1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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 __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
getelfclass(int fd)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
proc_init(pid_t pid,int flags,int status,struct proc_handle ** pphdl)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
proc_attach(pid_t pid,int flags,struct proc_handle ** pphdl)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
proc_create(const char * file,char * const * argv,char * const * envp,proc_child_func * pcf,void * child_arg,struct proc_handle ** pphdl)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
proc_free(struct proc_handle * phdl)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