From e2bf32dfabbfe6aabde4a0400b25b768b4481785 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= Date: Thu, 4 Mar 2021 18:14:26 +0000 Subject: [PATCH] docs: recommend SCRAM-SHA-256 SASL mech instead of SHA-1 variant MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The SHA-256 variant better meats modern security expectations. Also warn that the password file is storing entries in clear text. Reviewed-by: Marc-André Lureau Signed-off-by: Daniel P. Berrangé --- docs/system/vnc-security.rst | 7 ++++--- qemu.sasl | 11 ++++++----- 2 files changed, 10 insertions(+), 8 deletions(-) diff --git a/docs/system/vnc-security.rst b/docs/system/vnc-security.rst index 830f6acc73..4c1769eeb8 100644 --- a/docs/system/vnc-security.rst +++ b/docs/system/vnc-security.rst @@ -168,7 +168,7 @@ used is drastically reduced. In fact only the GSSAPI SASL mechanism provides an acceptable level of security by modern standards. Previous versions of QEMU referred to the DIGEST-MD5 mechanism, however, it has multiple serious flaws described in detail in RFC 6331 and thus should -never be used any more. The SCRAM-SHA-1 mechanism provides a simple +never be used any more. The SCRAM-SHA-256 mechanism provides a simple username/password auth facility similar to DIGEST-MD5, but does not support session encryption, so can only be used in combination with TLS. @@ -191,11 +191,12 @@ reasonable configuration is :: - mech_list: scram-sha-1 + mech_list: scram-sha-256 sasldb_path: /etc/qemu/passwd.db The ``saslpasswd2`` program can be used to populate the ``passwd.db`` -file with accounts. +file with accounts. Note that the ``passwd.db`` file stores passwords +in clear text. Other SASL configurations will be left as an exercise for the reader. Note that all mechanisms, except GSSAPI, should be combined with use of diff --git a/qemu.sasl b/qemu.sasl index fb8a92ba58..abdfc686be 100644 --- a/qemu.sasl +++ b/qemu.sasl @@ -19,15 +19,15 @@ mech_list: gssapi # If using TLS with VNC, or a UNIX socket only, it is possible to # enable plugins which don't provide session encryption. The -# 'scram-sha-1' plugin allows plain username/password authentication +# 'scram-sha-256' plugin allows plain username/password authentication # to be performed # -#mech_list: scram-sha-1 +#mech_list: scram-sha-256 # You can also list many mechanisms at once, and the VNC server will # negotiate which to use by considering the list enabled on the VNC # client. -#mech_list: scram-sha-1 gssapi +#mech_list: scram-sha-256 gssapi # Some older builds of MIT kerberos on Linux ignore this option & # instead need KRB5_KTNAME env var. @@ -38,7 +38,8 @@ mech_list: gssapi # mechanism this can be commented out. keytab: /etc/qemu/krb5.tab -# If using scram-sha-1 for username/passwds, then this is the file +# If using scram-sha-256 for username/passwds, then this is the file # containing the passwds. Use 'saslpasswd2 -a qemu [username]' -# to add entries, and 'sasldblistusers2 -f [sasldb_path]' to browse it +# to add entries, and 'sasldblistusers2 -f [sasldb_path]' to browse it. +# Note that this file stores passwords in clear text. #sasldb_path: /etc/qemu/passwd.db