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+ /*
+ * General skeleton for adding options to the access control language. The
+ * features offered by this module are documented in the hosts_options(5)
+ * manual page (source file: hosts_options.5, "nroff -man" format).
+ *
+ * Notes and warnings for those who want to add features:
+ *
+ * In case of errors, abort options processing and deny access. There are too
+ * many irreversible side effects to make error recovery feasible. For
+ * example, it makes no sense to continue after we have already changed the
+ * userid.
+ *
+ * In case of errors, do not terminate the process: the routines might be
+ * called from a long-running daemon that should run forever. Instead, call
+ * tcpd_jump() which does a non-local goto back into the hosts_access()
+ * routine.
+ *
+ * In case of severe errors, use clean_exit() instead of directly calling
+ * exit(), or the inetd may loop on an UDP request.
+ *
+ * In verification mode (for example, with the "tcpdmatch" command) the
+ * "dry_run" flag is set. In this mode, an option function should just "say"
+ * what it is going to do instead of really doing it.
+ *
+ * Some option functions do not return (for example, the twist option passes
+ * control to another program). In verification mode (dry_run flag is set)
+ * such options should clear the "dry_run" flag to inform the caller of this
+ * course of action.
+ */
+
+#ifndef lint
+static char sccsid[] = "@(#) options.c 1.17 96/02/11 17:01:31";
+#endif
+
+/* System libraries. */
+
+#include <sys/types.h>
+#include <sys/param.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <netinet/in.h>
+#include <netdb.h>
+#include <stdio.h>
+#include <syslog.h>
+#include <pwd.h>
+#include <grp.h>
+#include <ctype.h>
+#include <setjmp.h>
+#include <string.h>
+
+#ifndef MAXPATHNAMELEN
+#define MAXPATHNAMELEN BUFSIZ
+#endif
+
+/* Local stuff. */
+
+#include "tcpd.h"
+
+/* Options runtime support. */
+
+int dry_run = 0; /* flag set in verification mode */
+extern jmp_buf tcpd_buf; /* tcpd_jump() support */
+
+/* Options parser support. */
+
+static char whitespace_eq[] = "= \t\r\n";
+#define whitespace (whitespace_eq + 1)
+
+static char *get_field(); /* chew :-delimited field off string */
+static char *chop_string(); /* strip leading and trailing blanks */
+
+/* List of functions that implement the options. Add yours here. */
+
+static void user_option(); /* execute "user name.group" option */
+static void group_option(); /* execute "group name" option */
+static void umask_option(); /* execute "umask mask" option */
+static void linger_option(); /* execute "linger time" option */
+static void keepalive_option(); /* execute "keepalive" option */
+static void spawn_option(); /* execute "spawn command" option */
+static void twist_option(); /* execute "twist command" option */
+static void rfc931_option(); /* execute "rfc931" option */
+static void setenv_option(); /* execute "setenv name value" */
+static void nice_option(); /* execute "nice" option */
+static void severity_option(); /* execute "severity value" */
+static void allow_option(); /* execute "allow" option */
+static void deny_option(); /* execute "deny" option */
+static void banners_option(); /* execute "banners path" option */
+
+/* Structure of the options table. */
+
+struct option {
+ char *name; /* keyword name, case is ignored */
+ void (*func) (); /* function that does the real work */
+ int flags; /* see below... */
+};
+
+#define NEED_ARG (1<<1) /* option requires argument */
+#define USE_LAST (1<<2) /* option must be last */
+#define OPT_ARG (1<<3) /* option has optional argument */
+#define EXPAND_ARG (1<<4) /* do %x expansion on argument */
+
+#define need_arg(o) ((o)->flags & NEED_ARG)
+#define opt_arg(o) ((o)->flags & OPT_ARG)
+#define permit_arg(o) ((o)->flags & (NEED_ARG | OPT_ARG))
+#define use_last(o) ((o)->flags & USE_LAST)
+#define expand_arg(o) ((o)->flags & EXPAND_ARG)
+
+/* List of known keywords. Add yours here. */
+
+static struct option option_table[] = {
+ "user", user_option, NEED_ARG,
+ "group", group_option, NEED_ARG,
+ "umask", umask_option, NEED_ARG,
+ "linger", linger_option, NEED_ARG,
+ "keepalive", keepalive_option, 0,
+ "spawn", spawn_option, NEED_ARG | EXPAND_ARG,
+ "twist", twist_option, NEED_ARG | EXPAND_ARG | USE_LAST,
+ "rfc931", rfc931_option, OPT_ARG,
+ "setenv", setenv_option, NEED_ARG | EXPAND_ARG,
+ "nice", nice_option, OPT_ARG,
+ "severity", severity_option, NEED_ARG,
+ "allow", allow_option, USE_LAST,
+ "deny", deny_option, USE_LAST,
+ "banners", banners_option, NEED_ARG,
+ 0,
+};
+
+/* process_options - process access control options */
+
+void process_options(options, request)
+char *options;
+struct request_info *request;
+{
+ char *key;
+ char *value;
+ char *curr_opt;
+ char *next_opt;
+ struct option *op;
+ char bf[BUFSIZ];
+
+ for (curr_opt = get_field(options); curr_opt; curr_opt = next_opt) {
+ next_opt = get_field((char *) 0);
+
+ /*
+ * Separate the option into name and value parts. For backwards
+ * compatibility we ignore exactly one '=' between name and value.
+ */
+ curr_opt = chop_string(curr_opt);
+ if (*(value = curr_opt + strcspn(curr_opt, whitespace_eq))) {
+ if (*value != '=') {
+ *value++ = 0;
+ value += strspn(value, whitespace);
+ }
+ if (*value == '=') {
+ *value++ = 0;
+ value += strspn(value, whitespace);
+ }
+ }
+ if (*value == 0)
+ value = 0;
+ key = curr_opt;
+
+ /*
+ * Disallow missing option names (and empty option fields).
+ */
+ if (*key == 0)
+ tcpd_jump("missing option name");
+
+ /*
+ * Lookup the option-specific info and do some common error checks.
+ * Delegate option-specific processing to the specific functions.
+ */
+
+ for (op = option_table; op->name && STR_NE(op->name, key); op++)
+ /* VOID */ ;
+ if (op->name == 0)
+ tcpd_jump("bad option name: \"%s\"", key);
+ if (!value && need_arg(op))
+ tcpd_jump("option \"%s\" requires value", key);
+ if (value && !permit_arg(op))
+ tcpd_jump("option \"%s\" requires no value", key);
+ if (next_opt && use_last(op))
+ tcpd_jump("option \"%s\" must be at end", key);
+ if (value && expand_arg(op))
+ value = chop_string(percent_x(bf, sizeof(bf), value, request));
+ if (hosts_access_verbose)
+ syslog(LOG_DEBUG, "option: %s %s", key, value ? value : "");
+ (*(op->func)) (value, request);
+ }
+}
+
+/* allow_option - grant access */
+
+/* ARGSUSED */
+
+static void allow_option(value, request)
+char *value;
+struct request_info *request;
+{
+ longjmp(tcpd_buf, AC_PERMIT);
+}
+
+/* deny_option - deny access */
+
+/* ARGSUSED */
+
+static void deny_option(value, request)
+char *value;
+struct request_info *request;
+{
+ longjmp(tcpd_buf, AC_DENY);
+}
+
+/* banners_option - expand %<char>, terminate each line with CRLF */
+
+static void banners_option(value, request)
+char *value;
+struct request_info *request;
+{
+ char path[MAXPATHNAMELEN];
+ char ibuf[BUFSIZ];
+ char obuf[2 * BUFSIZ];
+ struct stat st;
+ int ch;
+ FILE *fp;
+
+ sprintf(path, "%s/%s", value, eval_daemon(request));
+ if ((fp = fopen(path, "r")) != 0) {
+ while ((ch = fgetc(fp)) == 0)
+ write(request->fd, "", 1);
+ ungetc(ch, fp);
+ while (fgets(ibuf, sizeof(ibuf) - 1, fp)) {
+ if (split_at(ibuf, '\n'))
+ strcat(ibuf, "\r\n");
+ percent_x(obuf, sizeof(obuf), ibuf, request);
+ write(request->fd, obuf, strlen(obuf));
+ }
+ fclose(fp);
+ } else if (stat(value, &st) < 0) {
+ tcpd_warn("%s: %m", value);
+ }
+}
+
+/* group_option - switch group id */
+
+/* ARGSUSED */
+
+static void group_option(value, request)
+char *value;
+struct request_info *request;
+{
+ struct group *grp;
+ struct group *getgrnam();
+
+ if ((grp = getgrnam(value)) == 0)
+ tcpd_jump("unknown group: \"%s\"", value);
+ endgrent();
+
+ if (dry_run == 0 && setgid(grp->gr_gid))
+ tcpd_jump("setgid(%s): %m", value);
+}
+
+/* user_option - switch user id */
+
+/* ARGSUSED */
+
+static void user_option(value, request)
+char *value;
+struct request_info *request;
+{
+ struct passwd *pwd;
+ struct passwd *getpwnam();
+ char *group;
+
+ if ((group = split_at(value, '.')) != 0)
+ group_option(group, request);
+ if ((pwd = getpwnam(value)) == 0)
+ tcpd_jump("unknown user: \"%s\"", value);
+ endpwent();
+
+ if (dry_run == 0 && setuid(pwd->pw_uid))
+ tcpd_jump("setuid(%s): %m", value);
+}
+
+/* umask_option - set file creation mask */
+
+/* ARGSUSED */
+
+static void umask_option(value, request)
+char *value;
+struct request_info *request;
+{
+ unsigned mask;
+ char junk;
+
+ if (sscanf(value, "%o%c", &mask, &junk) != 1 || (mask & 0777) != mask)
+ tcpd_jump("bad umask value: \"%s\"", value);
+ (void) umask(mask);
+}
+
+/* spawn_option - spawn a shell command and wait */
+
+/* ARGSUSED */
+
+static void spawn_option(value, request)
+char *value;
+struct request_info *request;
+{
+ if (dry_run == 0)
+ shell_cmd(value);
+}
+
+/* linger_option - set the socket linger time (Marc Boucher <marc@cam.org>) */
+
+/* ARGSUSED */
+
+static void linger_option(value, request)
+char *value;
+struct request_info *request;
+{
+ struct linger linger;
+ char junk;
+
+ if (sscanf(value, "%d%c", &linger.l_linger, &junk) != 1
+ || linger.l_linger < 0)
+ tcpd_jump("bad linger value: \"%s\"", value);
+ if (dry_run == 0) {
+ linger.l_onoff = (linger.l_linger != 0);
+ if (setsockopt(request->fd, SOL_SOCKET, SO_LINGER, (char *) &linger,
+ sizeof(linger)) < 0)
+ tcpd_warn("setsockopt SO_LINGER %d: %m", linger.l_linger);
+ }
+}
+
+/* keepalive_option - set the socket keepalive option */
+
+/* ARGSUSED */
+
+static void keepalive_option(value, request)
+char *value;
+struct request_info *request;
+{
+ static int on = 1;
+
+ if (dry_run == 0 && setsockopt(request->fd, SOL_SOCKET, SO_KEEPALIVE,
+ (char *) &on, sizeof(on)) < 0)
+ tcpd_warn("setsockopt SO_KEEPALIVE: %m");
+}
+
+/* nice_option - set nice value */
+
+/* ARGSUSED */
+
+static void nice_option(value, request)
+char *value;
+struct request_info *request;
+{
+ int niceval = 10;
+ char junk;
+
+ if (value != 0 && sscanf(value, "%d%c", &niceval, &junk) != 1)
+ tcpd_jump("bad nice value: \"%s\"", value);
+ if (dry_run == 0 && nice(niceval) < 0)
+ tcpd_warn("nice(%d): %m", niceval);
+}
+
+/* twist_option - replace process by shell command */
+
+static void twist_option(value, request)
+char *value;
+struct request_info *request;
+{
+ char *error;
+
+ if (dry_run != 0) {
+ dry_run = 0;
+ } else {
+ if (resident > 0)
+ tcpd_jump("twist option in resident process");
+
+ syslog(deny_severity, "twist %s to %s", eval_client(request), value);
+
+ /* Before switching to the shell, set up stdin, stdout and stderr. */
+
+#define maybe_dup2(from, to) ((from == to) ? to : (close(to), dup(from)))
+
+ if (maybe_dup2(request->fd, 0) != 0 ||
+ maybe_dup2(request->fd, 1) != 1 ||
+ maybe_dup2(request->fd, 2) != 2) {
+ error = "twist_option: dup: %m";
+ } else {
+ if (request->fd > 2)
+ close(request->fd);
+ (void) execl("/bin/sh", "sh", "-c", value, (char *) 0);
+ error = "twist_option: /bin/sh: %m";
+ }
+
+ /* Something went wrong: we MUST terminate the process. */
+
+ tcpd_warn(error);
+ clean_exit(request);
+ }
+}
+
+/* rfc931_option - look up remote user name */
+
+static void rfc931_option(value, request)
+char *value;
+struct request_info *request;
+{
+ int timeout;
+ char junk;
+
+ if (value != 0) {
+ if (sscanf(value, "%d%c", &timeout, &junk) != 1 || timeout <= 0)
+ tcpd_jump("bad rfc931 timeout: \"%s\"", value);
+ rfc931_timeout = timeout;
+ }
+ (void) eval_user(request);
+}
+
+/* setenv_option - set environment variable */
+
+/* ARGSUSED */
+
+static void setenv_option(value, request)
+char *value;
+struct request_info *request;
+{
+ char *var_value;
+
+ if (*(var_value = value + strcspn(value, whitespace)))
+ *var_value++ = 0;
+ if (setenv(chop_string(value), chop_string(var_value), 1))
+ tcpd_jump("memory allocation failure");
+}
+
+ /*
+ * The severity option goes last because it comes with a huge amount of ugly
+ * #ifdefs and tables.
+ */
+
+struct syslog_names {
+ char *name;
+ int value;
+};
+
+static struct syslog_names log_fac[] = {
+#ifdef LOG_KERN
+ "kern", LOG_KERN,
+#endif
+#ifdef LOG_USER
+ "user", LOG_USER,
+#endif
+#ifdef LOG_MAIL
+ "mail", LOG_MAIL,
+#endif
+#ifdef LOG_DAEMON
+ "daemon", LOG_DAEMON,
+#endif
+#ifdef LOG_AUTH
+ "auth", LOG_AUTH,
+#endif
+#ifdef LOG_LPR
+ "lpr", LOG_LPR,
+#endif
+#ifdef LOG_NEWS
+ "news", LOG_NEWS,
+#endif
+#ifdef LOG_UUCP
+ "uucp", LOG_UUCP,
+#endif
+#ifdef LOG_CRON
+ "cron", LOG_CRON,
+#endif
+#ifdef LOG_LOCAL0
+ "local0", LOG_LOCAL0,
+#endif
+#ifdef LOG_LOCAL1
+ "local1", LOG_LOCAL1,
+#endif
+#ifdef LOG_LOCAL2
+ "local2", LOG_LOCAL2,
+#endif
+#ifdef LOG_LOCAL3
+ "local3", LOG_LOCAL3,
+#endif
+#ifdef LOG_LOCAL4
+ "local4", LOG_LOCAL4,
+#endif
+#ifdef LOG_LOCAL5
+ "local5", LOG_LOCAL5,
+#endif
+#ifdef LOG_LOCAL6
+ "local6", LOG_LOCAL6,
+#endif
+#ifdef LOG_LOCAL7
+ "local7", LOG_LOCAL7,
+#endif
+ 0,
+};
+
+static struct syslog_names log_sev[] = {
+#ifdef LOG_EMERG
+ "emerg", LOG_EMERG,
+#endif
+#ifdef LOG_ALERT
+ "alert", LOG_ALERT,
+#endif
+#ifdef LOG_CRIT
+ "crit", LOG_CRIT,
+#endif
+#ifdef LOG_ERR
+ "err", LOG_ERR,
+#endif
+#ifdef LOG_WARNING
+ "warning", LOG_WARNING,
+#endif
+#ifdef LOG_NOTICE
+ "notice", LOG_NOTICE,
+#endif
+#ifdef LOG_INFO
+ "info", LOG_INFO,
+#endif
+#ifdef LOG_DEBUG
+ "debug", LOG_DEBUG,
+#endif
+ 0,
+};
+
+/* severity_map - lookup facility or severity value */
+
+static int severity_map(table, name)
+struct syslog_names *table;
+char *name;
+{
+ struct syslog_names *t;
+
+ for (t = table; t->name; t++)
+ if (STR_EQ(t->name, name))
+ return (t->value);
+ tcpd_jump("bad syslog facility or severity: \"%s\"", name);
+ /* NOTREACHED */
+}
+
+/* severity_option - change logging severity for this event (Dave Mitchell) */
+
+/* ARGSUSED */
+
+static void severity_option(value, request)
+char *value;
+struct request_info *request;
+{
+ char *level = split_at(value, '.');
+
+ allow_severity = deny_severity = level ?
+ severity_map(log_fac, value) | severity_map(log_sev, level) :
+ severity_map(log_sev, value);
+}
+
+/* get_field - return pointer to next field in string */
+
+static char *get_field(string)
+char *string;
+{
+ static char *last = "";
+ char *src;
+ char *dst;
+ char *ret;
+ int ch;
+
+ /*
+ * This function returns pointers to successive fields within a given
+ * string. ":" is the field separator; warn if the rule ends in one. It
+ * replaces a "\:" sequence by ":", without treating the result of
+ * substitution as field terminator. A null argument means resume search
+ * where the previous call terminated. This function destroys its
+ * argument.
+ *
+ * Work from explicit source or from memory. While processing \: we
+ * overwrite the input. This way we do not have to maintain buffers for
+ * copies of input fields.
+ */
+
+ src = dst = ret = (string ? string : last);
+ if (src[0] == 0)
+ return (0);
+
+ while (ch = *src) {
+ if (ch == ':') {
+ if (*++src == 0)
+ tcpd_warn("rule ends in \":\"");
+ break;
+ }
+ if (ch == '\\' && src[1] == ':')
+ src++;
+ *dst++ = *src++;
+ }
+ last = src;
+ *dst = 0;
+ return (ret);
+}
+
+/* chop_string - strip leading and trailing blanks from string */
+
+static char *chop_string(string)
+register char *string;
+{
+ char *start = 0;
+ char *end;
+ char *cp;
+
+ for (cp = string; *cp; cp++) {
+ if (!isspace(*cp)) {
+ if (start == 0)
+ start = cp;
+ end = cp;
+ }
+ }
+ return (start ? (end[1] = 0, start) : cp);
+}
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