netfilter: ipt_LOG: add bufferisation to call printk() once
Eric Dumazet [Mon, 4 Oct 2010 18:56:05 +0000 (20:56 +0200)]
ipt_LOG & ip6t_LOG use lot of calls to printk() and use a lock in a hope
several cpus wont mix their output in syslog.

printk() being very expensive [1], its better to call it once, on a
prebuilt and complete line. Also, with mixed IPv4 and IPv6 trafic,
separate IPv4/IPv6 locks dont avoid garbage.

I used an allocation of a 1024 bytes structure, sort of seq_printf() but
with a fixed size limit.
Use a static buffer if dynamic allocation failed.

Emit a once time alert if buffer size happens to be too short.

[1]: printk() has various features like printk_delay()...

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>

net/ipv4/netfilter/ipt_LOG.c
net/ipv6/netfilter/ip6t_LOG.c

index 915fc17..72ffc8f 100644 (file)
 #include <linux/netfilter/x_tables.h>
 #include <linux/netfilter_ipv4/ipt_LOG.h>
 #include <net/netfilter/nf_log.h>
+#include <net/netfilter/xt_log.h>
 
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
 MODULE_DESCRIPTION("Xtables: IPv4 packet logging to syslog");
 
-/* Use lock to serialize, so printks don't overlap */
-static DEFINE_SPINLOCK(log_lock);
-
 /* One level of recursion won't kill us */
-static void dump_packet(const struct nf_loginfo *info,
+static void dump_packet(struct sbuff *m,
+                       const struct nf_loginfo *info,
                        const struct sk_buff *skb,
                        unsigned int iphoff)
 {
@@ -48,32 +47,32 @@ static void dump_packet(const struct nf_loginfo *info,
 
        ih = skb_header_pointer(skb, iphoff, sizeof(_iph), &_iph);
        if (ih == NULL) {
-               printk("TRUNCATED");
+               sb_add(m, "TRUNCATED");
                return;
        }
 
        /* Important fields:
         * TOS, len, DF/MF, fragment offset, TTL, src, dst, options. */
        /* Max length: 40 "SRC=255.255.255.255 DST=255.255.255.255 " */
-       printk("SRC=%pI4 DST=%pI4 ",
+       sb_add(m, "SRC=%pI4 DST=%pI4 ",
               &ih->saddr, &ih->daddr);
 
        /* Max length: 46 "LEN=65535 TOS=0xFF PREC=0xFF TTL=255 ID=65535 " */
-       printk("LEN=%u TOS=0x%02X PREC=0x%02X TTL=%u ID=%u ",
+       sb_add(m, "LEN=%u TOS=0x%02X PREC=0x%02X TTL=%u ID=%u ",
               ntohs(ih->tot_len), ih->tos & IPTOS_TOS_MASK,
               ih->tos & IPTOS_PREC_MASK, ih->ttl, ntohs(ih->id));
 
        /* Max length: 6 "CE DF MF " */
        if (ntohs(ih->frag_off) & IP_CE)
-               printk("CE ");
+               sb_add(m, "CE ");
        if (ntohs(ih->frag_off) & IP_DF)
-               printk("DF ");
+               sb_add(m, "DF ");
        if (ntohs(ih->frag_off) & IP_MF)
-               printk("MF ");
+               sb_add(m, "MF ");
 
        /* Max length: 11 "FRAG:65535 " */
        if (ntohs(ih->frag_off) & IP_OFFSET)
-               printk("FRAG:%u ", ntohs(ih->frag_off) & IP_OFFSET);
+               sb_add(m, "FRAG:%u ", ntohs(ih->frag_off) & IP_OFFSET);
 
        if ((logflags & IPT_LOG_IPOPT) &&
            ih->ihl * 4 > sizeof(struct iphdr)) {
@@ -85,15 +84,15 @@ static void dump_packet(const struct nf_loginfo *info,
                op = skb_header_pointer(skb, iphoff+sizeof(_iph),
                                        optsize, _opt);
                if (op == NULL) {
-                       printk("TRUNCATED");
+                       sb_add(m, "TRUNCATED");
                        return;
                }
 
                /* Max length: 127 "OPT (" 15*4*2chars ") " */
-               printk("OPT (");
+               sb_add(m, "OPT (");
                for (i = 0; i < optsize; i++)
-                       printk("%02X", op[i]);
-               printk(") ");
+                       sb_add(m, "%02X", op[i]);
+               sb_add(m, ") ");
        }
 
        switch (ih->protocol) {
@@ -102,7 +101,7 @@ static void dump_packet(const struct nf_loginfo *info,
                const struct tcphdr *th;
 
                /* Max length: 10 "PROTO=TCP " */
-               printk("PROTO=TCP ");
+               sb_add(m, "PROTO=TCP ");
 
                if (ntohs(ih->frag_off) & IP_OFFSET)
                        break;
@@ -111,41 +110,41 @@ static void dump_packet(const struct nf_loginfo *info,
                th = skb_header_pointer(skb, iphoff + ih->ihl * 4,
                                        sizeof(_tcph), &_tcph);
                if (th == NULL) {
-                       printk("INCOMPLETE [%u bytes] ",
+                       sb_add(m, "INCOMPLETE [%u bytes] ",
                               skb->len - iphoff - ih->ihl*4);
                        break;
                }
 
                /* Max length: 20 "SPT=65535 DPT=65535 " */
-               printk("SPT=%u DPT=%u ",
+               sb_add(m, "SPT=%u DPT=%u ",
                       ntohs(th->source), ntohs(th->dest));
                /* Max length: 30 "SEQ=4294967295 ACK=4294967295 " */
                if (logflags & IPT_LOG_TCPSEQ)
-                       printk("SEQ=%u ACK=%u ",
+                       sb_add(m, "SEQ=%u ACK=%u ",
                               ntohl(th->seq), ntohl(th->ack_seq));
                /* Max length: 13 "WINDOW=65535 " */
-               printk("WINDOW=%u ", ntohs(th->window));
+               sb_add(m, "WINDOW=%u ", ntohs(th->window));
                /* Max length: 9 "RES=0x3F " */
-               printk("RES=0x%02x ", (u8)(ntohl(tcp_flag_word(th) & TCP_RESERVED_BITS) >> 22));
+               sb_add(m, "RES=0x%02x ", (u8)(ntohl(tcp_flag_word(th) & TCP_RESERVED_BITS) >> 22));
                /* Max length: 32 "CWR ECE URG ACK PSH RST SYN FIN " */
                if (th->cwr)
-                       printk("CWR ");
+                       sb_add(m, "CWR ");
                if (th->ece)
-                       printk("ECE ");
+                       sb_add(m, "ECE ");
                if (th->urg)
-                       printk("URG ");
+                       sb_add(m, "URG ");
                if (th->ack)
-                       printk("ACK ");
+                       sb_add(m, "ACK ");
                if (th->psh)
-                       printk("PSH ");
+                       sb_add(m, "PSH ");
                if (th->rst)
-                       printk("RST ");
+                       sb_add(m, "RST ");
                if (th->syn)
-                       printk("SYN ");
+                       sb_add(m, "SYN ");
                if (th->fin)
-                       printk("FIN ");
+                       sb_add(m, "FIN ");
                /* Max length: 11 "URGP=65535 " */
-               printk("URGP=%u ", ntohs(th->urg_ptr));
+               sb_add(m, "URGP=%u ", ntohs(th->urg_ptr));
 
                if ((logflags & IPT_LOG_TCPOPT) &&
                    th->doff * 4 > sizeof(struct tcphdr)) {
@@ -158,15 +157,15 @@ static void dump_packet(const struct nf_loginfo *info,
                                                iphoff+ih->ihl*4+sizeof(_tcph),
                                                optsize, _opt);
                        if (op == NULL) {
-                               printk("TRUNCATED");
+                               sb_add(m, "TRUNCATED");
                                return;
                        }
 
                        /* Max length: 127 "OPT (" 15*4*2chars ") " */
-                       printk("OPT (");
+                       sb_add(m, "OPT (");
                        for (i = 0; i < optsize; i++)
-                               printk("%02X", op[i]);
-                       printk(") ");
+                               sb_add(m, "%02X", op[i]);
+                       sb_add(m, ") ");
                }
                break;
        }
@@ -177,9 +176,9 @@ static void dump_packet(const struct nf_loginfo *info,
 
                if (ih->protocol == IPPROTO_UDP)
                        /* Max length: 10 "PROTO=UDP "     */
-                       printk("PROTO=UDP " );
+                       sb_add(m, "PROTO=UDP " );
                else    /* Max length: 14 "PROTO=UDPLITE " */
-                       printk("PROTO=UDPLITE ");
+                       sb_add(m, "PROTO=UDPLITE ");
 
                if (ntohs(ih->frag_off) & IP_OFFSET)
                        break;
@@ -188,13 +187,13 @@ static void dump_packet(const struct nf_loginfo *info,
                uh = skb_header_pointer(skb, iphoff+ih->ihl*4,
                                        sizeof(_udph), &_udph);
                if (uh == NULL) {
-                       printk("INCOMPLETE [%u bytes] ",
+                       sb_add(m, "INCOMPLETE [%u bytes] ",
                               skb->len - iphoff - ih->ihl*4);
                        break;
                }
 
                /* Max length: 20 "SPT=65535 DPT=65535 " */
-               printk("SPT=%u DPT=%u LEN=%u ",
+               sb_add(m, "SPT=%u DPT=%u LEN=%u ",
                       ntohs(uh->source), ntohs(uh->dest),
                       ntohs(uh->len));
                break;
@@ -221,7 +220,7 @@ static void dump_packet(const struct nf_loginfo *info,
                            [ICMP_ADDRESSREPLY] = 12 };
 
                /* Max length: 11 "PROTO=ICMP " */
-               printk("PROTO=ICMP ");
+               sb_add(m, "PROTO=ICMP ");
 
                if (ntohs(ih->frag_off) & IP_OFFSET)
                        break;
@@ -230,19 +229,19 @@ static void dump_packet(const struct nf_loginfo *info,
                ich = skb_header_pointer(skb, iphoff + ih->ihl * 4,
                                         sizeof(_icmph), &_icmph);
                if (ich == NULL) {
-                       printk("INCOMPLETE [%u bytes] ",
+                       sb_add(m, "INCOMPLETE [%u bytes] ",
                               skb->len - iphoff - ih->ihl*4);
                        break;
                }
 
                /* Max length: 18 "TYPE=255 CODE=255 " */
-               printk("TYPE=%u CODE=%u ", ich->type, ich->code);
+               sb_add(m, "TYPE=%u CODE=%u ", ich->type, ich->code);
 
                /* Max length: 25 "INCOMPLETE [65535 bytes] " */
                if (ich->type <= NR_ICMP_TYPES &&
                    required_len[ich->type] &&
                    skb->len-iphoff-ih->ihl*4 < required_len[ich->type]) {
-                       printk("INCOMPLETE [%u bytes] ",
+                       sb_add(m, "INCOMPLETE [%u bytes] ",
                               skb->len - iphoff - ih->ihl*4);
                        break;
                }
@@ -251,35 +250,35 @@ static void dump_packet(const struct nf_loginfo *info,
                case ICMP_ECHOREPLY:
                case ICMP_ECHO:
                        /* Max length: 19 "ID=65535 SEQ=65535 " */
-                       printk("ID=%u SEQ=%u ",
+                       sb_add(m, "ID=%u SEQ=%u ",
                               ntohs(ich->un.echo.id),
                               ntohs(ich->un.echo.sequence));
                        break;
 
                case ICMP_PARAMETERPROB:
                        /* Max length: 14 "PARAMETER=255 " */
-                       printk("PARAMETER=%u ",
+                       sb_add(m, "PARAMETER=%u ",
                               ntohl(ich->un.gateway) >> 24);
                        break;
                case ICMP_REDIRECT:
                        /* Max length: 24 "GATEWAY=255.255.255.255 " */
-                       printk("GATEWAY=%pI4 ", &ich->un.gateway);
+                       sb_add(m, "GATEWAY=%pI4 ", &ich->un.gateway);
                        /* Fall through */
                case ICMP_DEST_UNREACH:
                case ICMP_SOURCE_QUENCH:
                case ICMP_TIME_EXCEEDED:
                        /* Max length: 3+maxlen */
                        if (!iphoff) { /* Only recurse once. */
-                               printk("[");
-                               dump_packet(info, skb,
+                               sb_add(m, "[");
+                               dump_packet(m, info, skb,
                                            iphoff + ih->ihl*4+sizeof(_icmph));
-                               printk("] ");
+                               sb_add(m, "] ");
                        }
 
                        /* Max length: 10 "MTU=65535 " */
                        if (ich->type == ICMP_DEST_UNREACH &&
                            ich->code == ICMP_FRAG_NEEDED)
-                               printk("MTU=%u ", ntohs(ich->un.frag.mtu));
+                               sb_add(m, "MTU=%u ", ntohs(ich->un.frag.mtu));
                }
                break;
        }
@@ -292,19 +291,19 @@ static void dump_packet(const struct nf_loginfo *info,
                        break;
 
                /* Max length: 9 "PROTO=AH " */
-               printk("PROTO=AH ");
+               sb_add(m, "PROTO=AH ");
 
                /* Max length: 25 "INCOMPLETE [65535 bytes] " */
                ah = skb_header_pointer(skb, iphoff+ih->ihl*4,
                                        sizeof(_ahdr), &_ahdr);
                if (ah == NULL) {
-                       printk("INCOMPLETE [%u bytes] ",
+                       sb_add(m, "INCOMPLETE [%u bytes] ",
                               skb->len - iphoff - ih->ihl*4);
                        break;
                }
 
                /* Length: 15 "SPI=0xF1234567 " */
-               printk("SPI=0x%x ", ntohl(ah->spi));
+               sb_add(m, "SPI=0x%x ", ntohl(ah->spi));
                break;
        }
        case IPPROTO_ESP: {
@@ -312,7 +311,7 @@ static void dump_packet(const struct nf_loginfo *info,
                const struct ip_esp_hdr *eh;
 
                /* Max length: 10 "PROTO=ESP " */
-               printk("PROTO=ESP ");
+               sb_add(m, "PROTO=ESP ");
 
                if (ntohs(ih->frag_off) & IP_OFFSET)
                        break;
@@ -321,25 +320,25 @@ static void dump_packet(const struct nf_loginfo *info,
                eh = skb_header_pointer(skb, iphoff+ih->ihl*4,
                                        sizeof(_esph), &_esph);
                if (eh == NULL) {
-                       printk("INCOMPLETE [%u bytes] ",
+                       sb_add(m, "INCOMPLETE [%u bytes] ",
                               skb->len - iphoff - ih->ihl*4);
                        break;
                }
 
                /* Length: 15 "SPI=0xF1234567 " */
-               printk("SPI=0x%x ", ntohl(eh->spi));
+               sb_add(m, "SPI=0x%x ", ntohl(eh->spi));
                break;
        }
        /* Max length: 10 "PROTO 255 " */
        default:
-               printk("PROTO=%u ", ih->protocol);
+               sb_add(m, "PROTO=%u ", ih->protocol);
        }
 
        /* Max length: 15 "UID=4294967295 " */
        if ((logflags & IPT_LOG_UID) && !iphoff && skb->sk) {
                read_lock_bh(&skb->sk->sk_callback_lock);
                if (skb->sk->sk_socket && skb->sk->sk_socket->file)
-                       printk("UID=%u GID=%u ",
+                       sb_add(m, "UID=%u GID=%u ",
                                skb->sk->sk_socket->file->f_cred->fsuid,
                                skb->sk->sk_socket->file->f_cred->fsgid);
                read_unlock_bh(&skb->sk->sk_callback_lock);
@@ -347,7 +346,7 @@ static void dump_packet(const struct nf_loginfo *info,
 
        /* Max length: 16 "MARK=0xFFFFFFFF " */
        if (!iphoff && skb->mark)
-               printk("MARK=0x%x ", skb->mark);
+               sb_add(m, "MARK=0x%x ", skb->mark);
 
        /* Proto    Max log string length */
        /* IP:      40+46+6+11+127 = 230 */
@@ -364,7 +363,8 @@ static void dump_packet(const struct nf_loginfo *info,
        /* maxlen = 230+   91  + 230 + 252 = 803 */
 }
 
-static void dump_mac_header(const struct nf_loginfo *info,
+static void dump_mac_header(struct sbuff *m,
+                           const struct nf_loginfo *info,
                            const struct sk_buff *skb)
 {
        struct net_device *dev = skb->dev;
@@ -378,7 +378,7 @@ static void dump_mac_header(const struct nf_loginfo *info,
 
        switch (dev->type) {
        case ARPHRD_ETHER:
-               printk("MACSRC=%pM MACDST=%pM MACPROTO=%04x ",
+               sb_add(m, "MACSRC=%pM MACDST=%pM MACPROTO=%04x ",
                       eth_hdr(skb)->h_source, eth_hdr(skb)->h_dest,
                       ntohs(eth_hdr(skb)->h_proto));
                return;
@@ -387,17 +387,17 @@ static void dump_mac_header(const struct nf_loginfo *info,
        }
 
 fallback:
-       printk("MAC=");
+       sb_add(m, "MAC=");
        if (dev->hard_header_len &&
            skb->mac_header != skb->network_header) {
                const unsigned char *p = skb_mac_header(skb);
                unsigned int i;
 
-               printk("%02x", *p++);
+               sb_add(m, "%02x", *p++);
                for (i = 1; i < dev->hard_header_len; i++, p++)
-                       printk(":%02x", *p);
+                       sb_add(m, ":%02x", *p);
        }
-       printk(" ");
+       sb_add(m, " ");
 }
 
 static struct nf_loginfo default_loginfo = {
@@ -419,11 +419,12 @@ ipt_log_packet(u_int8_t pf,
               const struct nf_loginfo *loginfo,
               const char *prefix)
 {
+       struct sbuff *m = sb_open();
+
        if (!loginfo)
                loginfo = &default_loginfo;
 
-       spin_lock_bh(&log_lock);
-       printk("<%d>%sIN=%s OUT=%s ", loginfo->u.log.level,
+       sb_add(m, "<%d>%sIN=%s OUT=%s ", loginfo->u.log.level,
               prefix,
               in ? in->name : "",
               out ? out->name : "");
@@ -434,20 +435,20 @@ ipt_log_packet(u_int8_t pf,
 
                physindev = skb->nf_bridge->physindev;
                if (physindev && in != physindev)
-                       printk("PHYSIN=%s ", physindev->name);
+                       sb_add(m, "PHYSIN=%s ", physindev->name);
                physoutdev = skb->nf_bridge->physoutdev;
                if (physoutdev && out != physoutdev)
-                       printk("PHYSOUT=%s ", physoutdev->name);
+                       sb_add(m, "PHYSOUT=%s ", physoutdev->name);
        }
 #endif
 
        /* MAC logging for input path only. */
        if (in && !out)
-               dump_mac_header(loginfo, skb);
+               dump_mac_header(m, loginfo, skb);
+
+       dump_packet(m, loginfo, skb, 0);
 
-       dump_packet(loginfo, skb, 0);
-       printk("\n");
-       spin_unlock_bh(&log_lock);
+       sb_close(m);
 }
 
 static unsigned int
index 0a07ae7..09c8889 100644 (file)
@@ -23,6 +23,7 @@
 #include <linux/netfilter/x_tables.h>
 #include <linux/netfilter_ipv6/ip6_tables.h>
 #include <net/netfilter/nf_log.h>
+#include <net/netfilter/xt_log.h>
 
 MODULE_AUTHOR("Jan Rekorajski <baggins@pld.org.pl>");
 MODULE_DESCRIPTION("Xtables: IPv6 packet logging to syslog");
@@ -32,11 +33,9 @@ struct in_device;
 #include <net/route.h>
 #include <linux/netfilter_ipv6/ip6t_LOG.h>
 
-/* Use lock to serialize, so printks don't overlap */
-static DEFINE_SPINLOCK(log_lock);
-
 /* One level of recursion won't kill us */
-static void dump_packet(const struct nf_loginfo *info,
+static void dump_packet(struct sbuff *m,
+                       const struct nf_loginfo *info,
                        const struct sk_buff *skb, unsigned int ip6hoff,
                        int recurse)
 {
@@ -55,15 +54,15 @@ static void dump_packet(const struct nf_loginfo *info,
 
        ih = skb_header_pointer(skb, ip6hoff, sizeof(_ip6h), &_ip6h);
        if (ih == NULL) {
-               printk("TRUNCATED");
+               sb_add(m, "TRUNCATED");
                return;
        }
 
        /* Max length: 88 "SRC=0000.0000.0000.0000.0000.0000.0000.0000 DST=0000.0000.0000.0000.0000.0000.0000.0000 " */
-       printk("SRC=%pI6 DST=%pI6 ", &ih->saddr, &ih->daddr);
+       sb_add(m, "SRC=%pI6 DST=%pI6 ", &ih->saddr, &ih->daddr);
 
        /* Max length: 44 "LEN=65535 TC=255 HOPLIMIT=255 FLOWLBL=FFFFF " */
-       printk("LEN=%Zu TC=%u HOPLIMIT=%u FLOWLBL=%u ",
+       sb_add(m, "LEN=%Zu TC=%u HOPLIMIT=%u FLOWLBL=%u ",
               ntohs(ih->payload_len) + sizeof(struct ipv6hdr),
               (ntohl(*(__be32 *)ih) & 0x0ff00000) >> 20,
               ih->hop_limit,
@@ -78,35 +77,35 @@ static void dump_packet(const struct nf_loginfo *info,
 
                hp = skb_header_pointer(skb, ptr, sizeof(_hdr), &_hdr);
                if (hp == NULL) {
-                       printk("TRUNCATED");
+                       sb_add(m, "TRUNCATED");
                        return;
                }
 
                /* Max length: 48 "OPT (...) " */
                if (logflags & IP6T_LOG_IPOPT)
-                       printk("OPT ( ");
+                       sb_add(m, "OPT ( ");
 
                switch (currenthdr) {
                case IPPROTO_FRAGMENT: {
                        struct frag_hdr _fhdr;
                        const struct frag_hdr *fh;
 
-                       printk("FRAG:");
+                       sb_add(m, "FRAG:");
                        fh = skb_header_pointer(skb, ptr, sizeof(_fhdr),
                                                &_fhdr);
                        if (fh == NULL) {
-                               printk("TRUNCATED ");
+                               sb_add(m, "TRUNCATED ");
                                return;
                        }
 
                        /* Max length: 6 "65535 " */
-                       printk("%u ", ntohs(fh->frag_off) & 0xFFF8);
+                       sb_add(m, "%u ", ntohs(fh->frag_off) & 0xFFF8);
 
                        /* Max length: 11 "INCOMPLETE " */
                        if (fh->frag_off & htons(0x0001))
-                               printk("INCOMPLETE ");
+                               sb_add(m, "INCOMPLETE ");
 
-                       printk("ID:%08x ", ntohl(fh->identification));
+                       sb_add(m, "ID:%08x ", ntohl(fh->identification));
 
                        if (ntohs(fh->frag_off) & 0xFFF8)
                                fragment = 1;
@@ -120,7 +119,7 @@ static void dump_packet(const struct nf_loginfo *info,
                case IPPROTO_HOPOPTS:
                        if (fragment) {
                                if (logflags & IP6T_LOG_IPOPT)
-                                       printk(")");
+                                       sb_add(m, ")");
                                return;
                        }
                        hdrlen = ipv6_optlen(hp);
@@ -132,10 +131,10 @@ static void dump_packet(const struct nf_loginfo *info,
                                const struct ip_auth_hdr *ah;
 
                                /* Max length: 3 "AH " */
-                               printk("AH ");
+                               sb_add(m, "AH ");
 
                                if (fragment) {
-                                       printk(")");
+                                       sb_add(m, ")");
                                        return;
                                }
 
@@ -146,13 +145,13 @@ static void dump_packet(const struct nf_loginfo *info,
                                         * Max length: 26 "INCOMPLETE [65535
                                         *  bytes] )"
                                         */
-                                       printk("INCOMPLETE [%u bytes] )",
+                                       sb_add(m, "INCOMPLETE [%u bytes] )",
                                               skb->len - ptr);
                                        return;
                                }
 
                                /* Length: 15 "SPI=0xF1234567 */
-                               printk("SPI=0x%x ", ntohl(ah->spi));
+                               sb_add(m, "SPI=0x%x ", ntohl(ah->spi));
 
                        }
 
@@ -164,10 +163,10 @@ static void dump_packet(const struct nf_loginfo *info,
                                const struct ip_esp_hdr *eh;
 
                                /* Max length: 4 "ESP " */
-                               printk("ESP ");
+                               sb_add(m, "ESP ");
 
                                if (fragment) {
-                                       printk(")");
+                                       sb_add(m, ")");
                                        return;
                                }
 
@@ -177,23 +176,23 @@ static void dump_packet(const struct nf_loginfo *info,
                                eh = skb_header_pointer(skb, ptr, sizeof(_esph),
                                                        &_esph);
                                if (eh == NULL) {
-                                       printk("INCOMPLETE [%u bytes] )",
+                                       sb_add(m, "INCOMPLETE [%u bytes] )",
                                               skb->len - ptr);
                                        return;
                                }
 
                                /* Length: 16 "SPI=0xF1234567 )" */
-                               printk("SPI=0x%x )", ntohl(eh->spi) );
+                               sb_add(m, "SPI=0x%x )", ntohl(eh->spi) );
 
                        }
                        return;
                default:
                        /* Max length: 20 "Unknown Ext Hdr 255" */
-                       printk("Unknown Ext Hdr %u", currenthdr);
+                       sb_add(m, "Unknown Ext Hdr %u", currenthdr);
                        return;
                }
                if (logflags & IP6T_LOG_IPOPT)
-                       printk(") ");
+                       sb_add(m, ") ");
 
                currenthdr = hp->nexthdr;
                ptr += hdrlen;
@@ -205,7 +204,7 @@ static void dump_packet(const struct nf_loginfo *info,
                const struct tcphdr *th;
 
                /* Max length: 10 "PROTO=TCP " */
-               printk("PROTO=TCP ");
+               sb_add(m, "PROTO=TCP ");
 
                if (fragment)
                        break;
@@ -213,40 +212,40 @@ static void dump_packet(const struct nf_loginfo *info,
                /* Max length: 25 "INCOMPLETE [65535 bytes] " */
                th = skb_header_pointer(skb, ptr, sizeof(_tcph), &_tcph);
                if (th == NULL) {
-                       printk("INCOMPLETE [%u bytes] ", skb->len - ptr);
+                       sb_add(m, "INCOMPLETE [%u bytes] ", skb->len - ptr);
                        return;
                }
 
                /* Max length: 20 "SPT=65535 DPT=65535 " */
-               printk("SPT=%u DPT=%u ",
+               sb_add(m, "SPT=%u DPT=%u ",
                       ntohs(th->source), ntohs(th->dest));
                /* Max length: 30 "SEQ=4294967295 ACK=4294967295 " */
                if (logflags & IP6T_LOG_TCPSEQ)
-                       printk("SEQ=%u ACK=%u ",
+                       sb_add(m, "SEQ=%u ACK=%u ",
                               ntohl(th->seq), ntohl(th->ack_seq));
                /* Max length: 13 "WINDOW=65535 " */
-               printk("WINDOW=%u ", ntohs(th->window));
+               sb_add(m, "WINDOW=%u ", ntohs(th->window));
                /* Max length: 9 "RES=0x3C " */
-               printk("RES=0x%02x ", (u_int8_t)(ntohl(tcp_flag_word(th) & TCP_RESERVED_BITS) >> 22));
+               sb_add(m, "RES=0x%02x ", (u_int8_t)(ntohl(tcp_flag_word(th) & TCP_RESERVED_BITS) >> 22));
                /* Max length: 32 "CWR ECE URG ACK PSH RST SYN FIN " */
                if (th->cwr)
-                       printk("CWR ");
+                       sb_add(m, "CWR ");
                if (th->ece)
-                       printk("ECE ");
+                       sb_add(m, "ECE ");
                if (th->urg)
-                       printk("URG ");
+                       sb_add(m, "URG ");
                if (th->ack)
-                       printk("ACK ");
+                       sb_add(m, "ACK ");
                if (th->psh)
-                       printk("PSH ");
+                       sb_add(m, "PSH ");
                if (th->rst)
-                       printk("RST ");
+                       sb_add(m, "RST ");
                if (th->syn)
-                       printk("SYN ");
+                       sb_add(m, "SYN ");
                if (th->fin)
-                       printk("FIN ");
+                       sb_add(m, "FIN ");
                /* Max length: 11 "URGP=65535 " */
-               printk("URGP=%u ", ntohs(th->urg_ptr));
+               sb_add(m, "URGP=%u ", ntohs(th->urg_ptr));
 
                if ((logflags & IP6T_LOG_TCPOPT) &&
                    th->doff * 4 > sizeof(struct tcphdr)) {
@@ -260,15 +259,15 @@ static void dump_packet(const struct nf_loginfo *info,
                                                ptr + sizeof(struct tcphdr),
                                                optsize, _opt);
                        if (op == NULL) {
-                               printk("OPT (TRUNCATED)");
+                               sb_add(m, "OPT (TRUNCATED)");
                                return;
                        }
 
                        /* Max length: 127 "OPT (" 15*4*2chars ") " */
-                       printk("OPT (");
+                       sb_add(m, "OPT (");
                        for (i =0; i < optsize; i++)
-                               printk("%02X", op[i]);
-                       printk(") ");
+                               sb_add(m, "%02X", op[i]);
+                       sb_add(m, ") ");
                }
                break;
        }
@@ -279,9 +278,9 @@ static void dump_packet(const struct nf_loginfo *info,
 
                if (currenthdr == IPPROTO_UDP)
                        /* Max length: 10 "PROTO=UDP "     */
-                       printk("PROTO=UDP " );
+                       sb_add(m, "PROTO=UDP " );
                else    /* Max length: 14 "PROTO=UDPLITE " */
-                       printk("PROTO=UDPLITE ");
+                       sb_add(m, "PROTO=UDPLITE ");
 
                if (fragment)
                        break;
@@ -289,12 +288,12 @@ static void dump_packet(const struct nf_loginfo *info,
                /* Max length: 25 "INCOMPLETE [65535 bytes] " */
                uh = skb_header_pointer(skb, ptr, sizeof(_udph), &_udph);
                if (uh == NULL) {
-                       printk("INCOMPLETE [%u bytes] ", skb->len - ptr);
+                       sb_add(m, "INCOMPLETE [%u bytes] ", skb->len - ptr);
                        return;
                }
 
                /* Max length: 20 "SPT=65535 DPT=65535 " */
-               printk("SPT=%u DPT=%u LEN=%u ",
+               sb_add(m, "SPT=%u DPT=%u LEN=%u ",
                       ntohs(uh->source), ntohs(uh->dest),
                       ntohs(uh->len));
                break;
@@ -304,7 +303,7 @@ static void dump_packet(const struct nf_loginfo *info,
                const struct icmp6hdr *ic;
 
                /* Max length: 13 "PROTO=ICMPv6 " */
-               printk("PROTO=ICMPv6 ");
+               sb_add(m, "PROTO=ICMPv6 ");
 
                if (fragment)
                        break;
@@ -312,18 +311,18 @@ static void dump_packet(const struct nf_loginfo *info,
                /* Max length: 25 "INCOMPLETE [65535 bytes] " */
                ic = skb_header_pointer(skb, ptr, sizeof(_icmp6h), &_icmp6h);
                if (ic == NULL) {
-                       printk("INCOMPLETE [%u bytes] ", skb->len - ptr);
+                       sb_add(m, "INCOMPLETE [%u bytes] ", skb->len - ptr);
                        return;
                }
 
                /* Max length: 18 "TYPE=255 CODE=255 " */
-               printk("TYPE=%u CODE=%u ", ic->icmp6_type, ic->icmp6_code);
+               sb_add(m, "TYPE=%u CODE=%u ", ic->icmp6_type, ic->icmp6_code);
 
                switch (ic->icmp6_type) {
                case ICMPV6_ECHO_REQUEST:
                case ICMPV6_ECHO_REPLY:
                        /* Max length: 19 "ID=65535 SEQ=65535 " */
-                       printk("ID=%u SEQ=%u ",
+                       sb_add(m, "ID=%u SEQ=%u ",
                                ntohs(ic->icmp6_identifier),
                                ntohs(ic->icmp6_sequence));
                        break;
@@ -334,35 +333,35 @@ static void dump_packet(const struct nf_loginfo *info,
 
                case ICMPV6_PARAMPROB:
                        /* Max length: 17 "POINTER=ffffffff " */
-                       printk("POINTER=%08x ", ntohl(ic->icmp6_pointer));
+                       sb_add(m, "POINTER=%08x ", ntohl(ic->icmp6_pointer));
                        /* Fall through */
                case ICMPV6_DEST_UNREACH:
                case ICMPV6_PKT_TOOBIG:
                case ICMPV6_TIME_EXCEED:
                        /* Max length: 3+maxlen */
                        if (recurse) {
-                               printk("[");
-                               dump_packet(info, skb, ptr + sizeof(_icmp6h),
-                                           0);
-                               printk("] ");
+                               sb_add(m, "[");
+                               dump_packet(m, info, skb,
+                                           ptr + sizeof(_icmp6h), 0);
+                               sb_add(m, "] ");
                        }
 
                        /* Max length: 10 "MTU=65535 " */
                        if (ic->icmp6_type == ICMPV6_PKT_TOOBIG)
-                               printk("MTU=%u ", ntohl(ic->icmp6_mtu));
+                               sb_add(m, "MTU=%u ", ntohl(ic->icmp6_mtu));
                }
                break;
        }
        /* Max length: 10 "PROTO=255 " */
        default:
-               printk("PROTO=%u ", currenthdr);
+               sb_add(m, "PROTO=%u ", currenthdr);
        }
 
        /* Max length: 15 "UID=4294967295 " */
        if ((logflags & IP6T_LOG_UID) && recurse && skb->sk) {
                read_lock_bh(&skb->sk->sk_callback_lock);
                if (skb->sk->sk_socket && skb->sk->sk_socket->file)
-                       printk("UID=%u GID=%u ",
+                       sb_add(m, "UID=%u GID=%u ",
                                skb->sk->sk_socket->file->f_cred->fsuid,
                                skb->sk->sk_socket->file->f_cred->fsgid);
                read_unlock_bh(&skb->sk->sk_callback_lock);
@@ -370,10 +369,11 @@ static void dump_packet(const struct nf_loginfo *info,
 
        /* Max length: 16 "MARK=0xFFFFFFFF " */
        if (!recurse && skb->mark)
-               printk("MARK=0x%x ", skb->mark);
+               sb_add(m, "MARK=0x%x ", skb->mark);
 }
 
-static void dump_mac_header(const struct nf_loginfo *info,
+static void dump_mac_header(struct sbuff *m,
+                           const struct nf_loginfo *info,
                            const struct sk_buff *skb)
 {
        struct net_device *dev = skb->dev;
@@ -387,7 +387,7 @@ static void dump_mac_header(const struct nf_loginfo *info,
 
        switch (dev->type) {
        case ARPHRD_ETHER:
-               printk("MACSRC=%pM MACDST=%pM MACPROTO=%04x ",
+               sb_add(m, "MACSRC=%pM MACDST=%pM MACPROTO=%04x ",
                       eth_hdr(skb)->h_source, eth_hdr(skb)->h_dest,
                       ntohs(eth_hdr(skb)->h_proto));
                return;
@@ -396,7 +396,7 @@ static void dump_mac_header(const struct nf_loginfo *info,
        }
 
 fallback:
-       printk("MAC=");
+       sb_add(m, "MAC=");
        if (dev->hard_header_len &&
            skb->mac_header != skb->network_header) {
                const unsigned char *p = skb_mac_header(skb);
@@ -408,19 +408,19 @@ fallback:
                        p = NULL;
 
                if (p != NULL) {
-                       printk("%02x", *p++);
+                       sb_add(m, "%02x", *p++);
                        for (i = 1; i < len; i++)
-                               printk(":%02x", p[i]);
+                               sb_add(m, ":%02x", p[i]);
                }
-               printk(" ");
+               sb_add(m, " ");
 
                if (dev->type == ARPHRD_SIT) {
                        const struct iphdr *iph =
                                (struct iphdr *)skb_mac_header(skb);
-                       printk("TUNNEL=%pI4->%pI4 ", &iph->saddr, &iph->daddr);
+                       sb_add(m, "TUNNEL=%pI4->%pI4 ", &iph->saddr, &iph->daddr);
                }
        } else
-               printk(" ");
+               sb_add(m, " ");
 }
 
 static struct nf_loginfo default_loginfo = {
@@ -442,22 +442,23 @@ ip6t_log_packet(u_int8_t pf,
                const struct nf_loginfo *loginfo,
                const char *prefix)
 {
+       struct sbuff *m = sb_open();
+
        if (!loginfo)
                loginfo = &default_loginfo;
 
-       spin_lock_bh(&log_lock);
-       printk("<%d>%sIN=%s OUT=%s ", loginfo->u.log.level,
-               prefix,
-               in ? in->name : "",
-               out ? out->name : "");
+       sb_add(m, "<%d>%sIN=%s OUT=%s ", loginfo->u.log.level,
+              prefix,
+              in ? in->name : "",
+              out ? out->name : "");
 
        /* MAC logging for input path only. */
        if (in && !out)
-               dump_mac_header(loginfo, skb);
+               dump_mac_header(m, loginfo, skb);
+
+       dump_packet(m, loginfo, skb, skb_network_offset(skb), 1);
 
-       dump_packet(loginfo, skb, skb_network_offset(skb), 1);
-       printk("\n");
-       spin_unlock_bh(&log_lock);
+       sb_close(m);
 }
 
 static unsigned int