Throw PNSE if insufficient privileges when custom Ping payload was specified

src/libraries/System.Net.Ping/src/Resources/Strings.resx

@@ -87,4 +87,7 @@
   <data name="SystemNetPing_PlatformNotSupported" xml:space="preserve">
     <value>System.Net.Ping is not supported on this platform.</value>
   </data>
-</root>
+  <data name="net_ping_utility_custom_payload" xml:space="preserve">
+    <value>Unable to send custom ping payload. Run program under privileged user account or grant cap_net_raw capability using setcap(8).</value>
+  </data>
+</root>

src/libraries/System.Net.Ping/src/System/Net/NetworkInformation/Ping.PingUtility.cs

@@ -24,6 +24,14 @@ private Process GetPingProcess(IPAddress address, byte[] buffer, int timeout, Pi
                 throw new PlatformNotSupportedException(SR.net_ping_utility_not_found);
             }
 
+            // although the ping utility supports custom pattern via -p option, it supports
+            // specifying only up to 16B pattern which repeats in the payload. The option also might
+            // not be present in all distributions, so we forbid ping payload in general.
+            if (buffer != DefaultSendBuffer && buffer != Array.Empty<byte>())
+            {
+                throw new PlatformNotSupportedException(SR.net_ping_utility_custom_payload);
+            }
+
             UnixCommandLinePing.PingFragmentOptions fragmentOption = UnixCommandLinePing.PingFragmentOptions.Default;
             if (options != null && address.AddressFamily == AddressFamily.InterNetwork)
             {

src/libraries/System.Net.Ping/src/System/Net/NetworkInformation/Ping.cs

@@ -227,7 +227,7 @@ public PingReply Send(IPAddress address, int timeout, byte[] buffer, PingOptions
             {
                 return SendPingCore(addressSnapshot, buffer, timeout, options);
             }
-            catch (Exception e)
+            catch (Exception e) when (e is not PlatformNotSupportedException)
             {
                 throw new PingException(SR.net_ping, e);
             }
@@ -336,7 +336,7 @@ private async Task<PingReply> SendPingAsyncInternal(IPAddress address, int timeo
                 Task<PingReply> pingReplyTask = SendPingAsyncCore(addressSnapshot, buffer, timeout, options);
                 return await pingReplyTask.ConfigureAwait(false);
             }
-            catch (Exception e)
+            catch (Exception e) when (e is not PlatformNotSupportedException)
             {
                 throw new PingException(SR.net_ping, e);
             }
@@ -388,7 +388,7 @@ private PingReply GetAddressAndSend(string hostNameOrAddress, int timeout, byte[
                 IPAddress[] addresses = Dns.GetHostAddresses(hostNameOrAddress);
                 return SendPingCore(addresses[0], buffer, timeout, options);
             }
-            catch (Exception e)
+            catch (Exception e) when (e is not PlatformNotSupportedException)
             {
                 throw new PingException(SR.net_ping, e);
             }
@@ -407,7 +407,7 @@ private async Task<PingReply> GetAddressAndSendAsync(string hostNameOrAddress, i
                 Task<PingReply> pingReplyTask = SendPingAsyncCore(addresses[0], buffer, timeout, options);
                 return await pingReplyTask.ConfigureAwait(false);
             }
-            catch (Exception e)
+            catch (Exception e) when (e is not PlatformNotSupportedException)
             {
                 throw new PingException(SR.net_ping, e);
             }