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