From: Florian Westphal fw@strlen.de
commit c783a29c7e5934eabac2b760571489ad83bf4fd1 upstream.
This uses a pseudo-linearization scheme with a 64k global buffer, but BIG TCP arrival means IPv6 TCP stack can generate skbs that exceed this size.
Use skb_linearize. It should be possible to rewrite this to properly deal with segmented skbs (i.e., only do small chunk-wise accesses), but this is going to be a lot more intrusive than this because every helper function needs to get the sk_buff instead of a pointer to a raw data buffer.
In practice, provided we're really looking at FTP control channel packets, there should never be a case where we deal with huge packets.
Fixes: 7c4e983c4f3c ("net: allow gso_max_size to exceed 65536") Fixes: 0fe79f28bfaf ("net: allow gro_max_size to exceed 65536") Signed-off-by: Florian Westphal fw@strlen.de Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/netfilter/nf_conntrack_ftp.c | 24 ++++++------------------ 1 file changed, 6 insertions(+), 18 deletions(-)
diff --git a/net/netfilter/nf_conntrack_ftp.c b/net/netfilter/nf_conntrack_ftp.c index a414274338cf..0d9332e9cf71 100644 --- a/net/netfilter/nf_conntrack_ftp.c +++ b/net/netfilter/nf_conntrack_ftp.c @@ -34,11 +34,6 @@ MODULE_DESCRIPTION("ftp connection tracking helper"); MODULE_ALIAS("ip_conntrack_ftp"); MODULE_ALIAS_NFCT_HELPER(HELPER_NAME);
-/* This is slow, but it's simple. --RR */ -static char *ftp_buffer; - -static DEFINE_SPINLOCK(nf_ftp_lock); - #define MAX_PORTS 8 static u_int16_t ports[MAX_PORTS]; static unsigned int ports_c; @@ -398,6 +393,9 @@ static int help(struct sk_buff *skb, return NF_ACCEPT; }
+ if (unlikely(skb_linearize(skb))) + return NF_DROP; + th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph); if (th == NULL) return NF_ACCEPT; @@ -411,12 +409,8 @@ static int help(struct sk_buff *skb, } datalen = skb->len - dataoff;
- spin_lock_bh(&nf_ftp_lock); - fb_ptr = skb_header_pointer(skb, dataoff, datalen, ftp_buffer); - if (!fb_ptr) { - spin_unlock_bh(&nf_ftp_lock); - return NF_ACCEPT; - } + spin_lock_bh(&ct->lock); + fb_ptr = skb->data + dataoff;
ends_in_nl = (fb_ptr[datalen - 1] == '\n'); seq = ntohl(th->seq) + datalen; @@ -544,7 +538,7 @@ static int help(struct sk_buff *skb, if (ends_in_nl) update_nl_seq(ct, seq, ct_ftp_info, dir, skb); out: - spin_unlock_bh(&nf_ftp_lock); + spin_unlock_bh(&ct->lock); return ret; }
@@ -571,7 +565,6 @@ static const struct nf_conntrack_expect_policy ftp_exp_policy = { static void __exit nf_conntrack_ftp_fini(void) { nf_conntrack_helpers_unregister(ftp, ports_c * 2); - kfree(ftp_buffer); }
static int __init nf_conntrack_ftp_init(void) @@ -580,10 +573,6 @@ static int __init nf_conntrack_ftp_init(void)
NF_CT_HELPER_BUILD_BUG_ON(sizeof(struct nf_ct_ftp_master));
- ftp_buffer = kmalloc(65536, GFP_KERNEL); - if (!ftp_buffer) - return -ENOMEM; - if (ports_c == 0) ports[ports_c++] = FTP_PORT;
@@ -603,7 +592,6 @@ static int __init nf_conntrack_ftp_init(void) ret = nf_conntrack_helpers_register(ftp, ports_c * 2); if (ret < 0) { pr_err("failed to register helpers\n"); - kfree(ftp_buffer); return ret; }