Annotation of src/usr.bin/passwd/pwd_check.c, Revision 1.18
1.18 ! tobias 1: /* $OpenBSD: pwd_check.c,v 1.17 2021/08/28 06:46:49 robert 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) {
1.17 robert 100: fprintf(stderr, "Please enter a longer password.\n");
1.1 provos 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");
1.18 ! tobias 117: close(pipefds[0]);
! 118: close(pipefds[1]);
1.11 djm 119: goto out;
120: case 0:
121: (void)signal(SIGINT, SIG_DFL);
122: (void)signal(SIGQUIT, SIG_DFL);
123: uid = getuid();
124: gid = getgid();
125: if (setresgid(gid, gid, gid) == -1) {
126: warn("setresgid");
127: exit(1);
128: }
129: if (setgroups(1, &gid) == -1) {
130: warn("setgroups");
131: exit(1);
132: }
133: if (setresuid(uid, uid, uid) == -1) {
134: warn("setresuid");
135: exit(1);
136: }
137:
1.13 ajacouto 138: if (checker == NULL) {
1.14 deraadt 139: if (pledge("stdio", NULL) == -1)
140: err(1, "pledge");
141:
1.13 ajacouto 142: for (i = 0; i < sizeof(patterns) / sizeof(*patterns); i++) {
1.16 deraadt 143: int ret;
144:
1.13 ajacouto 145: if (regcomp(&rgx, patterns[i].match,
146: patterns[i].flags) != 0)
147: continue;
1.16 deraadt 148: ret = regexec(&rgx, password, 0, NULL, 0);
1.13 ajacouto 149: regfree(&rgx);
1.16 deraadt 150: if (ret == 0) {
1.17 robert 151: fprintf(stderr, "%s\n", patterns[i].response);
1.13 ajacouto 152: exit(1);
153: }
1.11 djm 154: }
1.13 ajacouto 155: /* no external checker in use, accept the password */
156: exit(0);
1.11 djm 157: }
1.14 deraadt 158:
159: if (pledge("stdio exec", NULL) == -1)
160: err(1, "pledge");
1.1 provos 161:
1.11 djm 162: /* Otherwise, pass control to checker program */
163: argp[2] = checker;
164: if (dup2(pipefds[0], STDIN_FILENO) == -1) {
165: warn("dup2");
1.1 provos 166: exit(1);
1.11 djm 167: }
1.1 provos 168: close(pipefds[0]);
169: close(pipefds[1]);
170:
1.11 djm 171: if (execv(_PATH_BSHELL, argp) == -1) {
172: warn("exec");
1.1 provos 173: exit(1);
1.11 djm 174: }
175: /* NOTREACHED */
176: default:
177: break; /* parent continues below */
1.1 provos 178: }
179:
1.11 djm 180: if (checker != NULL) {
181: /* Send the password to STDIN of child */
182: close(pipefds[0]);
183: write(pipefds[1], password, strlen(password) + 1);
184: close(pipefds[1]);
185: }
1.1 provos 186:
187: /* get the return value from the child */
1.16 deraadt 188: while (waitpid(child, &res, 0) == -1) {
1.18 ! tobias 189: if (errno != EINTR) {
! 190: warn("waitpid");
! 191: goto out;
! 192: }
1.16 deraadt 193: }
194: if (WIFEXITED(res) && WEXITSTATUS(res) == 0) {
1.15 mmcc 195: free(checker);
1.1 provos 196: return (1);
1.9 millert 197: }
1.1 provos 198:
199: out:
1.15 mmcc 200: free(checker);
1.17 robert 201: fprintf(stderr, "Please use a different password. Unusual capitalization,\n");
202: fprintf(stderr, "control characters, or digits are suggested.\n");
1.11 djm 203:
1.1 provos 204: return (0);
205: }
206:
1.6 deraadt 207: int
1.8 millert 208: pwd_gettries(login_cap_t *lc)
1.4 millert 209: {
210: quad_t ntries;
211:
212: if ((ntries = login_getcapnum(lc, "passwordtries", -1, -1)) != -1) {
1.10 moritz 213: if (ntries >= 0 && ntries <= INT_MAX)
1.9 millert 214: return((int)ntries);
215: fprintf(stderr,
216: "Warning: pwdtries out of range in /etc/login.conf");
1.4 millert 217: }
1.1 provos 218:
1.8 millert 219: /*
1.9 millert 220: * If no amount of tries is specified, return a default of 3,
221: * meaning that after 3 attempts where the user is foiled by the
222: * password checks, it will no longer be checked and they can set
223: * it to whatever they like. This is the historic BSD behavior.
1.1 provos 224: */
1.9 millert 225: return (3);
1.1 provos 226: }
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