This patch is intended to be applied on top of John Simpson's combined patch, see: http://qmail.jms1.net/patches/combined.shtml This patch adds support for signing and verifying emails with DKIM and DomainKeys. It requires the libdkim and libdomainkeys libraries be installed. To enable Dkim/DomainKeys, in addition to applying this patch, you must add -DDKIM to the first line of the conf-cc file. This patch does not make this change for you as it makes it much harder to combine patches. Installation instructions: % wget http://cr.yp.to/software/qmail-1.03.tar.gz % wget http://qmail.jms1.net/patches/qmail-1.03-jms1.7.08.patch % wget http://www.bltweb.net/qmail/qmail-1.03-jms1.7.08-dkim-r1.patch % tar xvzf qmail-1.03.tar.gz % mv qmail-1.03 qmail-1.03-jms1.7.08 % cd qmail-1.03-jms1.7.08 % patch < ../qmail-1.03-jms1.7.08.patch % patch -p1 < ../qmail-1.03-jms1.7.08-dkim-r1.patch % sed -ie '1s/$/ -DDKIM/' conf-cc More information is available at: http://www.brandonturner.net/blog/2009/03/dkim-and-domainkeys-for-qmail/ diff -Naur qmail-1.03.orig/Makefile qmail-1.03/Makefile --- qmail-1.03.orig/Makefile 2009-03-20 11:19:36.000000000 -0500 +++ qmail-1.03/Makefile 2009-03-20 11:19:50.000000000 -0500 @@ -1469,13 +1469,13 @@ timeoutconn.o tcpto.o now.o dns.o ip.o ipalloc.o strsalloc.o ipme.o quote.o \ ndelay.a case.a sig.a open.a lock.a seek.a getln.a stralloc.a alloc.a \ substdio.a error.a str.a fs.a auto_qmail.o base64.o qregex.o dns.lib \ -socket.lib +socket.lib env.a ./load qmail-remote control.o constmap.o timeoutread.o \ timeoutwrite.o timeoutconn.o tcpto.o now.o dns.o ip.o \ ipalloc.o strsalloc.o ipme.o quote.o ndelay.a case.a sig.a open.a \ lock.a seek.a getln.a stralloc.a alloc.a substdio.a error.a \ str.a fs.a auto_qmail.o base64.o qregex.o `cat dns.lib` \ - `cat socket.lib` -lssl -lcrypto + `cat socket.lib` -lssl -lcrypto env.a -ldkim -ldomainkeys qmail-remote.0: \ qmail-remote.8 @@ -1486,7 +1486,8 @@ subfd.h substdio.h scan.h case.h error.h auto_qmail.h control.h dns.h \ alloc.h quote.h ip.h ipalloc.h strsalloc.h ip.h gen_alloc.h ipme.h ip.h ipalloc.h strsalloc.h \ gen_alloc.h gen_allocdefs.h str.h now.h datetime.h exit.h constmap.h \ -tcpto.h readwrite.h timeoutconn.h timeoutread.h timeoutwrite.h +tcpto.h readwrite.h timeoutconn.h timeoutread.h timeoutwrite.h \ +env.h ./compile qmail-remote.c qmail-rspawn: \ @@ -1573,7 +1574,7 @@ fd.a wait.a datetime.a getln.a open.a sig.a case.a env.a stralloc.a \ alloc.a strerr.a substdio.a error.a str.a fs.a auto_qmail.o \ auto_break.o base64.o `cat socket.lib` `cat dns.lib` \ - -lssl -lcrypto -lcrypt + -lssl -lcrypto -lcrypt -ldkim -ldomainkeys qmail-smtpd.0: \ qmail-smtpd.8 diff -Naur qmail-1.03.orig/qmail-remote.8 qmail-1.03/qmail-remote.8 --- qmail-1.03.orig/qmail-remote.8 2009-03-20 11:19:36.000000000 -0500 +++ qmail-1.03/qmail-remote.8 2009-03-20 11:19:50.000000000 -0500 @@ -114,6 +114,17 @@ always exits zero. .SH "CONTROL FILES" .TP 5 +.I dksign +Path to the private key file(s) to use for performing DKIM and DomainKey +signing. If there is a % character in the environment variable, it is removed +and replaced by the domain name in the From: header, or the Sender: header if +it exists. If, after substituting the %, that file does not exist, each parent +domain in the From/Sender headers will be tried. If no domains match, +the message will not be signed. If there is no % and the file does not exist, +the message will not be sent and will remain in the queue. The selector will +be taken from the basename of the file. The private key should be created by +dknewkey, which comes with libdomainkey. +.TP 5 .I helohost Current host name, for use solely in saying hello to the remote SMTP server. diff -Naur qmail-1.03.orig/qmail-remote.c qmail-1.03/qmail-remote.c --- qmail-1.03.orig/qmail-remote.c 2009-03-20 11:19:36.000000000 -0500 +++ qmail-1.03/qmail-remote.c 2009-03-20 11:19:50.000000000 -0500 @@ -27,6 +27,11 @@ #include "readwrite.h" #include "timeoutconn.h" #include "qregex.h" +#ifdef DKIM +#include "env.h" +#include "dkim.h" +#include "domainkeys.h" +#endif #ifndef TLS #include "timeoutread.h" #include "timeoutwrite.h" @@ -88,6 +93,21 @@ Unable to switch to home directory. (#4.3.0)\n"); zerodie(); } void temp_control() { out("Z\ Unable to read control files. (#4.3.0)\n"); zerodie(); } +#ifdef DKIM +void temp_read_dkkey() { out("Z\ +Unable to read dkim key. (#4.3.0)\n"); zerodie(); } +void temp_find_dkkey() { out("Z\ +Unable to find dkim key. (#4.3.0)\n"); zerodie(); } +void temp_bad_dkkey() { out("Z\ +Bad dkim key. (#4.3.0)\n"); zerodie(); } +void temp_internal_bug() { out("Z\ +Internal bug (#4.3.0)\n"); zerodie(); } +void temp_cant_verify() { out("Z\ +Can't verify dk (#4.3.0)\n"); zerodie(); } +void temp_write() { out("ZUnable to write temp file (#4.3.0)\n"); zerodie(); } +void perm_dk_err() { out("D\ +Unknown dk error (#5.3.5)\n"); zerodie(); } +#endif void perm_partialline() { out("D\ SMTP cannot transfer messages with partial final lines. (#5.6.2)\n"); zerodie(); } void perm_usage() { out("D\ @@ -104,6 +124,79 @@ it isn't in my control/locals file, so I don't treat it as local. (#5.4.6)\n"); zerodie(); } + +#ifdef DKIM +#define DKLINELEN 64 +stralloc dksign = {0}; +char *pidfn; +int tempfdr; +int tempfdw; +char tempbuf[512]; + +void maybe_die_dk(e) DK_STAT e; { + switch(e) { + case DK_STAT_BADKEY: temp_bad_dkkey(); + case DK_STAT_CANTVRFY: temp_cant_verify(); + case DK_STAT_NORESOURCE: temp_nomem(); + case DK_STAT_ARGS: perm_dk_err(); + case DK_STAT_INTERNAL: temp_internal_bug(); + } +} +void maybe_die_dkim(e) int DKIM_CALL e; { + switch(e) { + case DKIM_OUT_OF_MEMORY: temp_nomem(); + case DKIM_INVALID_CONTEXT: perm_dk_err(); + case DKIM_NO_SENDER: perm_dk_err(); + case DKIM_BAD_PRIVATE_KEY: temp_bad_dkkey(); + case DKIM_BUFFER_TOO_SMALL: temp_nomem(); + } +} + +unsigned int pidfmt(s,seq) +char *s; +unsigned long seq; +{ + unsigned int i; + unsigned int len; + unsigned long mypid; + datetime_sec starttime; + + starttime = now(); + len = 0; + i = fmt_str(s,"/tmp/qmail-remote."); len += i; if (s) s += i; + i = fmt_ulong(s,mypid); len += i; if (s) s += i; + i = fmt_str(s,"."); len += i; if (s) s += i; + i = fmt_ulong(s,starttime); len += i; if (s) s += i; + i = fmt_str(s,"."); len += i; if (s) s += i; + i = fmt_ulong(s,seq); len += i; if (s) s += i; + ++len; if (s) *s++ = 0; + + return len; +} + +void pidopen() +{ + unsigned int len; + unsigned long seq; + + seq = 1; + len = pidfmt((char *) 0,seq); + pidfn = alloc(len); + if (!pidfn) temp_nomem(); + + for (seq = 1;seq < 10;++seq) + { + if (pidfmt((char *) 0,seq) > len) temp_internal_bug(); /* paranoia */ + pidfmt(pidfn,seq); + tempfdw = open_excl(pidfn); + if (tempfdw != -1) return; + } + + temp_oserr(); +} +#endif + + void outhost() { char x[IPFMT]; @@ -337,6 +430,194 @@ substdio_flush(&smtpto); } + +#ifdef DKIM +void blastdk() +{ + char *from; + char *selector; + char *sigptr; + int i; + int linelen; + time_t t; + char advice[2048]; + char szSignature[10024]; + stralloc dksig = {0}; + stralloc dkkeyfile = {0}; + stralloc dksignature = {0}; + substdio tempio; + DK_LIB *dklib; + DKIMContext dkim; + DK *dk; + int DKIM_CALL dkimst; + DKIMSignOptions dkimSOptions = {0}; + DK_STAT dkst; + + dklib = dk_init(0); + if (!dklib) temp_nomem(); + dk = dk_sign(dklib, &dkst, DK_CANON_NOFWS); + if (!dk) perm_dk_err(); + + pidopen(); + tempfdr = open_read(pidfn); + if (unlink(pidfn)==-1) temp_oserr(); + + substdio_fdbuf(&tempio,write,tempfdw,tempbuf,sizeof(tempbuf)); + for (;;) { + register int n; + register char *x; + + n = substdio_feed(&ssin); + if (n < 0) temp_read(); + if (!n) break; + x = substdio_PEEK(&ssin); + for(i=0; i= 500) quit("D"," failed on DATA command"); if (code >= 400) quit("Z"," failed on DATA command"); +#ifdef DKIM + if (dksign.s) + blastdk(); + else +#endif blast(); code = smtpcode(); flagcritical = 0; @@ -636,6 +922,11 @@ temp_control(); if(!stralloc_0(&tlsclientciphers)) temp_nomem(); #endif +#ifdef DKIM + if (control_readline(&dksign,"control/dksign") < 0) + temp_control(); + if(dksign.s) stralloc_0(&dksign); +#endif } void main(argc,argv) diff -Naur qmail-1.03.orig/qmail-smtpd.8 qmail-1.03/qmail-smtpd.8 --- qmail-1.03.orig/qmail-smtpd.8 2009-03-20 11:19:36.000000000 -0500 +++ qmail-1.03/qmail-smtpd.8 2009-03-20 11:19:50.000000000 -0500 @@ -428,11 +428,44 @@ .B TLS_SERVER_CERT variable points to) is not present or not readable. .TP 5 +.I DKVERIFY +Setting this variable will cause the message to be checked for DKIM and +DomainKeys signatures. The variable can be set to a desired set of letters +for DomainKeys and DKIM. Precisely, if you want a libdomainkey return status +to generate an error, include the letter, where A is the first return status +(DK_STAT_OK), B is the second (DK_STAT_BADSIG), etc. Similarly if you want a +libdkim return status to generate an error, include that letter, where A is the +first return status (DKIM_SUCCESS), B is the second (DKIM_FAIL), C is the third +(DKIM_BAD_SYNTAX), etc. The letter should be uppercase if you want a permanent +error to be returned, and lowercase if you want a temporary error to be +returned. The letter sets for libdomainkey and libdkim return codes should be +separated by a comma. + +For example, if you want to permanently reject messages that have a DomainKey +signature that has been revoked, include the letter 'J' in the +.B DKVERIFY +environment variable before the comma. To reject messages that have a DKIM +signature that has been revoked, include the letter 'I' in the DKVERIFY +environment variable after the comma + +A conservative set of letters is +.BR DEGIJKfh,CGHIJMQRkl . +Reject permanently DomainKey NOKEY, BADKEY, SYNTAX, ARGS, REVOKED, and INTERNAL +errors, and DKIM BAD_SYNTAX, SELECTOR_INVALID, SELECTOR_GRANULARITY_MISMATCH, +KEY_REVOKED, DOMAIN_TOO_LONG, KEY_INVALID, SELECTOR_ALGORITHM_MISMATCH, and +STAT_INCOMPAT errors. Reject temporarily DomainKey CANTVRFY and NORESOURCE and +DKIM DNS_TEMP_FAILURE and DNS_PERM_FAILURE. Add in B (BADSIG) before the comma +and DEFP (BAD, BAD_BUT_TESTING, EXPIRED, BODY_HASH_MISMATCH) after the comma if +you want to reject messages that have a signature that doesn't verify +(presumably because the message is a forgery or has been damaged in transit. +Note that qmail-smtpd always inserts the Authentication-Results header so that +messages can be rejected at delivery time, or in the mail reader. +.TP 5 .I DROP_PRE_GREET Many spammers will try to send commands to SMTP servers before the server has sent its inital greeting, even though this violates RFC 821. Setting this variable to a non-zero value will cause -.b qmail-smtpd +.B qmail-smtpd to pause for one second before sending the initial greeting, and drop any client connection which tries to send commands before the greeting has been sent. diff -Naur qmail-1.03.orig/qmail-smtpd.c qmail-1.03/qmail-smtpd.c --- qmail-1.03.orig/qmail-smtpd.c 2009-03-20 11:19:36.000000000 -0500 +++ qmail-1.03/qmail-smtpd.c 2009-03-20 11:20:49.000000000 -0500 @@ -35,6 +35,10 @@ #include "spf.h" #include "cdb.h" #include "auto_break.h" +#ifdef DKIM +#include "dkim.h" +#include "domainkeys.h" +#endif #define BMCHECK_BMF 0 #define BMCHECK_BMFNR 1 @@ -88,6 +92,16 @@ int log_rcpt = 0; unsigned long pw_expire = 0; char rcptcheck_err[1024]; +#ifdef DKIM +stralloc dkverify = {0}; +char *dkimverify = 0; +int put_dktemp = 0; +char *pidfn; +DK *dk; +DK_STAT dkst; +DKIMContext dkim; +#endif + #ifdef TLS unsigned int force_tls = 0; @@ -146,6 +160,12 @@ char ssoutbuf[512]; substdio ssout = SUBSTDIO_FDBUF(safewrite,1,ssoutbuf,sizeof ssoutbuf); +#ifdef DKIM +char tempbuf[512]; +int tempfdr; +int tempfdw; +substdio tempio; +#endif void flush() { substdio_flush(&ssout); } void out(s) char *s; { substdio_puts(&ssout,s); } @@ -202,6 +222,82 @@ void err_vrt() { out("553 sorry, this recipient is not in my validrcptto list (#5.7.1)\r\n"); } void die_vrt() { out("421 too many invalid addresses, goodbye (#4.3.0)\r\n"); flush(); _exit(1); } +#ifdef DKIM +void die_dk_err() { out("451 Unknown dk error (#4.3.0)\r\n"); flush(); _exit(1); } +void die_oserr() { out("421 System resources temporarily unavailable. (#4.3.0)\r\n"); flush(); _exit(1); } +void die_bad_dkkey() { out("451 Bad DomainKeys or DKIM key (#4.3.0)\r\n"); flush(); _exit(1); } +void die_cant_verify() { out("451 Can't verify DomainKeys or DKIM (#4.3.0)\r\n"); flush(); _exit(1); } +void die_dk_usage() { out("451 oops, problem with Domainkeys or DKIM args (#4.3.0)\r\n"); flush(); _exit(1); } +void die_temp_write() { out("421 Can't write temp buffer (#4.3.0)\r\n"); flush(); _exit(1); } + +void die_dk_reject() { out("554 DomainKeys permanently rejected message (#5.3.0)\r\n"); flush(); _exit(1); } +void die_dkim_reject() { out("554 DomainKeys Identified Mail (DKIM) permanently rejected message (#5.3.0)\r\n"); flush(); _exit(1); } +void die_dk_defer() { out("451 DomainKeys temporarily deferred message, please try again later (#4.3.0)\r\n"); flush(); _exit(1); } +void die_dkim_defer() { out("451 DomainKeys Identified Mail (DKIM) temporarily deferred message, please try again later (#4.3.0)\r\n"); flush(); _exit(1); } + +void maybe_die_dk(e) DK_STAT e; { + switch(e) { + case DK_STAT_BADKEY: die_bad_dkkey(); + case DK_STAT_CANTVRFY: die_cant_verify(); + case DK_STAT_NORESOURCE: die_nomem(); + case DK_STAT_ARGS: die_dk_usage(); + case DK_STAT_INTERNAL: die_dk_err(); + } +} +void maybe_die_dkim(e) int DKIM_CALL e; { + switch(e) { + case DKIM_OUT_OF_MEMORY: die_nomem(); + case DKIM_INVALID_CONTEXT: die_dk_usage(); + case DKIM_NO_SENDER: die_dk_usage(); + case DKIM_BAD_PRIVATE_KEY: die_bad_dkkey(); + case DKIM_BUFFER_TOO_SMALL: die_nomem(); + } +} + +unsigned int pidfmt(s,seq) +char *s; +unsigned long seq; +{ + unsigned int i; + unsigned int len; + unsigned long mypid; + datetime_sec starttime; + + starttime = now(); + len = 0; + i = fmt_str(s,"/tmp/qmail-smtpd."); len += i; if (s) s += i; + i = fmt_ulong(s,mypid); len += i; if (s) s += i; + i = fmt_str(s,"."); len += i; if (s) s += i; + i = fmt_ulong(s,starttime); len += i; if (s) s += i; + i = fmt_str(s,"."); len += i; if (s) s += i; + i = fmt_ulong(s,seq); len += i; if (s) s += i; + ++len; if (s) *s++ = 0; + + return len; +} + +void pidopen() +{ + unsigned int len; + unsigned long seq; + + seq = 1; + len = pidfmt((char *) 0,seq); + pidfn = alloc(len); + if (!pidfn) die_nomem(); + for (seq = 1;seq < 10;++seq) + { + if (pidfmt((char *) 0,seq) > len) die_oserr(); /* paranoia */ + pidfmt(pidfn,seq); + tempfdw = open_excl(pidfn); + if (tempfdw != -1) return; + } + + die_oserr(); +} + +#endif + stralloc greeting = {0}; stralloc spflocal = {0}; stralloc spfguess = {0}; @@ -330,6 +426,17 @@ if(x) { scan_ulong(x,&u); help_version = (int) u; } rcptcheck[0] = env_get("RCPTCHECK"); + +#ifdef DKIM + x = env_get("DKVERIFY"); + if(x) { + if(!stralloc_copys(&dkverify, x)) die_nomem(); + if(dkverify.s[str_chr(dkverify.s, ',')]) { + dkimverify = dkverify.s + str_chr(dkverify.s, ',') + 1; + dkverify.s[str_chr(dkverify.s, ',')] = '\0'; + } + } +#endif } int logregex = 0; @@ -1101,10 +1208,25 @@ void put(ch) char *ch; { +#ifdef DKIM + if(put_dktemp) { + if (substdio_put(&tempio,ch,1) == -1) die_temp_write(); + + if (*ch == '\n') DKIMVerifyProcess(&dkim, "\r\n", 2); + else DKIMVerifyProcess(&dkim, ch, 1); + + if (*ch == '\n') dkst = dk_message(dk, "\r\n", 2); + else dkst = dk_message(dk, ch, 1); + maybe_die_dk(dkst); + } else { +#endif if (bytestooverflow) if (!--bytestooverflow) qmail_fail(&qqt); qmail_put(&qqt,ch,1); +#ifdef DKIM + } +#endif } void blast(hops) @@ -1168,6 +1290,134 @@ } } +#ifdef DKIM +void blastdk(hops) +int *hops; +{ + int DKIM_CALL dkimst; + DKIMVerifyOptions dkimVOptions = {0}; + DKIMVerifyDetails *dkimVDetails; + int dkimVSigCount; + char dkimVPolicy[1024]; // See dkimverify.cpp Buffer + DK_LIB *dklib; + + if (dkverify.s && !relayclient) { + + dklib = dk_init(0); + if(!dklib) die_nomem(); + dk = dk_verify(dklib, &dkst); + if (!dk) die_dk_err(); + + dkimVOptions.nCheckPractices=1; + dkimst = DKIMVerifyInit(&dkim, &dkimVOptions); + maybe_die_dkim(dkimst); + + pidopen(); + tempfdr = open_read(pidfn); + if(unlink(pidfn) == -1) die_oserr(); + substdio_fdbuf(&tempio,write,tempfdw,tempbuf,sizeof(tempbuf)); + put_dktemp = 1; + } + + blast(hops); + + if (put_dktemp) { + int r; + char ch; + char *dkstatus = 0; + char *dkimstatus = 0; + char *dkreject = 0; + put_dktemp = 0; + + if (substdio_flush(&tempio) == -1) die_temp_write(); + close(tempfdw); + substdio_fdbuf(&tempio,read,tempfdr,ssinbuf,sizeof(ssinbuf)); + + dkst = dk_eom(dk, (void *)0); + maybe_die_dk(dkst); + dkimst = DKIMVerifyResults(&dkim); + + switch(dkst) { + case DK_STAT_OK: dkstatus = "pass (ok)"; break; + case DK_STAT_BADSIG: dkstatus = "fail (bad sig)"; break; + case DK_STAT_NOSIG: dkstatus = "none (no signature)"; break; + case DK_STAT_NOKEY: dkstatus = "fail (no key)"; break; + case DK_STAT_CANTVRFY: dkstatus = "temperror (can't verify)"; break; + case DK_STAT_BADKEY: dkstatus = "fail (bad key)"; break; + case DK_STAT_INTERNAL: dkstatus = "temperror (internal error)"; break; + case DK_STAT_ARGS: dkstatus = "neutral (args)"; break; + case DK_STAT_SYNTAX: dkstatus = "neutral (bad format)"; break; + case DK_STAT_NORESOURCE: dkstatus = "temperror (no resources)"; break; + case DK_STAT_REVOKED: dkstatus = "fail (revoked)"; break; + } + + if(dkimst==DKIM_SUCCESS || dkimst==DKIM_PARTIAL_SUCCESS) { + dkimstatus = "pass (ok)"; + } else { + int i; + dkimst = DKIMVerifyGetDetails(&dkim, &dkimVSigCount, &dkimVDetails, dkimVPolicy); + maybe_die_dkim(dkimst); + if (dkimVSigCount == 0) { + dkimst = DKIM_NO_SIGNATURES; + dkimstatus = "none (no signature)"; + } else { + for(i=0; i= MAXHOPS); if (hops) qmail_fail(&qqt); qmail_from(&qqt,mailfrom.s);