net/sctp/probe.c

   1 /*
   2  * sctp_probe - Observe the SCTP flow with kprobes.
   3  *
   4  * The idea for this came from Werner Almesberger's umlsim
   5  * Copyright (C) 2004, Stephen Hemminger <shemminger@osdl.org>
   6  *
   7  * Modified for SCTP from Stephen Hemminger's code
   8  * Copyright (C) 2010, Wei Yongjun <yjwei@cn.fujitsu.com>
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License as published by
  12  * the Free Software Foundation; either version 2 of the License, or
  13  * (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, write to the Free Software
  22  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  23  */
  24
  25 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  26
  27 #include <linux/kernel.h>
  28 #include <linux/kprobes.h>
  29 #include <linux/socket.h>
  30 #include <linux/sctp.h>
  31 #include <linux/proc_fs.h>
  32 #include <linux/vmalloc.h>
  33 #include <linux/module.h>
  34 #include <linux/kfifo.h>
  35 #include <linux/time.h>
  36 #include <net/net_namespace.h>
  37
  38 #include <net/sctp/sctp.h>
  39 #include <net/sctp/sm.h>
  40
  41 MODULE_SOFTDEP("pre: sctp");
  42 MODULE_AUTHOR("Wei Yongjun <yjwei@cn.fujitsu.com>");
  43 MODULE_DESCRIPTION("SCTP snooper");
  44 MODULE_LICENSE("GPL");
  45
  46 static int port __read_mostly = 0;
  47 MODULE_PARM_DESC(port, "Port to match (0=all)");
  48 module_param(port, int, 0);
  49
  50 static unsigned int fwmark __read_mostly = 0;
  51 MODULE_PARM_DESC(fwmark, "skb mark to match (0=no mark)");
  52 module_param(fwmark, uint, 0);
  53
  54 static int bufsize __read_mostly = 64 * 1024;
  55 MODULE_PARM_DESC(bufsize, "Log buffer size (default 64k)");
  56 module_param(bufsize, int, 0);
  57
  58 static int full __read_mostly = 1;
  59 MODULE_PARM_DESC(full, "Full log (1=every ack packet received,  0=only cwnd changes)");
  60 module_param(full, int, 0);
  61
  62 static const char procname[] = "sctpprobe";
  63
  64 static struct {
  65         struct kfifo      fifo;
  66         spinlock_t        lock;
  67         wait_queue_head_t wait;
  68         struct timespec64 tstart;
  69 } sctpw;
  70
  71 static __printf(1, 2) void printl(const char *fmt, ...)
  72 {
  73         va_list args;
  74         int len;
  75         char tbuf[256];
  76
  77         va_start(args, fmt);
  78         len = vscnprintf(tbuf, sizeof(tbuf), fmt, args);
  79         va_end(args);
  80
  81         kfifo_in_locked(&sctpw.fifo, tbuf, len, &sctpw.lock);
  82         wake_up(&sctpw.wait);
  83 }
  84
  85 static int sctpprobe_open(struct inode *inode, struct file *file)
  86 {
  87         kfifo_reset(&sctpw.fifo);
  88         ktime_get_ts64(&sctpw.tstart);
  89
  90         return 0;
  91 }
  92
  93 static ssize_t sctpprobe_read(struct file *file, char __user *buf,
  94                               size_t len, loff_t *ppos)
  95 {
  96         int error = 0, cnt = 0;
  97         unsigned char *tbuf;
  98
  99         if (!buf)
 100                 return -EINVAL;
 101
 102         if (len == 0)
 103                 return 0;
 104
 105         tbuf = vmalloc(len);
 106         if (!tbuf)
 107                 return -ENOMEM;
 108
 109         error = wait_event_interruptible(sctpw.wait,
 110                                          kfifo_len(&sctpw.fifo) != 0);
 111         if (error)
 112                 goto out_free;
 113
 114         cnt = kfifo_out_locked(&sctpw.fifo, tbuf, len, &sctpw.lock);
 115         error = copy_to_user(buf, tbuf, cnt) ? -EFAULT : 0;
 116
 117 out_free:
 118         vfree(tbuf);
 119
 120         return error ? error : cnt;
 121 }
 122
 123 static const struct file_operations sctpprobe_fops = {
 124         .owner  = THIS_MODULE,
 125         .open   = sctpprobe_open,
 126         .read   = sctpprobe_read,
 127         .llseek = noop_llseek,
 128 };
 129
 130 static sctp_disposition_t jsctp_sf_eat_sack(struct net *net,
 131                                             const struct sctp_endpoint *ep,
 132                                             const struct sctp_association *asoc,
 133                                             const sctp_subtype_t type,
 134                                             void *arg,
 135                                             sctp_cmd_seq_t *commands)
 136 {
 137         struct sctp_chunk *chunk = arg;
 138         struct sk_buff *skb = chunk->skb;
 139         struct sctp_transport *sp;
 140         static __u32 lcwnd = 0;
 141         struct timespec64 now;
 142
 143         sp = asoc->peer.primary_path;
 144
 145         if (((port == 0 && fwmark == 0) ||
 146              asoc->peer.port == port ||
 147              ep->base.bind_addr.port == port ||
 148              (fwmark > 0 && skb->mark == fwmark)) &&
 149             (full || sp->cwnd != lcwnd)) {
 150                 lcwnd = sp->cwnd;
 151
 152                 ktime_get_ts64(&now);
 153                 now = timespec64_sub(now, sctpw.tstart);
 154
 155                 printl("%lu.%06lu ", (unsigned long) now.tv_sec,
 156                        (unsigned long) now.tv_nsec / NSEC_PER_USEC);
 157
 158                 printl("%p %5d %5d %5d %8d %5d ", asoc,
 159                        ep->base.bind_addr.port, asoc->peer.port,
 160                        asoc->pathmtu, asoc->peer.rwnd, asoc->unack_data);
 161
 162                 list_for_each_entry(sp, &asoc->peer.transport_addr_list,
 163                                         transports) {
 164                         if (sp == asoc->peer.primary_path)
 165                                 printl("*");
 166
 167                         printl("%pISc %2u %8u %8u %8u %8u %8u ",
 168                                &sp->ipaddr, sp->state, sp->cwnd, sp->ssthresh,
 169                                sp->flight_size, sp->partial_bytes_acked,
 170                                sp->pathmtu);
 171                 }
 172                 printl("\n");
 173         }
 174
 175         jprobe_return();
 176         return 0;
 177 }
 178
 179 static struct jprobe sctp_recv_probe = {
 180         .kp     = {
 181                 .symbol_name = "sctp_sf_eat_sack_6_2",
 182         },
 183         .entry  = jsctp_sf_eat_sack,
 184 };
 185
 186 static __init int sctp_setup_jprobe(void)
 187 {
 188         int ret = register_jprobe(&sctp_recv_probe);
 189
 190         if (ret) {
 191                 if (request_module("sctp"))
 192                         goto out;
 193                 ret = register_jprobe(&sctp_recv_probe);
 194         }
 195
 196 out:
 197         return ret;
 198 }
 199
 200 static __init int sctpprobe_init(void)
 201 {
 202         int ret = -ENOMEM;
 203
 204         /* Warning: if the function signature of sctp_sf_eat_sack_6_2,
 205          * has been changed, you also have to change the signature of
 206          * jsctp_sf_eat_sack, otherwise you end up right here!
 207          */
 208         BUILD_BUG_ON(__same_type(sctp_sf_eat_sack_6_2,
 209                                  jsctp_sf_eat_sack) == 0);
 210
 211         init_waitqueue_head(&sctpw.wait);
 212         spin_lock_init(&sctpw.lock);
 213         if (kfifo_alloc(&sctpw.fifo, bufsize, GFP_KERNEL))
 214                 return ret;
 215
 216         if (!proc_create(procname, S_IRUSR, init_net.proc_net,
 217                          &sctpprobe_fops))
 218                 goto free_kfifo;
 219
 220         ret = sctp_setup_jprobe();
 221         if (ret)
 222                 goto remove_proc;
 223
 224         pr_info("probe registered (port=%d/fwmark=%u) bufsize=%u\n",
 225                 port, fwmark, bufsize);
 226         return 0;
 227
 228 remove_proc:
 229         remove_proc_entry(procname, init_net.proc_net);
 230 free_kfifo:
 231         kfifo_free(&sctpw.fifo);
 232         return ret;
 233 }
 234
 235 static __exit void sctpprobe_exit(void)
 236 {
 237         kfifo_free(&sctpw.fifo);
 238         remove_proc_entry(procname, init_net.proc_net);
 239         unregister_jprobe(&sctp_recv_probe);
 240 }
 241
 242 module_init(sctpprobe_init);
 243 module_exit(sctpprobe_exit);