSD_version >= 701000
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321 struct kinfo_vmentry *freep, *kve;
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322 int i, cnt;
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323
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324 freep = kinfo_getvmmap(ph->pid, &cnt);
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325 if (freep == NULL) {
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326 print_debug("can't get vm map for pid\n", ph->pid);
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327 return false;
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328 }
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329
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330 for (i = 0; i < cnt; i++) {
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331 kve = &freep[i];
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332 if ((kve->kve_flags & KVME_FLAG_COW) &&
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333 kve->kve_path != NULL &&
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334 strlen(kve->kve_path) > 0) {
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335
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336 if (find_lib(ph, kve->kve_path) == false) {
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337 lib_info* lib;
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338 if ((lib = add_lib_info(ph, kve->kve_path,
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339 (uintptr_t) kve->kve_start)) == NULL)
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340 continue; // ignore, add_lib_info prints error
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341
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342 // we don't need to keep the library open, symtab is already
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343 // built. Only for core dump we need to keep the fd open.
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344 close(lib->fd);
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345 lib->fd = -1;
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346 }
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347 }
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348 }
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349
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350 free(freep);
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351
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352 return true;
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353 #else
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354 char *l_name;
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355 struct link_map *lmap;
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356 uintptr_t lmap_addr;
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357
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358 if ((l_name = malloc(BUF_SIZE)) == NULL)
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359 return false;
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360
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361 if ((lmap = malloc(sizeof(*lmap))) == NULL) {
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362 free(l_name);
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363 return false;
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364 }
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365
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366 lmap_addr = linkmap_addr(ph);
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367
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368 if (lmap_addr == 0) {
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369 free(l_name);
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370 free(lmap);
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371 return false;
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372 }
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373
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374 do {
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375 if (process_read_data(ph, lmap_addr, (char *)lmap, sizeof(*lmap)) != true) {
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376 print_debug("process_read_data failed for lmap_addr %p\n", lmap_addr);
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377 free (l_name);
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378 free (lmap);
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379 return false;
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380 }
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381
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382 if (process_read_data(ph, (uintptr_t)lmap->l_name, l_name,
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383 BUF_SIZE) != true) {
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384 print_debug("process_read_data failed for lmap->l_name %p\n",
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385 lmap->l_name);
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386 free (l_name);
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387 free (lmap);
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388 return false;
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389 }
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390
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391 if (find_lib(ph, l_name) == false) {
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392 lib_info* lib;
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393 if ((lib = add_lib_info(ph, l_name,
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394 (uintptr_t) lmap->l_addr)) == NULL)
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395 continue; // ignore, add_lib_info prints error
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396
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397 // we don't need to keep the library open, symtab is already
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398 // built. Only for core dump we need to keep the fd open.
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399 close(lib->fd);
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400 lib->fd = -1;
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401 }
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402 lmap_addr = (uintptr_t)lmap->l_next;
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403 } while (lmap->l_next != NULL);
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404
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405 free (l_name);
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406 free (lmap);
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407
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408 return true;
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409 #endif
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410 }
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411
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412 // detach a given pid
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413 static bool ptrace_detach(pid_t pid) {
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414 if (pid && ptrace(PT_DETACH, pid, (caddr_t)1, 0) < 0) {
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415 print_debug("ptrace(PTRACE_DETACH, ..) failed for %d\n", pid);
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416 return false;
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417 } else {
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418 return true;
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419 }
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420 }
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421
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422 static void process_cleanup(struct ps_prochandle* ph) {
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423 ptrace_detach(ph->pid);
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424 }
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425
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426 static ps_prochandle_ops process_ops = {
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427 .release= process_cleanup,
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428 .p_pread= process_read_data,
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429 .p_pwrite= process_write_data,
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430 .get_lwp_regs= process_get_lwp_regs,
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431 .get_lwp_info= process_get_lwp_info
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432 };
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433
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434 // attach to the process. One and only one exposed stuff
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435 struct ps_prochandle* Pgrab(pid_t pid) {
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436 struct ps_prochandle* ph = NULL;
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|
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437 thread_info* thr = NULL;
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|
|
438
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|
|
439 if ( (ph = (struct ps_prochandle*) calloc(1, sizeof(struct ps_prochandle))) == NULL) {
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440 print_debug("can't allocate memory for ps_prochandle\n");
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441 return NULL;
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|
|
442 }
|
|
|
443
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|
|
444 if (ptrace_attach(pid) != true) {
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|
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445 free(ph);
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446 return NULL;
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|
|
447 }
|
|
|
448
|
|
|
449 // initialize ps_prochandle
|
|
|
450 ph->pid = pid;
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|
|
451
|
|
|
452 // initialize vtable
|
|
|
453 ph->ops = &process_ops;
|
|
|
454
|
|
|
455 // read library info and symbol tables, must do this before attaching threads,
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|
|
456 // as the symbols in the pthread library will be used to figure out
|
|
|
457 // the list of threads within the same process.
|
|
|
458 if (read_lib_info(ph) != true) {
|
|
|
459 ptrace_detach(pid);
|
|
|
460 free(ph);
|
|
|
461 return NULL;
|
|
|
462 }
|
|
|
463
|
|
|
464 // read thread info
|
|
|
465 read_thread_info(ph, add_new_thread);
|
|
|
466
|
|
|
467 return ph;
|
|
|
468 }
|
