1 /* $NetBSD: pt_filter.c,v 1.13 2021/04/12 09:18:14 mrg Exp $ */
2
3 /*
4 * Copyright (c) 1999 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD
8 * Foundation by Brian Grayson, and is dedicated to Rebecca
9 * Margaret Pollard-Grayson.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
22 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
23 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
24 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
30 * POSSIBILITY OF SUCH DAMAGE.
31 */
32
33 #include <sys/cdefs.h>
34 #ifndef lint
35 __RCSID("$NetBSD: pt_filter.c,v 1.13 2021/04/12 09:18:14 mrg Exp $");
36 #endif /* not lint */
37
38 #include <stdio.h>
39 #include <unistd.h>
40 #include <stdlib.h>
41 #include <errno.h>
42 #include <string.h>
43 #include <err.h>
44 #include <sys/types.h>
45 #include <sys/param.h>
46 #include <sys/syslog.h>
47
48 #include "portald.h"
49
50 /*
51 * Key will be <key><path>. We let the configuration file
52 * tell us how to filter the file.
53 */
54
55 #define FILTER_CMD_SIZE 8192
56
57 static void fill_cmd(char **, char *, char *, int);
58
59 static void
fill_cmd(char ** cmdv,char * path,char * buff,int n)60 fill_cmd(char **cmdv, char *path, char *buff, int n)
61 {
62 int i;
63 /* Make tempbuff at least as large as buff. */
64 char *tempbuff = malloc(n);
65 if (tempbuff == NULL)
66 err(1, NULL);
67
68 strncpy(tempbuff, cmdv[0], n - 1);
69 tempbuff[n - 1] = '\0';
70 for (i = 1; cmdv[i]; i++) {
71 strncat(tempbuff, " ", n - strlen(tempbuff));
72 strncat(tempbuff, cmdv[i], n - strlen(tempbuff));
73 }
74 strncat(tempbuff, " ", n - strlen(tempbuff));
75 /* Now do the snprintf into buff. */
76 snprintf(buff, n, tempbuff, path);
77 free(tempbuff);
78 }
79
80
81 /*
82 * Strip v[1], replace %s in v[2] v[3] ... with the remainder
83 * of the path, and exec v[2] v[3] ... on the remainder.
84 */
85 int
portal_rfilter(struct portal_cred * pcr,char * key,char ** v,int * fdp)86 portal_rfilter(struct portal_cred *pcr, char *key, char **v, int *fdp)
87 {
88 char cmd[FILTER_CMD_SIZE];
89 char *path;
90 FILE *fp;
91 int error = 0;
92 char percent_s[] = "%s";
93
94 error = lose_credentials(pcr);
95 if (error != 0)
96 return error;
97
98 #ifdef DEBUG
99 fprintf(stderr, "rfilter: Got key %s\n", key);
100 #endif
101
102 if (!v[1] || !v[2]) {
103 syslog(LOG_ERR,
104 "rfilter: got strip-key of %s, and command start of %s\n",
105 v[1], v[2]);
106 exit(1);
107 }
108 /*
109 * Format for rfilter in config file:
110 *
111 * matchkey rfilter stripkey cmd [arg1] [arg2] ...
112 * any of arg1, arg2, etc. can have %s, in which case %s
113 * will be replaced by the full path. If arg1 is
114 * missing, %s is assumed, i.e.
115 * bogus1 rfilter bogus1/ cmd1
116 * is equivalent to
117 * bogus1 rfilter bogus1/ cmd1 %s
118 */
119 /*
120 * v[3] could be NULL, or could point to "".
121 */
122 if (!v[3] || strlen(v[3]) == 0)
123 v[3] = percent_s; /* Handle above assumption. */
124 path = key;
125 /* Strip out stripkey if it matches leading part of key. */
126 if (!strncmp(v[1], key, strlen(v[1])))
127 path += strlen(v[1]);
128 /*
129 * v[0] is key match, v[1] says how much to strip, v[2]
130 * is beginning of command proper. The first %s in v[2]
131 * ... will be replaced with the path.
132 */
133 fill_cmd(v + 2, path, cmd, FILTER_CMD_SIZE);
134 if (strlen(cmd) >= FILTER_CMD_SIZE) {
135 syslog(LOG_WARNING,
136 "Warning: potential overflow on string! Length was %lu\n",
137 (unsigned long)strlen(cmd));
138 return ENAMETOOLONG;
139 }
140 #ifdef DEBUG
141 fprintf(stderr, "rfilter: Using cmd of %s\n", cmd);
142 #endif
143 fp = popen(cmd, "r");
144 if (fp == NULL)
145 return errno;
146
147 /* Before returning, restore original uid and gid. */
148 /* But only do this if we were root to start with. */
149 if (getuid() == 0) {
150 if ((seteuid((uid_t) 0) < 0) || (setegid((gid_t) 0) < 0)) {
151 error = errno;
152 syslog(LOG_WARNING, "setcred: %m");
153 pclose(fp);
154 fp = NULL;
155 }
156 }
157 if (fp)
158 fdp[0] = fileno(fp);
159 return error;
160 }
161
162 int
portal_wfilter(struct portal_cred * pcr,char * key,char ** v,int * fdp)163 portal_wfilter(struct portal_cred *pcr, char *key, char **v, int *fdp)
164 {
165 char cmd[FILTER_CMD_SIZE];
166 char *path;
167 FILE *fp;
168 int error = 0;
169 int cred_change_err = 0;
170
171 cred_change_err = lose_credentials(pcr);
172 if (cred_change_err != 0)
173 return cred_change_err;
174
175 path = key + (v[1] ? strlen(v[1]) : 0);
176 /*
177 * v[0] is key match, v[1] says how much to strip, v[2]
178 * is beginning of command proper.
179 */
180 fill_cmd(v + 2, path, cmd, FILTER_CMD_SIZE);
181 if (strlen(cmd) >= FILTER_CMD_SIZE) {
182 syslog(LOG_WARNING,
183 "Warning: potential overflow on string! Length was %lu\n",
184 (unsigned long)strlen(cmd));
185 return ENAMETOOLONG;
186 }
187 fp = popen(cmd, "w");
188 if (fp == NULL) {
189 return errno;
190 }
191 /* Before returning, restore original uid and gid. */
192 /* But only do this if we were root to start with. */
193 if (getuid() == 0) {
194 if ((seteuid((uid_t) 0) < 0) || (setegid((gid_t) 0) < 0)) {
195 error = errno;
196 syslog(LOG_WARNING, "setcred: %m");
197 pclose(fp);
198 fp = NULL;
199 }
200 }
201 if (fp)
202 fdp[0] = fileno(fp);
203 return error;
204 }
205