[NETFILTER]: nf_conntrack_ftp: fix newline sequence number calculation When the packet size is changed by the FTP NAT helper, the connection tracking helper adjusts the sequence number of the newline character by the size difference. This is wrong because NAT sequence number adjustment happens after helpers are called, so the unadjusted number is compared to the already adjusted one. Based on report by YU, Haitao Signed-off-by: Patrick McHardy --- commit 4aa8feb60ca94d73f6ebb186b088e78970e2dcc7 tree 3245b16e02ec807d8535ad3e84c9fa974ba68e85 parent ce7fed0c554b66ea7ea36abb91d69fa74fa3a3e2 author Patrick McHardy Thu, 24 May 2007 20:05:57 +0200 committer Patrick McHardy Thu, 24 May 2007 20:05:57 +0200 include/linux/netfilter/nf_conntrack_ftp.h | 3 +-- net/ipv4/netfilter/nf_nat_ftp.c | 20 ++++++-------------- net/netfilter/nf_conntrack_ftp.c | 5 ++--- 3 files changed, 9 insertions(+), 19 deletions(-) diff --git a/include/linux/netfilter/nf_conntrack_ftp.h b/include/linux/netfilter/nf_conntrack_ftp.h index 81453ea..b7c360f 100644 --- a/include/linux/netfilter/nf_conntrack_ftp.h +++ b/include/linux/netfilter/nf_conntrack_ftp.h @@ -37,8 +37,7 @@ extern unsigned int (*nf_nat_ftp_hook)(struct sk_buff **pskb, enum nf_ct_ftp_type type, unsigned int matchoff, unsigned int matchlen, - struct nf_conntrack_expect *exp, - u32 *seq); + struct nf_conntrack_expect *exp); #endif /* __KERNEL__ */ #endif /* _NF_CONNTRACK_FTP_H */ diff --git a/net/ipv4/netfilter/nf_nat_ftp.c b/net/ipv4/netfilter/nf_nat_ftp.c index 751b598..e6bc8e5 100644 --- a/net/ipv4/netfilter/nf_nat_ftp.c +++ b/net/ipv4/netfilter/nf_nat_ftp.c @@ -40,8 +40,7 @@ mangle_rfc959_packet(struct sk_buff **pskb, unsigned int matchoff, unsigned int matchlen, struct nf_conn *ct, - enum ip_conntrack_info ctinfo, - u32 *seq) + enum ip_conntrack_info ctinfo) { char buffer[sizeof("nnn,nnn,nnn,nnn,nnn,nnn")]; @@ -50,7 +49,6 @@ mangle_rfc959_packet(struct sk_buff **pskb, DEBUGP("calling nf_nat_mangle_tcp_packet\n"); - *seq += strlen(buffer) - matchlen; return nf_nat_mangle_tcp_packet(pskb, ct, ctinfo, matchoff, matchlen, buffer, strlen(buffer)); } @@ -63,8 +61,7 @@ mangle_eprt_packet(struct sk_buff **pskb, unsigned int matchoff, unsigned int matchlen, struct nf_conn *ct, - enum ip_conntrack_info ctinfo, - u32 *seq) + enum ip_conntrack_info ctinfo) { char buffer[sizeof("|1|255.255.255.255|65535|")]; @@ -72,7 +69,6 @@ mangle_eprt_packet(struct sk_buff **pskb, DEBUGP("calling nf_nat_mangle_tcp_packet\n"); - *seq += strlen(buffer) - matchlen; return nf_nat_mangle_tcp_packet(pskb, ct, ctinfo, matchoff, matchlen, buffer, strlen(buffer)); } @@ -85,8 +81,7 @@ mangle_epsv_packet(struct sk_buff **pskb, unsigned int matchoff, unsigned int matchlen, struct nf_conn *ct, - enum ip_conntrack_info ctinfo, - u32 *seq) + enum ip_conntrack_info ctinfo) { char buffer[sizeof("|||65535|")]; @@ -94,14 +89,13 @@ mangle_epsv_packet(struct sk_buff **pskb, DEBUGP("calling nf_nat_mangle_tcp_packet\n"); - *seq += strlen(buffer) - matchlen; return nf_nat_mangle_tcp_packet(pskb, ct, ctinfo, matchoff, matchlen, buffer, strlen(buffer)); } static int (*mangle[])(struct sk_buff **, __be32, u_int16_t, unsigned int, unsigned int, struct nf_conn *, - enum ip_conntrack_info, u32 *seq) + enum ip_conntrack_info) = { [NF_CT_FTP_PORT] = mangle_rfc959_packet, [NF_CT_FTP_PASV] = mangle_rfc959_packet, @@ -116,8 +110,7 @@ static unsigned int nf_nat_ftp(struct sk_buff **pskb, enum nf_ct_ftp_type type, unsigned int matchoff, unsigned int matchlen, - struct nf_conntrack_expect *exp, - u32 *seq) + struct nf_conntrack_expect *exp) { __be32 newip; u_int16_t port; @@ -145,8 +138,7 @@ static unsigned int nf_nat_ftp(struct sk_buff **pskb, if (port == 0) return NF_DROP; - if (!mangle[type](pskb, newip, port, matchoff, matchlen, ct, ctinfo, - seq)) { + if (!mangle[type](pskb, newip, port, matchoff, matchlen, ct, ctinfo)) { nf_conntrack_unexpect_related(exp); return NF_DROP; } diff --git a/net/netfilter/nf_conntrack_ftp.c b/net/netfilter/nf_conntrack_ftp.c index 3357642..09add2f 100644 --- a/net/netfilter/nf_conntrack_ftp.c +++ b/net/netfilter/nf_conntrack_ftp.c @@ -48,8 +48,7 @@ unsigned int (*nf_nat_ftp_hook)(struct sk_buff **pskb, enum nf_ct_ftp_type type, unsigned int matchoff, unsigned int matchlen, - struct nf_conntrack_expect *exp, - u32 *seq); + struct nf_conntrack_expect *exp); EXPORT_SYMBOL_GPL(nf_nat_ftp_hook); #if 0 @@ -521,7 +520,7 @@ static int help(struct sk_buff **pskb, nf_nat_ftp = rcu_dereference(nf_nat_ftp_hook); if (nf_nat_ftp && ct->status & IPS_NAT_MASK) ret = nf_nat_ftp(pskb, ctinfo, search[dir][i].ftptype, - matchoff, matchlen, exp, &seq); + matchoff, matchlen, exp); else { /* Can't expect this? Best to drop packet now. */ if (nf_conntrack_expect_related(exp) != 0)