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Re: [PATCH 2 of 8] QUIC: added check to prevent packet output with discarded keys

Roman Arutyunyan
September 18, 2023 03:10AM
Hi,

On Thu, Sep 07, 2023 at 07:13:54PM +0400, Sergey Kandaurov wrote:
> # HG changeset patch
> # User Sergey Kandaurov <pluknet@nginx.com>
> # Date 1694041352 -14400
> # Thu Sep 07 03:02:32 2023 +0400
> # Node ID 02c86eac80c907adb7790c79ac6892afabcee5f4
> # Parent be1862a28fd8575a88475215ccfce995e392dfab
> QUIC: added check to prevent packet output with discarded keys.
>
> In addition to triggering alert, it ensures that such packets won't be sent.
>
> With the previous change that marks server keys as discarded by zeroing the
> key lengh, it is now an error to send packets with discarded keys. OpenSSL
> based stacks tolerate such behaviour because key length isn't used in packet
> protection, but BoringSSL will raise the UNSUPPORTED_KEY_SIZE cipher error.
> It won't be possible to use discarded keys with reused crypto contexts.
>
> diff --git a/src/event/quic/ngx_event_quic_output.c b/src/event/quic/ngx_event_quic_output.c
> --- a/src/event/quic/ngx_event_quic_output.c
> +++ b/src/event/quic/ngx_event_quic_output.c
> @@ -519,6 +519,21 @@ ngx_quic_output_packet(ngx_connection_t
>
> qc = ngx_quic_get_connection(c);
>
> + if (!ngx_quic_keys_available(qc->keys, ctx->level, 1)) {
> + ngx_log_error(NGX_LOG_ALERT, c->log, 0, "quic %s write keys discarded",
> + ngx_quic_level_name(ctx->level));
> +
> + while (!ngx_queue_empty(&ctx->frames)) {
> + q = ngx_queue_head(&ctx->frames);
> + ngx_queue_remove(q);
> +
> + f = ngx_queue_data(q, ngx_quic_frame_t, queue);
> + ngx_quic_free_frame(c, f);
> + }
> +
> + return 0;
> + }
> +
> ngx_quic_init_packet(c, ctx, &pkt, qc->path);
>
> min_payload = ngx_quic_payload_size(&pkt, min);
> _______________________________________________
> nginx-devel mailing list
> nginx-devel@nginx.org
> https://mailman.nginx.org/mailman/listinfo/nginx-devel

In ngx_quic_create_datagrams(), before calling ngx_quic_output_packet(),
ngx_quic_generate_ack() generates ACK frames for the current level.
Maybe it's better to add this block before generating ACKs? Otherwise we
generate an ACK and then immediately remove it. This technically would require
a similar block in ngx_quic_create_segments(), although the application level
should normally never be in a discarded key situation.

It's true however that the next patch partially solves the issue by not
generating the last handshake ACK. That however does not seem to be a complete
solution since there could be previous ACKs. In my opinion, this patch
provides a better and more general solution than the next one.

--
Roman Arutyunyan
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Subject Author Views Posted

[PATCH 0 of 8] [quic] reusing crypto contexts, and more

Sergey Kandaurov 471 September 07, 2023 11:18AM

[PATCH 1 of 8] QUIC: split keys availability checks to read and write sides

Sergey Kandaurov 82 September 07, 2023 11:18AM

Re: [PATCH 1 of 8] QUIC: split keys availability checks to read and write sides

Roman Arutyunyan 81 September 21, 2023 09:30AM

[PATCH 2 of 8] QUIC: added check to prevent packet output with discarded keys

Sergey Kandaurov 76 September 07, 2023 11:18AM

Re: [PATCH 2 of 8] QUIC: added check to prevent packet output with discarded keys

Roman Arutyunyan 84 September 18, 2023 03:10AM

Re: [PATCH 2 of 8] QUIC: added check to prevent packet output with discarded keys

Sergey Kandaurov 94 October 13, 2023 11:10AM

[PATCH 3 of 8] QUIC: prevented output of ACK frame when discarding handshake keys

Sergey Kandaurov 76 September 07, 2023 11:18AM

[PATCH 4 of 8] QUIC: renamed protection functions

Sergey Kandaurov 74 September 07, 2023 11:18AM

Re: [PATCH 4 of 8] QUIC: renamed protection functions

Roman Arutyunyan 83 September 21, 2023 09:32AM

[PATCH 5 of 8] QUIC: reusing crypto contexts for packet protection

Sergey Kandaurov 80 September 07, 2023 11:18AM

Re: [PATCH 5 of 8] QUIC: reusing crypto contexts for packet protection

Roman Arutyunyan 93 September 19, 2023 09:54AM

Re: [PATCH 5 of 8] QUIC: reusing crypto contexts for packet protection

Sergey Kandaurov 77 October 13, 2023 11:14AM

Re: [PATCH 5 of 8] QUIC: reusing crypto contexts for packet protection

Sergey Kandaurov 75 October 17, 2023 06:40AM

Re: [PATCH 5 of 8] QUIC: reusing crypto contexts for packet protection

Sergey Kandaurov 93 October 23, 2023 06:38PM

[PATCH 6 of 8] QUIC: reusing crypto contexts for header protection

Sergey Kandaurov 76 September 07, 2023 11:18AM

Re: [PATCH 6 of 8] QUIC: reusing crypto contexts for header protection

Roman Arutyunyan 74 September 20, 2023 08:14AM

Re: [PATCH 6 of 8] QUIC: reusing crypto contexts for header protection

Sergey Kandaurov 71 October 13, 2023 11:14AM

[PATCH 7 of 8] QUIC: cleaned up now unused ngx_quic_ciphers() calls

Sergey Kandaurov 80 September 07, 2023 11:18AM

Re: [PATCH 7 of 8] QUIC: cleaned up now unused ngx_quic_ciphers() calls

Roman Arutyunyan 90 September 20, 2023 08:28AM

Re: [PATCH 7 of 8] QUIC: cleaned up now unused ngx_quic_ciphers() calls

Sergey Kandaurov 83 October 13, 2023 11:16AM

[PATCH 8 of 8] QUIC: explicitly zero out unused keying material

Sergey Kandaurov 74 September 07, 2023 11:18AM

Re: [PATCH 8 of 8] QUIC: explicitly zero out unused keying material

Roman Arutyunyan 78 September 21, 2023 09:30AM

Re: [PATCH 8 of 8] QUIC: explicitly zero out unused keying material

Sergey Kandaurov 70 October 13, 2023 11:16AM

[PATCH 00 of 11] [quic] reusing crypto contexts, and more #2

Sergey Kandaurov 74 October 18, 2023 11:28AM

[PATCH 01 of 11] QUIC: split keys availability checks to read and write sides

Sergey Kandaurov 72 October 18, 2023 11:28AM

[PATCH 02 of 11] QUIC: added safety belt to prevent using discarded keys

Sergey Kandaurov 73 October 18, 2023 11:28AM

[PATCH 03 of 11] QUIC: prevented generating ACK frames with discarded keys

Sergey Kandaurov 71 October 18, 2023 11:28AM

[PATCH 04 of 11] QUIC: renamed protection functions

Sergey Kandaurov 67 October 18, 2023 11:28AM

[PATCH 05 of 11] QUIC: reusing crypto contexts for packet protection

Sergey Kandaurov 71 October 18, 2023 11:28AM

[PATCH 06 of 11] QUIC: common code for crypto open and seal operations

Sergey Kandaurov 71 October 18, 2023 11:28AM

[PATCH 07 of 11] QUIC: reusing crypto contexts for header protection

Sergey Kandaurov 69 October 18, 2023 11:30AM

[PATCH 08 of 11] QUIC: cleaned up now unused ngx_quic_ciphers() calls

Sergey Kandaurov 70 October 18, 2023 11:30AM

[PATCH 09 of 11] QUIC: simplified ngx_quic_ciphers() API

Sergey Kandaurov 67 October 18, 2023 11:30AM

[PATCH 10 of 11] QUIC: removed key field from ngx_quic_secret_t

Sergey Kandaurov 72 October 18, 2023 11:30AM

[PATCH 11 of 11] QUIC: explicitly zero out unused keying material

Sergey Kandaurov 70 October 18, 2023 11:38AM

Re: [PATCH 00 of 11] [quic] reusing crypto contexts, and more #2

Roman Arutyunyan 77 October 20, 2023 03:28AM



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