1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2018 The FreeBSD Foundation
5 *
6 * This software was developed by Mark Johnston under sponsorship from
7 * the FreeBSD Foundation.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions are
11 * met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in
16 * the documentation and/or other materials provided with the distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 */
30
31 #include <sys/types.h>
32 #include <sys/capsicum.h>
33 #include <sys/dnv.h>
34 #include <sys/nv.h>
35 #include <sys/queue.h>
36 #include <sys/wait.h>
37
38 #include <net/if.h>
39 #include <netinet/in.h>
40
41 #include <capsicum_helpers.h>
42 #include <errno.h>
43 #include <stdlib.h>
44 #include <string.h>
45 #include <unistd.h>
46
47 #include <libcasper.h>
48 #include <libcasper_service.h>
49
50 #include "rtsold.h"
51
52 /*
53 * Run the script and return the write end of a pipe to the main process.
54 * Return -1 and set errno on error.
55 */
56 static int
script_run(char ** argv)57 script_run(char **argv)
58 {
59 pid_t pid;
60 int fd[2], null;
61
62 if (pipe(fd) != 0)
63 return (-1);
64 if ((pid = fork()) < 0)
65 return (-1);
66 if (pid == 0) {
67 (void)close(fd[1]);
68 null = open("/dev/null", O_RDWR);
69 if (null < 0)
70 _exit(1);
71 if (dup2(fd[0], STDIN_FILENO) != STDIN_FILENO)
72 _exit(1);
73
74 closefrom(3);
75 (void)execve(argv[0], argv, NULL);
76 _exit(1);
77 } else
78 (void)close(fd[0]);
79
80 return (fd[1]);
81 }
82
83 int
cap_script_run(cap_channel_t * cap,const char * const * argv)84 cap_script_run(cap_channel_t *cap, const char *const *argv)
85 {
86 #ifdef WITH_CASPER
87 nvlist_t *nvl;
88 size_t argc;
89 int error, wfd;
90
91 for (argc = 0; argv[argc] != NULL; argc++)
92 ;
93
94 nvl = nvlist_create(0);
95 nvlist_add_string(nvl, "cmd", "script_run");
96 nvlist_add_string_array(nvl, "argv", argv, argc);
97 nvl = cap_xfer_nvlist(cap, nvl);
98 if (nvl == NULL)
99 return (-1);
100
101 error = (int)dnvlist_get_number(nvl, "error", 0);
102 if (error == 0)
103 wfd = nvlist_take_descriptor(nvl, "fd");
104 nvlist_destroy(nvl);
105 if (error != 0)
106 errno = error;
107 return (error == 0 ? wfd : -1);
108 #else
109 (void)cap;
110 return (script_run(__DECONST(char **, argv)));
111 #endif
112 }
113
114 /*
115 * Wait for a child process to exit, and return its status.
116 * Return -1 and set errno upon error.
117 */
118 static int
script_wait(int * statusp)119 script_wait(int *statusp)
120 {
121 int error;
122
123 error = wait(statusp);
124 return (error >= 0 ? 0 : -1);
125 }
126
127 int
cap_script_wait(cap_channel_t * cap,int * statusp)128 cap_script_wait(cap_channel_t *cap, int *statusp)
129 {
130 #ifdef WITH_CASPER
131 nvlist_t *nvl;
132 int error;
133
134 nvl = nvlist_create(0);
135 nvlist_add_string(nvl, "cmd", "script_wait");
136 nvl = cap_xfer_nvlist(cap, nvl);
137 if (nvl == NULL)
138 return (-1);
139
140 error = (int)dnvlist_get_number(nvl, "error", 0);
141 if (error == 0)
142 *statusp = (int)nvlist_get_number(nvl, "status");
143 nvlist_destroy(nvl);
144 if (error != 0)
145 errno = error;
146 return (error == 0 ? 0 : -1);
147 #else
148 (void)cap;
149 return (script_wait(statusp));
150 #endif
151 }
152
153 #ifdef WITH_CASPER
154 static int
script_command(const char * cmd,const nvlist_t * limits,nvlist_t * nvlin,nvlist_t * nvlout)155 script_command(const char *cmd, const nvlist_t *limits, nvlist_t *nvlin,
156 nvlist_t *nvlout)
157 {
158 cap_rights_t rights;
159 const char *const *iargv, *const *scripts;
160 char **argv;
161 size_t argc, i, nscripts;
162 int error, fd, status;
163
164 if (strcmp(cmd, "script_wait") == 0) {
165 /* Wait for the result of a previous "script_run" command. */
166 if (script_wait(&status) == -1)
167 return (errno);
168 nvlist_add_number(nvlout, "status", status);
169 return (0);
170 }
171 if (strcmp(cmd, "script_run") != 0)
172 return (EINVAL);
173
174 /*
175 * Validate the argv against the limits specified at initialization
176 * time.
177 */
178 iargv = nvlist_get_string_array(nvlin, "argv", &argc);
179 if (argc == 0)
180 return (EINVAL);
181 scripts = nvlist_get_string_array(limits, "scripts", &nscripts);
182 for (i = 0; i < nscripts; i++)
183 if (strcmp(iargv[0], scripts[i]) == 0)
184 break;
185 if (i == nscripts)
186 return (EINVAL);
187
188 /*
189 * The nvlist API does not permit NULL pointers in an array, so we have
190 * to add the nul terminator ourselves. Yuck.
191 */
192 argv = calloc(argc + 1, sizeof(*argv));
193 if (argv == NULL)
194 return (errno);
195 memcpy(argv, iargv, sizeof(*argv) * argc);
196
197 fd = script_run(argv);
198 error = errno;
199 free(argv);
200 if (fd < 0)
201 return (error);
202
203 (void)caph_rights_limit(fd, cap_rights_init(&rights, CAP_WRITE));
204 nvlist_move_descriptor(nvlout, "fd", fd);
205 return (0);
206 }
207
208 static int
script_limit(const nvlist_t * oldlimits,const nvlist_t * newlimits)209 script_limit(const nvlist_t *oldlimits, const nvlist_t *newlimits)
210 {
211 const char *name;
212 void *cookie;
213 int nvtype;
214 bool hasscripts;
215
216 /* Limits may only be set once. */
217 if (oldlimits != NULL)
218 return (ENOTCAPABLE);
219
220 cookie = NULL;
221 hasscripts = false;
222 while ((name = nvlist_next(newlimits, &nvtype, &cookie)) != NULL) {
223 if (nvtype == NV_TYPE_STRING_ARRAY &&
224 strcmp(name, "scripts") == 0)
225 hasscripts = true;
226 else
227 return (EINVAL);
228 }
229 if (!hasscripts)
230 return (EINVAL);
231 return (0);
232 }
233
234 CREATE_SERVICE("rtsold.script", script_limit, script_command, 0);
235 #endif /* WITH_CASPER */
236