DKIM: fix parsing of pubkey RR

Broken-since: 2658a023286f

diff --git a/doc/doc-txt/ChangeLog b/doc/doc-txt/ChangeLog
index 1c8e060c18ead559c1dbe75c12d77285f1e733ed..68632f5162776978aae4e8ceb53fbeb691fc3f43 100644 (file)
--- a/doc/doc-txt/ChangeLog
+++ b/doc/doc-txt/ChangeLog
@@ -59,6 +59,10 @@ JH/11 Lookups built as dynamic-load modules which support a single lookup
 JH/12 Bug 3112: Fix logging of config-file position for "obsolete lookup
       syntax". Previously, the end of the top-level file was reported.
 
+JH/13 Bug 3120: Fix parsing of DKIM pubkey DNS record. Previously a crafted
+      record could crash the meesage recieve process. Investigation by
+      Maxim Galaganov.
+
 Exim version 4.98
 -----------------
 

diff --git a/src/src/functions.h b/src/src/functions.h
index c9bb8cd700b27a592d305119b5588fa010de5ce7..57c4bb45cb638a6c06a816bfdd46381116303665 100644 (file)
--- a/src/src/functions.h
+++ b/src/src/functions.h
@@ -991,7 +991,7 @@ return g ? (unsigned)g->ptr : 0;
 static inline uschar
 gstring_last_char(gstring * g)
 {
-return g->s[g->ptr-1];
+return g ? g->s[g->ptr-1] : '\0';
 }
 
 static inline void

diff --git a/src/src/miscmods/pdkim/pdkim.c b/src/src/miscmods/pdkim/pdkim.c
index c60e0686b0b384d877460af48d042e0a40698602..9d240dac1a7a1a3c4276f64876cd3cb24bec16ad 100644 (file)
--- a/src/src/miscmods/pdkim/pdkim.c
+++ b/src/src/miscmods/pdkim/pdkim.c
@@ -649,7 +649,12 @@ for (const uschar * ele = raw_record, * tspec, * end, * val; *ele; ele = end)
       gstring * g = string_cat(NULL, val);
       while (isspace(gstring_last_char(g)))
        gstring_trim(g, 1);
-      val = string_from_gstring(g);
+      if (!(val = string_from_gstring(g)))
+       {
+       DEBUG(D_acl)
+         debug_printf(" Missing value for tag '%.*s'\n", taglen, tspec);
+       return NULL;
+       }
       }
 
     if (taglen == 1) switch (tspec[0])

diff --git a/test/dnszones-src/db.test.ex b/test/dnszones-src/db.test.ex
index d6de7aa6c21c798bf3555844cfe8536461ff7c75..cf5128a976460476389ea33a6c73ad11308364e1 100644 (file)
--- a/test/dnszones-src/db.test.ex
+++ b/test/dnszones-src/db.test.ex
@@ -603,6 +603,7 @@ DELAY=1500 delay1500 A HOSTIPV4
 ;
 ; Deliberate bad version, having extra backslashes
 ; sha256-hash-only version.... appears to be too long, gets truncated
+; Bad records, missing a value for the key
 ;
 ; Another, 512-bit (with a Notes field)
 ; 512 requiring sha1 hash
@@ -611,6 +612,8 @@ DELAY=1500 delay1500 A HOSTIPV4
 sel._domainkey TXT "v=DKIM1; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDXRFf+VhT+lCgFhhSkinZKcFNeRzjYdW8vT29Rbb3NadvTFwAd+cVLPFwZL8H5tUD/7JbUPqNTCPxmpgIL+V5T4tEZMorHatvvUM2qfcpQ45IfsZ+YdhbIiAslHCpy4xNxIR3zylgqRUF4+Dtsaqy3a5LhwMiKCLrnzhXk1F1hxwIDAQAB"
 sel_bad._domainkey TXT "v=DKIM1\; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDXRFf+VhT+lCgFhhSkinZKcFNeRzjYdW8vT29Rbb3NadvTFwAd+cVLPFwZL8H5tUD/7JbUPqNTCPxmpgIL+V5T4tEZMorHatvvUM2qfcpQ45IfsZ+YdhbIiAslHCpy4xNxIR3zylgqRUF4+Dtsaqy3a5LhwMiKCLrnzhXk1F1hxwIDAQAB"
 sel_sha256._domainkey TXT "v=DKIM1; h=sha256; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDXRFf+VhT+lCgFhhSkinZKcFNeRzjYdW8vT29Rbb3NadvTFwAd+cVLPFwZL8H5tUD/7JbUPqNTCPxmpgIL+V5T4tEZMorHatvvUM2qfcpQ45IfsZ+YdhbIiAslHCpy4xNxIR3zylgqRUF4+Dtsaqy3a5LhwMiKCLrnzhXk1F1hxwIDAQAB"
+sel_nullkey._domainkey TXT "v=DKIM1; p="
+sel_snullkey._domainkey TXT "v=DKIM1; p= "
 
 ses._domainkey TXT "v=DKIM1; n=halfkilo; p=MFwwDQYJKoZIhvcNAQEBBQADSwAwSAJBAL6eAQxd9didJ0/+05iDwJOqT6ly826Vi8aGPecsBiYK5/tAT97fxXk+dPWMZp9kQxtknEzYjYjAydzf+HQ2yJMCAwEAAQ=="
 ses_sha1._domainkey TXT "v=DKIM1; h=sha1; p=MFwwDQYJKoZIhvcNAQEBBQADSwAwSAJBAL6eAQxd9didJ0/+05iDwJOqT6ly826Vi8aGPecsBiYK5/tAT97fxXk+dPWMZp9kQxtknEzYjYjAydzf+HQ2yJMCAwEAAQ=="

diff --git a/test/log/4506 b/test/log/4506
index 00139412faba5e8a6abb95011cee2701d31e182c..4dea2f852e3050ff543fdb0f4c0451d7a06994c9 100644 (file)
--- a/test/log/4506
+++ b/test/log/4506
@@ -31,13 +31,26 @@
 1999-03-02 09:44:33 10HmbD-000000005vi-0000 Authentication-Results: myhost.test.ex
 1999-03-02 09:44:33 10HmbD-000000005vi-0000 dkim_state DOES NOT include pass
 1999-03-02 09:44:33 10HmbD-000000005vi-0000 <= CALLER@bloggs.com H=(xxx) [127.0.0.1] P=smtp S=sss id=20180418125440.Horde.vVKB6E7UvpLfJsPzv2ZPs6z@webmail.sego.es
-1999-03-02 09:44:33 exim x.yz daemon started: pid=p1235, no queue runs, listening for SMTP on port PORT_D
-1999-03-02 09:44:33 10HmbE-000000005vi-0000 unknown
+1999-03-02 09:44:33 10HmbE-000000005vi-0000 DKIM: d=test.ex s=sel_nullkey [failed key import]
+1999-03-02 09:44:33 10HmbE-000000005vi-0000 DKIM: validation error: error:068000E0:asn1 encoding routines::too small
 1999-03-02 09:44:33 10HmbE-000000005vi-0000 signer: test.ex bits: 0
-1999-03-02 09:44:33 10HmbE-000000005vi-0000 DKIM: d=test.ex s=sel c=simple/simple a=rsa-sha1 b=0 [invalid - signature tag missing or invalid]
-1999-03-02 09:44:33 10HmbE-000000005vi-0000 Authentication-Results: myhost.test.ex;\n  dkim=neutral (signature tag missing or invalid)\n                header.d=test.ex header.s=sel header.a=rsa-sha1
+1999-03-02 09:44:33 10HmbE-000000005vi-0000 DKIM: d=test.ex s=sel_nullkey c=simple/simple a=rsa-sha1 b=1024 [invalid - syntax error in public key record]
+1999-03-02 09:44:33 10HmbE-000000005vi-0000 Authentication-Results: myhost.test.ex;\n  dkim=neutral (public key record import problem)\n                header.d=test.ex header.s=sel_nullkey header.a=rsa-sha1
 1999-03-02 09:44:33 10HmbE-000000005vi-0000 dkim_state DOES NOT include pass
 1999-03-02 09:44:33 10HmbE-000000005vi-0000 <= CALLER@bloggs.com H=(xxx) [127.0.0.1] P=smtp S=sss id=qwerty1234@disco-zombie.net
+1999-03-02 09:44:33 10HmbF-000000005vi-0000 DKIM: d=test.ex s=sel_snullkey [failed key import]
+1999-03-02 09:44:33 10HmbF-000000005vi-0000 signer: test.ex bits: 0
+1999-03-02 09:44:33 10HmbF-000000005vi-0000 DKIM: d=test.ex s=sel_snullkey c=simple/simple a=rsa-sha1 b=1024 [invalid - syntax error in public key record]
+1999-03-02 09:44:33 10HmbF-000000005vi-0000 Authentication-Results: myhost.test.ex;\n  dkim=neutral (public key record import problem)\n                header.d=test.ex header.s=sel_snullkey header.a=rsa-sha1
+1999-03-02 09:44:33 10HmbF-000000005vi-0000 dkim_state DOES NOT include pass
+1999-03-02 09:44:33 10HmbF-000000005vi-0000 <= CALLER@bloggs.com H=(xxx) [127.0.0.1] P=smtp S=sss id=qwerty1234@disco-zombie.net
+1999-03-02 09:44:33 exim x.yz daemon started: pid=p1235, no queue runs, listening for SMTP on port PORT_D
+1999-03-02 09:44:33 10HmbG-000000005vi-0000 unknown
+1999-03-02 09:44:33 10HmbG-000000005vi-0000 signer: test.ex bits: 0
+1999-03-02 09:44:33 10HmbG-000000005vi-0000 DKIM: d=test.ex s=sel c=simple/simple a=rsa-sha1 b=0 [invalid - signature tag missing or invalid]
+1999-03-02 09:44:33 10HmbG-000000005vi-0000 Authentication-Results: myhost.test.ex;\n  dkim=neutral (signature tag missing or invalid)\n                header.d=test.ex header.s=sel header.a=rsa-sha1
+1999-03-02 09:44:33 10HmbG-000000005vi-0000 dkim_state DOES NOT include pass
+1999-03-02 09:44:33 10HmbG-000000005vi-0000 <= CALLER@bloggs.com H=(xxx) [127.0.0.1] P=smtp S=sss id=qwerty1234@disco-zombie.net
 1999-03-02 09:44:33 exim x.yz daemon started: pid=p1236, no queue runs, listening for SMTP on port PORT_D
 1999-03-02 09:44:33 10HmaX-000000005vi-0000 signer: test.ex bits: 0
 1999-03-02 09:44:33 10HmaX-000000005vi-0000 DKIM: d=test.ex s=sel c=simple/simple a=rsa-sha1 b=0 [invalid - signature tag missing or invalid]

diff --git a/test/scripts/4500-DKIM/4506 b/test/scripts/4500-DKIM/4506
index 0257511c4cca80f2ac99f5be9f51a20d247fee7a..89670d8ea70e8ef9b1386a1505eac6a216c2a075 100644 (file)
--- a/test/scripts/4500-DKIM/4506
+++ b/test/scripts/4500-DKIM/4506
@@ -6228,6 +6228,56 @@ Mavis Wanczyk
 
 Do You Need A Helping Hand?
 
+.
+??? 250
+QUIT
+??? 221
+****
+#
+#
+# These should fail verify (missing pubkey in DNS record)
+client 127.0.0.1 PORT_D
+??? 220
+HELO xxx
+??? 250
+MAIL FROM:<CALLER@bloggs.com>
+??? 250
+RCPT TO:<a@test.ex>
+??? 250
+DATA
+??? 354
+DKIM-Signature: v=1; a=rsa-sha1; c=simple/simple; d=test.ex; h=from:to
+        :date:message-id:subject; s=sel_nullkey; bh=OB9dZVu7+5/ufs3TH9leIcEpXSo=; b=
+        CoaRNB2Z59hSnhTzT8bYbMIN3P57XAVcFeV5oGEl4aKmhm6Mtu2uIc7B2z9k5+A/
+        +KFIE9HRj7eg9kPzagoPIvI84WE5PN5yRehMjJI6WqhM3V+bQDHkb8ubSmiaYxY5
+        B2Pd/kEGgHUlMDB0Hug4FMMt7GcFxagKspthOT/Pso0=
+From: mrgus@test.ex
+To: bakawolf@yahoo.com
+Date: Thu, 19 Nov 2015 17:00:07 -0700
+Message-ID: <qwerty1234@disco-zombie.net>
+Subject: simple test
+
+This is a simple test.
+.
+??? 250
+MAIL FROM:<CALLER@bloggs.com>
+??? 250
+RCPT TO:<a@test.ex>
+??? 250
+DATA
+??? 354
+DKIM-Signature: v=1; a=rsa-sha1; c=simple/simple; d=test.ex; h=from:to
+        :date:message-id:subject; s=sel_snullkey; bh=OB9dZVu7+5/ufs3TH9leIcEpXSo=; b=
+        CoaRNB2Z59hSnhTzT8bYbMIN3P57XAVcFeV5oGEl4aKmhm6Mtu2uIc7B2z9k5+A/
+        +KFIE9HRj7eg9kPzagoPIvI84WE5PN5yRehMjJI6WqhM3V+bQDHkb8ubSmiaYxY5
+        B2Pd/kEGgHUlMDB0Hug4FMMt7GcFxagKspthOT/Pso0=
+From: mrgus@test.ex
+To: bakawolf@yahoo.com
+Date: Thu, 19 Nov 2015 17:00:07 -0700
+Message-ID: <qwerty1234@disco-zombie.net>
+Subject: simple test
+
+This is a simple test.
 .
 ??? 250
 QUIT