1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 3 * 4 * Copyright (c) 2008 John Birrell (jb@freebsd.org) 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #include <sys/types.h> 30 #include <sys/sysctl.h> 31 #include <sys/user.h> 32 #include <sys/wait.h> 33 34 #include <err.h> 35 #include <errno.h> 36 #include <fcntl.h> 37 #include <limits.h> 38 #include <stdlib.h> 39 #include <string.h> 40 #include <unistd.h> 41 42 #include <libelf.h> 43 #include <libprocstat.h> 44 45 #include "_libproc.h" 46 47 extern char * const *environ; 48 49 static int getelfclass(int); 50 static int proc_init(pid_t, int, int, struct proc_handle **); 51 52 static int 53 getelfclass(int fd) 54 { 55 GElf_Ehdr ehdr; 56 Elf *e; 57 int class; 58 59 class = ELFCLASSNONE; 60 61 if ((e = elf_begin(fd, ELF_C_READ, NULL)) == NULL) 62 goto out; 63 if (gelf_getehdr(e, &ehdr) == NULL) 64 goto out; 65 class = ehdr.e_ident[EI_CLASS]; 66 out: 67 (void)elf_end(e); 68 return (class); 69 } 70 71 static int 72 proc_init(pid_t pid, int flags, int status, struct proc_handle **pphdl) 73 { 74 struct kinfo_proc *kp; 75 struct proc_handle *phdl; 76 int error, class, count, fd; 77 78 error = ENOMEM; 79 if ((phdl = malloc(sizeof(*phdl))) == NULL) 80 goto out; 81 82 memset(phdl, 0, sizeof(*phdl)); 83 phdl->public.pid = pid; 84 phdl->flags = flags; 85 phdl->status = status; 86 phdl->procstat = procstat_open_sysctl(); 87 if (phdl->procstat == NULL) 88 goto out; 89 90 /* Obtain a path to the executable. */ 91 if ((kp = procstat_getprocs(phdl->procstat, KERN_PROC_PID, pid, 92 &count)) == NULL) 93 goto out; 94 error = procstat_getpathname(phdl->procstat, kp, phdl->execpath, 95 sizeof(phdl->execpath)); 96 procstat_freeprocs(phdl->procstat, kp); 97 if (error != 0) 98 goto out; 99 100 /* Use it to determine the data model for the process. */ 101 if ((fd = open(phdl->execpath, O_RDONLY)) < 0) { 102 error = errno; 103 goto out; 104 } 105 class = getelfclass(fd); 106 switch (class) { 107 case ELFCLASS64: 108 phdl->model = PR_MODEL_LP64; 109 break; 110 case ELFCLASS32: 111 phdl->model = PR_MODEL_ILP32; 112 break; 113 case ELFCLASSNONE: 114 default: 115 error = EINVAL; 116 break; 117 } 118 (void)close(fd); 119 120 out: 121 *pphdl = phdl; 122 return (error); 123 } 124 125 int 126 proc_attach(pid_t pid, int flags, struct proc_handle **pphdl) 127 { 128 struct proc_handle *phdl; 129 int error, status; 130 131 if (pid == 0 || (pid == getpid() && (flags & PATTACH_RDONLY) == 0)) 132 return (EINVAL); 133 if (elf_version(EV_CURRENT) == EV_NONE) 134 return (ENOENT); 135 136 /* 137 * Allocate memory for the process handle, a structure containing 138 * all things related to the process. 139 */ 140 error = proc_init(pid, flags, PS_RUN, &phdl); 141 if (error != 0) 142 goto out; 143 144 if ((flags & PATTACH_RDONLY) == 0) { 145 if (ptrace(PT_ATTACH, proc_getpid(phdl), 0, 0) != 0) { 146 error = errno; 147 DPRINTF("ERROR: cannot ptrace child process %d", pid); 148 goto out; 149 } 150 151 /* Wait for the child process to stop. */ 152 if (waitpid(pid, &status, WUNTRACED) == -1) { 153 error = errno; 154 DPRINTF("ERROR: child process %d didn't stop as expected", pid); 155 goto out; 156 } 157 158 /* Check for an unexpected status. */ 159 if (!WIFSTOPPED(status)) 160 DPRINTFX("ERROR: child process %d status 0x%x", pid, status); 161 else 162 phdl->status = PS_STOP; 163 164 if ((flags & PATTACH_NOSTOP) != 0) 165 proc_continue(phdl); 166 } 167 168 out: 169 if (error != 0 && phdl != NULL) { 170 proc_free(phdl); 171 phdl = NULL; 172 } 173 *pphdl = phdl; 174 return (error); 175 } 176 177 int 178 proc_create(const char *file, char * const *argv, char * const *envp, 179 proc_child_func *pcf, void *child_arg, struct proc_handle **pphdl) 180 { 181 struct proc_handle *phdl; 182 int error, status; 183 pid_t pid; 184 185 if (elf_version(EV_CURRENT) == EV_NONE) 186 return (ENOENT); 187 188 error = 0; 189 phdl = NULL; 190 191 if ((pid = fork()) == -1) 192 error = errno; 193 else if (pid == 0) { 194 /* The child expects to be traced. */ 195 if (ptrace(PT_TRACE_ME, 0, 0, 0) != 0) 196 _exit(1); 197 198 if (pcf != NULL) 199 (*pcf)(child_arg); 200 201 if (envp != NULL) 202 environ = envp; 203 204 execvp(file, argv); 205 206 _exit(2); 207 /* NOTREACHED */ 208 } else { 209 /* Wait for the child process to stop. */ 210 if (waitpid(pid, &status, WUNTRACED) == -1) { 211 error = errno; 212 DPRINTF("ERROR: child process %d didn't stop as expected", pid); 213 goto bad; 214 } 215 216 /* Check for an unexpected status. */ 217 if (!WIFSTOPPED(status)) { 218 error = ENOENT; 219 DPRINTFX("ERROR: child process %d status 0x%x", pid, status); 220 goto bad; 221 } 222 223 /* The parent owns the process handle. */ 224 error = proc_init(pid, 0, PS_IDLE, &phdl); 225 if (error == 0) 226 phdl->status = PS_STOP; 227 228 bad: 229 if (error != 0 && phdl != NULL) { 230 proc_free(phdl); 231 phdl = NULL; 232 } 233 } 234 *pphdl = phdl; 235 return (error); 236 } 237 238 void 239 proc_free(struct proc_handle *phdl) 240 { 241 struct file_info *file; 242 size_t i; 243 244 for (i = 0; i < phdl->nmappings; i++) { 245 file = phdl->mappings[i].file; 246 if (file != NULL && --file->refs == 0) { 247 if (file->elf != NULL) { 248 (void)elf_end(file->elf); 249 (void)close(file->fd); 250 if (file->symtab.nsyms > 0) 251 free(file->symtab.index); 252 if (file->dynsymtab.nsyms > 0) 253 free(file->dynsymtab.index); 254 } 255 free(file); 256 } 257 } 258 if (phdl->maparrsz > 0) 259 free(phdl->mappings); 260 if (phdl->procstat != NULL) 261 procstat_close(phdl->procstat); 262 if (phdl->rdap != NULL) 263 rd_delete(phdl->rdap); 264 free(phdl); 265 } 266