1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2008 John Birrell ([email protected])
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 #include <sys/types.h>
31 #include <sys/sysctl.h>
32 #include <sys/user.h>
33 #include <sys/wait.h>
34
35 #include <err.h>
36 #include <errno.h>
37 #include <fcntl.h>
38 #include <limits.h>
39 #include <stdlib.h>
40 #include <string.h>
41 #include <unistd.h>
42
43 #include <libelf.h>
44 #include <libprocstat.h>
45
46 #include "_libproc.h"
47
48 extern char * const *environ;
49
50 static int getelfclass(int);
51 static int proc_init(pid_t, int, int, struct proc_handle **);
52
53 static int
getelfclass(int fd)54 getelfclass(int fd)
55 {
56 GElf_Ehdr ehdr;
57 Elf *e;
58 int class;
59
60 class = ELFCLASSNONE;
61
62 if ((e = elf_begin(fd, ELF_C_READ, NULL)) == NULL)
63 goto out;
64 if (gelf_getehdr(e, &ehdr) == NULL)
65 goto out;
66 class = ehdr.e_ident[EI_CLASS];
67 out:
68 (void)elf_end(e);
69 return (class);
70 }
71
72 static int
proc_init(pid_t pid,int flags,int status,struct proc_handle ** pphdl)73 proc_init(pid_t pid, int flags, int status, struct proc_handle **pphdl)
74 {
75 struct kinfo_proc *kp;
76 struct proc_handle *phdl;
77 int error, class, count, fd;
78
79 error = ENOMEM;
80 if ((phdl = malloc(sizeof(*phdl))) == NULL)
81 goto out;
82
83 memset(phdl, 0, sizeof(*phdl));
84 phdl->public.pid = pid;
85 phdl->flags = flags;
86 phdl->status = status;
87 phdl->procstat = procstat_open_sysctl();
88 if (phdl->procstat == NULL)
89 goto out;
90
91 /* Obtain a path to the executable. */
92 if ((kp = procstat_getprocs(phdl->procstat, KERN_PROC_PID, pid,
93 &count)) == NULL)
94 goto out;
95 error = procstat_getpathname(phdl->procstat, kp, phdl->execpath,
96 sizeof(phdl->execpath));
97 procstat_freeprocs(phdl->procstat, kp);
98 if (error != 0)
99 goto out;
100
101 /* Use it to determine the data model for the process. */
102 if ((fd = open(phdl->execpath, O_RDONLY)) < 0) {
103 error = errno;
104 goto out;
105 }
106 class = getelfclass(fd);
107 switch (class) {
108 case ELFCLASS64:
109 phdl->model = PR_MODEL_LP64;
110 break;
111 case ELFCLASS32:
112 phdl->model = PR_MODEL_ILP32;
113 break;
114 case ELFCLASSNONE:
115 default:
116 error = EINVAL;
117 break;
118 }
119 (void)close(fd);
120
121 out:
122 *pphdl = phdl;
123 return (error);
124 }
125
126 int
proc_attach(pid_t pid,int flags,struct proc_handle ** pphdl)127 proc_attach(pid_t pid, int flags, struct proc_handle **pphdl)
128 {
129 struct proc_handle *phdl;
130 int error, status;
131
132 if (pid == 0 || (pid == getpid() && (flags & PATTACH_RDONLY) == 0))
133 return (EINVAL);
134 if (elf_version(EV_CURRENT) == EV_NONE)
135 return (ENOENT);
136
137 /*
138 * Allocate memory for the process handle, a structure containing
139 * all things related to the process.
140 */
141 error = proc_init(pid, flags, PS_RUN, &phdl);
142 if (error != 0)
143 goto out;
144
145 if ((flags & PATTACH_RDONLY) == 0) {
146 if (ptrace(PT_ATTACH, proc_getpid(phdl), 0, 0) != 0) {
147 error = errno;
148 DPRINTF("ERROR: cannot ptrace child process %d", pid);
149 goto out;
150 }
151
152 /* Wait for the child process to stop. */
153 if (waitpid(pid, &status, WUNTRACED) == -1) {
154 error = errno;
155 DPRINTF("ERROR: child process %d didn't stop as expected", pid);
156 goto out;
157 }
158
159 /* Check for an unexpected status. */
160 if (!WIFSTOPPED(status))
161 DPRINTFX("ERROR: child process %d status 0x%x", pid, status);
162 else
163 phdl->status = PS_STOP;
164
165 if ((flags & PATTACH_NOSTOP) != 0)
166 proc_continue(phdl);
167 }
168
169 out:
170 if (error != 0 && phdl != NULL) {
171 proc_free(phdl);
172 phdl = NULL;
173 }
174 *pphdl = phdl;
175 return (error);
176 }
177
178 int
proc_create(const char * file,char * const * argv,char * const * envp,proc_child_func * pcf,void * child_arg,struct proc_handle ** pphdl)179 proc_create(const char *file, char * const *argv, char * const *envp,
180 proc_child_func *pcf, void *child_arg, struct proc_handle **pphdl)
181 {
182 struct proc_handle *phdl;
183 int error, status;
184 pid_t pid;
185
186 if (elf_version(EV_CURRENT) == EV_NONE)
187 return (ENOENT);
188
189 error = 0;
190 phdl = NULL;
191
192 if ((pid = fork()) == -1)
193 error = errno;
194 else if (pid == 0) {
195 /* The child expects to be traced. */
196 if (ptrace(PT_TRACE_ME, 0, 0, 0) != 0)
197 _exit(1);
198
199 if (pcf != NULL)
200 (*pcf)(child_arg);
201
202 if (envp != NULL)
203 environ = envp;
204
205 execvp(file, argv);
206
207 _exit(2);
208 /* NOTREACHED */
209 } else {
210 /* Wait for the child process to stop. */
211 if (waitpid(pid, &status, WUNTRACED) == -1) {
212 error = errno;
213 DPRINTF("ERROR: child process %d didn't stop as expected", pid);
214 goto bad;
215 }
216
217 /* Check for an unexpected status. */
218 if (!WIFSTOPPED(status)) {
219 error = ENOENT;
220 DPRINTFX("ERROR: child process %d status 0x%x", pid, status);
221 goto bad;
222 }
223
224 /* The parent owns the process handle. */
225 error = proc_init(pid, 0, PS_IDLE, &phdl);
226 if (error == 0)
227 phdl->status = PS_STOP;
228
229 bad:
230 if (error != 0 && phdl != NULL) {
231 proc_free(phdl);
232 phdl = NULL;
233 }
234 }
235 *pphdl = phdl;
236 return (error);
237 }
238
239 void
proc_free(struct proc_handle * phdl)240 proc_free(struct proc_handle *phdl)
241 {
242 struct file_info *file;
243 size_t i;
244
245 for (i = 0; i < phdl->nmappings; i++) {
246 file = phdl->mappings[i].file;
247 if (file != NULL && --file->refs == 0) {
248 if (file->elf != NULL) {
249 (void)elf_end(file->elf);
250 (void)close(file->fd);
251 if (file->symtab.nsyms > 0)
252 free(file->symtab.index);
253 if (file->dynsymtab.nsyms > 0)
254 free(file->dynsymtab.index);
255 }
256 free(file);
257 }
258 }
259 if (phdl->maparrsz > 0)
260 free(phdl->mappings);
261 if (phdl->procstat != NULL)
262 procstat_close(phdl->procstat);
263 if (phdl->rdap != NULL)
264 rd_delete(phdl->rdap);
265 free(phdl);
266 }
267