diff --git a/OvmfPkg/README b/OvmfPkg/README index 3dd28474ea..70f0c41526 100644 --- a/OvmfPkg/README +++ b/OvmfPkg/README @@ -303,16 +303,27 @@ and encrypted connection. * Besides the trusted certificates, it's also possible to configure the trusted cipher suites for HTTPS through another fw_cfg entry: etc/edk2/https/ciphers. - -fw_cfg name=etc/edk2/https/ciphers,file= - OVMF expects a binary UINT16 array which comprises the cipher suites HEX IDs(*4). If the cipher suite list is given, OVMF will choose the cipher suite from the intersection of the given list and the built-in cipher suites. Otherwise, OVMF just chooses whatever proper cipher suites from the built-in ones. - While the tool(*5) to create the cipher suite array is still under - development, the array can be generated with the following script: + - Using QEMU 5.2 or later, QEMU can expose the ordered list of permitted TLS + cipher suites from the host side to OVMF: + + -object tls-cipher-suites,id=mysuite0,priority=@SYSTEM \ + -fw_cfg name=etc/edk2/https/ciphers,gen_id=mysuite0 + + (Refer to the QEMU manual and to + for more + information on the "priority" property.) + + - Using QEMU 5.1 or earlier, the array has to be passed from a file: + + -fw_cfg name=etc/edk2/https/ciphers,file= + + whose contents can be generated with the following script, for example: export LC_ALL=C openssl ciphers -V \ @@ -337,15 +348,10 @@ and encrypted connection. -e 's/^ *0x([0-9A-F]{2}),0x([0-9A-F]{2}) - .*$/\\\\x\1 \\\\x\2/p' \ | xargs -r -- printf -- '%b' > ciphers.bin -* In the future (after release 2.12), QEMU should populate both above fw_cfg - files automatically from the local host configuration, and enable the user - to override either with dedicated options or properties. - (*1) See "31.4.1 Signature Database" in UEFI specification 2.7 errata A. (*2) p11-kit: https://github.com/p11-glue/p11-kit/ (*3) efisiglist: https://github.com/rhboot/pesign/blob/master/src/efisiglist.c (*4) https://wiki.mozilla.org/Security/Server_Side_TLS#Cipher_names_correspondence_table -(*5) update-crypto-policies: https://gitlab.com/redhat-crypto/fedora-crypto-policies === OVMF Flash Layout ===