esp, ah: modernize the crypto algorithm selections

The crypto algorithms selected by the ESP and AH kconfig options are
out-of-date with the guidance of RFC 8221, which lists the legacy
algorithms MD5 and DES as "MUST NOT" be implemented, and some more
modern algorithms like AES-GCM and HMAC-SHA256 as "MUST" be implemented.
But the options select the legacy algorithms, not the modern ones.

Therefore, modify these options to select the MUST algorithms --
and *only* the MUST algorithms.

Also improve the help text.

Note that other algorithms may still be explicitly enabled in the
kconfig, and the choice of which to actually use is still controlled by
userspace.  This change only modifies the list of algorithms for which
kernel support is guaranteed to be present.

Suggested-by: Herbert Xu <herbert@gondor.apana.org.au>
Suggested-by: Steffen Klassert <steffen.klassert@secunet.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Corentin Labbe <clabbe@baylibre.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

diff --git a/net/ipv4/Kconfig b/net/ipv4/Kconfig
index 39a7a21744dc03bd61f102c38d261e70ff110405..dc9dfaef77e5a405e7ea1b29e0a1c2195ac117a4 100644 (file)
--- a/net/ipv4/Kconfig
+++ b/net/ipv4/Kconfig
@@ -342,7 +342,14 @@ config INET_AH
        tristate "IP: AH transformation"
        select XFRM_AH
        ---help---
-         Support for IPsec AH.
+         Support for IPsec AH (Authentication Header).
+
+         AH can be used with various authentication algorithms.  Besides
+         enabling AH support itself, this option enables the generic
+         implementations of the algorithms that RFC 8221 lists as MUST be
+         implemented.  If you need any other algorithms, you'll need to enable
+         them in the crypto API.  You should also enable accelerated
+         implementations of any needed algorithms when available.
 
          If unsure, say Y.
 
@@ -350,7 +357,14 @@ config INET_ESP
        tristate "IP: ESP transformation"
        select XFRM_ESP
        ---help---
-         Support for IPsec ESP.
+         Support for IPsec ESP (Encapsulating Security Payload).
+
+         ESP can be used with various encryption and authentication algorithms.
+         Besides enabling ESP support itself, this option enables the generic
+         implementations of the algorithms that RFC 8221 lists as MUST be
+         implemented.  If you need any other algorithms, you'll need to enable
+         them in the crypto API.  You should also enable accelerated
+         implementations of any needed algorithms when available.
 
          If unsure, say Y.
 

diff --git a/net/ipv6/Kconfig b/net/ipv6/Kconfig
index 70313f16319dd2f1d8ab05b1288fadff2769f42a..414a68b16869ec57683be8b65675d9c11ae24f81 100644 (file)
--- a/net/ipv6/Kconfig
+++ b/net/ipv6/Kconfig
@@ -51,7 +51,14 @@ config INET6_AH
        tristate "IPv6: AH transformation"
        select XFRM_AH
        ---help---
-         Support for IPsec AH.
+         Support for IPsec AH (Authentication Header).
+
+         AH can be used with various authentication algorithms.  Besides
+         enabling AH support itself, this option enables the generic
+         implementations of the algorithms that RFC 8221 lists as MUST be
+         implemented.  If you need any other algorithms, you'll need to enable
+         them in the crypto API.  You should also enable accelerated
+         implementations of any needed algorithms when available.
 
          If unsure, say Y.
 
@@ -59,7 +66,14 @@ config INET6_ESP
        tristate "IPv6: ESP transformation"
        select XFRM_ESP
        ---help---
-         Support for IPsec ESP.
+         Support for IPsec ESP (Encapsulating Security Payload).
+
+         ESP can be used with various encryption and authentication algorithms.
+         Besides enabling ESP support itself, this option enables the generic
+         implementations of the algorithms that RFC 8221 lists as MUST be
+         implemented.  If you need any other algorithms, you'll need to enable
+         them in the crypto API.  You should also enable accelerated
+         implementations of any needed algorithms when available.
 
          If unsure, say Y.
 

diff --git a/net/xfrm/Kconfig b/net/xfrm/Kconfig
index b2ff8df2c836ef92d2bfc30ed5752c911dddb237..e77ba529229cf511c8aacb813901758c67a07388 100644 (file)
--- a/net/xfrm/Kconfig
+++ b/net/xfrm/Kconfig
@@ -67,26 +67,29 @@ config XFRM_STATISTICS
 
          If unsure, say N.
 
+# This option selects XFRM_ALGO along with the AH authentication algorithms that
+# RFC 8221 lists as MUST be implemented.
 config XFRM_AH
        tristate
        select XFRM_ALGO
        select CRYPTO
        select CRYPTO_HMAC
-       select CRYPTO_MD5
-       select CRYPTO_SHA1
+       select CRYPTO_SHA256
 
+# This option selects XFRM_ALGO along with the ESP encryption and authentication
+# algorithms that RFC 8221 lists as MUST be implemented.
 config XFRM_ESP
        tristate
        select XFRM_ALGO
        select CRYPTO
+       select CRYPTO_AES
        select CRYPTO_AUTHENC
-       select CRYPTO_HMAC
-       select CRYPTO_MD5
        select CRYPTO_CBC
-       select CRYPTO_SHA1
-       select CRYPTO_DES
        select CRYPTO_ECHAINIV
+       select CRYPTO_GCM
+       select CRYPTO_HMAC
        select CRYPTO_SEQIV
+       select CRYPTO_SHA256
 
 config XFRM_IPCOMP
        tristate