CVE-2014-3144/CVE-2014-3145 filter: prevent nla from peeking beyond eom (rhbz 1096775, 1096784)
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Josh Boyer
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Bugzilla: 1096784
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Upstream-status: 3.15
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From 0e1e9b265ec6c9b69ba5443e0d11aaa9a92ded53 Mon Sep 17 00:00:00 2001
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From: Mathias Krause <minipli@googlemail.com>
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Date: Sun, 13 Apr 2014 18:23:33 +0200
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Subject: [PATCH] filter: prevent nla extensions to peek beyond the end of the
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message
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Upstream commit 05ab8f2647e4221cbdb3856dd7d32bd5407316b3
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The BPF_S_ANC_NLATTR and BPF_S_ANC_NLATTR_NEST extensions fail to check
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for a minimal message length before testing the supplied offset to be
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within the bounds of the message. This allows the subtraction of the nla
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header to underflow and therefore -- as the data type is unsigned --
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allowing far to big offset and length values for the search of the
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netlink attribute.
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The remainder calculation for the BPF_S_ANC_NLATTR_NEST extension is
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also wrong. It has the minuend and subtrahend mixed up, therefore
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calculates a huge length value, allowing to overrun the end of the
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message while looking for the netlink attribute.
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The following three BPF snippets will trigger the bugs when attached to
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a UNIX datagram socket and parsing a message with length 1, 2 or 3.
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,-[ PoC for missing size check in BPF_S_ANC_NLATTR ]--
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| ld #0x87654321
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| ldx #42
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| ld #nla
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| ret a
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`---
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,-[ PoC for the same bug in BPF_S_ANC_NLATTR_NEST ]--
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| ld #0x87654321
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| ldx #42
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| ld #nlan
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| ret a
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`---
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,-[ PoC for wrong remainder calculation in BPF_S_ANC_NLATTR_NEST ]--
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| ; (needs a fake netlink header at offset 0)
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| ld #0
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| ldx #42
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| ld #nlan
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| ret a
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`---
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Fix the first issue by ensuring the message length fulfills the minimal
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size constrains of a nla header. Fix the second bug by getting the math
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for the remainder calculation right.
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Fixes: 4738c1db15 ("[SKFILTER]: Add SKF_ADF_NLATTR instruction")
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Fixes: d214c7537b ("filter: add SKF_AD_NLATTR_NEST to look for nested..")
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Cc: Patrick McHardy <kaber@trash.net>
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Cc: Pablo Neira Ayuso <pablo@netfilter.org>
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Signed-off-by: Mathias Krause <minipli@googlemail.com>
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Acked-by: Daniel Borkmann <dborkman@redhat.com>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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---
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net/core/filter.c | 10 +++++++++-
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1 file changed, 9 insertions(+), 1 deletion(-)
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diff --git a/net/core/filter.c b/net/core/filter.c
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index ad30d626a5bd..7be35b5fc22f 100644
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--- a/net/core/filter.c
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+++ b/net/core/filter.c
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@@ -355,6 +355,10 @@ load_b:
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if (skb_is_nonlinear(skb))
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return 0;
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+
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+ if (skb->len < sizeof(struct nlattr))
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+ return 0;
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+
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if (A > skb->len - sizeof(struct nlattr))
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return 0;
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@@ -371,11 +375,15 @@ load_b:
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if (skb_is_nonlinear(skb))
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return 0;
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+
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+ if (skb->len < sizeof(struct nlattr))
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+ return 0;
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+
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if (A > skb->len - sizeof(struct nlattr))
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return 0;
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nla = (struct nlattr *)&skb->data[A];
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- if (nla->nla_len > A - skb->len)
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+ if (nla->nla_len > skb->len - A)
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return 0;
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nla = nla_find_nested(nla, X);
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--
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1.9.0
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@ -794,6 +794,9 @@ Patch25087: jme-fix-dma-unmap-error.patch
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Patch25088: floppy-ignore-kernel-only-members-in-fdrawcmd-ioctl-input.patch
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Patch25089: floppy-don-t-write-kernel-only-members-to-fdrawcmd-ioctl-output.patch
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# CVE-2014-3144 CVE-2014-3145 rhbz 1096775, 1096784
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Patch25090: filter-prevent-nla-extensions-to-peek-beyond-the-end.patch
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# END OF PATCH DEFINITIONS
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%endif
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@ -1541,6 +1544,9 @@ ApplyPatch jme-fix-dma-unmap-error.patch
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ApplyPatch floppy-ignore-kernel-only-members-in-fdrawcmd-ioctl-input.patch
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ApplyPatch floppy-don-t-write-kernel-only-members-to-fdrawcmd-ioctl-output.patch
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# CVE-2014-3144 CVE-2014-3145 rhbz 1096775, 1096784
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ApplyPatch filter-prevent-nla-extensions-to-peek-beyond-the-end.patch
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# END OF PATCH APPLICATIONS
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%endif
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@ -2352,6 +2358,9 @@ fi
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# ||----w |
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# || ||
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%changelog
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* Mon May 12 2014 Josh Boyer <jwboyer@fedoraproject.org>
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- CVE-2014-3144/CVE-2014-3145 filter: prevent nla from peeking beyond eom (rhbz 1096775, 1096784)
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* Fri May 09 2014 Josh Boyer <jwboyer@fedoraproject.org>
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- CVE-2014-1738 CVE-2014-1737 floppy: priv esclation (rhbz 1094299 1096195)
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