OvmfPkg/README: add HTTPS Boot

Add the new section for HTTPS Boot.

Changes in v2:
  - Fixed the typos
  - Added the command for p11-kit based on Laszlo's suggestion
  - Also added the efisiglist command
  - Elaborated how to create the customized cipher suite list
  - Mentioned the changes in QEMU in the future based on Laszlo's
    suggestion

Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Gary Lin <glin@suse.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
[lersek@redhat.com: trivial typo fixes; update-crypto-policies URL fix]

1 files changed, 88 insertions, 0 deletions

diff --git a/OvmfPkg/README b/OvmfPkg/README
index 00fb718482..7415419d2d 100644
--- a/OvmfPkg/README
+++ b/OvmfPkg/README
@@ -254,6 +254,94 @@ longer.)
     VirtioNetDxe         |                                        x

     Intel BootUtil (X64) |   x

 

+=== HTTPS Boot ===

+

+HTTPS Boot is an alternative solution to PXE. It replaces the tftp server

+with a HTTPS server so the firmware can download the images through a trusted

+and encrypted connection.

+

+* To enable HTTPS Boot, you have to build OVMF with -D HTTP_BOOT_ENABLE and

+  -D TLS_ENABLE. The former brings in the HTTP stack from NetworkPkg while

+  the latter enables TLS support in both NetworkPkg and CryptoPkg.

+

+* By default, there is no trusted certificate. The user has to import the

+  certificates either manually with "Tls Auth Configuration" utility in the

+  firmware UI or through the fw_cfg entry, etc/edk2/https/cacerts.

+

+  -fw_cfg name=etc/edk2/https/cacerts,file=<certdb>

+

+  The blob for etc/edk2/https/cacerts has to be in the format of Signature

+  Database(*1). You can use p11-kit(*2) or efisiglit(*3) to create the

+  certificate list.

+

+  If you want to create the certificate list based on the CA certificates

+  in your local host, p11-kit will be a good choice. Here is the command to

+  create the list:

+

+  p11-kit extract --format=edk2-cacerts --filter=ca-anchors \

+    --overwrite --purpose=server-auth <certdb>

+

+  If you only want to import one certificate, efisiglist is the tool for you:

+

+  efisiglist -a <cert file> -o <certdb>

+

+  Please note that the certificate has to be in the DER format.

+

+  You can also append a certificate to the existing list with the following

+  command:

+

+  efisiglist -i <old certdb> -a <cert file> -o <new certdb>

+

+  NOTE: You may need the patch to make efisiglist generate the correct header.

+  (https://github.com/rhboot/pesign/pull/40)

+

+* 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=<cipher suites>

+

+  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:

+

+  export LC_ALL=C

+  openssl ciphers -V \

+  | sed -r -n \

+     -e 's/^ *0x([0-9A-F]{2}),0x([0-9A-F]{2}) - .*$/\\\\x\1 \\\\x\2/p' \

+  | xargs -r -- printf -- '%b' > ciphers.bin

+

+  This script creates ciphers.bin that contains all the cipher suite IDs

+  supported by openssl according to the local host configuration.

+

+  You may want to enable only a limited set of cipher suites. Then, you

+  should check the validity of your list first:

+

+  openssl ciphers -V <cipher list>

+

+  If all the cipher suites in your list map to the proper HEX IDs, go ahead

+  to modify the script and execute it:

+

+  export LC_ALL=C

+  openssl ciphers -V <cipher list> \

+  | sed -r -n \

+     -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 ===

 

 Like all current IA32/X64 system designs, OVMF's firmware device (rom/flash)