[PATCH ipsec-next v5] xfrm: redact SA secret with lockdown confidentiality

[Steffen Klassert]

On Tue, Nov 17, 2020 at 05:47:23PM +0100, Antony Antony wrote:
> redact XFRM SA secret in the netlink response to xfrm_get_sa()
> or dumpall sa.
> Enable lockdown, confidentiality mode, at boot or at run time.
> 
> e.g. when enabled:
> cat /sys/kernel/security/lockdown
> none integrity [confidentiality]
> 
> ip xfrm state
> src 172.16.1.200 dst 172.16.1.100
> 	proto esp spi 0x00000002 reqid 2 mode tunnel
> 	replay-window 0
> 	aead rfc4106(gcm(aes)) 0x0000000000000000000000000000000000000000 96
> 
> note: the aead secret is redacted.
> Redacting secret is also a FIPS 140-2 requirement.
> 
> v1->v2
>  - add size checks before memset calls
> v2->v3
>  - replace spaces with tabs for consistency
> v3->v4
>  - use kernel lockdown instead of a /proc setting
> v4->v5
>  - remove kconfig option
> 
> Reviewed-by: Stephan Mueller <smueller at chronox.de>
> Signed-off-by: Antony Antony <antony.antony at secunet.com>
> ---
>  include/linux/security.h |  1 +
>  net/xfrm/xfrm_user.c     | 74 ++++++++++++++++++++++++++++++++++++----
>  security/security.c      |  1 +
>  3 files changed, 69 insertions(+), 7 deletions(-)

I'm ok with this and I plan to apply it to ipsec-next if I do not see
objections from the LSM people.