summaryrefslogtreecommitdiffstats
path: root/src/postdrop/postdrop.c
diff options
context:
space:
mode:
Diffstat (limited to 'src/postdrop/postdrop.c')
-rw-r--r--src/postdrop/postdrop.c530
1 files changed, 530 insertions, 0 deletions
diff --git a/src/postdrop/postdrop.c b/src/postdrop/postdrop.c
new file mode 100644
index 0000000..5e35d1d
--- /dev/null
+++ b/src/postdrop/postdrop.c
@@ -0,0 +1,530 @@
+/*++
+/* 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) or \fBpostlogd\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 (in the
+/* case of \fBsendmail\fR(1), with the "-C" option), 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 privileged Postfix
+/* process will import from a non-Postfix parent process, or name=value
+/* environment overrides.
+/* .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 (see 'postconf -d' output)\fR"
+/* A prefix that is prepended to the process name in syslog
+/* records, so that, for example, "smtpd" becomes "prefix/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
+/* postlogd(8), Postfix logging
+/* 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
+/*
+/* Wietse Venema
+/* Google, Inc.
+/* 111 8th Avenue
+/* New York, NY 10011, 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 <errno.h>
+#include <warn_stat.h>
+
+/* Utility library. */
+
+#include <msg.h>
+#include <mymalloc.h>
+#include <vstream.h>
+#include <vstring.h>
+#include <msg_vstream.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 <mail_dict.h>
+#include <user_acl.h>
+#include <rec_attr_map.h>
+#include <mail_parm_split.h>
+#include <maillog_client.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.
+ *
+ * To avoid privilege escalation in a set-gid program, Postfix logging
+ * functions must not be called from a user-triggered signal handler,
+ * because Postfix logging functions may allocate memory on the fly (as
+ * does the syslog() library function), and the memory allocator is not
+ * reentrant.
+ *
+ * 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;
+ int from_count = 0;
+ int rcpt_count = 0;
+ int validate_input = 1;
+
+ /*
+ * 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);
+ maillog_client_init(mail_task("postdrop"), MAILLOG_CLIENT_FLAG_NONE);
+ set_mail_conf_str(VAR_PROCNAME, var_procname = mystrdup(argv[0]));
+
+ /*
+ * Check the Postfix library version as soon as we enable logging.
+ */
+ MAIL_VERSION_CHECK;
+
+ /*
+ * 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.
+ */
+ mail_conf_read();
+ /* Re-evaluate mail_task() after reading main.cf. */
+ maillog_client_init(mail_task("postdrop"), MAILLOG_CLIENT_FLAG_NONE);
+ get_mail_conf_str_table(str_table);
+
+ /*
+ * Mail submission access control. Should this be in the user-land gate,
+ * or in the daemon process?
+ */
+ mail_dict_init();
+ if ((errstr = check_user_acl_byuid(VAR_SUBMIT_ACL, 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);
+
+ /*
+ * This program is installed with setgid privileges. Strip the process
+ * environment so that we don't have to trust the C library.
+ */
+ import_env = mail_parm_split(VAR_IMPORT_ENVIRON, var_import_environ);
+ 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);
+ if (signal(SIGTERM, SIG_IGN) == SIG_DFL)
+ 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,
+ SEND_ATTR_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, CA_VSTREAM_CTL_PATH("stdin"), CA_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;
+ /* Check these at submission time instead of pickup time. */
+ if (rec_type == REC_TYPE_FROM)
+ from_count++;
+ if (rec_type == REC_TYPE_RCPT)
+ rcpt_count++;
+ /* Limit the attribute types that users may specify. */
+ 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);
+ validate_input = 0;
+ errno = saved_errno;
+ break;
+ }
+ if (rec_type == REC_TYPE_END)
+ break;
+ }
+ vstring_free(buf);
+
+ /*
+ * As of Postfix 2.7 the pickup daemon discards mail without recipients.
+ * Such mail may enter the maildrop queue when "postsuper -r" is invoked
+ * before the queue manager deletes an already delivered message. Looking
+ * at file ownership is not a good way to make decisions on what mail to
+ * discard. Instead, the pickup server now requires that new submissions
+ * always have at least one recipient record.
+ *
+ * The Postfix sendmail command already rejects mail without recipients.
+ * However, in the future postdrop may receive mail via other programs,
+ * so we add a redundant recipient check here for future proofing.
+ *
+ * The test for the sender address is just for consistency of error
+ * reporting (report at submission time instead of pickup time). Besides
+ * the segment terminator records, there aren't any other mandatory
+ * records in a Postfix submission queue file.
+ */
+ if (validate_input && (from_count == 0 || rcpt_count == 0)) {
+ status = CLEANUP_STAT_BAD;
+ mail_stream_cleanup(dst);
+ }
+
+ /*
+ * Finish the file.
+ */
+ else 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,
+ SEND_ATTR_INT(MAIL_ATTR_STATUS, status),
+ SEND_ATTR_STR(MAIL_ATTR_WHY, ""),
+ ATTR_TYPE_END);
+ vstream_fflush(VSTREAM_OUT);
+ exit(status);
+}