| Message ID | 20190702000132.88836-1-cfir@google.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Herbert Xu |
| Headers | show |
| Series | crypto: ccp/gcm - use const time tag comparison. | expand |
On Mon, Jul 01, 2019 at 05:01:32PM -0700, Cfir Cohen wrote: > Avoid leaking GCM tag through timing side channel. > > Signed-off-by: Cfir Cohen <cfir@google.com> > --- > drivers/crypto/ccp/ccp-ops.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/crypto/ccp/ccp-ops.c b/drivers/crypto/ccp/ccp-ops.c > index db8de89d990f..633670220f6c 100644 > --- a/drivers/crypto/ccp/ccp-ops.c > +++ b/drivers/crypto/ccp/ccp-ops.c > @@ -840,7 +840,8 @@ static int ccp_run_aes_gcm_cmd(struct ccp_cmd_queue *cmd_q, > if (ret) > goto e_tag; > > - ret = memcmp(tag.address, final_wa.address, AES_BLOCK_SIZE); > + ret = crypto_memneq(tag.address, final_wa.address, > + AES_BLOCK_SIZE) ? -EBADMSG : 0; > ccp_dm_free(&tag); > } > > -- > 2.22.0.410.gd8fdbe21b5-goog > Looks like this needs: Fixes: 36cf515b9bbe ("crypto: ccp - Enable support for AES GCM on v5 CCPs") Cc: <stable@vger.kernel.org> # v4.12+ - Eric
On 7/1/19 7:25 PM, Eric Biggers wrote: > On Mon, Jul 01, 2019 at 05:01:32PM -0700, Cfir Cohen wrote: >> Avoid leaking GCM tag through timing side channel. >> >> Signed-off-by: Cfir Cohen <cfir@google.com> >> --- >> drivers/crypto/ccp/ccp-ops.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/crypto/ccp/ccp-ops.c b/drivers/crypto/ccp/ccp-ops.c >> index db8de89d990f..633670220f6c 100644 >> --- a/drivers/crypto/ccp/ccp-ops.c >> +++ b/drivers/crypto/ccp/ccp-ops.c >> @@ -840,7 +840,8 @@ static int ccp_run_aes_gcm_cmd(struct ccp_cmd_queue *cmd_q, >> if (ret) >> goto e_tag; >> >> - ret = memcmp(tag.address, final_wa.address, AES_BLOCK_SIZE); >> + ret = crypto_memneq(tag.address, final_wa.address, >> + AES_BLOCK_SIZE) ? -EBADMSG : 0; >> ccp_dm_free(&tag); >> } >> >> -- >> 2.22.0.410.gd8fdbe21b5-goog >> > > Looks like this needs: > > Fixes: 36cf515b9bbe ("crypto: ccp - Enable support for AES GCM on v5 CCPs") > Cc: <stable@vger.kernel.org> # v4.12+ Yes, it does. For clarity, does that mean you've taken care of this?
On Tue, Jul 02, 2019 at 03:41:23PM +0000, Gary R Hook wrote: > On 7/1/19 7:25 PM, Eric Biggers wrote: > > On Mon, Jul 01, 2019 at 05:01:32PM -0700, Cfir Cohen wrote: > >> Avoid leaking GCM tag through timing side channel. > >> > >> Signed-off-by: Cfir Cohen <cfir@google.com> > >> --- > >> drivers/crypto/ccp/ccp-ops.c | 3 ++- > >> 1 file changed, 2 insertions(+), 1 deletion(-) > >> > >> diff --git a/drivers/crypto/ccp/ccp-ops.c b/drivers/crypto/ccp/ccp-ops.c > >> index db8de89d990f..633670220f6c 100644 > >> --- a/drivers/crypto/ccp/ccp-ops.c > >> +++ b/drivers/crypto/ccp/ccp-ops.c > >> @@ -840,7 +840,8 @@ static int ccp_run_aes_gcm_cmd(struct ccp_cmd_queue *cmd_q, > >> if (ret) > >> goto e_tag; > >> > >> - ret = memcmp(tag.address, final_wa.address, AES_BLOCK_SIZE); > >> + ret = crypto_memneq(tag.address, final_wa.address, > >> + AES_BLOCK_SIZE) ? -EBADMSG : 0; > >> ccp_dm_free(&tag); > >> } > >> > >> -- > >> 2.22.0.410.gd8fdbe21b5-goog > >> > > > > Looks like this needs: > > > > Fixes: 36cf515b9bbe ("crypto: ccp - Enable support for AES GCM on v5 CCPs") > > Cc: <stable@vger.kernel.org> # v4.12+ > > > Yes, it does. For clarity, does that mean you've taken care of this? > Herbert is the person who will apply this, so he'd need to do it. But it might be better just to resend. - Eric
diff --git a/drivers/crypto/ccp/ccp-ops.c b/drivers/crypto/ccp/ccp-ops.c index db8de89d990f..633670220f6c 100644 --- a/drivers/crypto/ccp/ccp-ops.c +++ b/drivers/crypto/ccp/ccp-ops.c @@ -840,7 +840,8 @@ static int ccp_run_aes_gcm_cmd(struct ccp_cmd_queue *cmd_q, if (ret) goto e_tag; - ret = memcmp(tag.address, final_wa.address, AES_BLOCK_SIZE); + ret = crypto_memneq(tag.address, final_wa.address, + AES_BLOCK_SIZE) ? -EBADMSG : 0; ccp_dm_free(&tag); }
Avoid leaking GCM tag through timing side channel. Signed-off-by: Cfir Cohen <cfir@google.com> --- drivers/crypto/ccp/ccp-ops.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)