gss/gsscred/gsscred_file.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident	"%Z%%M%	%I%	%E% SMI"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <ctype.h>
#include "gsscred.h"

/*
 *  gsscred utility
 *  Manages mapping between a security principal name and unix uid.
 *  Implementation file for the file based gsscred utility.
 */

#define	MAX_ENTRY_LEN 1024

static const char credFile[] = "/etc/gss/gsscred_db";
static const char credFileTmp[] = "/etc/gss/gsscred_db.tmp";
static const int expNameTokIdLen = 2;
static const int mechOidLenLen = 2;
static const int krb5OidTagLen = 1;
static const int krb5OidLenLen = 1;
static const int nameLen = 4;
static const int krb5OidLen = 9;

/*
 * Multiply by two given that the token has already gone through hex string
 * expansion.
 */
#define	NAME_OFFSET (expNameTokIdLen + mechOidLenLen + krb5OidTagLen + \
	krb5OidLenLen + krb5OidLen + nameLen) * 2

static int matchEntry(const char *entry, const gss_buffer_t name,
		const char *uid, uid_t *uidOut);

/*
 * file_addGssCredEntry
 *
 * Adds a new entry to the gsscred table.
 * Does not check for duplicate entries.
 */
int file_addGssCredEntry(const gss_buffer_t hexName, const char *uid,
		const char *comment, char **errDetails)
{
	FILE *fp;
	char tmpBuf[256];

	if ((fp = fopen(credFile, "a")) == NULL) {
		if (errDetails) {
			(void) snprintf(tmpBuf, sizeof (tmpBuf),
				gettext("Unable to open gsscred file [%s]"),
				credFile);
			*errDetails = strdup(tmpBuf);
		}
		return (0);
	}

	(void) fprintf(fp,
		    "%s\t%s\t%s\n", (char *)hexName->value, uid, comment);
	(void) fclose(fp);
	return (1);
}  /* *******  file_addGssCredEntry ****** */


/*
 * file_getGssCredEntry
 *
 * Searches the file for the file matching the name.  Since the name
 * contains a mechanism identifier, to search for all names for a given
 * mechanism just supply the mechanism portion in the name buffer.
 * To search by uid only, supply a non-null value of uid.
 */
int file_getGssCredEntry(const gss_buffer_t name, const char *uid,
		char **errDetails)
{
	FILE *fp;
	char entry[MAX_ENTRY_LEN+1];

	if ((fp = fopen(credFile, "r")) == NULL) {

		if (errDetails) {
			(void) snprintf(entry, sizeof (entry),
				gettext("Unable to open gsscred file [%s]"),
				credFile);
			*errDetails = strdup(entry);
		}

		return (0);
	}

	/* go through the file in sequential order */
	while (fgets(entry, MAX_ENTRY_LEN, fp) != NULL) {
		/* is there any search criteria */
		if (name == NULL && uid == NULL) {
			(void) fprintf(stdout, "%s", entry);
			continue;
		}

		if (matchEntry(entry, name, uid, NULL))
			(void) fprintf(stdout, "%s", entry);

	}	 /* while */

	(void) fclose(fp);
	return (1);
}  /* file_getGssCredEntry */

/*
 * file_getGssCredUid
 *
 * GSS entry point for retrieving user uid information.
 * We need to go through the entire file to ensure that
 * the last matching entry is retrieved - this is because
 * new entries are added to the end, and in case of
 * duplicates we want to get the latest entry.
 */
int
file_getGssCredUid(const gss_buffer_t expName, uid_t *uidOut)
{
	FILE *fp;
	char entry[MAX_ENTRY_LEN+1];
	int retVal = 0;

	if ((fp = fopen(credFile, "r")) == NULL)
		return (0);

	/* go through the entire file in sequential order */
	while (fgets(entry, MAX_ENTRY_LEN, fp) != NULL) {
		if (matchEntry(entry, expName, NULL, uidOut)) {
			retVal = 1;
		}
	} /* while */

	(void) fclose(fp);
	return (retVal);
} /* file_getGssCredUid */


/*
 *
 * file_deleteGssCredEntry
 *
 * removes entries form file that match the delete criteria
 */
int file_deleteGssCredEntry(const gss_buffer_t name, const char *uid,
		char **errDetails)
{
	FILE *fp, *tempFp;
	char entry[MAX_ENTRY_LEN+1];
	int foundOne = 0;

	/* are we deleting everyone? */
	if (name == NULL && uid == NULL) {

		if ((fp = fopen(credFile, "w")) == NULL) {

			if (errDetails) {
				(void) snprintf(entry, sizeof (entry),
					gettext("Unable to open gsscred"
						" file [%s]"),
					credFile);
				*errDetails = strdup(entry);
			}
			return (0);
		}

		(void) fclose(fp);
		return (1);
	}

	/* selective delete - might still be everyone */
	if ((fp = fopen(credFile, "r")) == NULL) {

		if (errDetails) {
			(void) snprintf(entry, sizeof (entry),
				gettext("Unable to open gsscred file [%s]"),
				credFile);
			*errDetails = strdup(entry);
		}
		return (0);
	}

	/* also need to open temp file */
	if ((tempFp = fopen(credFileTmp, "w")) == NULL) {
		if (errDetails) {
			(void) snprintf(entry, sizeof (entry),
				gettext("Unable to open gsscred temporary"
					" file [%s]"),
				credFileTmp);
			*errDetails = strdup(entry);
		}

		(void) fclose(fp);
		return (0);
	}

	/* go through all the entries sequentially removing ones that match */
	while (fgets(entry, MAX_ENTRY_LEN, fp) != NULL) {

		if (!matchEntry(entry, name, uid, NULL))
			(void) fputs(entry, tempFp);
		else
			foundOne = 1;
	}
	(void) fclose(tempFp);
	(void) fclose(fp);

	/* now make the tempfile the gsscred file */
	(void) rename(credFileTmp, credFile);
	(void) unlink(credFileTmp);

	if (!foundOne) {
		*errDetails = strdup(gettext("No users found"));
		return (0);
	}
	return (1);
}  /* file_deleteGssCredEntry */


/*
 *
 * match entry
 *
 * checks if the specified entry matches the supplied criteria
 * returns 1 if yes, 0 if no
 * uidOut value can be used to retrieve the uid from the entry
 * when the uid string is passed in, the uidOut value is not set
 */
static int matchEntry(const char *entry, const gss_buffer_t name,
		const char *uid, uid_t *uidOut)
{
	char fullEntry[MAX_ENTRY_LEN+1], *item, *item_buf, *name_buf;
	char dilims[] = "\t \n";
	/*
	 * item_len is the length of the token in the gsscred_db.
	 * name_len is the length of the token passed to this function.
	 */
	int item_len, name_len;
	/*
	 * This is the hex encoding of the beginning of all exported name
	 * tokens for the Kerberos V mechanism.  We need this to detect old,
	 * incorrectly exported name tokens; see below.
	 */
	char *krb5_ntok_prefix = "0401000B06092A864886F712010202";
	/*
	 * This is the hex encoded GSS_C_NT_USER_NAME OID, needed for the same
	 * reason as krb5_ntok_prefix.
	 */
	char *gss_u_name = "2A864886F71201020101";

	if (entry == NULL || isspace(*entry))
		return (0);

	/* save the entry since strtok will chop it up */
	(void) strcpy(fullEntry, entry);

	if ((item = strtok(fullEntry, dilims)) == NULL)
		return (0);

	/* do we need to search the name */
	if (name != NULL) {

		item_len = strlen(item);
		name_len = name->length;
		name_buf = name->value;

		/* we can match the prefix of the string */
		if (item_len < name_len)
			return (0);

		if (strncmp(item, name->value, name_len) != 0) {

			/*
			 * The following section is needed in order to detect
			 * two existing errant formats in the gsscred db.
			 *
			 * 1. Exported names that have a trailing null byte
			 * ("00" in two hex characters) with the name length
			 * incremented to account for the extra null byte.
			 *
			 * 2. Exported names that have the name type length
			 * and name type OID prepended to the exported name.
			 *
			 */
			if (strncmp(name->value, krb5_ntok_prefix,
			    strlen(krb5_ntok_prefix)) != 0)
				return (0);

			if (strncmp(item, krb5_ntok_prefix,
			    strlen(krb5_ntok_prefix)) != 0)
				return (0);

			if ((item_buf = strstr(item, gss_u_name)) == NULL)
				return (0);

			item_buf += strlen(gss_u_name);

			name_buf += NAME_OFFSET;

			if ((strlen(item_buf) != strlen(name_buf)) &&
			    (strncmp(item_buf + (strlen(item_buf) - 2), "00", 2)
			    != 0))
				return (0);

			/*
			 * Here we compare the end of name_len, given
			 * that item_len could have two extra "00"
			 * representing the null byte.
			 */
			if (strncmp(item_buf, name_buf, name_len - NAME_OFFSET)
			    != 0)
				return (0);
		} else
			/*
			 * We only strncmp() so we could check for old,
			 * broken exported name tokens for the krb5 mech.
			 * For any other exported name tokens we want exact
			 * matches only.
			 */
			if (item_len != name_len)
				return (0);

		/* do we need to check the uid - if not then we found it */
		if (uid == NULL) {
			/* do we ned to parse out the uid ? */
			if (uidOut) {
				if ((item = strtok(NULL, dilims)) == NULL)
					return (0);
				*uidOut = atol(item);
			}
			return (1);
		}

		/* continue with checking the uid */
	}

	if (uid == NULL)
		return (1);

	/* get the next token from the string - the uid */
	if ((item = strtok(NULL, dilims)) == NULL)
		return (0);

	if (strcmp(item, uid) == 0)
		return (1);

	return (0);
}  /* *******  matchEntry ****** */