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From 1bb4312264f71a91c9afd22bf2b9c1fdbd00dc7a Mon Sep 17 00:00:00 2001
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From: Eric Garver <e@erig.me>
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Date: Mon, 3 Dec 2018 12:40:41 -0500
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Subject: [PATCH 03/23] nftables: fix panic mode not filtering output packets
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This simplifies policy in the nftables backend by filtering only on the
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prerouting and output hooks. The others hooks are unnecessary since
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we're using a higher precedence.
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Also fixes an issue when re-enabling panic mode multiple times. Due to
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rule de-duplication the policy drop rule was not being re-added.
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Fixes: rhbz 1579740
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Fixes: a0f683dfef2c ("nftables: fix policy")
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(cherry picked from commit 2f5608b4897ff99afbb1c2425a94df035031c1a2)
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---
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src/firewall/core/nftables.py | 36 +++++++++--------------------------
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1 file changed, 9 insertions(+), 27 deletions(-)
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diff --git a/src/firewall/core/nftables.py b/src/firewall/core/nftables.py
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index 69236a9600c2..44cd4f9e1752 100644
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--- a/src/firewall/core/nftables.py
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+++ b/src/firewall/core/nftables.py
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@@ -314,38 +314,20 @@ class nftables(object):
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# packets while initially starting and for panic mode. As such, using
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# hooks with a higher priority than our base chains is sufficient.
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#
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- table_chains = []
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- for table in list(IPTABLES_TO_NFT_HOOK.keys()):
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- for chain in IPTABLES_TO_NFT_HOOK[table]:
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- table_chains.append((table, chain))
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-
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table_name = TABLE_NAME + "_" + "policy_drop"
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- def _policy_drop_helper(table, chain, family, rules):
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- _chain = "%s_%s" % (table, chain)
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- _hook = IPTABLES_TO_NFT_HOOK[table][chain][0]
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- # add hooks with priority -1, only contain drop rule
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- _priority = IPTABLES_TO_NFT_HOOK[table][chain][1] - 1
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- _add_chain = "add chain %s %s %s '{ type filter hook %s priority %d ; }'" % \
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- (family, table_name, _chain, _hook, _priority)
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- rules.append(splitArgs(_add_chain))
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- rules.append(["add", "rule", family, table_name, _chain, "drop"])
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-
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rules = []
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if policy == "DROP":
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- for family in ["inet", "ip", "ip6"]:
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- rules.append(["add", "table", family, table_name])
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-
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- for table,chain in table_chains:
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- if table == "nat":
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- # nat requires two families
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- for family in ["ip", "ip6"]:
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- _policy_drop_helper(table, chain, family, rules)
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- else:
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- _policy_drop_helper(table, chain, "inet", rules)
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+ rules.append(["add", "table", "inet", table_name])
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+
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+ # To drop everything we need to use the "raw" priority. These occur
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+ # before conntrack, mangle, nat, etc
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+ for hook in ["prerouting", "output"]:
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+ _add_chain = "add chain inet %s %s_%s '{ type filter hook %s priority %d ; policy drop ; }'" % \
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+ (table_name, "raw", hook, hook, -300 + NFT_HOOK_OFFSET - 1)
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+ rules.append(splitArgs(_add_chain))
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elif policy == "ACCEPT":
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- for family in ["inet", "ip", "ip6"]:
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- rules.append(["delete", "table", family, table_name])
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+ rules.append(["delete", "table", "inet", table_name])
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else:
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FirewallError(UNKNOWN_ERROR, "not implemented")
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--
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2.20.1
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