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
getelfclass(int fd)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
proc_init(pid_t pid,int flags,int status,struct proc_handle ** pphdl)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
proc_attach(pid_t pid,int flags,struct proc_handle ** pphdl)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
proc_create(const char * file,char * const * argv,char * const * envp,proc_child_func * pcf,void * child_arg,struct proc_handle ** pphdl)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
proc_free(struct proc_handle * phdl)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