/*++ /* NAME /* postdrop 1 /* SUMMARY /* Postfix mail posting utility /* SYNOPSIS /* \fBpostdrop\fR [\fB-rv\fR] [\fB-c \fIconfig_dir\fR] /* DESCRIPTION /* The \fBpostdrop\fR(1) command creates a file in the \fBmaildrop\fR /* directory and copies its standard input to the file. /* /* Options: /* .IP "\fB-c \fIconfig_dir\fR" /* The \fBmain.cf\fR configuration file is in the named directory /* instead of the default configuration directory. See also the /* MAIL_CONFIG environment setting below. /* .IP \fB-r\fR /* Use a Postfix-internal protocol for reading the message from /* standard input, and for reporting status information on standard /* output. This is currently the only supported method. /* .IP \fB-v\fR /* Enable verbose logging for debugging purposes. Multiple \fB-v\fR /* options make the software increasingly verbose. As of Postfix 2.3, /* this option is available for the super-user only. /* SECURITY /* .ad /* .fi /* The command is designed to run with set-group ID privileges, so /* that it can write to the \fBmaildrop\fR queue directory and so that /* it can connect to Postfix daemon processes. /* DIAGNOSTICS /* Fatal errors: malformed input, I/O error, out of memory. Problems /* are logged to \fBsyslogd\fR(8) and to the standard error stream. /* When the input is incomplete, or when the process receives a HUP, /* INT, QUIT or TERM signal, the queue file is deleted. /* ENVIRONMENT /* .ad /* .fi /* .IP MAIL_CONFIG /* Directory with the \fBmain.cf\fR file. In order to avoid exploitation /* of set-group ID privileges, a non-standard directory is allowed only /* if: /* .RS /* .IP \(bu /* The name is listed in the standard \fBmain.cf\fR file with the /* \fBalternate_config_directories\fR configuration parameter. /* .IP \(bu /* The command is invoked by the super-user. /* .RE /* CONFIGURATION PARAMETERS /* .ad /* .fi /* The following \fBmain.cf\fR parameters are especially relevant to /* this program. /* The text below provides only a parameter summary. See /* \fBpostconf\fR(5) for more details including examples. /* .IP "\fBalternate_config_directories (empty)\fR" /* A list of non-default Postfix configuration directories that may /* be specified with "-c config_directory" on the command line, or /* via the MAIL_CONFIG environment parameter. /* .IP "\fBconfig_directory (see 'postconf -d' output)\fR" /* The default location of the Postfix main.cf and master.cf /* configuration files. /* .IP "\fBimport_environment (see 'postconf -d' output)\fR" /* The list of environment parameters that a Postfix process will /* import from a non-Postfix parent process. /* .IP "\fBqueue_directory (see 'postconf -d' output)\fR" /* The location of the Postfix top-level queue directory. /* .IP "\fBsyslog_facility (mail)\fR" /* The syslog facility of Postfix logging. /* .IP "\fBsyslog_name (postfix)\fR" /* The mail system name that is prepended to the process name in syslog /* records, so that "smtpd" becomes, for example, "postfix/smtpd". /* .IP "\fBtrigger_timeout (10s)\fR" /* The time limit for sending a trigger to a Postfix daemon (for /* example, the \fBpickup\fR(8) or \fBqmgr\fR(8) daemon). /* .PP /* Available in Postfix version 2.2 and later: /* .IP "\fBauthorized_submit_users (static:anyone)\fR" /* List of users who are authorized to submit mail with the \fBsendmail\fR(1) /* command (and with the privileged \fBpostdrop\fR(1) helper command). /* FILES /* /var/spool/postfix/maildrop, maildrop queue /* SEE ALSO /* sendmail(1), compatibility interface /* postconf(5), configuration parameters /* syslogd(8), system logging /* LICENSE /* .ad /* .fi /* The Secure Mailer license must be distributed with this software. /* AUTHOR(S) /* Wietse Venema /* IBM T.J. Watson Research /* P.O. Box 704 /* Yorktown Heights, NY 10598, USA /*--*/ /* System library. */ #include <sys_defs.h> #include <sys/stat.h> #include <unistd.h> #include <stdlib.h> #include <stdio.h> /* remove() */ #include <string.h> #include <stdlib.h> #include <signal.h> #include <syslog.h> #include <errno.h> /* Utility library. */ #include <msg.h> #include <mymalloc.h> #include <vstream.h> #include <vstring.h> #include <msg_vstream.h> #include <msg_syslog.h> #include <argv.h> #include <iostuff.h> #include <stringops.h> /* Global library. */ #include <mail_proto.h> #include <mail_queue.h> #include <mail_params.h> #include <mail_version.h> #include <mail_conf.h> #include <mail_task.h> #include <clean_env.h> #include <mail_stream.h> #include <cleanup_user.h> #include <record.h> #include <rec_type.h> #include <user_acl.h> #include <rec_attr_map.h> /* Application-specific. */ /* * WARNING WARNING WARNING * * This software is designed to run set-gid. In order to avoid exploitation of * privilege, this software should not run any external commands, nor should * it take any information from the user unless that information can be * properly sanitized. To get an idea of how much information a process can * inherit from a potentially hostile user, examine all the members of the * process structure (typically, in /usr/include/sys/proc.h): the current * directory, open files, timers, signals, environment, command line, umask, * and so on. */ /* * Local mail submission access list. */ char *var_submit_acl; static const CONFIG_STR_TABLE str_table[] = { VAR_SUBMIT_ACL, DEF_SUBMIT_ACL, &var_submit_acl, 0, 0, 0, }; /* * Queue file name. Global, so that the cleanup routine can find it when * called by the run-time error handler. */ static char *postdrop_path; /* postdrop_sig - catch signal and clean up */ static void postdrop_sig(int sig) { /* * This is the fatal error handler. Don't try to do anything fancy. * * msg_vstream does not allocate memory, but msg_syslog may indirectly in * syslog(), so it should not be called from a user-triggered signal * handler. * * Assume atomic signal() updates, even when emulated with sigaction(). We * use the in-kernel SIGINT handler address as an atomic variable to * prevent nested postdrop_sig() calls. For this reason, main() must * configure postdrop_sig() as SIGINT handler before other signal * handlers are allowed to invoke postdrop_sig(). */ if (signal(SIGINT, SIG_IGN) != SIG_IGN) { (void) signal(SIGQUIT, SIG_IGN); (void) signal(SIGTERM, SIG_IGN); (void) signal(SIGHUP, SIG_IGN); if (postdrop_path) { (void) remove(postdrop_path); postdrop_path = 0; } /* Future proofing. If you need exit() here then you broke Postfix. */ if (sig) _exit(sig); } } /* postdrop_cleanup - callback for the runtime error handler */ static void postdrop_cleanup(void) { postdrop_sig(0); } MAIL_VERSION_STAMP_DECLARE; /* main - the main program */ int main(int argc, char **argv) { struct stat st; int fd; int c; VSTRING *buf; int status; MAIL_STREAM *dst; int rec_type; static char *segment_info[] = { REC_TYPE_POST_ENVELOPE, REC_TYPE_POST_CONTENT, REC_TYPE_POST_EXTRACT, "" }; char **expected; uid_t uid = getuid(); ARGV *import_env; const char *error_text; char *attr_name; char *attr_value; const char *errstr; char *junk; struct timeval start; int saved_errno; /* * Fingerprint executables and core dumps. */ MAIL_VERSION_STAMP_ALLOCATE; /* * Be consistent with file permissions. */ umask(022); /* * To minimize confusion, make sure that the standard file descriptors * are open before opening anything else. XXX Work around for 44BSD where * fstat can return EBADF on an open file descriptor. */ for (fd = 0; fd < 3; fd++) if (fstat(fd, &st) == -1 && (close(fd), open("/dev/null", O_RDWR, 0)) != fd) msg_fatal("open /dev/null: %m"); /* * Set up logging. Censor the process name: it is provided by the user. */ argv[0] = "postdrop"; msg_vstream_init(argv[0], VSTREAM_ERR); msg_syslog_init(mail_task("postdrop"), LOG_PID, LOG_FACILITY); set_mail_conf_str(VAR_PROCNAME, var_procname = mystrdup(argv[0])); /* * Parse JCL. This program is set-gid and must sanitize all command-line * arguments. The configuration directory argument is validated by the * mail configuration read routine. Don't do complex things until we have * completed initializations. */ while ((c = GETOPT(argc, argv, "c:rv")) > 0) { switch (c) { case 'c': if (setenv(CONF_ENV_PATH, optarg, 1) < 0) msg_fatal("out of memory"); break; case 'r': /* forward compatibility */ break; case 'v': if (geteuid() == 0) msg_verbose++; break; default: msg_fatal("usage: %s [-c config_dir] [-v]", argv[0]); } } /* * Read the global configuration file and extract configuration * information. Some claim that the user should supply the working * directory instead. That might be OK, given that this command needs * write permission in a subdirectory called "maildrop". However we still * need to reliably detect incomplete input, and so we must perform * record-level I/O. With that, we should also take the opportunity to * perform some sanity checks on the input. */ mail_conf_read(); if (strcmp(var_syslog_name, DEF_SYSLOG_NAME) != 0) msg_syslog_init(mail_task("postdrop"), LOG_PID, LOG_FACILITY); get_mail_conf_str_table(str_table); /* * Mail submission access control. Should this be in the user-land gate, * or in the daemon process? */ if ((errstr = check_user_acl_byuid(var_submit_acl, uid)) != 0) msg_fatal("User %s(%ld) is not allowed to submit mail", errstr, (long) uid); /* * Stop run-away process accidents by limiting the queue file size. This * is not a defense against DOS attack. */ if (var_message_limit > 0 && get_file_limit() > var_message_limit) set_file_limit((off_t) var_message_limit); /* * Strip the environment so we don't have to trust the C library. */ import_env = argv_split(var_import_environ, ", \t\r\n"); clean_env(import_env->argv); argv_free(import_env); if (chdir(var_queue_dir)) msg_fatal("chdir %s: %m", var_queue_dir); if (msg_verbose) msg_info("chdir %s", var_queue_dir); /* * Set up signal handlers and a runtime error handler so that we can * clean up incomplete output. * * postdrop_sig() uses the in-kernel SIGINT handler address as an atomic * variable to prevent nested postdrop_sig() calls. For this reason, the * SIGINT handler must be configured before other signal handlers are * allowed to invoke postdrop_sig(). */ signal(SIGPIPE, SIG_IGN); signal(SIGXFSZ, SIG_IGN); signal(SIGINT, postdrop_sig); signal(SIGQUIT, postdrop_sig); signal(SIGTERM, postdrop_sig); if (signal(SIGHUP, SIG_IGN) == SIG_DFL) signal(SIGHUP, postdrop_sig); msg_cleanup(postdrop_cleanup); /* End of initializations. */ /* * Don't trust the caller's time information. */ GETTIMEOFDAY(&start); /* * Create queue file. mail_stream_file() never fails. Send the queue ID * to the caller. Stash away a copy of the queue file name so we can * clean up in case of a fatal error or an interrupt. */ dst = mail_stream_file(MAIL_QUEUE_MAILDROP, MAIL_CLASS_PUBLIC, var_pickup_service, 0444); attr_print(VSTREAM_OUT, ATTR_FLAG_NONE, ATTR_TYPE_STR, MAIL_ATTR_QUEUEID, dst->id, ATTR_TYPE_END); vstream_fflush(VSTREAM_OUT); postdrop_path = mystrdup(VSTREAM_PATH(dst->stream)); /* * Copy stdin to file. The format is checked so that we can recognize * incomplete input and cancel the operation. With the sanity checks * applied here, the pickup daemon could skip format checks and pass a * file descriptor to the cleanup daemon. These are by no means all * sanity checks - the cleanup service and queue manager services will * reject messages that lack required information. * * If something goes wrong, slurp up the input before responding to the * client, otherwise the client will give up after detecting SIGPIPE. * * Allow attribute records if the attribute specifies the MIME body type * (sendmail -B). */ vstream_control(VSTREAM_IN, VSTREAM_CTL_PATH, "stdin", VSTREAM_CTL_END); buf = vstring_alloc(100); expected = segment_info; /* Override time information from the untrusted caller. */ rec_fprintf(dst->stream, REC_TYPE_TIME, REC_TYPE_TIME_FORMAT, REC_TYPE_TIME_ARG(start)); for (;;) { /* Don't allow PTR records. */ rec_type = rec_get_raw(VSTREAM_IN, buf, var_line_limit, REC_FLAG_NONE); if (rec_type == REC_TYPE_EOF) { /* request cancelled */ mail_stream_cleanup(dst); if (remove(postdrop_path)) msg_warn("uid=%ld: remove %s: %m", (long) uid, postdrop_path); else if (msg_verbose) msg_info("remove %s", postdrop_path); myfree(postdrop_path); postdrop_path = 0; exit(0); } if (rec_type == REC_TYPE_ERROR) msg_fatal("uid=%ld: malformed input", (long) uid); if (strchr(*expected, rec_type) == 0) msg_fatal("uid=%ld: unexpected record type: %d", (long) uid, rec_type); if (rec_type == **expected) expected++; /* Override time information from the untrusted caller. */ if (rec_type == REC_TYPE_TIME) continue; if (rec_type == REC_TYPE_ATTR) { if ((error_text = split_nameval(vstring_str(buf), &attr_name, &attr_value)) != 0) { msg_warn("uid=%ld: ignoring malformed record: %s: %.200s", (long) uid, error_text, vstring_str(buf)); continue; } #define STREQ(x,y) (strcmp(x,y) == 0) if ((STREQ(attr_name, MAIL_ATTR_ENCODING) && (STREQ(attr_value, MAIL_ATTR_ENC_7BIT) || STREQ(attr_value, MAIL_ATTR_ENC_8BIT) || STREQ(attr_value, MAIL_ATTR_ENC_NONE))) || STREQ(attr_name, MAIL_ATTR_DSN_ENVID) || STREQ(attr_name, MAIL_ATTR_DSN_NOTIFY) || rec_attr_map(attr_name) || (STREQ(attr_name, MAIL_ATTR_RWR_CONTEXT) && (STREQ(attr_value, MAIL_ATTR_RWR_LOCAL) || STREQ(attr_value, MAIL_ATTR_RWR_REMOTE))) || STREQ(attr_name, MAIL_ATTR_TRACE_FLAGS)) { /* XXX */ rec_fprintf(dst->stream, REC_TYPE_ATTR, "%s=%s", attr_name, attr_value); } else { msg_warn("uid=%ld: ignoring attribute record: %.200s=%.200s", (long) uid, attr_name, attr_value); } continue; } if (REC_PUT_BUF(dst->stream, rec_type, buf) < 0) { /* rec_get() errors must not clobber errno. */ saved_errno = errno; while ((rec_type = rec_get_raw(VSTREAM_IN, buf, var_line_limit, REC_FLAG_NONE)) != REC_TYPE_END && rec_type != REC_TYPE_EOF) if (rec_type == REC_TYPE_ERROR) msg_fatal("uid=%ld: malformed input", (long) uid); errno = saved_errno; break; } if (rec_type == REC_TYPE_END) break; } vstring_free(buf); /* * Finish the file. */ if ((status = mail_stream_finish(dst, (VSTRING *) 0)) != 0) { msg_warn("uid=%ld: %m", (long) uid); postdrop_cleanup(); } /* * Disable deletion on fatal error before reporting success, so the file * will not be deleted after we have taken responsibility for delivery. */ if (postdrop_path) { junk = postdrop_path; postdrop_path = 0; myfree(junk); } /* * Send the completion status to the caller and terminate. */ attr_print(VSTREAM_OUT, ATTR_FLAG_NONE, ATTR_TYPE_INT, MAIL_ATTR_STATUS, status, ATTR_TYPE_STR, MAIL_ATTR_WHY, "", ATTR_TYPE_END); vstream_fflush(VSTREAM_OUT); exit(status); }