mdw@git.distorted.org.uk Git - yaid/blob - linux.c

   1 /* -*-c-*-
   2  *
   3  * Discover the owner of a connection (Linux version)
   4  *
   5  * (c) 2012 Straylight/Edgeware
   6  */
   7
   8 /*----- Licensing notice --------------------------------------------------*
   9  *
  10  * This file is part of Yet Another Ident Daemon (YAID).
  11  *
  12  * YAID is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License as published by
  14  * the Free Software Foundation; either version 2 of the License, or
  15  * (at your option) any later version.
  16  *
  17  * YAID is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with YAID; if not, write to the Free Software Foundation,
  24  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  25  */
  26
  27 /*----- Header files ------------------------------------------------------*/
  28
  29 #include "yaid.h"
  30
  31 /*----- Static variables --------------------------------------------------*/
  32
  33 static FILE *natfp;
  34
  35 /*----- Address-type operations -------------------------------------------*/
  36
  37 struct addrops_sys {
  38   const char *procfile;
  39   const char *nfl3name;
  40   int (*parseaddr)(char **, union addr *);
  41 };
  42
  43 #define PROCFILE_IPV4 "/proc/net/tcp"
  44 #define NFL3NAME_IPV4 "ipv4"
  45
  46 static int parseaddr_ipv4(char **pp, union addr *a)
  47   { a->ipv4.s_addr = strtoul(*pp, pp, 16); return (0); }
  48
  49 #define PROCFILE_IPV6 "/proc/net/tcp6"
  50 #define NFL3NAME_IPV6 "ipv6"
  51
  52 static int parseaddr_ipv6(char **pp, union addr *a)
  53 {
  54   int i, j;
  55   unsigned long y;
  56   char *p = *pp;
  57   unsigned x;
  58
  59   for (i = 0; i < 4; i++) {
  60     y = 0;
  61     for (j = 0; j < 8; j++) {
  62       if ('0' <= *p && *p <= '9') x = *p - '0';
  63       else if ('a' <= *p && *p <= 'f') x = *p - 'a'+ 10;
  64       else if ('A' <= *p && *p <= 'F') x = *p - 'A'+ 10;
  65       else return (-1);
  66       y = (y << 4) | x;
  67       p++;
  68     }
  69     a->ipv6.s6_addr32[i] = y;
  70   }
  71   *pp = p;
  72   return (0);
  73 }
  74
  75 #define DEFOPSYS(ty, TY)                                                \
  76   const struct addrops_sys addrops_sys_##ty = {                         \
  77     PROCFILE_##TY, NFL3NAME_##TY, parseaddr_##ty                        \
  78   };
  79 ADDRTYPES(DEFOPSYS)
  80 #undef DEFOPSYS
  81
  82 /*----- Main code ---------------------------------------------------------*/
  83
  84 static int get_default_gw(int af, union addr *a)
  85 {
  86   int fd;
  87   char buf[32768];
  88   struct nlmsghdr *nlmsg;
  89   struct rtgenmsg *rtgen;
  90   const struct rtattr *rta;
  91   const struct rtmsg *rtm;
  92   ssize_t n, nn;
  93   int rc = 0;
  94   static unsigned long seq = 0x48b4aec4;
  95
  96   if ((fd = socket(AF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE)) < 0)
  97     die(1, "failed to create netlink socket: %s", strerror(errno));
  98
  99   nlmsg = (struct nlmsghdr *)buf;
 100   assert(NLMSG_SPACE(sizeof(*rtgen)) < sizeof(buf));
 101   nlmsg->nlmsg_len = NLMSG_LENGTH(sizeof(*rtgen));
 102   nlmsg->nlmsg_type = RTM_GETROUTE;
 103   nlmsg->nlmsg_flags = NLM_F_REQUEST | NLM_F_ROOT;
 104   nlmsg->nlmsg_seq = ++seq;
 105   nlmsg->nlmsg_pid = 0;
 106
 107   rtgen = (struct rtgenmsg *)NLMSG_DATA(nlmsg);
 108   rtgen->rtgen_family = af;
 109
 110   if (write(fd, nlmsg, nlmsg->nlmsg_len) < 0)
 111     die(1, "failed to send RTM_GETROUTE request: %s", strerror(errno));
 112
 113   for (;;) {
 114     if ((n = read(fd, buf, sizeof(buf))) < 0)
 115       die(1, "failed to read RTM_GETROUTE response: %s", strerror(errno));
 116     nlmsg = (struct nlmsghdr *)buf;
 117     if (nlmsg->nlmsg_seq != seq) continue;
 118     assert(nlmsg->nlmsg_flags & NLM_F_MULTI);
 119
 120     for (; NLMSG_OK(nlmsg, n); nlmsg = NLMSG_NEXT(nlmsg, n)) {
 121       if (nlmsg->nlmsg_type == NLMSG_DONE) goto done;
 122       if (nlmsg->nlmsg_type != RTM_NEWROUTE) continue;
 123       rtm = (const struct rtmsg *)NLMSG_DATA(nlmsg);
 124
 125       if (rtm->rtm_family != af ||
 126           rtm->rtm_dst_len > 0 ||
 127           rtm->rtm_src_len > 0 ||
 128           rtm->rtm_type != RTN_UNICAST ||
 129           rtm->rtm_scope != RT_SCOPE_UNIVERSE ||
 130           rtm->rtm_tos != 0)
 131         continue;
 132
 133       for (rta = RTM_RTA(rtm), nn = RTM_PAYLOAD(nlmsg);
 134            RTA_OK(rta, nn); rta = RTA_NEXT(rta, nn)) {
 135         if (rta->rta_type == RTA_GATEWAY) {
 136           assert(RTA_PAYLOAD(rta) <= sizeof(*a));
 137           memcpy(a, RTA_DATA(rta), RTA_PAYLOAD(rta));
 138           rc = 1;
 139         }
 140       }
 141     }
 142   }
 143
 144 done:
 145   close(fd);
 146   return (rc);
 147 }
 148
 149 void identify(struct query *q)
 150 {
 151   FILE *fp = 0;
 152   dstr d = DSTR_INIT;
 153   char *p, *pp;
 154   struct socket s[4];
 155   int i;
 156   int gwp = 0;
 157   unsigned fl;
 158 #define F_SADDR 1u
 159 #define F_SPORT 2u
 160 #define F_DADDR 4u
 161 #define F_DPORT 8u
 162 #define F_ALL (F_SADDR | F_SPORT | F_DADDR | F_DPORT)
 163 #define F_ESTAB 16u
 164   uid_t uid;
 165   enum { LOC, REM, ST, UID, NFIELD };
 166   int f, ff[NFIELD];
 167
 168   if (get_default_gw(q->ao->af, &s[0].addr) &&
 169       q->ao->addreq(&s[0].addr, &q->s[R].addr))
 170     gwp = 1;
 171
 172   if ((fp = fopen(q->ao->sys->procfile, "r")) == 0) {
 173     logmsg(q, LOG_ERR, "failed to open `%s' for reading: %s",
 174            q->ao->sys->procfile, strerror(errno));
 175     goto err_unk;
 176   }
 177
 178 #define NEXTFIELD do {                                                  \
 179   for (p = pp; isspace((unsigned char)*p); p++);                        \
 180   for (pp = p; *pp && !isspace((unsigned char)*pp); pp++);              \
 181   if (*pp) *pp++ = 0;                                                   \
 182 } while (0)
 183
 184   if (dstr_putline(&d, fp) == EOF) {
 185     logmsg(q, LOG_ERR, "failed to read header line from `%s': %s",
 186            q->ao->sys->procfile,
 187            ferror(fp) ? strerror(errno) : "unexpected EOF");
 188     goto err_unk;
 189   }
 190
 191   for (i = 0; i < NFIELD; i++) ff[i] = -1;
 192   pp = d.buf;
 193   for (f = 0;; f++) {
 194     NEXTFIELD; if (!*p) break;
 195     if (strcmp(p, "local_address") == 0)
 196       ff[LOC] = f;
 197     else if (strcmp(p, "rem_address") == 0 ||
 198              strcmp(p, "remote_address") == 0)
 199       ff[REM] = f;
 200     else if (strcmp(p, "uid") == 0)
 201       ff[UID] = f;
 202     else if (strcmp(p, "st") == 0)
 203       ff[ST] = f;
 204     else if (strcmp(p, "rx_queue") == 0 ||
 205              strcmp(p, "tm->when") == 0)
 206       f--;
 207   }
 208   for (i = 0; i < NFIELD; i++) {
 209     if (ff[i] < 0) {
 210       logmsg(q, LOG_ERR, "failed to find required fields in `%s'",
 211              q->ao->sys->procfile);
 212       goto err_unk;
 213     }
 214   }
 215
 216   for (;;) {
 217     DRESET(&d);
 218     if (dstr_putline(&d, fp) == EOF) break;
 219     pp = d.buf;
 220     uid = -1;
 221     for (f = 0;; f++) {
 222       NEXTFIELD; if (!*p) break;
 223       if (f == ff[LOC]) { i = L; goto compare; }
 224       else if (f == ff[REM]) { i = R; goto compare; }
 225       else if (f == ff[UID]) uid = atoi(p);
 226       else if (f == ff[ST]) {
 227         if (strtol(p, 0, 16) != 1) goto next_row;
 228       }
 229       continue;
 230
 231     compare:
 232       if (q->ao->sys->parseaddr(&p, &s[0].addr)) goto next_row;
 233       if (*p != ':') break; p++;
 234       s[0].port = strtoul(p, 0, 16);
 235       if (!sockeq(q->ao, &q->s[i], &s[0]) &&
 236           (i != R || !gwp || q->s[R].port != s[0].port))
 237         goto next_row;
 238     }
 239     if (uid != -1) {
 240       q->resp = R_UID;
 241       q->u.uid = uid;
 242       goto done;
 243     }
 244   next_row:;
 245   }
 246
 247   if (ferror(fp)) {
 248     logmsg(q, LOG_ERR, "failed to read connection table `%s': %s",
 249            q->ao->sys->procfile, strerror(errno));
 250     goto err_unk;
 251   }
 252
 253   if (natfp) {
 254     rewind(natfp);
 255
 256     for (;;) {
 257       DRESET(&d);
 258       if (dstr_putline(&d, natfp) == EOF) break;
 259       pp = d.buf;
 260
 261       NEXTFIELD; if (!*p) break;
 262       if (strcmp(p, q->ao->sys->nfl3name)) continue;
 263       NEXTFIELD; if (!*p) break;
 264       NEXTFIELD; if (!*p) break;
 265       if (strcmp(p, "tcp") != 0) continue;
 266       i = 0;
 267       fl = 0;
 268       for (;;) {
 269         NEXTFIELD; if (!*p) break;
 270         if (strcmp(p, "ESTABLISHED") == 0)
 271           fl |= F_ESTAB;
 272         else if (strncmp(p, "src=", 4) == 0) {
 273           inet_pton(q->ao->af, p + 4, &s[i].addr);
 274           fl |= F_SADDR;
 275         } else if (strncmp(p, "dst=", 4) == 0) {
 276           inet_pton(q->ao->af, p + 4, &s[i + 1].addr);
 277           fl |= F_DADDR;
 278         } else if (strncmp(p, "sport=", 6) == 0) {
 279           s[i].port = atoi(p + 6);
 280           fl |= F_SPORT;
 281         } else if (strncmp(p, "dport=", 6) == 0) {
 282           s[i + 1].port = atoi(p + 6);
 283           fl |= F_DPORT;
 284         }
 285         if ((fl & F_ALL) == F_ALL) {
 286           fl &= ~F_ALL;
 287           if (i < 4) i += 2;
 288           else break;
 289         }
 290       }
 291
 292 #ifdef notdef
 293       {
 294         dstr dd = DSTR_INIT;
 295         dstr_putf(&dd, "%sestab ", (fl & F_ESTAB) ? " " : "!");
 296         dputsock(&dd, q->ao, &s[0]);
 297         dstr_puts(&dd, "<->");
 298         dputsock(&dd, q->ao, &s[1]);
 299         dstr_puts(&dd, " | ");
 300         dputsock(&dd, q->ao, &s[2]);
 301         dstr_puts(&dd, "<->");
 302         dputsock(&dd, q->ao, &s[3]);
 303         printf("parsed: %s\n", dd.buf);
 304         dstr_destroy(&dd);
 305       }
 306 #endif
 307
 308       if (!(fl & F_ESTAB)) continue;
 309
 310       for (i = 0; i < 4; i++)
 311         if (sockeq(q->ao, &s[i], &q->s[L])) goto found_local;
 312       continue;
 313       putchar('.');
 314     found_local:
 315       if (!sockeq(q->ao, &s[i^1], &s[i^2]) ||
 316           !sockeq(q->ao, &s[i^1], &q->s[R]))
 317         continue;
 318       q->resp = R_NAT;
 319       q->u.nat = s[i^3];
 320       goto done;
 321     }
 322
 323     /* Reached the end of the NAT file. */
 324     if (ferror(natfp)) {
 325       logmsg(q, LOG_ERR, "failed to read `/proc/net/nf_conntrack': %s",
 326              strerror(errno));
 327       goto err_unk;
 328     }
 329   }
 330
 331 #undef NEXTFIELD
 332
 333   logmsg(q, LOG_NOTICE, "connection not found");
 334   q->resp = R_ERROR;
 335   q->u.error = E_NOUSER;
 336   goto done;
 337 err_unk:
 338   q->resp = R_ERROR;
 339   q->u.error = E_UNKNOWN;
 340 done:
 341   dstr_destroy(&d);
 342   if (fp) fclose(fp);
 343 }
 344
 345 void init_sys(void)
 346 {
 347   if ((natfp = fopen("/proc/net/nf_conntrack", "r")) == 0 &&
 348       errno != ENOENT) {
 349     die(1, "failed to open `/proc/net/nf_conntrack' for reading: %s",
 350         strerror(errno));
 351   }
 352 }
 353
 354 /*----- That's all, folks -------------------------------------------------*/