package/network/services/dnsmasq/patches/002-fix-race-on-interface-flaps.patch

   1 From a0358e5ddbc1ef3dec791f11f95f5dbe56087a5e Mon Sep 17 00:00:00 2001
   2 From: Simon Kelley <simon@thekelleys.org.uk>
   3 Date: Sat, 7 Jun 2014 13:38:48 +0100
   4 Subject: [PATCH] Handle async notification of address changes using the event
   5  system.
   6
   7 ---
   8  CHANGELOG     |  4 ++++
   9  src/bpf.c     |  6 +++---
  10  src/dhcp6.c   | 10 ----------
  11  src/dnsmasq.c | 13 +++++++++++--
  12  src/dnsmasq.h |  6 ++++--
  13  src/netlink.c | 39 ++++++++++-----------------------------
  14  src/network.c | 11 +++--------
  15  7 files changed, 35 insertions(+), 54 deletions(-)
  16
  17 --- a/CHANGELOG
  18 +++ b/CHANGELOG
  19 @@ -15,6 +15,10 @@ version 2.71
  20             regression introduced in 2.69. Thanks to James Hunt and
  21             the Ubuntu crowd for assistance in fixing this.
  22
  23 +           Fix race condition which could lock up dnsmasq when an
  24 +           interface goes down and up rapidly. Thanks to Conrad
  25 +           Kostecki for helping to chase this down.
  26 +
  27
  28  version 2.70
  29              Fix crash, introduced in 2.69, on TCP request when dnsmasq
  30 --- a/src/bpf.c
  31 +++ b/src/bpf.c
  32 @@ -376,7 +376,7 @@ void route_init(void)
  33      die(_("cannot create PF_ROUTE socket: %s"), NULL, EC_BADNET);
  34  }
  35
  36 -void route_sock(time_t now)
  37 +void route_sock(void)
  38  {
  39    struct if_msghdr *msg;
  40    int rc = recv(daemon->routefd, daemon->packet, daemon->packet_buff_sz, 0);
  41 @@ -401,7 +401,7 @@ void route_sock(time_t now)
  42     else if (msg->ifm_type == RTM_NEWADDR)
  43       {
  44         del_family = 0;
  45 -       newaddress(now);
  46 +       send_newaddr();
  47       }
  48     else if (msg->ifm_type == RTM_DELADDR)
  49       {
  50 @@ -439,7 +439,7 @@ void route_sock(time_t now)
  51                of += sizeof(long) - (diff & (sizeof(long) - 1));
  52            }
  53
  54 -       newaddress(now);
  55 +       send_newaddr();
  56       }
  57  }
  58
  59 --- a/src/dnsmasq.c
  60 +++ b/src/dnsmasq.c
  61 @@ -917,10 +917,10 @@ int main (int argc, char **argv)
  62
  63  #if defined(HAVE_LINUX_NETWORK)
  64        if (FD_ISSET(daemon->netlinkfd, &rset))
  65 -       netlink_multicast(now);
  66 +       netlink_multicast();
  67  #elif defined(HAVE_BSD_NETWORK)
  68        if (FD_ISSET(daemon->routefd, &rset))
  69 -       route_sock(now);
  70 +       route_sock();
  71  #endif
  72
  73        /* Check for changes to resolv files once per second max. */
  74 @@ -1037,6 +1037,11 @@ void send_alarm(time_t event, time_t now
  75      }
  76  }
  77
  78 +void send_newaddr(void)
  79 +{
  80 +  send_event(pipewrite, EVENT_NEWADDR, 0, NULL);
  81 +}
  82 +
  83  void send_event(int fd, int event, int data, char *msg)
  84  {
  85    struct event_desc ev;
  86 @@ -1230,6 +1235,10 @@ static void async_event(int pipe, time_t
  87         if (daemon->log_file != NULL)
  88           log_reopen(daemon->log_file);
  89         break;
  90 +
  91 +      case EVENT_NEWADDR:
  92 +       newaddress(now);
  93 +       break;
  94
  95        case EVENT_TERM:
  96         /* Knock all our children on the head. */
  97 --- a/src/dnsmasq.h
  98 +++ b/src/dnsmasq.h
  99 @@ -165,6 +165,7 @@ struct event_desc {
 100  #define EVENT_LUA_ERR   19
 101  #define EVENT_TFTP_ERR  20
 102  #define EVENT_INIT      21
 103 +#define EVENT_NEWADDR   22
 104
 105  /* Exit codes. */
 106  #define EC_GOOD        0
 107 @@ -1289,6 +1290,7 @@ unsigned char *extended_hwaddr(int hwtyp
 108  int make_icmp_sock(void);
 109  int icmp_ping(struct in_addr addr);
 110  #endif
 111 +void send_newaddr(void);
 112  void send_alarm(time_t event, time_t now);
 113  void send_event(int fd, int event, int data, char *msg);
 114  void clear_cache_and_reload(time_t now);
 115 @@ -1297,7 +1299,7 @@ void poll_resolv(int force, int do_reloa
 116  /* netlink.c */
 117  #ifdef HAVE_LINUX_NETWORK
 118  void netlink_init(void);
 119 -void netlink_multicast(time_t now);
 120 +void netlink_multicast(void);
 121  #endif
 122
 123  /* bpf.c */
 124 @@ -1306,7 +1308,7 @@ void init_bpf(void);
 125  void send_via_bpf(struct dhcp_packet *mess, size_t len,
 126                   struct in_addr iface_addr, struct ifreq *ifr);
 127  void route_init(void);
 128 -void route_sock(time_t now);
 129 +void route_sock(void);
 130  #endif
 131
 132  /* bpf.c or netlink.c */
 133 --- a/src/netlink.c
 134 +++ b/src/netlink.c
 135 @@ -38,7 +38,7 @@
 136  static struct iovec iov;
 137  static u32 netlink_pid;
 138
 139 -static int nl_async(struct nlmsghdr *h);
 140 +static void nl_async(struct nlmsghdr *h);
 141
 142  void netlink_init(void)
 143  {
 144 @@ -142,7 +142,7 @@ int iface_enumerate(int family, void *pa
 145    struct nlmsghdr *h;
 146    ssize_t len;
 147    static unsigned int seq = 0;
 148 -  int callback_ok = 1, newaddr = 0;
 149 +  int callback_ok = 1;
 150
 151    struct {
 152      struct nlmsghdr nlh;
 153 @@ -191,21 +191,10 @@ int iface_enumerate(int family, void *pa
 154         if (h->nlmsg_seq != seq || h->nlmsg_pid != netlink_pid || h->nlmsg_type == NLMSG_ERROR)
 155           {
 156             /* May be multicast arriving async */
 157 -           if (nl_async(h))
 158 -             {
 159 -               newaddr = 1;
 160 -               enumerate_interfaces(1); /* reset */
 161 -             }
 162 +           nl_async(h);
 163           }
 164         else if (h->nlmsg_type == NLMSG_DONE)
 165 -         {
 166 -           /* handle async new interface address arrivals, these have to be done
 167 -              after we complete as we're not re-entrant */
 168 -           if (newaddr)
 169 -             newaddress(dnsmasq_time());
 170 -
 171 -           return callback_ok;
 172 -         }
 173 +         return callback_ok;
 174         else if (h->nlmsg_type == RTM_NEWADDR && family != AF_UNSPEC && family != AF_LOCAL)
 175           {
 176             struct ifaddrmsg *ifa = NLMSG_DATA(h);
 177 @@ -330,11 +319,11 @@ int iface_enumerate(int family, void *pa
 178      }
 179  }
 180
 181 -void netlink_multicast(time_t now)
 182 +void netlink_multicast(void)
 183  {
 184    ssize_t len;
 185    struct nlmsghdr *h;
 186 -  int flags, newaddr = 0;
 187 +  int flags;
 188
 189    /* don't risk blocking reading netlink messages here. */
 190    if ((flags = fcntl(daemon->netlinkfd, F_GETFL)) == -1 ||
 191 @@ -343,24 +332,19 @@ void netlink_multicast(time_t now)
 192
 193    if ((len = netlink_recv()) != -1)
 194      for (h = (struct nlmsghdr *)iov.iov_base; NLMSG_OK(h, (size_t)len); h = NLMSG_NEXT(h, len))
 195 -      if (nl_async(h))
 196 -       newaddr = 1;
 197 +      nl_async(h);
 198
 199    /* restore non-blocking status */
 200    fcntl(daemon->netlinkfd, F_SETFL, flags);
 201 -
 202 -  if (newaddr)
 203 -    newaddress(now);
 204  }
 205
 206 -static int nl_async(struct nlmsghdr *h)
 207 +static void nl_async(struct nlmsghdr *h)
 208  {
 209    if (h->nlmsg_type == NLMSG_ERROR)
 210      {
 211        struct nlmsgerr *err = NLMSG_DATA(h);
 212        if (err->error != 0)
 213         my_syslog(LOG_ERR, _("netlink returns error: %s"), strerror(-(err->error)));
 214 -      return 0;
 215      }
 216    else if (h->nlmsg_pid == 0 && h->nlmsg_type == RTM_NEWROUTE)
 217      {
 218 @@ -385,18 +369,15 @@ static int nl_async(struct nlmsghdr *h)
 219               else if (daemon->rfd_save && daemon->rfd_save->refcount != 0)
 220                 fd = daemon->rfd_save->fd;
 221               else
 222 -               return 0;
 223 +               return;
 224
 225               while(sendto(fd, daemon->packet, daemon->packet_len, 0,
 226                            &daemon->srv_save->addr.sa, sa_len(&daemon->srv_save->addr)) == -1 && retry_send());
 227             }
 228         }
 229 -      return 0;
 230      }
 231    else if (h->nlmsg_type == RTM_NEWADDR || h->nlmsg_type == RTM_DELADDR)
 232 -    return 1; /* clever bind mode - rescan */
 233 -
 234 -  return 0;
 235 +    send_newaddr();
 236  }
 237  #endif
 238
 239 --- a/src/network.c
 240 +++ b/src/network.c
 241 @@ -551,7 +551,7 @@ static int iface_allowed_v4(struct in_ad
 242  int enumerate_interfaces(int reset)
 243  {
 244    static struct addrlist *spare = NULL;
 245 -  static int done = 0, active = 0;
 246 +  static int done = 0;
 247    struct iface_param param;
 248    int errsave, ret = 1;
 249    struct addrlist *addr, *tmp;
 250 @@ -570,14 +570,11 @@ int enumerate_interfaces(int reset)
 251        return 1;
 252      }
 253
 254 -  if (done || active)
 255 +  if (done)
 256      return 1;
 257
 258    done = 1;
 259
 260 -  /* protect against recusive calls from iface_enumerate(); */
 261 -  active = 1;
 262 -
 263    if ((param.fd = socket(PF_INET, SOCK_DGRAM, 0)) == -1)
 264      return 0;
 265
 266 @@ -677,10 +674,8 @@ int enumerate_interfaces(int reset)
 267      }
 268
 269    errno = errsave;
 270 -
 271    spare = param.spare;
 272 -  active = 0;
 273 -
 274 +
 275    return ret;
 276  }
 277