1 /* $OpenBSD: skeyaudit.c,v 1.29 2019/06/28 13:35:03 deraadt Exp $ */ 2 3 /* 4 * Copyright (c) 1997, 2000, 2003 Todd C. Miller <millert@openbsd.org> 5 * 6 * Permission to use, copy, modify, and distribute this software for any 7 * purpose with or without fee is hereby granted, provided that the above 8 * copyright notice and this permission notice appear in all copies. 9 * 10 * THE SOFTWARE IS PROVIDED "AS IS" AND TODD C. MILLER DISCLAIMS ALL 11 * WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES 12 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL TODD C. MILLER BE LIABLE 13 * FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION 15 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN 16 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 17 * 18 * Sponsored in part by the Defense Advanced Research Projects 19 * Agency (DARPA) and Air Force Research Laboratory, Air Force 20 * Materiel Command, USAF, under agreement number F39502-99-1-0512. 21 */ 22 23 #include <sys/wait.h> 24 25 #include <err.h> 26 #include <errno.h> 27 #include <fcntl.h> 28 #include <limits.h> 29 #include <login_cap.h> 30 #include <paths.h> 31 #include <pwd.h> 32 #include <stdio.h> 33 #include <stdlib.h> 34 #include <string.h> 35 #include <unistd.h> 36 #include <skey.h> 37 38 void notify(struct passwd *, int, int); 39 void sanitise_stdfd(void); 40 FILE *runsendmail(struct passwd *, int *); 41 __dead void usage(void); 42 43 void 44 sanitise_stdfd(void) 45 { 46 int nullfd, dupfd; 47 48 if ((nullfd = dupfd = open(_PATH_DEVNULL, O_RDWR)) == -1) { 49 fprintf(stderr, "Couldn't open /dev/null: %s\n", 50 strerror(errno)); 51 exit(1); 52 } 53 while (++dupfd <= STDERR_FILENO) { 54 /* Only populate closed fds. */ 55 if (fcntl(dupfd, F_GETFL) == -1 && errno == EBADF) { 56 if (dup2(nullfd, dupfd) == -1) { 57 fprintf(stderr, "dup2: %s\n", strerror(errno)); 58 exit(1); 59 } 60 } 61 } 62 if (nullfd > STDERR_FILENO) 63 close(nullfd); 64 } 65 66 int 67 main(int argc, char **argv) 68 { 69 struct passwd *pw; 70 struct skey key; 71 char *name; 72 int ch, left, aflag, iflag, limit; 73 74 if (pledge("stdio rpath wpath flock getpw proc exec id", NULL) == -1) 75 err(1, "pledge"); 76 77 aflag = iflag = 0; 78 limit = 12; 79 while ((ch = getopt(argc, argv, "ail:")) != -1) 80 switch(ch) { 81 case 'a': 82 if (getuid() != 0) 83 errx(1, "only root may use the -a flag"); 84 aflag = 1; 85 break; 86 case 'i': 87 iflag = 1; 88 break; 89 case 'l': 90 errno = 0; 91 if ((limit = (int)strtol(optarg, NULL, 10)) == 0) 92 errno = ERANGE; 93 if (errno) { 94 warn("key limit"); 95 usage(); 96 } 97 break; 98 default: 99 usage(); 100 } 101 102 if (iflag) { 103 if (pledge("stdio rpath wpath flock getpw", NULL) == -1) 104 err(1, "pledge"); 105 } 106 107 /* If we are in interactive mode, STDOUT_FILENO *must* be open. */ 108 if (iflag && fcntl(STDOUT_FILENO, F_GETFL) == -1 && errno == EBADF) 109 exit(1); 110 111 /* 112 * Make sure STDIN_FILENO, STDOUT_FILENO, and STDERR_FILENO are open. 113 * If not, open /dev/null in their place or bail. 114 */ 115 sanitise_stdfd(); 116 117 if (argc - optind > 0) 118 usage(); 119 120 /* Need key.keyfile zero'd at the very least */ 121 (void)memset(&key, 0, sizeof(key)); 122 123 left = 0; 124 if (aflag) { 125 while ((ch = skeygetnext(&key)) == 0) { 126 left = key.n - 1; 127 if ((pw = getpwnam(key.logname)) == NULL) 128 continue; 129 if (left >= limit) 130 continue; 131 (void)fclose(key.keyfile); 132 key.keyfile = NULL; 133 notify(pw, left, iflag); 134 } 135 if (ch == -1) 136 errx(-1, "cannot open %s", _PATH_SKEYDIR); 137 } else { 138 if ((pw = getpwuid(getuid())) == NULL) 139 errx(1, "no passwd entry for uid %u", getuid()); 140 if ((name = strdup(pw->pw_name)) == NULL) 141 err(1, "cannot allocate memory"); 142 sevenbit(name); 143 144 switch (skeylookup(&key, name)) { 145 case 0: /* Success! */ 146 left = key.n - 1; 147 break; 148 case -1: /* File error */ 149 errx(1, "cannot open %s/%s", _PATH_SKEYDIR, 150 name); 151 break; 152 case 1: /* Unknown user */ 153 errx(1, "user %s is not listed in %s", name, 154 _PATH_SKEYDIR); 155 } 156 (void)fclose(key.keyfile); 157 158 if (left < limit) 159 notify(pw, left, iflag); 160 } 161 162 exit(0); 163 } 164 165 void 166 notify(struct passwd *pw, int seq, int interactive) 167 { 168 static char hostname[HOST_NAME_MAX+1]; 169 pid_t pid; 170 FILE *out; 171 172 /* Only set this once */ 173 if (hostname[0] == '\0' && gethostname(hostname, sizeof(hostname)) == -1) 174 strlcpy(hostname, "unknown", sizeof(hostname)); 175 176 if (interactive) 177 out = stdout; 178 else 179 out = runsendmail(pw, &pid); 180 181 if (!interactive) 182 (void)fprintf(out, 183 "Auto-Submitted: auto-generated\n" 184 "To: %s\nSubject: IMPORTANT action required\n", pw->pw_name); 185 186 if (seq) 187 (void)fprintf(out, 188 "\nYou are nearing the end of your current S/Key sequence for account\n\ 189 %s on system %s.\n\n\ 190 Your S/Key sequence number is now %d. When it reaches zero\n\ 191 you will no longer be able to use S/Key to log into the system.\n\n", 192 pw->pw_name, hostname, seq); 193 else 194 (void)fprintf(out, 195 "\nYou are at the end of your current S/Key sequence for account\n\ 196 %s on system %s.\n\n\ 197 At this point you can no longer use S/Key to log into the system.\n\n", 198 pw->pw_name, hostname); 199 (void)fprintf(out, 200 "Type \"skeyinit -s\" to reinitialize your sequence number.\n\n"); 201 202 if (!interactive) { 203 (void)fclose(out); 204 (void)waitpid(pid, NULL, 0); 205 } 206 } 207 208 FILE * 209 runsendmail(struct passwd *pw, pid_t *pidp) 210 { 211 FILE *fp; 212 int pfd[2]; 213 pid_t pid; 214 215 if (pipe(pfd) == -1) 216 return(NULL); 217 218 switch (pid = fork()) { 219 case -1: /* fork(2) failed */ 220 (void)close(pfd[0]); 221 (void)close(pfd[1]); 222 return(NULL); 223 case 0: /* In child */ 224 (void)close(pfd[1]); 225 (void)dup2(pfd[0], STDIN_FILENO); 226 (void)close(pfd[0]); 227 228 /* Run sendmail as target user not root */ 229 if (getuid() == 0 && 230 setusercontext(NULL, pw, pw->pw_uid, LOGIN_SETALL) != 0) { 231 warn("cannot set user context"); 232 _exit(127); 233 } 234 235 execl(_PATH_SENDMAIL, "sendmail", "-t", (char *)NULL); 236 warn("cannot run \"%s -t\"", _PATH_SENDMAIL); 237 _exit(127); 238 } 239 240 /* In parent */ 241 *pidp = pid; 242 fp = fdopen(pfd[1], "w"); 243 (void)close(pfd[0]); 244 245 return(fp); 246 } 247 248 __dead void 249 usage(void) 250 { 251 extern char *__progname; 252 253 (void)fprintf(stderr, "usage: %s [-ai] [-l limit]\n", 254 __progname); 255 exit(1); 256 } 257