[SCM] GNU Inetutils branch, master, updated. inetutils-1_9_4-22-g05a2f93

[Mats Erik Andersson]

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- Log -----------------------------------------------------------------
http://git.savannah.gnu.org/cgit/inetutils.git/commit/?id=05a2f938e3f56ce0136966136410c5f9e20c37a7


commit 05a2f938e3f56ce0136966136410c5f9e20c37a7
Author: Mats Erik Andersson <address@hidden>
Date:   Fri Feb 12 14:45:33 2016 +0100

    ping: Implement subprivileged echo method.
    
    The change implements a setuid-less use case of echo pinging
    for use on GNU/Linux systems.  The new mode is the fallback
    when a raw socket mode fails.

diff --git a/ChangeLog b/ChangeLog
index 6b53b0c..3c42992 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,17 @@
+2016-02-12  Mats Erik Andersson  <address@hidden>
+
+       ping: Implement subprivileged echo method.
+       Add fallback code usable by GNU/Linux to create a datagram
+       socket for sending ICMP ECHOREQUEST.  The change is related
+       to issue #37252.
+
+       * ping/libping.c (useless_ident): New variable.
+       (ping_init): When a raw socket fails, fall back to a datagram
+       socket.  In case of success, increase `useless_ident' since
+       the kernel choses a packet identity, overwriting our choice.
+       (my_echo_reply, ping_recv): Short circuit the tests for packet
+       identity with the value of `useless_identity'.
+
 2016-02-09  Mats Erik Andersson  <address@hidden>
 
        * configure.ac (missing ipv6 or icmp6): Disable `ping6' using
diff --git a/ping/libping.c b/ping/libping.c
index e85d58b..0d77d41 100644
--- a/ping/libping.c
+++ b/ping/libping.c
@@ -39,6 +39,8 @@
 
 #include "ping.h"
 
+static int useless_ident = 0;  /* Relevant at least for Linux.  */
+
 static size_t _ping_packetsize (PING * p);
 
 size_t
@@ -72,8 +74,28 @@ ping_init (int type, int ident)
   if (fd < 0)
     {
       if (errno == EPERM || errno == EACCES)
-       fprintf (stderr, "ping: Lacking privilege for raw socket.\n");
-      return NULL;
+       {
+         errno = 0;
+
+         /* At least Linux can allow subprivileged users to send ICMP
+          * packets formally encapsulated and built as a datagram socket,
+          * but then the identity number is set by the kernel itself.
+          */
+         fd = socket (AF_INET, SOCK_DGRAM, proto->p_proto);
+         if (fd < 0)
+           {
+             if (errno == EPERM || errno == EACCES || errno == EPROTONOSUPPORT)
+               fprintf (stderr, "ping: Lacking privilege for icmp socket.\n");
+             else
+               fprintf (stderr, "ping: %s\n", strerror (errno));
+
+             return NULL;
+           }
+
+         useless_ident++;      /* SOCK_DGRAM overrides our set identity.  */
+       }
+      else
+       return NULL;
     }
 
   /* Allocate PING structure and initialize it to default values */
@@ -172,7 +194,7 @@ my_echo_reply (PING * p, icmphdr_t * icmp)
   return (orig_ip->ip_dst.s_addr == p->ping_dest.ping_sockaddr.sin_addr.s_addr
          && orig_ip->ip_p == IPPROTO_ICMP
          && orig_icmp->icmp_type == ICMP_ECHO
-         && ntohs (orig_icmp->icmp_id) == p->ping_ident);
+         && (ntohs (orig_icmp->icmp_id) == p->ping_ident || useless_ident));
 }
 
 int
@@ -206,7 +228,7 @@ ping_recv (PING * p)
     case ICMP_ADDRESSREPLY:
       /*    case ICMP_ROUTERADV: */
 
-      if (ntohs (icmp->icmp_id) != p->ping_ident)
+      if (ntohs (icmp->icmp_id) != p->ping_ident && useless_ident == 0)
        return -1;
 
       if (rc)

-----------------------------------------------------------------------

Summary of changes:
 ChangeLog      |   14 ++++++++++++++
 ping/libping.c |   30 ++++++++++++++++++++++++++----
 2 files changed, 40 insertions(+), 4 deletions(-)


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