On 27-May-2023, at 7:43 PM, Simon Horman [off-list ref] wrote:

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On Sat, May 27, 2023 at 07:49:26AM +0000, Ashwin Dayanand Kamat wrote:

quoted

quoted

On 25-Mar-2023, at 12:03 PM, Ashwin Dayanand Kamat [off-list ref] wrote:

quoted

On 23-Mar-2023, at 2:16 AM, Simon Horman [off-list ref] wrote:

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On Wed, Mar 22, 2023 at 07:34:40PM +0530, Ashwin Dayanand Kamat wrote:

quoted

MD5 is not FIPS compliant. But still md5 was used as the default
algorithm for sctp if fips was enabled.
Due to this, listen() system call in ltp tests was failing for sctp
in fips environment, with below error message.

[ 6397.892677] sctp: failed to load transform for md5: -2

Fix is to not assign md5 as default algorithm for sctp
if fips_enabled is true. Instead make sha1 as default algorithm.

Fixes: ltp testcase failure "cve-2018-5803 sctp_big_chunk"
Signed-off-by: Ashwin Dayanand Kamat <redacted>
---
v2:
the listener can still fail if fips mode is enabled after
that the netns is initialized. So taking action in sctp_listen_start()
and buming a ratelimited notice the selected hmac is changed due to fips.
---
net/sctp/socket.c | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index b91616f819de..a1107f42869e 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c

@@ -49,6 +49,7 @@

#include <linux/poll.h>
#include <linux/init.h>
#include <linux/slab.h>
+#include <linux/fips.h>
#include <linux/file.h>
#include <linux/compat.h>
#include <linux/rhashtable.h>

@@ -8496,6 +8497,15 @@ static int sctp_listen_start(struct sock *sk, int backlog)

struct crypto_shash *tfm = NULL;
char alg[32];

+ if (fips_enabled && !strcmp(sp->sctp_hmac_alg, "md5")) {
+#if (IS_ENABLED(CONFIG_SCTP_DEFAULT_COOKIE_HMAC_SHA1))

I'm probably misunderstanding things, but would
IS_ENABLED(CONFIG_SCTP_COOKIE_HMAC_SHA1)
be more appropriate here?

Hi Simon,
I have moved the same check from sctp_init() to here based on the review for v1 patch.
Please let me know if there is any alternative which can be used?

Thanks,
Ashwin Kamat

Hi Team,
Any update on this?

Hi Ashwin,

I don't recall exactly what I was thinking 2 months ago.
But looking at this a second time it seems that I may have misread your
patch: I now have no objections to it in its original form.

Thanks Simon.
I have Updated the v3 patch with some minor changes.  Please review the same.

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