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[2/2] crypto: make the sha1 library optional

Message ID 20220709211849.210850-3-ebiggers@kernel.org
State New
Headers show
Series crypto: make the sha1 library optional | expand

Commit Message

Eric Biggers July 9, 2022, 9:18 p.m. UTC 
From: Eric Biggers <ebiggers@google.com>

Since the Linux RNG no longer uses sha1_transform(), the SHA-1 library
is no longer needed unconditionally.  Make it possible to build the
Linux kernel without the SHA-1 library by putting it behind a kconfig
option, and selecting this new option from the kconfig options that gate
the remaining users: CRYPTO_SHA1 for crypto/sha1_generic.c, BPF for
kernel/bpf/core.c, and IPV6 for net/ipv6/addrconf.c.

Unfortunately, since BPF is selected by NET, for now this can only make
a difference for kernels built without networking support.

Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 crypto/Kconfig      | 1 +
 init/Kconfig        | 1 +
 lib/crypto/Kconfig  | 3 +++
 lib/crypto/Makefile | 3 ++-
 net/ipv6/Kconfig    | 1 +
 5 files changed, 8 insertions(+), 1 deletion(-)

Comments

Alexei Starovoitov July 15, 2022, 1:18 a.m. UTC | #1 
On Mon, Jul 11, 2022 at 11:22 AM Jakub Kicinski <kuba@kernel.org> wrote:
>
> On Sat,  9 Jul 2022 14:18:49 -0700 Eric Biggers wrote:
> > Since the Linux RNG no longer uses sha1_transform(), the SHA-1 library
> > is no longer needed unconditionally.  Make it possible to build the
> > Linux kernel without the SHA-1 library by putting it behind a kconfig
> > option, and selecting this new option from the kconfig options that gate
> > the remaining users: CRYPTO_SHA1 for crypto/sha1_generic.c, BPF for
> > kernel/bpf/core.c, and IPV6 for net/ipv6/addrconf.c.
> >
> > Unfortunately, since BPF is selected by NET, for now this can only make
> > a difference for kernels built without networking support.
>
> > diff --git a/init/Kconfig b/init/Kconfig
> > index c984afc489dead..d8d0b4bdfe4195 100644
> > --- a/init/Kconfig
> > +++ b/init/Kconfig
> > @@ -1472,6 +1472,7 @@ config HAVE_PCSPKR_PLATFORM
> >  # interpreter that classic socket filters depend on
> >  config BPF
> >       bool
> > +     select CRYPTO_LIB_SHA1
> >
>
> Let's give it an explicit CC: bpf@
>
> > diff --git a/net/ipv6/Kconfig b/net/ipv6/Kconfig
> > index bf2e5e5fe14273..658bfed1df8b17 100644
> > --- a/net/ipv6/Kconfig
> > +++ b/net/ipv6/Kconfig
> > @@ -7,6 +7,7 @@
> >  menuconfig IPV6
> >       tristate "The IPv6 protocol"
> >       default y
> > +     select CRYPTO_LIB_SHA1
> >       help
> >         Support for IP version 6 (IPv6).
>
> FWIW:
> Acked-by: Jakub Kicinski <kuba@kernel.org>

Acked-by: Alexei Starovoitov <ast@kernel.org>

I believe I found the right full patch set in lore.
In the future (if there are follow ups)
please cc the full patchset to us.
Thanks!
diff mbox series

Patch

diff --git a/crypto/Kconfig b/crypto/Kconfig
index 59489a300cd100..bf15ca5eb9d367 100644
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -880,6 +880,7 @@  config CRYPTO_RMD160
 config CRYPTO_SHA1
 	tristate "SHA1 digest algorithm"
 	select CRYPTO_HASH
+	select CRYPTO_LIB_SHA1
 	help
 	  SHA-1 secure hash standard (FIPS 180-1/DFIPS 180-2).
 
diff --git a/init/Kconfig b/init/Kconfig
index c984afc489dead..d8d0b4bdfe4195 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1472,6 +1472,7 @@  config HAVE_PCSPKR_PLATFORM
 # interpreter that classic socket filters depend on
 config BPF
 	bool
+	select CRYPTO_LIB_SHA1
 
 menuconfig EXPERT
 	bool "Configure standard kernel features (expert users)"
diff --git a/lib/crypto/Kconfig b/lib/crypto/Kconfig
index 2082af43d51fbe..9ff549f63540fa 100644
--- a/lib/crypto/Kconfig
+++ b/lib/crypto/Kconfig
@@ -121,6 +121,9 @@  config CRYPTO_LIB_CHACHA20POLY1305
 	select CRYPTO_LIB_POLY1305
 	select CRYPTO_ALGAPI
 
+config CRYPTO_LIB_SHA1
+	tristate
+
 config CRYPTO_LIB_SHA256
 	tristate
 
diff --git a/lib/crypto/Makefile b/lib/crypto/Makefile
index d28111ba54fcb2..919cbb2c220d61 100644
--- a/lib/crypto/Makefile
+++ b/lib/crypto/Makefile
@@ -34,7 +34,8 @@  libpoly1305-y					:= poly1305-donna32.o
 libpoly1305-$(CONFIG_ARCH_SUPPORTS_INT128)	:= poly1305-donna64.o
 libpoly1305-y					+= poly1305.o
 
-obj-y						+= sha1.o
+obj-$(CONFIG_CRYPTO_LIB_SHA1)			+= libsha1.o
+libsha1-y					:= sha1.o
 
 obj-$(CONFIG_CRYPTO_LIB_SHA256)			+= libsha256.o
 libsha256-y					:= sha256.o
diff --git a/net/ipv6/Kconfig b/net/ipv6/Kconfig
index bf2e5e5fe14273..658bfed1df8b17 100644
--- a/net/ipv6/Kconfig
+++ b/net/ipv6/Kconfig
@@ -7,6 +7,7 @@ 
 menuconfig IPV6
 	tristate "The IPv6 protocol"
 	default y
+	select CRYPTO_LIB_SHA1
 	help
 	  Support for IP version 6 (IPv6).