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Date: Wed, 12 Dec 2012 10:31:41 +0100
From: Daniel Borkmann <dborkman@...hat.com>
To: David Miller <davem@...emloft.net>
Cc: netdev@...r.kernel.org, Daniel Borkmann <dborkman@...hat.com>,
Ani Sinha <ani@...stanetworks.com>,
Eric Dumazet <eric.dumazet@...il.com>
Subject: [PATCH] net: filter: return -EINVAL if BPF_S_ANC* operation is not supported
Currently, we return -EINVAL for malicious or wrong BPF filters.
However, this is not done for BPF_S_ANC* operations, which makes it
more difficult to detect if it's actually supported or not by the
BPF machine. Therefore, we should also return -EINVAL if K is within
the SKF_AD_OFF universe and the ancillary operation did not match.
Cc: Ani Sinha <ani@...stanetworks.com>
Cc: Eric Dumazet <eric.dumazet@...il.com>
Signed-off-by: Daniel Borkmann <dborkman@...hat.com>
---
net/core/filter.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/net/core/filter.c b/net/core/filter.c
index c23543c..de9bed4 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -531,7 +531,7 @@ int sk_chk_filter(struct sock_filter *filter, unsigned int flen)
[BPF_JMP|BPF_JSET|BPF_K] = BPF_S_JMP_JSET_K,
[BPF_JMP|BPF_JSET|BPF_X] = BPF_S_JMP_JSET_X,
};
- int pc;
+ int pc, anc_found;
if (flen == 0 || flen > BPF_MAXINSNS)
return -EINVAL;
@@ -592,8 +592,10 @@ int sk_chk_filter(struct sock_filter *filter, unsigned int flen)
case BPF_S_LD_W_ABS:
case BPF_S_LD_H_ABS:
case BPF_S_LD_B_ABS:
+ anc_found = 0;
#define ANCILLARY(CODE) case SKF_AD_OFF + SKF_AD_##CODE: \
code = BPF_S_ANC_##CODE; \
+ anc_found = 1; \
break
switch (ftest->k) {
ANCILLARY(PROTOCOL);
@@ -610,6 +612,10 @@ int sk_chk_filter(struct sock_filter *filter, unsigned int flen)
ANCILLARY(VLAN_TAG);
ANCILLARY(VLAN_TAG_PRESENT);
}
+
+ /* ancillary operation unkown or unsupported */
+ if (anc_found == 0 && ftest->k >= SKF_AD_OFF)
+ return -EINVAL;
}
ftest->code = code;
}
--
1.7.11.7
--
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