Annotation of src/usr.bin/passwd/pwd_check.c, Revision 1.15
1.15 ! mmcc 1: /* $OpenBSD: pwd_check.c,v 1.14 2015/11/26 19:01:47 deraadt Exp $ */
1.9 millert 2:
1.1 provos 3: /*
4: * Copyright 2000 Niels Provos <provos@citi.umich.edu>
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: * 3. All advertising materials mentioning features or use of this software
16: * must display the following acknowledgement:
17: * This product includes software developed by Niels Provos.
18: * 4. The name of the author may not be used to endorse or promote products
19: * derived from this software without specific prior written permission.
20: *
21: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
22: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
23: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
24: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
25: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
26: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
30: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31: */
32:
33: #include <sys/types.h>
34: #include <sys/wait.h>
1.2 millert 35:
36: #include <stdio.h>
1.1 provos 37: #include <stdlib.h>
1.2 millert 38: #include <string.h>
1.1 provos 39: #include <unistd.h>
40: #include <limits.h>
1.2 millert 41: #include <errno.h>
1.3 millert 42: #include <err.h>
1.1 provos 43: #include <regex.h>
44: #include <grp.h>
45: #include <paths.h>
1.4 millert 46: #include <login_cap.h>
1.11 djm 47: #include <signal.h>
1.12 djm 48:
49: int pwd_check(login_cap_t *, char *);
50: int pwd_gettries(login_cap_t *);
1.1 provos 51:
52: struct pattern {
53: char *match;
54: int flags;
55: char *response;
56: };
57:
58: struct pattern patterns[] = {
59: {
1.6 deraadt 60: "^[0-9]*$",
1.1 provos 61: REG_EXTENDED|REG_NOSUB,
62: "Please don't use all-digit passwords."
63: },
64: {
65: "^[a-z]{1,9}$",
66: REG_EXTENDED|REG_NOSUB,
67: "Please don't use an all-lower case password."
68: },
69: {
70: "^[a-z]{1,6}[0-9]+$",
71: REG_EXTENDED|REG_NOSUB|REG_ICASE,
72: "Please use a more complicated password."
73: },
74: {
75: "^([a-z][0-9]){1,4}$",
76: REG_EXTENDED|REG_NOSUB|REG_ICASE,
77: "Please use a more complicated password."
78: },
79: {
80: "^([0-9][a-z]){1,4}$",
81: REG_EXTENDED|REG_NOSUB|REG_ICASE,
82: "Please use a more complicated password."
83: }
84: };
85:
86: int
1.8 millert 87: pwd_check(login_cap_t *lc, char *password)
1.1 provos 88: {
89: regex_t rgx;
1.4 millert 90: int i, res, min_len;
1.9 millert 91: char *checker;
1.11 djm 92: char *argp[] = { "sh", "-c", NULL, NULL};
1.1 provos 93: int pipefds[2];
1.7 tedu 94: pid_t child;
1.11 djm 95: uid_t uid;
96: gid_t gid;
1.6 deraadt 97:
1.9 millert 98: min_len = (int)login_getcapnum(lc, "minpasswordlen", 6, 6);
1.4 millert 99: if (min_len > 0 && strlen(password) < min_len) {
1.1 provos 100: printf("Please enter a longer password.\n");
101: return (0);
102: }
103:
1.11 djm 104: /* External password check program */
1.9 millert 105: checker = login_getcapstr(lc, "passwordcheck", NULL, NULL);
1.1 provos 106:
1.11 djm 107: /* Pipes are only used for external checker */
108: if (checker != NULL && pipe(pipefds) == -1) {
1.1 provos 109: warn("pipe");
110: goto out;
111: }
112:
1.11 djm 113: /* Check password in low-privileged child */
114: switch (child = fork()) {
115: case -1:
116: warn("fork");
117: goto out;
118: case 0:
119: (void)signal(SIGINT, SIG_DFL);
120: (void)signal(SIGQUIT, SIG_DFL);
121: uid = getuid();
122: gid = getgid();
123: if (setresgid(gid, gid, gid) == -1) {
124: warn("setresgid");
125: exit(1);
126: }
127: if (setgroups(1, &gid) == -1) {
128: warn("setgroups");
129: exit(1);
130: }
131: if (setresuid(uid, uid, uid) == -1) {
132: warn("setresuid");
133: exit(1);
134: }
135:
1.13 ajacouto 136: if (checker == NULL) {
1.14 deraadt 137: if (pledge("stdio", NULL) == -1)
138: err(1, "pledge");
139:
1.13 ajacouto 140: for (i = 0; i < sizeof(patterns) / sizeof(*patterns); i++) {
141: if (regcomp(&rgx, patterns[i].match,
142: patterns[i].flags) != 0)
143: continue;
144: res = regexec(&rgx, password, 0, NULL, 0);
145: regfree(&rgx);
146: if (res == 0) {
147: printf("%s\n", patterns[i].response);
148: exit(1);
149: }
1.11 djm 150: }
1.13 ajacouto 151: /* no external checker in use, accept the password */
152: exit(0);
1.11 djm 153: }
1.14 deraadt 154:
155: if (pledge("stdio exec", NULL) == -1)
156: err(1, "pledge");
1.1 provos 157:
1.11 djm 158: /* Otherwise, pass control to checker program */
159: argp[2] = checker;
160: if (dup2(pipefds[0], STDIN_FILENO) == -1) {
161: warn("dup2");
1.1 provos 162: exit(1);
1.11 djm 163: }
1.1 provos 164: close(pipefds[0]);
165: close(pipefds[1]);
166:
1.11 djm 167: if (execv(_PATH_BSHELL, argp) == -1) {
168: warn("exec");
1.1 provos 169: exit(1);
1.11 djm 170: }
171: /* NOTREACHED */
172: default:
173: break; /* parent continues below */
1.1 provos 174: }
175:
1.11 djm 176: if (checker != NULL) {
177: /* Send the password to STDIN of child */
178: close(pipefds[0]);
179: write(pipefds[1], password, strlen(password) + 1);
180: close(pipefds[1]);
181: }
1.1 provos 182:
183: /* get the return value from the child */
1.7 tedu 184: wait(&child);
1.9 millert 185: if (WIFEXITED(child) && WEXITSTATUS(child) == 0) {
1.15 ! mmcc 186: free(checker);
1.1 provos 187: return (1);
1.9 millert 188: }
1.1 provos 189:
190: out:
1.15 ! mmcc 191: free(checker);
1.6 deraadt 192: printf("Please use a different password. Unusual capitalization,\n");
193: printf("control characters, or digits are suggested.\n");
1.11 djm 194:
1.1 provos 195: return (0);
196: }
197:
1.6 deraadt 198: int
1.8 millert 199: pwd_gettries(login_cap_t *lc)
1.4 millert 200: {
201: quad_t ntries;
202:
203: if ((ntries = login_getcapnum(lc, "passwordtries", -1, -1)) != -1) {
1.10 moritz 204: if (ntries >= 0 && ntries <= INT_MAX)
1.9 millert 205: return((int)ntries);
206: fprintf(stderr,
207: "Warning: pwdtries out of range in /etc/login.conf");
1.4 millert 208: }
1.1 provos 209:
1.8 millert 210: /*
1.9 millert 211: * If no amount of tries is specified, return a default of 3,
212: * meaning that after 3 attempts where the user is foiled by the
213: * password checks, it will no longer be checked and they can set
214: * it to whatever they like. This is the historic BSD behavior.
1.1 provos 215: */
1.9 millert 216: return (3);
1.1 provos 217: }
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