selftests/bpf: Check that JMP32 pointer vs zero jumps are not predictedgrafted

Add jmp32_ptr_vs_zero_jne: the fall-through of the 32-bit compare, which
the verifier used to skip, contains an out of bounds map value access,
hence w/o the previous patch the program is accepted. See previous patch
for detailed description.

Reported-by: Nicholas Carlini <npc@anthropic.com>
Suggested-by: Nicholas Carlini <npc@anthropic.com>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/20260904083325.2083493-6-eddyz87@gmail.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>

1 files changed, 46 insertions, 0 deletions

diff --git a/Documentation/networking/ipsec.rst b/Documentation/networking/ipsec.rst
new file mode 100644
index 000000000..afe9d7b48
--- /dev/null
+++ b/Documentation/networking/ipsec.rst
@@ -0,0 +1,46 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=====
+IPsec
+=====
+
+
+Here documents known IPsec corner cases which need to be keep in mind when
+deploy various IPsec configuration in real world production environment.
+
+1. IPcomp:
+	   Small IP packet won't get compressed at sender, and failed on
+	   policy check on receiver.
+
+Quote from RFC3173::
+
+  2.2. Non-Expansion Policy
+
+   If the total size of a compressed payload and the IPComp header, as
+   defined in section 3, is not smaller than the size of the original
+   payload, the IP datagram MUST be sent in the original non-compressed
+   form.  To clarify: If an IP datagram is sent non-compressed, no
+
+   IPComp header is added to the datagram.  This policy ensures saving
+   the decompression processing cycles and avoiding incurring IP
+   datagram fragmentation when the expanded datagram is larger than the
+   MTU.
+
+   Small IP datagrams are likely to expand as a result of compression.
+   Therefore, a numeric threshold should be applied before compression,
+   where IP datagrams of size smaller than the threshold are sent in the
+   original form without attempting compression.  The numeric threshold
+   is implementation dependent.
+
+Current IPComp implementation is indeed by the book, while as in practice
+when sending non-compressed packet to the peer (whether or not packet len
+is smaller than the threshold or the compressed len is larger than original
+packet len), the packet is dropped when checking the policy as this packet
+matches the selector but not coming from any XFRM layer, i.e., with no
+security path. Such naked packet will not eventually make it to upper layer.
+The result is much more wired to the user when ping peer with different
+payload length.
+
+One workaround is try to set "level use" for each policy if user observed
+above scenario. The consequence of doing so is small packet(uncompressed)
+will skip policy checking on receiver side.