| 1 | #include <stdlib.h> |
| 2 | #include <stdio.h> |
| 3 | #include <unistd.h> |
| 4 | #include <krb5.h> |
| 5 | #include <time.h> |
| 6 | #include <string.h> |
| 7 | #include <signal.h> |
| 8 | #include <sys/wait.h> |
| 9 | |
| 10 | volatile int died = 0; |
| 11 | pid_t child; |
| 12 | int execmode = 0, failsafe = 0; |
| 13 | int verbose = 0, quiet = 0; |
| 14 | time_t renewat; |
| 15 | |
| 16 | krb5_context context = NULL; |
| 17 | krb5_ccache ccache = NULL; |
| 18 | |
| 19 | void cleanup_krb5(void) |
| 20 | { |
| 21 | if(ccache != NULL) |
| 22 | krb5_cc_close(context, ccache); |
| 23 | ccache = NULL; |
| 24 | if(context != NULL) |
| 25 | krb5_free_context(context); |
| 26 | context = NULL; |
| 27 | } |
| 28 | |
| 29 | void sighandler(int sig) |
| 30 | { |
| 31 | switch(sig) { |
| 32 | case SIGCHLD: |
| 33 | died = 1; |
| 34 | break; |
| 35 | case SIGHUP: |
| 36 | case SIGINT: |
| 37 | case SIGTERM: |
| 38 | if(execmode) |
| 39 | kill(child, sig); |
| 40 | break; |
| 41 | } |
| 42 | } |
| 43 | |
| 44 | void renew(void) |
| 45 | { |
| 46 | int ret; |
| 47 | krb5_principal me; |
| 48 | krb5_creds creds; |
| 49 | |
| 50 | if(context == NULL) |
| 51 | return; |
| 52 | if(ccache == NULL) { |
| 53 | if((ret = krb5_cc_default(context, &ccache)) != 0) { |
| 54 | if(!quiet) |
| 55 | fprintf(stderr, "could not initialize Kerberos context: %s\n", error_message(ret)); |
| 56 | return; |
| 57 | } |
| 58 | } |
| 59 | |
| 60 | me = NULL; |
| 61 | memset(&creds, 0, sizeof(creds)); |
| 62 | if((ret = krb5_cc_get_principal(context, ccache, &me)) != 0) { |
| 63 | if(!quiet) |
| 64 | fprintf(stderr, "could not get principal from cache: %s\n", error_message(ret)); |
| 65 | goto out; |
| 66 | } |
| 67 | if((ret = krb5_get_renewed_creds(context, &creds, me, ccache, NULL)) != 0) { |
| 68 | if(!quiet) |
| 69 | fprintf(stderr, "could not get renewed credentials: %s\n", error_message(ret)); |
| 70 | goto out; |
| 71 | } |
| 72 | if((ret = krb5_cc_initialize(context, ccache, me)) != 0) { |
| 73 | if(!quiet) |
| 74 | fprintf(stderr, "could not reinitialize cache: %s\n", error_message(ret)); |
| 75 | krb5_free_cred_contents(context, &creds); |
| 76 | goto out; |
| 77 | } |
| 78 | if((ret = krb5_cc_store_cred(context, ccache, &creds)) != 0) { |
| 79 | if(!quiet) |
| 80 | fprintf(stderr, "could not store renewed credentials: %s\n", error_message(ret)); |
| 81 | krb5_free_cred_contents(context, &creds); |
| 82 | goto out; |
| 83 | } |
| 84 | krb5_free_cred_contents(context, &creds); |
| 85 | if(verbose >= 1) |
| 86 | printf("successfully renewed credentials\n"); |
| 87 | |
| 88 | out: |
| 89 | if(me != NULL) |
| 90 | krb5_free_principal(context, me); |
| 91 | } |
| 92 | |
| 93 | time_t goodrenewtime(void) |
| 94 | { |
| 95 | int ret; |
| 96 | krb5_principal me; |
| 97 | krb5_cc_cursor cur; |
| 98 | krb5_creds creds; |
| 99 | time_t now, good; |
| 100 | |
| 101 | if(context == NULL) |
| 102 | return(-1); |
| 103 | if(ccache == NULL) { |
| 104 | if((ret = krb5_cc_default(context, &ccache)) != 0) { |
| 105 | if(!quiet) |
| 106 | fprintf(stderr, "could not initialize Kerberos context: %s\n", error_message(ret)); |
| 107 | return(-1); |
| 108 | } |
| 109 | } |
| 110 | |
| 111 | me = NULL; |
| 112 | cur = NULL; |
| 113 | good = -1; |
| 114 | if((ret = krb5_cc_get_principal(context, ccache, &me)) != 0) { |
| 115 | if(!quiet) |
| 116 | fprintf(stderr, "could not get principal from cache: %s\n", error_message(ret)); |
| 117 | goto out; |
| 118 | } |
| 119 | if((ret = krb5_cc_start_seq_get(context, ccache, &cur)) != 0) { |
| 120 | if(!quiet) |
| 121 | fprintf(stderr, "could not open credentials cache: %s\n", error_message(ret)); |
| 122 | goto out; |
| 123 | } |
| 124 | now = time(NULL); |
| 125 | while(!krb5_cc_next_cred(context, ccache, &cur, &creds)) { |
| 126 | if(!strcmp(krb5_princ_component(context, creds.server, 0)->data, KRB5_TGS_NAME) && |
| 127 | !strcmp(krb5_princ_component(context, creds.server, 1)->data, me->realm.data)) { |
| 128 | if(!creds.times.starttime) |
| 129 | creds.times.starttime = creds.times.authtime; |
| 130 | good = (creds.times.starttime + (((creds.times.endtime - creds.times.starttime) * 9) / 10)); |
| 131 | break; |
| 132 | } |
| 133 | krb5_free_cred_contents(context, &creds); |
| 134 | } |
| 135 | |
| 136 | out: |
| 137 | if(cur != NULL) |
| 138 | krb5_cc_end_seq_get(context, ccache, &cur); |
| 139 | if(me != NULL) |
| 140 | krb5_free_principal(context, me); |
| 141 | return(good); |
| 142 | } |
| 143 | |
| 144 | int main(int argc, char **argv) |
| 145 | { |
| 146 | char *p; |
| 147 | int c; |
| 148 | time_t interval, now; |
| 149 | pid_t wpid; |
| 150 | int ret, status; |
| 151 | |
| 152 | interval = -1; |
| 153 | while((c = getopt(argc, argv, "+hi:vqf")) != -1) { |
| 154 | switch(c) { |
| 155 | case 'v': |
| 156 | verbose++; |
| 157 | break; |
| 158 | case 'q': |
| 159 | quiet = 1; |
| 160 | break; |
| 161 | case 'f': |
| 162 | failsafe = 1; |
| 163 | break; |
| 164 | case 'i': |
| 165 | p = optarg + strlen(optarg) - 1; |
| 166 | if((*p >= 'a') && (*p <= 'z')) { |
| 167 | if(*p == 'm') |
| 168 | interval = 60; |
| 169 | else if(*p == 'h') |
| 170 | interval = 3600; |
| 171 | else if(*p == 'd') |
| 172 | interval = 86400; |
| 173 | else |
| 174 | interval = 1; |
| 175 | *p = 0; |
| 176 | } else { |
| 177 | interval = 1; |
| 178 | } |
| 179 | interval *= atoi(optarg); |
| 180 | break; |
| 181 | case 'h': |
| 182 | case '?': |
| 183 | case ':': |
| 184 | default: |
| 185 | fprintf(stderr, "usage: krb5-agent [-hvqf] [-i interval] [program args...]\n"); |
| 186 | exit((c == 'h')?0:1); |
| 187 | } |
| 188 | } |
| 189 | |
| 190 | atexit(cleanup_krb5); |
| 191 | if((ret = krb5_init_context(&context)) != 0) { |
| 192 | if(!quiet) |
| 193 | fprintf(stderr, "could not initialize Kerberos context: %s\n", error_message(ret)); |
| 194 | if(!failsafe) |
| 195 | exit(1); |
| 196 | } |
| 197 | if(context != NULL) { |
| 198 | if((ret = krb5_cc_default(context, &ccache)) != 0) { |
| 199 | if(!quiet) |
| 200 | fprintf(stderr, "could not initialize Kerberos context: %s\n", error_message(ret)); |
| 201 | if(!failsafe) |
| 202 | exit(1); |
| 203 | } |
| 204 | } |
| 205 | |
| 206 | if(optind < argc) { |
| 207 | execmode = 1; |
| 208 | signal(SIGCHLD, sighandler); |
| 209 | if((child = fork()) < 0) { |
| 210 | perror("fork"); |
| 211 | exit(1); |
| 212 | } |
| 213 | if(child == 0) { |
| 214 | char buf[80]; |
| 215 | snprintf(buf, 80, "KRB5_AGENT_PID=%i", getppid()); |
| 216 | putenv(buf); |
| 217 | execvp(argv[optind], argv + optind); |
| 218 | perror(argv[optind]); |
| 219 | exit(255); |
| 220 | } |
| 221 | signal(SIGHUP, sighandler); |
| 222 | signal(SIGINT, sighandler); |
| 223 | signal(SIGTERM, sighandler); |
| 224 | } |
| 225 | now = time(NULL); |
| 226 | if(interval >= 0) |
| 227 | renewat = now + interval; |
| 228 | while(1) { |
| 229 | if(died) { |
| 230 | wpid = waitpid(-1, &status, WNOHANG); |
| 231 | if(wpid < 0) { |
| 232 | perror("waitpid"); |
| 233 | } else if(execmode && (wpid == child)) { |
| 234 | /* Try to preserve exit status as best as we can... */ |
| 235 | if(WIFEXITED(status)) { |
| 236 | exit(WEXITSTATUS(status)); |
| 237 | } else { |
| 238 | cleanup_krb5(); |
| 239 | signal(WTERMSIG(status), SIG_DFL); |
| 240 | kill(getpid(), WTERMSIG(status)); |
| 241 | exit(255); |
| 242 | } |
| 243 | } |
| 244 | died = 0; |
| 245 | } |
| 246 | if(interval < 0) { |
| 247 | if((renewat = goodrenewtime()) < 0) { |
| 248 | renewat = -1; |
| 249 | } else if(verbose >= 2) { |
| 250 | printf("will renew tickets at %s", ctime(&renewat)); |
| 251 | } |
| 252 | } |
| 253 | if(renewat < 0) |
| 254 | sleep(60); |
| 255 | else |
| 256 | sleep(renewat - now); |
| 257 | now = time(NULL); |
| 258 | if((renewat >= 0) && (now >= renewat)) { |
| 259 | renew(); |
| 260 | now = time(NULL); |
| 261 | if(interval >= 0) |
| 262 | renewat = now + interval; |
| 263 | } |
| 264 | } |
| 265 | } |
| 266 | |
| 267 | /* |
| 268 | * Local Variables: |
| 269 | * compile-command: "gcc -Wall -g -o krb5-agent krb5-agent.c -lkrb5" |
| 270 | * End: |
| 271 | */ |