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| author | Daniel Axtens <dja@axtens.net> | 2019-06-11 11:54:31 +1000 |
|---|---|---|
| committer | Herbert Xu <herbert@gondor.apana.org.au> | 2019-06-20 14:18:33 +0800 |
| commit | f651bd96b20127d1ebc449f01aaaa79277f0574b (patch) | |
| tree | d0dd97b1b630a8424f814efa6f832ac0b0613ea9 | |
| parent | 334d37c9e26364511f0673ef155e2ad207316e90 (diff) | |
| download | linux-f651bd96b20127d1ebc449f01aaaa79277f0574b.tar.gz linux-f651bd96b20127d1ebc449f01aaaa79277f0574b.tar.bz2 linux-f651bd96b20127d1ebc449f01aaaa79277f0574b.zip | |
crypto: vmx - Document CTR mode counter width quirks
The CTR code comes from OpenSSL, where it does a 32-bit counter.
The kernel has a 128-bit counter. This difference has lead to
issues.
Document it.
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
| -rw-r--r-- | drivers/crypto/vmx/aesp8-ppc.pl | 22 |
1 files changed, 20 insertions, 2 deletions
diff --git a/drivers/crypto/vmx/aesp8-ppc.pl b/drivers/crypto/vmx/aesp8-ppc.pl index 9c6b5c1d6a1a..db874367b602 100644 --- a/drivers/crypto/vmx/aesp8-ppc.pl +++ b/drivers/crypto/vmx/aesp8-ppc.pl @@ -1286,6 +1286,24 @@ ___ ######################################################################### {{{ # CTR procedure[s] # + +####################### WARNING: Here be dragons! ####################### +# +# This code is written as 'ctr32', based on a 32-bit counter used +# upstream. The kernel does *not* use a 32-bit counter. The kernel uses +# a 128-bit counter. +# +# This leads to subtle changes from the upstream code: the counter +# is incremented with vaddu_q_m rather than vaddu_w_m. This occurs in +# both the bulk (8 blocks at a time) path, and in the individual block +# path. Be aware of this when doing updates. +# +# See: +# 1d4aa0b4c181 ("crypto: vmx - Fixing AES-CTR counter bug") +# 009b30ac7444 ("crypto: vmx - CTR: always increment IV as quadword") +# https://github.com/openssl/openssl/pull/8942 +# +######################################################################### my ($inp,$out,$len,$key,$ivp,$x10,$rounds,$idx)=map("r$_",(3..10)); my ($rndkey0,$rndkey1,$inout,$tmp)= map("v$_",(0..3)); my ($ivec,$inptail,$inpperm,$outhead,$outperm,$outmask,$keyperm,$one)= @@ -1357,7 +1375,7 @@ Loop_ctr32_enc: addi $idx,$idx,16 bdnz Loop_ctr32_enc - vadduqm $ivec,$ivec,$one + vadduqm $ivec,$ivec,$one # Kernel change for 128-bit vmr $dat,$inptail lvx $inptail,0,$inp addi $inp,$inp,16 @@ -1501,7 +1519,7 @@ Load_ctr32_enc_key: $SHL $len,$len,4 vadduqm $out1,$ivec,$one # counter values ... - vadduqm $out2,$ivec,$two + vadduqm $out2,$ivec,$two # (do all ctr adds as 128-bit) vxor $out0,$ivec,$rndkey0 # ... xored with rndkey[0] le?li $idx,8 vadduqm $out3,$out1,$two |