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From 6d1b02218a591ff95053b22c1ed802355e44878d Mon Sep 17 00:00:00 2001
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From: Phil Sutter <phil@nwl.cc>
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Date: Tue, 18 Jan 2022 22:39:08 +0100
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Subject: [PATCH] xshared: Fix response to unprivileged users
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Expected behaviour in both variants is:
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* Print help without error, append extension help if -m and/or -j
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options are present
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* Indicate lack of permissions in an error message for anything else
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With iptables-nft, this was broken basically from day 1. Shared use of
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do_parse() then somewhat broke legacy: it started complaining about
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inability to create a lock file.
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Fix this by making iptables-nft assume extension revision 0 is present
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if permissions don't allow to verify. This is consistent with legacy.
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Second part is to exit directly after printing help - this avoids having
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to make the following code "nop-aware" to prevent privileged actions.
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Signed-off-by: Phil Sutter <phil@nwl.cc>
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Reviewed-by: Florian Westphal <fw@strlen.de>
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(cherry picked from commit 26ecdf53960658771c0fc582f72a4025e2887f75)
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Conflicts:
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iptables/xshared.c
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-> Some chunks not applied as not necessary in RHEL8.
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---
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iptables/nft.c | 5 ++
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.../testcases/iptables/0008-unprivileged_0 | 60 +++++++++++++++++++
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2 files changed, 65 insertions(+)
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create mode 100755 iptables/tests/shell/testcases/iptables/0008-unprivileged_0
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diff --git a/iptables/nft.c b/iptables/nft.c
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index dc5490c085364..c5cc6f83bf573 100644
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--- a/iptables/nft.c
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+++ b/iptables/nft.c
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@@ -3110,6 +3110,11 @@ int nft_compatible_revision(const char *name, uint8_t rev, int opt)
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err:
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mnl_socket_close(nl);
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+ /* pretend revision 0 is valid if not permitted to check -
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+ * this is required for printing extension help texts as user */
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+ if (ret < 0 && errno == EPERM && rev == 0)
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+ return 1;
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+
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return ret < 0 ? 0 : 1;
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}
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diff --git a/iptables/tests/shell/testcases/iptables/0008-unprivileged_0 b/iptables/tests/shell/testcases/iptables/0008-unprivileged_0
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new file mode 100755
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index 0000000000000..43e3bc8721dbd
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--- /dev/null
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+++ b/iptables/tests/shell/testcases/iptables/0008-unprivileged_0
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@@ -0,0 +1,60 @@
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+#!/bin/bash
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+
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+# iptables may print match/target specific help texts
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+# help output should work for unprivileged users
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+
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+run() {
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+ echo "running: $*" >&2
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+ runuser -u nobody -- "$@"
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+}
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+
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+grep_or_rc() {
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+ declare -g rc
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+ grep -q "$*" && return 0
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+ echo "missing in output: $*" >&2
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+ return 1
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+}
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+
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+out=$(run $XT_MULTI iptables --help)
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+let "rc+=$?"
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+grep_or_rc "iptables -h (print this help information)" <<< "$out"
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+let "rc+=$?"
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+
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+out=$(run $XT_MULTI iptables -m limit --help)
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+let "rc+=$?"
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+grep_or_rc "limit match options:" <<< "$out"
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+let "rc+=$?"
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+
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+out=$(run $XT_MULTI iptables -p tcp --help)
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+let "rc+=$?"
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+grep_or_rc "tcp match options:" <<< "$out"
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+let "rc+=$?"
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+
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+out=$(run $XT_MULTI iptables -j DNAT --help)
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+let "rc+=$?"
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+grep_or_rc "DNAT target options:" <<< "$out"
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+let "rc+=$?"
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+
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+out=$(run $XT_MULTI iptables -p tcp -j DNAT --help)
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+let "rc+=$?"
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+grep_or_rc "tcp match options:" <<< "$out"
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+let "rc+=$?"
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+out=$(run $XT_MULTI iptables -p tcp -j DNAT --help)
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+let "rc+=$?"
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+grep_or_rc "DNAT target options:" <<< "$out"
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+let "rc+=$?"
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+
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+
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+run $XT_MULTI iptables -L 2>&1 | \
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+ grep_or_rc "Permission denied"
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+let "rc+=$?"
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+
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+run $XT_MULTI iptables -A FORWARD -p tcp --dport 123 2>&1 | \
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+ grep_or_rc "Permission denied"
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+let "rc+=$?"
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+
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+run $XT_MULTI iptables -A FORWARD -j DNAT --to-destination 1.2.3.4 2>&1 | \
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+ grep_or_rc "Permission denied"
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+let "rc+=$?"
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+
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+exit $rc
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--
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2.34.1
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