65 lines
2.2 KiB
Diff
65 lines
2.2 KiB
Diff
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From 64f34f34acedad6cce70f2dd91c82a814d4ffe34 Mon Sep 17 00:00:00 2001
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From: Phil Sutter <psutter@redhat.com>
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Date: Wed, 19 May 2021 18:03:43 +0200
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Subject: [PATCH] src: Support odd-sized payload matches
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Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1934926
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Upstream Status: nftables commit 8a927c56d83ed
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commit 8a927c56d83ed0f78785011bd92a53edc25a0ca0
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Author: Phil Sutter <phil@nwl.cc>
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Date: Tue Oct 27 17:05:25 2020 +0100
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src: Support odd-sized payload matches
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When expanding a payload match, don't disregard oversized templates at
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the right offset. A more flexible user may extract less bytes from the
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packet if only parts of a field are interesting, e.g. only the prefix of
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source/destination address. Support that by using the template, but fix
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the length. Later when creating a relational expression for it, detect
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the unusually small payload expression length and turn the RHS value
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into a prefix expression.
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Signed-off-by: Phil Sutter <phil@nwl.cc>
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---
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src/netlink_delinearize.c | 6 ++++++
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src/payload.c | 5 +++++
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2 files changed, 11 insertions(+)
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diff --git a/src/netlink_delinearize.c b/src/netlink_delinearize.c
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index 88dbd5a..8bdee12 100644
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--- a/src/netlink_delinearize.c
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+++ b/src/netlink_delinearize.c
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@@ -1577,6 +1577,12 @@ static void payload_match_expand(struct rule_pp_ctx *ctx,
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tmp = constant_expr_splice(right, left->len);
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expr_set_type(tmp, left->dtype, left->byteorder);
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+ if (left->payload.tmpl && (left->len < left->payload.tmpl->len)) {
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+ mpz_lshift_ui(tmp->value, left->payload.tmpl->len - left->len);
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+ tmp->len = left->payload.tmpl->len;
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+ tmp = prefix_expr_alloc(&tmp->location, tmp, left->len);
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+ }
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+
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nexpr = relational_expr_alloc(&expr->location, expr->op,
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left, tmp);
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if (expr->op == OP_EQ)
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diff --git a/src/payload.c b/src/payload.c
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index 3576400..45280ef 100644
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--- a/src/payload.c
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+++ b/src/payload.c
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@@ -746,6 +746,11 @@ void payload_expr_expand(struct list_head *list, struct expr *expr,
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expr->payload.offset += tmpl->len;
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if (expr->len == 0)
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return;
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+ } else if (expr->len > 0) {
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+ new = payload_expr_alloc(&expr->location, desc, i);
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+ new->len = expr->len;
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+ list_add_tail(&new->list, list);
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+ return;
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} else
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break;
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}
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--
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1.8.3.1
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