1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 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/cdefs.h> 30 __FBSDID("$FreeBSD$"); 31 32 #include <sys/types.h> 33 #include <sys/sysctl.h> 34 #include <sys/user.h> 35 #include <sys/wait.h> 36 37 #include <err.h> 38 #include <errno.h> 39 #include <fcntl.h> 40 #include <limits.h> 41 #include <stdlib.h> 42 #include <string.h> 43 #include <unistd.h> 44 45 #include <libelf.h> 46 #include <libprocstat.h> 47 48 #include "_libproc.h" 49 50 extern char * const *environ; 51 52 static int getelfclass(int); 53 static int proc_init(pid_t, int, int, struct proc_handle **); 54 55 static int 56 getelfclass(int fd) 57 { 58 GElf_Ehdr ehdr; 59 Elf *e; 60 int class; 61 62 class = ELFCLASSNONE; 63 64 if ((e = elf_begin(fd, ELF_C_READ, NULL)) == NULL) 65 goto out; 66 if (gelf_getehdr(e, &ehdr) == NULL) 67 goto out; 68 class = ehdr.e_ident[EI_CLASS]; 69 out: 70 (void)elf_end(e); 71 return (class); 72 } 73 74 static int 75 proc_init(pid_t pid, int flags, int status, struct proc_handle **pphdl) 76 { 77 struct kinfo_proc *kp; 78 struct proc_handle *phdl; 79 int error, class, count, fd; 80 81 error = ENOMEM; 82 if ((phdl = malloc(sizeof(*phdl))) == NULL) 83 goto out; 84 85 memset(phdl, 0, sizeof(*phdl)); 86 phdl->public.pid = pid; 87 phdl->flags = flags; 88 phdl->status = status; 89 phdl->procstat = procstat_open_sysctl(); 90 if (phdl->procstat == NULL) 91 goto out; 92 93 /* Obtain a path to the executable. */ 94 if ((kp = procstat_getprocs(phdl->procstat, KERN_PROC_PID, pid, 95 &count)) == NULL) 96 goto out; 97 error = procstat_getpathname(phdl->procstat, kp, phdl->execpath, 98 sizeof(phdl->execpath)); 99 procstat_freeprocs(phdl->procstat, kp); 100 if (error != 0) 101 goto out; 102 103 /* Use it to determine the data model for the process. */ 104 if ((fd = open(phdl->execpath, O_RDONLY)) < 0) { 105 error = errno; 106 goto out; 107 } 108 class = getelfclass(fd); 109 switch (class) { 110 case ELFCLASS64: 111 phdl->model = PR_MODEL_LP64; 112 break; 113 case ELFCLASS32: 114 phdl->model = PR_MODEL_ILP32; 115 break; 116 case ELFCLASSNONE: 117 default: 118 error = EINVAL; 119 break; 120 } 121 (void)close(fd); 122 123 out: 124 *pphdl = phdl; 125 return (error); 126 } 127 128 int 129 proc_attach(pid_t pid, int flags, struct proc_handle **pphdl) 130 { 131 struct proc_handle *phdl; 132 int error, status; 133 134 if (pid == 0 || (pid == getpid() && (flags & PATTACH_RDONLY) == 0)) 135 return (EINVAL); 136 if (elf_version(EV_CURRENT) == EV_NONE) 137 return (ENOENT); 138 139 /* 140 * Allocate memory for the process handle, a structure containing 141 * all things related to the process. 142 */ 143 error = proc_init(pid, flags, PS_RUN, &phdl); 144 if (error != 0) 145 goto out; 146 147 if ((flags & PATTACH_RDONLY) == 0) { 148 if (ptrace(PT_ATTACH, proc_getpid(phdl), 0, 0) != 0) { 149 error = errno; 150 DPRINTF("ERROR: cannot ptrace child process %d", pid); 151 goto out; 152 } 153 154 /* Wait for the child process to stop. */ 155 if (waitpid(pid, &status, WUNTRACED) == -1) { 156 error = errno; 157 DPRINTF("ERROR: child process %d didn't stop as expected", pid); 158 goto out; 159 } 160 161 /* Check for an unexpected status. */ 162 if (!WIFSTOPPED(status)) 163 DPRINTFX("ERROR: child process %d status 0x%x", pid, status); 164 else 165 phdl->status = PS_STOP; 166 167 if ((flags & PATTACH_NOSTOP) != 0) 168 proc_continue(phdl); 169 } 170 171 out: 172 if (error != 0 && phdl != NULL) { 173 proc_free(phdl); 174 phdl = NULL; 175 } 176 *pphdl = phdl; 177 return (error); 178 } 179 180 int 181 proc_create(const char *file, char * const *argv, char * const *envp, 182 proc_child_func *pcf, void *child_arg, struct proc_handle **pphdl) 183 { 184 struct proc_handle *phdl; 185 int error, status; 186 pid_t pid; 187 188 if (elf_version(EV_CURRENT) == EV_NONE) 189 return (ENOENT); 190 191 error = 0; 192 phdl = NULL; 193 194 if ((pid = fork()) == -1) 195 error = errno; 196 else if (pid == 0) { 197 /* The child expects to be traced. */ 198 if (ptrace(PT_TRACE_ME, 0, 0, 0) != 0) 199 _exit(1); 200 201 if (pcf != NULL) 202 (*pcf)(child_arg); 203 204 if (envp != NULL) 205 environ = envp; 206 207 execvp(file, argv); 208 209 _exit(2); 210 /* NOTREACHED */ 211 } else { 212 /* Wait for the child process to stop. */ 213 if (waitpid(pid, &status, WUNTRACED) == -1) { 214 error = errno; 215 DPRINTF("ERROR: child process %d didn't stop as expected", pid); 216 goto bad; 217 } 218 219 /* Check for an unexpected status. */ 220 if (!WIFSTOPPED(status)) { 221 error = ENOENT; 222 DPRINTFX("ERROR: child process %d status 0x%x", pid, status); 223 goto bad; 224 } 225 226 /* The parent owns the process handle. */ 227 error = proc_init(pid, 0, PS_IDLE, &phdl); 228 if (error == 0) 229 phdl->status = PS_STOP; 230 231 bad: 232 if (error != 0 && phdl != NULL) { 233 proc_free(phdl); 234 phdl = NULL; 235 } 236 } 237 *pphdl = phdl; 238 return (error); 239 } 240 241 void 242 proc_free(struct proc_handle *phdl) 243 { 244 struct file_info *file; 245 size_t i; 246 247 for (i = 0; i < phdl->nmappings; i++) { 248 file = phdl->mappings[i].file; 249 if (file != NULL && --file->refs == 0) { 250 if (file->elf != NULL) { 251 (void)elf_end(file->elf); 252 (void)close(file->fd); 253 if (file->symtab.nsyms > 0) 254 free(file->symtab.index); 255 if (file->dynsymtab.nsyms > 0) 256 free(file->dynsymtab.index); 257 } 258 free(file); 259 } 260 } 261 if (phdl->maparrsz > 0) 262 free(phdl->mappings); 263 if (phdl->procstat != NULL) 264 procstat_close(phdl->procstat); 265 if (phdl->rdap != NULL) 266 rd_delete(phdl->rdap); 267 free(phdl); 268 } 269