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author | Pablo Neira Ayuso <pablo@netfilter.org> | 2008-11-20 08:49:27 (GMT) |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2008-11-20 08:49:27 (GMT) |
commit | d214c7537bbf2f247991fb65b3420b0b3d712c67 (patch) | |
tree | 11c26aa8c7c93d0bc15f206d65b3ddac3a6a8c33 | |
parent | 68fd991020fdf51bc94327d288ae4ae5d0b8dced (diff) | |
download | linux-fsl-qoriq-d214c7537bbf2f247991fb65b3420b0b3d712c67.tar.xz |
filter: add SKF_AD_NLATTR_NEST to look for nested attributes
SKF_AD_NLATTR allows us to find the first matching attribute in a
stream of netlink attributes from one offset to the end of the
netlink message. This is not suitable to look for a specific
matching inside a set of nested attributes.
For example, in ctnetlink messages, if we look for the CTA_V6_SRC
attribute in a message that talks about an IPv4 connection,
SKF_AD_NLATTR returns the offset of CTA_STATUS which has the same
value of CTA_V6_SRC but outside the nest. To differenciate
CTA_STATUS and CTA_V6_SRC, we would have to make assumptions on the
size of the attribute and the usual offset, resulting in horrible
BSF code.
This patch adds SKF_AD_NLATTR_NEST, which is a variant of
SKF_AD_NLATTR, that looks for an attribute inside the limits of
a nested attributes, but not further.
This patch validates that we have enough room to look for the
nested attributes - based on a suggestion from Patrick McHardy.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Acked-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r-- | include/linux/filter.h | 3 | ||||
-rw-r--r-- | net/core/filter.c | 19 |
2 files changed, 21 insertions, 1 deletions
diff --git a/include/linux/filter.h b/include/linux/filter.h index b6ea9aa..1354aaf 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -122,7 +122,8 @@ struct sock_fprog /* Required for SO_ATTACH_FILTER. */ #define SKF_AD_PKTTYPE 4 #define SKF_AD_IFINDEX 8 #define SKF_AD_NLATTR 12 -#define SKF_AD_MAX 16 +#define SKF_AD_NLATTR_NEST 16 +#define SKF_AD_MAX 20 #define SKF_NET_OFF (-0x100000) #define SKF_LL_OFF (-0x200000) diff --git a/net/core/filter.c b/net/core/filter.c index df37443..d1d779c 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -319,6 +319,25 @@ load_b: A = 0; continue; } + case SKF_AD_NLATTR_NEST: { + struct nlattr *nla; + + if (skb_is_nonlinear(skb)) + return 0; + if (A > skb->len - sizeof(struct nlattr)) + return 0; + + nla = (struct nlattr *)&skb->data[A]; + if (nla->nla_len > A - skb->len) + return 0; + + nla = nla_find_nested(nla, X); + if (nla) + A = (void *)nla - (void *)skb->data; + else + A = 0; + continue; + } default: return 0; } |