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
47extern char * const *environ;
48
49static int	getelfclass(int);
50static int	proc_init(pid_t, int, int, struct proc_handle **);
51
52static int
53getelfclass(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];
66out:
67	(void)elf_end(e);
68	return (class);
69}
70
71static int
72proc_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
120out:
121	*pphdl = phdl;
122	return (error);
123}
124
125int
126proc_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
168out:
169	if (error != 0 && phdl != NULL) {
170		proc_free(phdl);
171		phdl = NULL;
172	}
173	*pphdl = phdl;
174	return (error);
175}
176
177int
178proc_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
228bad:
229		if (error != 0 && phdl != NULL) {
230			proc_free(phdl);
231			phdl = NULL;
232		}
233	}
234	*pphdl = phdl;
235	return (error);
236}
237
238void
239proc_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