X-Git-Url: https://git.exim.org/users/heiko/exim.git/blobdiff_plain/f3908561b1eef15d57608ab6b346125bf2a11478..5d4da40d5b25b4f4029b46246c9757b42929bd87:/doc/doc-docbook/spec.xfpt?ds=inline diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt index 7d5b3b3cf..16d276ee8 100644 --- a/doc/doc-docbook/spec.xfpt +++ b/doc/doc-docbook/spec.xfpt @@ -11595,10 +11595,15 @@ preserve some of the authentication information in the variable user/password authenticator configuration might preserve the user name for use in the routers. Note that this is not the same information that is saved in &$sender_host_authenticated$&. + When a message is submitted locally (that is, not over a TCP connection) the value of &$authenticated_id$& is normally the login name of the calling process. However, a trusted user can override this by means of the &%-oMai%& command line option. +.new +This second case also sets up inforamtion used by the +&$authresults$& expansion item. +.wen .vitem &$authenticated_fail_id$& .cindex "authentication" "fail" "id" @@ -23936,6 +23941,24 @@ For testing purposes, this value can be overridden by the &%-oB%& command line option. +.new +.option dane_require_tls_ciphers smtp string&!! unset +.cindex "TLS" "requiring specific ciphers for DANE" +.cindex "cipher" "requiring specific" +.cindex DANE "TLS ciphers" +This option may be used to override &%tls_require_ciphers%& for connections +where DANE has been determined to be in effect. +If not set, then &%tls_require_ciphers%& will be used. +Normal SMTP delivery is not able to make strong demands of TLS cipher +configuration, because delivery will fall back to plaintext. Once DANE has +been determined to be in effect, there is no plaintext fallback and making the +TLS cipherlist configuration stronger will increase security, rather than +counter-intuitively decreasing it. +If the option expands to be empty or is forced to fail, then it will +be treated as unset and &%tls_require_ciphers%& will be used instead. +.wen + + .option data_timeout smtp time 5m This sets a timeout for the transmission of each block in the data portion of the message. As a result, the overall timeout for a message depends on the size @@ -28097,8 +28120,7 @@ that DNS lookups they do for the server have not been tampered with. The domain to this server, its A record, its TLSA record and any associated CNAME records must all be covered by DNSSEC. 2) add TLSA DNS records. These say what the server certificate for a TLS connection should be. -3) offer a server certificate, or certificate chain, in TLS connections which is traceable to the one -defined by (one of?) the TSLA records +3) offer a server certificate, or certificate chain, in TLS connections which is is anchored by one of the TLSA records. There are no changes to Exim specific to server-side operation of DANE. Support for client-side operation of DANE can be included at compile time by defining SUPPORT_DANE=yes @@ -28153,8 +28175,9 @@ This modification of hosts_request_ocsp is only done if it has the default value those who use &%hosts_require_ocsp%&, should consider the interaction with DANE in their OCSP settings. -For client-side DANE there are two new smtp transport options, &%hosts_try_dane%& and &%hosts_require_dane%&. -The latter variant will result in failure if the target host is not DNSSEC-secured. +For client-side DANE there are three new smtp transport options, &%hosts_try_dane%&, &%hosts_require_dane%& +and &%dane_require_tls_ciphers%&. +The require variant will result in failure if the target host is not DNSSEC-secured. DANE will only be usable if the target host has DNSSEC-secured MX, A and TLSA records. @@ -28163,6 +28186,14 @@ If a TLSA lookup is done and succeeds, a DANE-verified TLS connection will be required for the host. If it does not, the host will not be used; there is no fallback to non-DANE or non-TLS. +If DANE is requested and usable, then the TLS cipher list configuration +prefers to use the option &%dane_require_tls_ciphers%& and falls +back to &%tls_require_ciphers%& only if that is unset. +This lets you configure "decent crypto" for DANE and "better than nothing +crypto" as the default. Note though that while GnuTLS lets the string control +which versions of TLS/SSL will be negotiated, OpenSSL does not and you're +limited to ciphersuite constraints. + If DANE is requested and useable (see above) the following transport options are ignored: .code hosts_require_tls @@ -38939,6 +38970,7 @@ openssl rsa -in dkim_rsa.private -out /dev/stdout -pubout -outform PEM .endd Take the base-64 lines from the output of the second command, concatenated, for the DNS TXT record. +See section 3.6 of RFC6376 for the record specification. Under GnuTLS: .code @@ -38961,19 +38993,16 @@ for some transition period. The "_CRYPTO_SIGN_ED25519" macro will be defined if support is present for EC keys. -As of writing, producing EC key materials is not well supported -by the major libraries. OpenSSL 1.1.1 and GnuTLS 3.6.0 can create private keys: +OpenSSL 1.1.1 and GnuTLS 3.6.0 can create Ed25519 private keys: .code openssl genpkey -algorithm ed25519 -out dkim_ed25519.private certtool --generate-privkey --key-type=ed25519 --outfile=dkim_ed25519.private .endd -To help in producing the required public key value for a DNS record -the release package &_util/_& directory contains source for a utility -buildable with GnuTLS 3.6.0; -use it like this: +To produce the required public key value for a DNS record: .code -ed25519_privkey_pem_to_pubkey_raw_b64 dkim_ed25519.private +openssl pkey -outform DER -pubout -in dkim_ed25519.private | tail -c +13 | base64 +certtool --load_privkey=dkim_ed25519.private --pubkey_info --outder | tail -c +13 | base64 .endd .wen @@ -39346,18 +39375,11 @@ its domain as well. This should be treated like "none". .vitem &%permerror%& This indicates a syntax error in the SPF record of the queried domain. -You may deny messages when this occurs. (Changed in 4.83) +You may deny messages when this occurs. .vitem &%temperror%& This indicates a temporary error during all processing, including Exim's SPF processing. You may defer messages when this occurs. -(Changed in 4.83) - -.vitem &%err_temp%& -Same as permerror, deprecated in 4.83, will be removed in a future release. - -.vitem &%err_perm%& -Same as temperror, deprecated in 4.83, will be removed in a future release. .endlist You can prefix each string with an exclamation mark to invert