[PATCH 1/1] OvmfPkg/README: add HTTPS Boot

[Gary Lin <glin@suse.com>]

Add the new section for HTTPS Boot.

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>
---
 OvmfPkg/README | 50 ++++++++++++++++++++
 1 file changed, 50 insertions(+)

diff --git a/OvmfPkg/README b/OvmfPkg/README
index 00fb71848200..a84b6a30aaed 100644
--- a/OvmfPkg/README
+++ b/OvmfPkg/README
@@ -254,6 +254,56 @@ 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
+  the later enables TLS support in both NetworkPkg and CryptPkg.
+
+* 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=<sigdb>
+
+  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.
+
+* Bsides 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 is compirsed of 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. Of course, you can append your own list to
+  "openssl ciphers -V" in the script to limit the supported cipher suites.
+
+(*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://github.com/nmav/fedora-crypto-policies
+
 === OVMF Flash Layout ===
 
 Like all current IA32/X64 system designs, OVMF's firmware device (rom/flash)
-- 
2.16.3