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-rw-r--r--libpamc/test/modules/pam_secret.c669
1 files changed, 669 insertions, 0 deletions
diff --git a/libpamc/test/modules/pam_secret.c b/libpamc/test/modules/pam_secret.c
new file mode 100644
index 0000000..f1c74c6
--- /dev/null
+++ b/libpamc/test/modules/pam_secret.c
@@ -0,0 +1,669 @@
+/*
+ * $Id$
+ *
+ * Copyright (c) 1999 Andrew G. Morgan <morgan@linux.kernel.org>
+ */
+
+/*
+ * WARNING: AS WRITTEN THIS CODE IS NOT SECURE. THE MD5 IMPLEMENTATION
+ * NEEDS TO BE INTEGRATED MORE NATIVELY.
+ */
+
+#include <fcntl.h>
+#include <pwd.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include <security/pam_modules.h>
+#include <security/pam_client.h>
+#include <security/_pam_macros.h>
+
+/*
+ * This is a sample module that demonstrates the use of binary prompts
+ * and how they can be used to implement sophisticated authentication
+ * schemes.
+ */
+
+struct ps_state_s {
+ int retval; /* last retval returned by the authentication fn */
+ int state; /* what state the module was in when it
+ returned incomplete */
+
+ char *username; /* the name of the local user */
+
+ char server_cookie[33]; /* storage for 32 bytes of server cookie */
+ char client_cookie[33]; /* storage for 32 bytes of client cookie */
+
+ char *secret_data; /* pointer to <NUL> terminated secret_data */
+ int invalid_secret; /* indication of whether the secret is valid */
+
+ pamc_bp_t current_prompt; /* place to store the current prompt */
+ pamc_bp_t current_reply; /* place to receive the reply prompt */
+};
+
+#define PS_STATE_ID "PAM_SECRET__STATE"
+#define PS_AGENT_ID "secret@here"
+#define PS_STATE_DEAD 0
+#define PS_STATE_INIT 1
+#define PS_STATE_PROMPT1 2
+#define PS_STATE_PROMPT2 3
+
+#define MAX_LEN_HOSTNAME 512
+#define MAX_FILE_LINE_LEN 1024
+
+/*
+ * Routine for generating 16*8 bits of random data represented in ASCII hex
+ */
+
+static int generate_cookie(unsigned char *buffer_33)
+{
+ static const char hexarray[] = "0123456789abcdef";
+ int i, fd;
+
+ /* fill buffer_33 with 32 hex characters (lower case) + '\0' */
+ fd = open("/dev/urandom", O_RDONLY);
+ if (fd < 0) {
+ D(("failed to open /dev/urandom"));
+ return 0;
+ }
+ read(fd, buffer_33 + 16, 16);
+ close(fd);
+
+ /* expand top 16 bytes into 32 nibbles */
+ for (i=0; i<16; ++i) {
+ buffer_33[2*i ] = hexarray[(buffer_33[16+i] & 0xf0)>>4];
+ buffer_33[2*i+1] = hexarray[(buffer_33[16+i] & 0x0f)];
+ }
+
+ buffer_33[32] = '\0';
+
+ return 1;
+}
+
+/*
+ * XXX - This is a hack, and is fundamentally insecure. Its subject to
+ * all sorts of attacks not to mention the fact that all our secrets
+ * will be displayed on the command line for someone doing 'ps' to
+ * see. This is just for programming convenience in this instance, it
+ * needs to be replaced with the md5 code. Although I am loath to
+ * add yet another instance of md5 code to the Linux-PAM source code.
+ * [Need to think of a cleaner way to do this for the distribution as
+ * a whole...]
+ */
+
+#define COMMAND_FORMAT "/bin/echo -n '%s|%s|%s'|/usr/bin/md5sum -"
+
+int create_digest(const char *d1, const char *d2, const char *d3,
+ char *buffer_33)
+{
+ int length;
+ char *buffer;
+ FILE *pipe;
+
+ length = strlen(d1)+strlen(d2)+strlen(d3)+sizeof(COMMAND_FORMAT);
+ buffer = malloc(length);
+ if (buffer == NULL) {
+ D(("out of memory"));
+ return 0;
+ }
+
+ sprintf(buffer, COMMAND_FORMAT, d1,d2,d3);
+
+ D(("executing pipe [%s]", buffer));
+ pipe = popen(buffer, "r");
+ memset(buffer, 0, length);
+ free(buffer);
+
+ if (pipe == NULL) {
+ D(("failed to launch pipe"));
+ return 0;
+ }
+
+ if (fgets(buffer_33, 33, pipe) == NULL) {
+ D(("failed to read digest"));
+ return 0;
+ }
+
+ if (strlen(buffer_33) != 32) {
+ D(("digest was not 32 chars"));
+ return 0;
+ }
+
+ fclose(pipe);
+
+ D(("done [%s]", buffer_33));
+
+ return 1;
+}
+
+/*
+ * method to attempt to instruct the application's conversation function
+ */
+
+static int converse(pam_handle_t *pamh, struct ps_state_s *new)
+{
+ int retval;
+ struct pam_conv *conv;
+
+ D(("called"));
+
+ retval = pam_get_item(pamh, PAM_CONV, (const void **) &conv);
+ if (retval == PAM_SUCCESS) {
+ struct pam_message msg;
+ struct pam_response *single_reply;
+ const struct pam_message *msg_ptr;
+
+ memset(&msg, 0, sizeof(msg));
+ msg.msg_style = PAM_BINARY_PROMPT;
+ msg.msg = (const char *) new->current_prompt;
+ msg_ptr = &msg;
+
+ single_reply = NULL;
+ retval = conv->conv(1, &msg_ptr, &single_reply, conv->appdata_ptr);
+ if (retval == PAM_SUCCESS) {
+ if ((single_reply == NULL) || (single_reply->resp == NULL)) {
+ retval == PAM_CONV_ERR;
+ } else {
+ new->current_reply = (pamc_bp_t) single_reply->resp;
+ single_reply->resp = NULL;
+ }
+ }
+
+ if (single_reply) {
+ free(single_reply);
+ }
+ }
+
+#ifdef PAM_DEBUG
+ if (retval == PAM_SUCCESS) {
+ D(("reply has length=%d and control=%u",
+ PAM_BP_LENGTH(new->current_reply),
+ PAM_BP_CONTROL(new->current_reply)));
+ }
+ D(("returning %s", pam_strerror(pamh, retval)));
+#endif
+
+ return retval;
+}
+
+/*
+ * identify the secret in question
+ */
+
+#define SECRET_FILE_FORMAT "%s/.secret@here"
+
+char *identify_secret(char *identity, const char *user)
+{
+ struct passwd *pwd;
+ char *temp;
+ FILE *secrets;
+ int length_id;
+
+ pwd = getpwnam(user);
+ if ((pwd == NULL) || (pwd->pw_dir == NULL)) {
+ D(("user [%s] is not known", user));
+ return NULL;
+ }
+
+ length_id = strlen(pwd->pw_dir) + sizeof(SECRET_FILE_FORMAT);
+ temp = malloc(length_id);
+ if (temp == NULL) {
+ D(("out of memory"));
+ pwd = NULL;
+ return NULL;
+ }
+
+ sprintf(temp, SECRET_FILE_FORMAT, pwd->pw_dir);
+ pwd = NULL;
+
+ D(("opening key file [%s]", temp));
+ secrets = fopen(temp, "r");
+ memset(temp, 0, length_id);
+
+ if (secrets == NULL) {
+ D(("failed to open key file"));
+ return NULL;
+ }
+
+ length_id = strlen(identity);
+ temp = malloc(MAX_FILE_LINE_LEN);
+
+ for (;;) {
+ char *secret = NULL;
+
+ if (fgets(temp, MAX_FILE_LINE_LEN, secrets) == NULL) {
+ fclose(secrets);
+ return NULL;
+ }
+
+ D(("cf[%s][%s]", identity, temp));
+ if (memcmp(temp, identity, length_id)) {
+ continue;
+ }
+
+ D(("found entry"));
+ fclose(secrets);
+
+ for (secret=temp+length_id; *secret; ++secret) {
+ if (!(*secret == ' ' || *secret == '\n' || *secret == '\t')) {
+ break;
+ }
+ }
+
+ memmove(temp, secret, MAX_FILE_LINE_LEN-(secret-(temp+length_id)));
+ secret = temp;
+
+ for (; *secret; ++secret) {
+ if (*secret == ' ' || *secret == '\n' || *secret == '\t') {
+ break;
+ }
+ }
+
+ if (*secret) {
+ *secret = '\0';
+ }
+
+ D(("secret found [%s]", temp));
+
+ return temp;
+ }
+
+ /* NOT REACHED */
+}
+
+/*
+ * function to perform the two message authentication process
+ * (with support for event driven conversation functions)
+ */
+
+static int auth_sequence(pam_handle_t *pamh,
+ const struct ps_state_s *old, struct ps_state_s *new)
+{
+ const char *rhostname;
+ const char *rusername;
+ int retval;
+
+ retval = pam_get_item(pamh, PAM_RUSER, (const void **) &rusername);
+ if ((retval != PAM_SUCCESS) || (rusername == NULL)) {
+ D(("failed to obtain an rusername"));
+ new->state = PS_STATE_DEAD;
+ return PAM_AUTH_ERR;
+ }
+
+ retval = pam_get_item(pamh, PAM_RHOST, (const void **) &rhostname);
+ if ((retval != PAM_SUCCESS) || (rhostname == NULL)) {
+ D(("failed to identify local hostname: ", pam_strerror(pamh, retval)));
+ new->state = PS_STATE_DEAD;
+ return PAM_AUTH_ERR;
+ }
+
+ D(("switch on new->state=%d [%s@%s]", new->state, rusername, rhostname));
+ switch (new->state) {
+
+ case PS_STATE_INIT:
+ {
+ const char *user = NULL;
+
+ retval = pam_get_user(pamh, &user, NULL);
+
+ if ((retval == PAM_SUCCESS) && (user == NULL)) {
+ D(("success but no username?"));
+ new->state = PS_STATE_DEAD;
+ retval = PAM_USER_UNKNOWN;
+ }
+
+ if (retval != PAM_SUCCESS) {
+ if (retval == PAM_CONV_AGAIN) {
+ retval = PAM_INCOMPLETE;
+ } else {
+ new->state = PS_STATE_DEAD;
+ }
+ D(("state init failed: %s", pam_strerror(pamh, retval)));
+ return retval;
+ }
+
+ /* nothing else in this 'case' can be retried */
+
+ new->username = strdup(user);
+ if (new->username == NULL) {
+ D(("out of memory"));
+ new->state = PS_STATE_DEAD;
+ return PAM_BUF_ERR;
+ }
+
+ if (! generate_cookie(new->server_cookie)) {
+ D(("problem generating server cookie"));
+ new->state = PS_STATE_DEAD;
+ return PAM_ABORT;
+ }
+
+ new->current_prompt = NULL;
+ PAM_BP_RENEW(&new->current_prompt, PAM_BPC_SELECT,
+ sizeof(PS_AGENT_ID) + strlen(rusername) + 1
+ + strlen(rhostname) + 1 + 32);
+ sprintf(PAM_BP_WDATA(new->current_prompt),
+ PS_AGENT_ID "/%s@%s|%.32s", rusername, rhostname,
+ new->server_cookie);
+
+ /* note, the BP is guaranteed by the spec to be <NUL> terminated */
+ D(("initialization packet [%s]", PAM_BP_DATA(new->current_prompt)));
+
+ /* fall through */
+ new->state = PS_STATE_PROMPT1;
+
+ D(("fall through to state_prompt1"));
+ }
+
+ case PS_STATE_PROMPT1:
+ {
+ int i, length;
+
+ /* send {secret@here/jdoe@client.host|<s_cookie>} */
+ retval = converse(pamh, new);
+ if (retval != PAM_SUCCESS) {
+ if (retval == PAM_CONV_AGAIN) {
+ D(("conversation failed to complete"));
+ return PAM_INCOMPLETE;
+ } else {
+ new->state = PS_STATE_DEAD;
+ return retval;
+ }
+ }
+
+ if (retval != PAM_SUCCESS) {
+ D(("failed to read ruser@rhost"));
+ new->state = PS_STATE_DEAD;
+ return PAM_AUTH_ERR;
+ }
+
+ /* expect to receive the following {<seqid>|<a_cookie>} */
+ if (new->current_reply == NULL) {
+ D(("converstation returned [%s] but gave no reply",
+ pam_strerror(pamh, retval)));
+ new->state = PS_STATE_DEAD;
+ return PAM_CONV_ERR;
+ }
+
+ /* find | */
+ length = PAM_BP_LENGTH(new->current_reply);
+ for (i=0; i<length; ++i) {
+ if (PAM_BP_RDATA(new->current_reply)[i] == '|') {
+ break;
+ }
+ }
+ if (i >= length) {
+ D(("malformed response (no |) of length %d", length));
+ new->state = PS_STATE_DEAD;
+ return PAM_CONV_ERR;
+ }
+ if ((length - ++i) != 32) {
+ D(("cookie is incorrect length (%d,%d) %d != 32",
+ length, i, length-i));
+ new->state = PS_STATE_DEAD;
+ return PAM_CONV_ERR;
+ }
+
+ /* copy client cookie */
+ memcpy(new->client_cookie, PAM_BP_RDATA(new->current_reply)+i, 32);
+
+ /* generate a prompt that is length(seqid) + length(|) + 32 long */
+ PAM_BP_RENEW(&new->current_prompt, PAM_BPC_OK, i+32);
+ /* copy the head of the response prompt */
+ memcpy(PAM_BP_WDATA(new->current_prompt),
+ PAM_BP_RDATA(new->current_reply), i);
+ PAM_BP_RENEW(&new->current_reply, 0, 0);
+
+ /* look up the secret */
+ new->invalid_secret = 0;
+
+ if (new->secret_data == NULL) {
+ char *ruser_rhost;
+
+ ruser_rhost = malloc(strlen(rusername)+2+strlen(rhostname));
+ if (ruser_rhost == NULL) {
+ D(("out of memory"));
+ new->state = PS_STATE_DEAD;
+ return PAM_BUF_ERR;
+ }
+ sprintf(ruser_rhost, "%s@%s", rusername, rhostname);
+ new->secret_data = identify_secret(ruser_rhost, new->username);
+
+ memset(ruser_rhost, 0, strlen(ruser_rhost));
+ free(ruser_rhost);
+ }
+
+ if (new->secret_data == NULL) {
+ D(("secret not found for user"));
+ new->invalid_secret = 1;
+
+ /* need to make up a secret */
+ new->secret_data = malloc(32 + 1);
+ if (new->secret_data == NULL) {
+ D(("out of memory"));
+ new->state = PS_STATE_DEAD;
+ return PAM_BUF_ERR;
+ }
+ if (! generate_cookie(new->secret_data)) {
+ D(("what's up - no fake cookie generated?"));
+ new->state = PS_STATE_DEAD;
+ return PAM_ABORT;
+ }
+ }
+
+ /* construct md5[<client_cookie>|<server_cookie>|<secret_data>] */
+ if (! create_digest(new->client_cookie, new->server_cookie,
+ new->secret_data,
+ PAM_BP_WDATA(new->current_prompt)+i)) {
+ D(("md5 digesting failed"));
+ new->state = PS_STATE_DEAD;
+ return PAM_ABORT;
+ }
+
+ /* prompt2 is now constructed - fall through to send it */
+ }
+
+ case PS_STATE_PROMPT2:
+ {
+ /* send {<seqid>|md5[<client_cookie>|<server_cookie>|<secret_data>]} */
+ retval = converse(pamh, new);
+ if (retval != PAM_SUCCESS) {
+ if (retval == PAM_CONV_AGAIN) {
+ D(("conversation failed to complete"));
+ return PAM_INCOMPLETE;
+ } else {
+ new->state = PS_STATE_DEAD;
+ return retval;
+ }
+ }
+
+ /* After we complete this section, we should not be able to
+ recall this authentication function. So, we force all
+ future calls into the weeds. */
+
+ new->state = PS_STATE_DEAD;
+
+ /* expect reply:{md5[<secret_data>|<server_cookie>|<client_cookie>]} */
+
+ {
+ int cf;
+ char expectation[33];
+
+ if (!create_digest(new->secret_data, new->server_cookie,
+ new->client_cookie, expectation)) {
+ new->state = PS_STATE_DEAD;
+ return PAM_ABORT;
+ }
+
+ cf = strcmp(expectation, PAM_BP_RDATA(new->current_reply));
+ memset(expectation, 0, sizeof(expectation));
+ if (cf || new->invalid_secret) {
+ D(("failed to authenticate"));
+ return PAM_AUTH_ERR;
+ }
+ }
+
+ D(("correctly authenticated :)"));
+ return PAM_SUCCESS;
+ }
+
+ default:
+ new->state = PS_STATE_DEAD;
+
+ case PS_STATE_DEAD:
+
+ D(("state is currently dead/unknown"));
+ return PAM_AUTH_ERR;
+ }
+
+ fprintf(stderr, "pam_secret: this should not be reached\n");
+ return PAM_ABORT;
+}
+
+static void clean_data(pam_handle_t *pamh, void *datum, int error_status)
+{
+ struct ps_state_s *data = datum;
+
+ D(("liberating datum=%p", datum));
+
+ if (data) {
+ D(("renew prompt"));
+ PAM_BP_RENEW(&data->current_prompt, 0, 0);
+ D(("renew reply"));
+ PAM_BP_RENEW(&data->current_reply, 0, 0);
+ D(("overwrite datum"));
+ memset(data, 0, sizeof(struct ps_state_s));
+ D(("liberate datum"));
+ free(data);
+ }
+
+ D(("done."));
+}
+
+/*
+ * front end for the authentication function
+ */
+
+int pam_sm_authenticate(pam_handle_t *pamh, int flags,
+ int argc, const char **argv)
+{
+ int retval;
+ struct ps_state_s *new_data;
+ const struct ps_state_s *old_data;
+
+ D(("called"));
+
+ new_data = calloc(1, sizeof(struct ps_state_s));
+ if (new_data == NULL) {
+ D(("out of memory"));
+ return PAM_BUF_ERR;
+ }
+ new_data->retval = PAM_SUCCESS;
+
+ retval = pam_get_data(pamh, PS_STATE_ID, (const void **) &old_data);
+ if (retval == PAM_SUCCESS) {
+ new_data->state = old_data->state;
+ memcpy(new_data->server_cookie, old_data->server_cookie, 32);
+ memcpy(new_data->client_cookie, old_data->client_cookie, 32);
+ if (old_data->username) {
+ new_data->username = strdup(old_data->username);
+ }
+ if (old_data->secret_data) {
+ new_data->secret_data = strdup(old_data->secret_data);
+ }
+ if (old_data->current_prompt) {
+ int length;
+
+ length = PAM_BP_LENGTH(old_data->current_prompt);
+ PAM_BP_RENEW(&new_data->current_prompt,
+ PAM_BP_CONTROL(old_data->current_prompt), length);
+ PAM_BP_FILL(new_data->current_prompt, 0, length,
+ PAM_BP_RDATA(old_data->current_prompt));
+ }
+ /* don't need to duplicate current_reply */
+ } else {
+ old_data = NULL;
+ new_data->state = PS_STATE_INIT;
+ }
+
+ D(("call auth_sequence"));
+ new_data->retval = auth_sequence(pamh, old_data, new_data);
+ D(("returned from auth_sequence"));
+
+ retval = pam_set_data(pamh, PS_STATE_ID, new_data, clean_data);
+ if (retval != PAM_SUCCESS) {
+ D(("unable to store new_data"));
+ } else {
+ retval = new_data->retval;
+ }
+
+ old_data = new_data = NULL;
+
+ D(("done (%d)", retval));
+ return retval;
+}
+
+/*
+ * front end for the credential setting function
+ */
+
+#define AUTH_SESSION_TICKET_ENV_FORMAT "AUTH_SESSION_TICKET="
+
+int pam_sm_setcred(pam_handle_t *pamh, int flags,
+ int argc, const char **argv)
+{
+ int retval;
+ const struct ps_state_s *old_data;
+
+ D(("called"));
+
+ /* XXX - need to pay attention to the various flavors of call */
+
+ /* XXX - need provide an option to turn this feature on/off: if
+ other modules want to supply an AUTH_SESSION_TICKET, we should
+ leave it up to the admin which module dominiates. */
+
+ retval = pam_get_data(pamh, PS_STATE_ID, (const void **) &old_data);
+ if (retval != PAM_SUCCESS) {
+ D(("no data to base decision on"));
+ return PAM_AUTH_ERR;
+ }
+
+ /*
+ * If ok, export a derived shared secret session ticket to the
+ * client's PAM environment - the ticket has the form
+ *
+ * AUTH_SESSION_TICKET =
+ * md5[<server_cookie>|<secret_data>|<client_cookie>]
+ *
+ * This is a precursor to supporting a spoof resistant trusted
+ * path mechanism. This shared secret ticket can be used to add
+ * a hard-to-guess checksum to further authentication data.
+ */
+
+ retval = old_data->retval;
+ if (retval == PAM_SUCCESS) {
+ char envticket[sizeof(AUTH_SESSION_TICKET_ENV_FORMAT)+32];
+
+ memcpy(envticket, AUTH_SESSION_TICKET_ENV_FORMAT,
+ sizeof(AUTH_SESSION_TICKET_ENV_FORMAT));
+
+ if (! create_digest(old_data->server_cookie, old_data->secret_data,
+ old_data->client_cookie,
+ envticket+sizeof(AUTH_SESSION_TICKET_ENV_FORMAT)-1
+ )) {
+ D(("unable to generate a digest for session ticket"));
+ return PAM_ABORT;
+ }
+
+ D(("putenv[%s]", envticket));
+ retval = pam_putenv(pamh, envticket);
+ memset(envticket, 0, sizeof(envticket));
+ }
+
+ old_data = NULL;
+ D(("done (%d)", retval));
+
+ return retval;
+}
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