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-rw-r--r--src/qmail-dksign.c511
1 files changed, 511 insertions, 0 deletions
diff --git a/src/qmail-dksign.c b/src/qmail-dksign.c
new file mode 100644
index 0000000..5135cd4
--- /dev/null
+++ b/src/qmail-dksign.c
@@ -0,0 +1,511 @@
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <unistd.h>
+#include "sig.h"
+#include "stralloc.h"
+#include "buffer.h"
+#include "error.h"
+#include "auto_qmail.h"
+#include "control.h"
+#include "str.h"
+#include "exit.h"
+#include "case.h"
+#include "constmap.h"
+#include "uint_t.h"
+#include "fd.h"
+#include "logmsg.h"
+#include "open.h"
+#include "fmt.h"
+#include "fmtqfn.h"
+#include "readwrite.h"
+#include "qmail.h"
+#include "wait.h"
+#include "pathexec.h"
+#include "rcpthosts.h"
+
+#define WHO "qmail-dksign"
+
+#define DOMAINKEYS "ssl/domainkeys/"
+
+/** @file qmail-dksign.c -- generate signature and attach in DKIM header to outgoing message
+
+ Steps:
+ ------
+ a) DKIM controls: get private key for sending domain
+ b) Prepare two staging files at queue/dkim (before and after signing)
+ c) Read input at fd0 and insert CR for every line and store at dkim/x/pre
+ d) DKIM sign the message with provided private key and store at dkim/y/post
+ e) Copy signed file from fd to 0
+ f) Invoke qmail-remote (respecting the \r\n)
+ g) Remove staging files (pre/post)
+
+ Hack for hybrid signatures:
+ ---------------------------
+
+ a) selector is a link to RSA private key
+ b) selector2 is a link to Ed25519 private key
+ c) Both are provided in the 'selector' field of dkimdomains separated by colon
+ d) The coupled selector information is provided to qmail-dkim as: -yselector ,-Yselector2
+ e) The RSA privat key is given unaltered
+ f) The Ed25519 private is supplied as additional argument
+ */
+
+char bufin[1000]; // RFC 5322: 998 chars - why?
+buffer bi = BUFFER_INIT(read,0,bufin,sizeof(bufin));
+char bufout[1000];
+buffer bo = BUFFER_INIT(write,1,bufout,sizeof(bufout));
+
+void die(int e) { _exit(e); }
+void die_write(char *fn) { unlink(fn); die(53); };
+void die_read() { die(54); };
+void out(char *s) { if (buffer_puts(&bo,s) == -1) _exit(111); }
+void zero() { if (buffer_put(&bo,"\0",1) == -1) _exit(111); }
+void zerodie() { zero(); buffer_flush(&bo); _exit(111); }
+
+stralloc fndkin = {0};
+stralloc fndkout = {0};
+
+stralloc sender = {0}; // will be re-written
+stralloc senddomain = {0};
+stralloc originator = {0};
+stralloc dkimdomains = {0};
+struct constmap mapdkimdomains;
+
+stralloc ecckey = {0};
+stralloc rsakey = {0};
+char *dkimparams = 0;
+
+void temp_nomem()
+{
+ out("ZOut of memory. (#4.3.0)\n");
+ zerodie();
+}
+void temp_chdir()
+{
+ out("ZUnable to switch to target directory. (#4.3.0)\n");
+ zerodie();
+}
+void temp_create()
+{
+ out("ZUnable to create DKIM stage file: ");
+ out(error_str(errno));
+ out(fndkin.s); out(". (#4.3.0)\n");
+ zerodie();
+}
+void temp_unlink()
+{
+ out("ZUnable to unlink DKIM stage file. (#4.3.0)\n");
+ zerodie();
+}
+void temp_control()
+{
+ out("ZUnable to read DKIM control files. (#4.3.0)\n");
+ zerodie();
+}
+void perm_usage()
+{
+ out("Zqmail-dksign was invoked improperly. (#5.3.5)\n");
+ zerodie();
+}
+void temp_read()
+{
+ out("DUnable to read message for DKIM signing. (#4.3.0)\n");
+ zerodie();
+}
+void temp_nosignkey()
+{
+ out("DCan't read sign key: ");
+ out(rsakey.s);
+ out(" or ");
+ out(ecckey.s);
+ out(". (#4.3.0)\n");
+ zerodie();
+}
+
+int get_controls()
+{
+ int i;
+ stralloc domname = {0};
+
+ if (control_init() == -1) temp_control();
+
+ switch (control_readfile(&dkimdomains,"control/dkimdomains",0)) {
+ case -1: return 0;
+ case 0: if (!constmap_init(&mapdkimdomains,"",0,1)) temp_nomem(); break;
+ case 1: if (!constmap_init(&mapdkimdomains,dkimdomains.s,dkimdomains.len,1)) temp_nomem(); break;
+ }
+
+/* Check for disabled DKIM send domains */
+
+ if (!stralloc_copys(&domname,"!")) temp_nomem();
+ if (!stralloc_cats(&domname,senddomain.s)) temp_nomem();
+ if (constmap(&mapdkimdomains,domname.s,domname.len)) return 0;
+
+/* Parenting domains; senddomain 0-terminated; lowercase */
+
+ for (i = 0; i <= senddomain.len; ++i) {
+ if ((i == 0) || (senddomain.s[i] == '.'))
+ if ((dkimparams = constmap(&mapdkimdomains,senddomain.s + i,senddomain.len - i - 1))) {
+ if (!stralloc_copys(&sender,senddomain.s + i)) temp_nomem();
+ if (!stralloc_0(&sender)) temp_nomem();
+ return 3;
+ }
+ }
+
+/* We sign only senddomains we take responsibility for: rcpthosts */
+
+ if ((dkimparams = constmap(&mapdkimdomains,"=",1))) {
+ if (rcpthosts_init() == -1) temp_control();
+ if (rcpthosts(originator.s,originator.len)) {
+ if ((control_readline(&sender,"control/defaultdomain") != 1))
+ if (control_readline(&sender,"control/me") == -1) temp_control();
+ if (!stralloc_0(&sender)) temp_nomem();
+ return 2;
+ }
+ }
+
+/* Default settings for MTA: 'defaultdomain' or even 'me' */
+
+ if ((dkimparams = constmap(&mapdkimdomains,"*",1))) {
+ if ((control_readline(&sender,"control/defaultdomain") != 1))
+ if (control_readline(&sender,"control/me") == -1) temp_control();
+ if (!stralloc_0(&sender)) temp_nomem();
+ return 1;
+ }
+
+ return 0;
+}
+
+void fnmake_dkim(unsigned long id)
+{
+ fndkin.len = fmtqfn(fndkin.s,"queue/dkim/",id,1);
+ id += id;
+ fndkout.len = fmtqfn(fndkout.s,"queue/dkim/",id,1);
+}
+
+void dkim_unlink()
+{
+ if (unlink(fndkin.s) == -1)
+ if (errno != ENOENT) temp_unlink();
+ if (unlink(fndkout.s) == -1)
+ if (errno != ENOENT) temp_unlink();
+}
+
+void dkim_stage()
+{
+ int r;
+ int fd;
+ char ch;
+ struct stat st;
+
+ if (!stralloc_ready(&fndkin,FMTQFN)) temp_nomem();
+ if (!stralloc_ready(&fndkout,FMTQFN)) temp_nomem();
+
+ fnmake_dkim(getpid()); // pre-staging
+ dkim_unlink(); // duplicate, left over file
+ fd = open_excl(fndkin.s);
+ if (fd == -1) die_write(fndkin.s);
+
+ buffer_init(&bi,read,0,bufin,sizeof(bufin));
+ buffer_init(&bo,write,fd,bufout,sizeof(bufout));
+
+ for (;;) {
+ r = buffer_get(&bi,&ch,1);
+ if (r == 0) break;
+ if (r == -1) temp_read();
+ if (ch == '\r') continue;
+
+ while (ch != '\n') {
+ buffer_put(&bo,&ch,1);
+ r = buffer_get(&bi,&ch,1);
+ if (r == -1) temp_read();
+ }
+ buffer_put(&bo,"\r\n",2);
+ }
+
+ if (buffer_flush(&bo) == -1) die(51);
+ if (fstat(fd,&st) == -1) die_read();
+ if (fsync(fd) == -1) die_write(fndkin.s);
+ if (close(fd) == -1) die_write(fndkin.s);
+}
+
+/* to construct DKIM information */
+
+stralloc selector = {0};
+stralloc selectore = {0};
+stralloc sdid = {0};
+stralloc auid = {0};
+stralloc expire = {0};
+stralloc canon = {0}; // -c r = relax, s = simple, t = relaxed/simple, u = simple/realxed
+stralloc hash = {0}; // -z 1/2/3/4/5 sha1/sha2/both/ed25519/ed25519+rsa-sha256
+stralloc length = {0}; // -l
+
+/**
+
+ qmail-dkim [-h|-v|-s] [tags] <msgfile> [<RSAkeyfile> <outfile> <Ed25519keyfile>]
+ --------------------------------------------------------------------------------
+ tags:
+ ----
+ -c<canonicalization> - r=relaxed [DEFAULT], s=simple, t=relaxed/simple, u=simple/relaxed
+ -d<sdid> - Signing Domain Identifier,if not provided it will be determined from the envelope originator/from header
+ -i<auid> - Agent User Identifier, usually the sender's email address (optional)
+ -l - include body length tag (optional)
+ -q - include query method tag
+ -t - include a timestamp tag (optional)
+ -x<expire_time> - the expire time in seconds since epoch (optional, DEFAULT = current time + 604800)
+ -y<selector> - set RSA selector (DEFAULT: default)
+ -Y<selector> - set Ed25519 selector (DEFAULT: default)
+ -z<hash> - set signature type (1=sha1, 2=sha256, 3=both, 4=ed25519, 5=hybrid)
+*/
+
+int dkim_sign(const char *rsakeyfile,const char *ecckeyfile,const char *fnin,const char *fnout)
+{
+ int child;
+ int wstat;
+ char *(args[17]);
+ int i = 0;
+
+ args[i] = "qmail-dkim"; ++i;
+ args[i] = "-s"; ++i;
+ args[i] = "-q"; ++i;
+ if (sdid.len > 3) { args[i] = sdid.s; ++i; }
+ if (selector.len > 3) { args[i] = selector.s; ++i; }
+ if (selectore.len > 3) { args[i] = selectore.s; ++i; }
+ if (auid.len > 3) { args[i] = auid.s; ++i; }
+ if (expire.len > 3) { args[i] = expire.s; ++i; }
+ if (canon.len > 2) { args[i] = canon.s; ++i; }
+ if (hash.len > 2) { args[i] = hash.s; ++i; }
+ if (length.len > 2) { args[i] = length.s; ++i; }
+ args[i] = fnin; ++i;
+ args[i] = rsakeyfile; ++i;
+ args[i] = fnout; ++i;
+ if (str_len(ecckeyfile) > 3) { args[i] = ecckeyfile; ++i; }
+ args[i] = 0;
+
+ if (!(child = vfork())) {
+ pathexec(args);
+ if (errno) _exit(111);
+ _exit(100);
+ }
+
+ wait_pid(&wstat,child);
+ if (wait_crashed(wstat)) return 1;
+
+ switch (wait_exitcode(wstat)) {
+ case 1: return 1;
+ default: return 0;
+ }
+}
+
+int qmail_remote(char **qargs,int fd)
+{
+ int child;
+ int wstat;
+ char *(args[5]);
+
+ args[0] = "qmail-remote";
+ args[1] = qargs[1];
+ args[2] = qargs[2];
+ args[3] = qargs[3];
+ args[4] = 0;
+
+ if (!(child = vfork())) {
+ if (fd) {
+ if (fd_move(0,fd) == -1) _exit(111);
+ if (fd_copy(2,1) == -1) _exit(111);
+ }
+ pathexec(args);
+ if (errno) _exit(111);
+ _exit(100);
+ }
+
+ wait_pid(&wstat,child);
+ if (wait_crashed(wstat)) return 1;
+
+ switch (wait_exitcode(wstat)) {
+ case 111: return 1;
+ default: return 0;
+ }
+}
+
+void dkim_setup()
+{
+ int c, i, j, k, l;
+ char *opt, *pos;
+
+ /* defaults: selector=default, IETF format, q=dns/txt, z=2, c=r */
+
+ if (!stralloc_copys(&sdid,"-d")) temp_nomem();
+ if (!stralloc_cat(&sdid,&sender)) temp_nomem();
+ if (!stralloc_0(&sdid)) temp_nomem();
+ if (!stralloc_copys(&selector,"-ydefault")) temp_nomem();
+ if (!stralloc_0(&selector)) temp_nomem();
+ if (!stralloc_copys(&selectore,"-Yeddy")) temp_nomem();
+ if (!stralloc_0(&selectore)) temp_nomem();
+ if (!stralloc_copys(&canon,"-cr")) temp_nomem();
+ if (!stralloc_0(&canon)) temp_nomem();
+ if (!stralloc_copys(&hash,"-z2")) temp_nomem();
+ if (!stralloc_0(&hash)) temp_nomem();
+
+ /* domain:selector,selectore|sdid|[auid|~]|expire|c:z:l; c=[r|s|t|u], z=[1,2,3,4,5], l=l */
+
+ if (dkimparams && *dkimparams) {
+ i = str_chr(dkimparams,'|');
+ pos = dkimparams + i;
+ if (*pos == '|' || *pos == '\0') { // selector
+ dkimparams[i] = '\0';
+ c = str_chr(dkimparams,','); // selectore=eddy
+ if (dkimparams[c] == ',') {
+ dkimparams[c] = '\0';
+ if (str_len(dkimparams + c + 1)) {
+ if (!stralloc_copys(&selectore,"-Y")) temp_nomem();
+ if (!stralloc_cats(&selectore,dkimparams + c + 1)) temp_nomem();
+ if (!stralloc_0(&selectore)) temp_nomem();
+ }
+ } else if (str_len(dkimparams)) { // selector=default
+ if (!stralloc_copys(&selector,"-y")) temp_nomem();
+ if (!stralloc_cats(&selector,dkimparams)) temp_nomem();
+ if (!stralloc_0(&selector)) temp_nomem();
+ }
+
+ j = str_chr(dkimparams + i + 1,'|');
+ pos = dkimparams + i + j + 1;
+ if (*pos == '|' || *pos == '\0') { // sdid; domain in DKIM header
+ dkimparams[i + j + 1] = '\0';
+ if (!stralloc_copys(&sdid,"-d")) temp_nomem();
+ if (!stralloc_cats(&sdid,dkimparams + i + 1)) temp_nomem();
+ if (!stralloc_0(&sdid)) temp_nomem();
+
+ k = str_chr(dkimparams + i + j + 2,'|');
+ pos = dkimparams + i + j + k + 2;
+ if (*pos == '|' || *pos == '\0') { // auid = identifier
+ dkimparams[i + j + k + 2] = '\0';
+ if (!stralloc_copys(&auid,"-i")) temp_nomem();
+ if (dkimparams[i + j + 2] == '~') {
+ if (!stralloc_cat(&auid,&originator)) temp_nomem();
+ } else
+ if (!stralloc_cats(&auid,dkimparams + i + j + 2)) temp_nomem();
+
+ if (!stralloc_0(&auid)) temp_nomem();
+
+ l = str_chr(dkimparams + i + j + k + 3,'|');
+ pos = dkimparams + i + j + k + l + 3;
+ if (*pos == '|' || *pos == '\0') { // expire after n secs
+ dkimparams[i + j + k + l + 3] = '\0';
+ if (!stralloc_copys(&expire,"-x")) temp_nomem();
+ if (!stralloc_cats(&expire,dkimparams + i + j + k + 3)) temp_nomem();
+ if (!stralloc_0(&expire)) temp_nomem();
+
+ /* Options to follow */
+
+ opt = dkimparams + i + j + k + l + 4;
+ if (*opt == '\0') return;
+ if (*opt != ':') {
+ if (!stralloc_copys(&canon,"-c")) temp_nomem(); // canonicalization
+ if (!stralloc_catb(&canon,opt,1)) temp_nomem();
+ if (!stralloc_0(&canon)) temp_nomem();
+ ++opt; if (*opt == '\0') return; // next colon
+ }
+ if (*opt != ':' || *opt == '\0') return;
+ if (*opt == ':') ++opt;
+ if (*opt != ':') {
+ if (!stralloc_copys(&hash,"-z")) temp_nomem(); // hash
+ if (!stralloc_catb(&hash,opt,1)) temp_nomem();
+ if (!stralloc_0(&hash)) temp_nomem();
+ ++opt; if (*opt == '\0') return; // next colon
+ }
+ if (*opt != ':' || *opt == '\0') return;
+ if (*opt == ':') ++opt;
+ if (*opt != ':' && *opt == 'l') {
+ if (!stralloc_copys(&length,"-l")) temp_nomem(); // length
+ if (!stralloc_0(&length)) temp_nomem();
+ }
+ }
+ }
+ }
+ }
+ }
+
+ return;
+}
+
+int main(int argc,char **args)
+{
+ int i;
+ int fdin = 0; // initial read from FD 0
+ int nkey = 0;
+ char *(qargs[4]);
+ struct stat st;
+
+ qargs[0] = args[0];
+ qargs[1] = args[1]; // host
+ qargs[2] = args[2]; // originator
+ qargs[3] = args[3]; // recipient
+
+ umask(033);
+ sig_pipeignore();
+ if (argc < 4) perm_usage();
+ if (chdir(auto_qmail) == -1) temp_chdir();
+
+ if (str_len(args[2]) > 2) {
+ i = str_chr(args[2],'@');
+ if (*(args[2] + i) == '@')
+ if (!stralloc_copys(&senddomain,args[2] + i + 1)) temp_nomem();
+ }
+ if (!stralloc_0(&senddomain)) temp_nomem();
+ if (!stralloc_copys(&originator,args[2])) temp_nomem();
+
+ if (!get_controls()) {
+ qmail_remote(qargs,fdin);
+ _exit(0);
+ }
+
+ dkim_setup(); // sender is evaluated from originator (senddomain)
+
+ /* Setup keys: they are composed from selector */
+
+ case_lowerb(sender.s,sender.len); // needs to be lowercase
+ if (!stralloc_copys(&rsakey,DOMAINKEYS)) temp_nomem();
+ if (!stralloc_cats(&rsakey,sender.s)) temp_nomem();
+ if (!stralloc_cats(&rsakey,"/")) temp_nomem();
+
+ if (!stralloc_copys(&ecckey,DOMAINKEYS)) temp_nomem();
+ if (!stralloc_cats(&ecckey,sender.s)) temp_nomem();
+ if (!stralloc_cats(&ecckey,"/")) temp_nomem();
+
+ /* RSA key common for SHA1 and SHA256: rsakeyfile -> selector */
+
+ if (!stralloc_cats(&rsakey,selector.s + 2)) temp_nomem(); // -y prepended
+ if (!stralloc_0(&rsakey)) temp_nomem();
+ if (stat(rsakey.s,&st) != -1)
+ if (open_read(rsakey.s) > 0) ++nkey;
+
+ /* ECC key follows: ecckeyfile -> (,)selector2 */
+
+ if (!stralloc_cats(&ecckey,selectore.s + 2)) temp_nomem(); // -Y prepended
+ if (!stralloc_0(&ecckey)) temp_nomem();
+ if (stat(ecckey.s,&st) != -1)
+ if (open_read(ecckey.s) > 0) ++nkey;
+
+ /* We got keys - go for staging */
+
+ if (nkey) { // otherwise no key exists; why bother
+ dkim_stage();
+ if (!dkim_sign(rsakey.s,ecckey.s,fndkin.s,fndkout.s)) {
+ fdin = open_read(fndkout.s);
+ if (fdin == -1) die_read();
+ } else {
+ fdin = open_read(fndkin.s); // DKIM key failed to sign
+ if (fdin == -1) die_read();
+ }
+ } else
+ temp_nosignkey();
+
+ qmail_remote(qargs,fdin); // closes fdin
+ if (nkey) dkim_unlink();
+
+ _exit(0);
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-22 08:11:13 +0000