| 1 | #include <stdlib.h> |
| 2 | #include <stdio.h> |
| 3 | #include <unistd.h> |
| 4 | #include <string.h> |
| 5 | #include <stdarg.h> |
| 6 | #include <malloc.h> |
| 7 | #include <krb5.h> |
| 8 | |
| 9 | #define PAM_SM_AUTH |
| 10 | |
| 11 | #include <security/pam_modules.h> |
| 12 | |
| 13 | #define DEF_INSTANCE "autologin" |
| 14 | |
| 15 | struct options |
| 16 | { |
| 17 | char *realm; |
| 18 | char *instance; |
| 19 | char *keytab; |
| 20 | int debug; |
| 21 | }; |
| 22 | |
| 23 | struct data |
| 24 | { |
| 25 | krb5_context ctx; |
| 26 | krb5_ccache cc; |
| 27 | krb5_principal me; |
| 28 | }; |
| 29 | |
| 30 | static void log(int prio, char *format, ...) |
| 31 | { |
| 32 | va_list args; |
| 33 | char buf[1024]; |
| 34 | |
| 35 | va_start(args, format); |
| 36 | snprintf(buf, sizeof(buf), "pam_krb5auto[%i]: %s", getpid(), format); |
| 37 | vsyslog(prio, buf, args); |
| 38 | va_end(args); |
| 39 | } |
| 40 | |
| 41 | static struct options *parseopts(int argc, const char **argv) |
| 42 | { |
| 43 | int i; |
| 44 | struct options *opts; |
| 45 | |
| 46 | opts = malloc(sizeof(*opts)); |
| 47 | memset(opts, 0, sizeof(*opts)); |
| 48 | for(i = 0; i < argc; i++) { |
| 49 | if(!strncmp(argv[i], "realm=", 6)) |
| 50 | opts->realm = strdup(argv[i] + 6); |
| 51 | if(!strncmp(argv[i], "instance=", 9)) |
| 52 | opts->instance = strdup(argv[i] + 9); |
| 53 | if(!strncmp(argv[i], "keytab=", 7)) |
| 54 | opts->keytab = strdup(argv[i] + 7); |
| 55 | if(!strcmp(argv[i], "debug")) |
| 56 | opts->debug = 1; |
| 57 | } |
| 58 | return(opts); |
| 59 | } |
| 60 | |
| 61 | static void freeopts(struct options *opts) |
| 62 | { |
| 63 | if(opts->realm != NULL) |
| 64 | free(opts->realm); |
| 65 | if(opts->instance != NULL) |
| 66 | free(opts->instance); |
| 67 | if(opts->keytab != NULL) |
| 68 | free(opts->keytab); |
| 69 | free(opts); |
| 70 | } |
| 71 | |
| 72 | static void freedata(struct data *data) |
| 73 | { |
| 74 | if(data->me != NULL) |
| 75 | krb5_free_principal(data->ctx, data->me); |
| 76 | if(data->ctx != NULL) |
| 77 | krb5_free_context(data->ctx); |
| 78 | free(data); |
| 79 | } |
| 80 | |
| 81 | static void cleanupdata(pam_handle_t *pamh, struct data *data, int error_status) |
| 82 | { |
| 83 | freedata(data); |
| 84 | } |
| 85 | |
| 86 | static struct data *getdata(pam_handle_t *pamh, struct options *opts) |
| 87 | { |
| 88 | int ret; |
| 89 | struct data *data; |
| 90 | char buf[1024]; |
| 91 | const char *user, *instance; |
| 92 | |
| 93 | data = NULL; |
| 94 | pam_get_data(pamh, "krb5auto-data", (const void **)&data); |
| 95 | if(data == NULL) { |
| 96 | if(opts->debug) |
| 97 | log(LOG_DEBUG, "creating new instance"); |
| 98 | data = malloc(sizeof(*data)); |
| 99 | memset(data, 0, sizeof(*data)); |
| 100 | if((ret = krb5_init_context(&data->ctx)) != 0) { |
| 101 | log(LOG_CRIT, "could not create krb5 context: %s", error_message(ret)); |
| 102 | freedata(data); |
| 103 | return(NULL); |
| 104 | } |
| 105 | pam_get_user(pamh, &user, NULL); |
| 106 | if(opts->instance) |
| 107 | instance = opts->instance; |
| 108 | else |
| 109 | instance = DEF_INSTANCE; |
| 110 | if(opts->realm) |
| 111 | snprintf(buf, sizeof(buf), "%s/%s@%s", user, instance, opts->realm); |
| 112 | else |
| 113 | snprintf(buf, sizeof(buf), "%s/%s", user, instance); |
| 114 | if((ret = krb5_parse_name(data->ctx, buf, &data->me)) != 0) { |
| 115 | log(LOG_ERR, "could not parse principal name `%s': %s", buf, error_message(ret)); |
| 116 | freedata(data); |
| 117 | return(NULL); |
| 118 | } |
| 119 | pam_set_data(pamh, "krb5auto-data", data, (void (*)(pam_handle_t *, void *, int))cleanupdata); |
| 120 | } |
| 121 | return(data); |
| 122 | } |
| 123 | |
| 124 | static void savecreds(struct options *opts, struct data *data) |
| 125 | { |
| 126 | } |
| 127 | |
| 128 | PAM_EXTERN int pam_sm_authenticate(pam_handle_t *pamh, int flags, int argc, const char **argv) |
| 129 | { |
| 130 | return(PAM_IGNORE); |
| 131 | } |
| 132 | |
| 133 | PAM_EXTERN int pam_sm_setcred(pam_handle_t *pamh, int flags, int argc, const char **argv) |
| 134 | { |
| 135 | struct options *opts; |
| 136 | struct data *data; |
| 137 | |
| 138 | opts = parseopts(argc, argv); |
| 139 | data = getdata(pamh, opts); |
| 140 | if(data == NULL) { |
| 141 | log(LOG_ERR, "could not get data, erroring out"); |
| 142 | return(PAM_SERVICE_ERR); |
| 143 | } |
| 144 | if(flags & PAM_ESTABLISH_CRED) { |
| 145 | savecreds(opts, data); |
| 146 | } |
| 147 | freeopts(opts); |
| 148 | return(PAM_IGNORE); |
| 149 | } |
| 150 | |
| 151 | /* |
| 152 | * Local Variables: |
| 153 | * compile-command: "gcc -Wall -g --shared -fPIC -o pam_krb5auto.so pam_krb5auto.c" |
| 154 | * End: |
| 155 | */ |