Date: Wed, 12 Sep 2012 09:50:18 +0000 (UTC) From: Gleb Smirnoff <glebius@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r240385 - head/lib/libc/sys Message-ID: <201209120950.q8C9oIcP039955@svn.freebsd.org>
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Author: glebius Date: Wed Sep 12 09:50:17 2012 New Revision: 240385 URL: http://svn.freebsd.org/changeset/base/240385 Log: Describe in detail required conditions for receiving the SCM_CREDS control message and suggest to use LOCAL_CREDS setsockopt() for reliability. Modified: head/lib/libc/sys/recv.2 Modified: head/lib/libc/sys/recv.2 ============================================================================== --- head/lib/libc/sys/recv.2 Wed Sep 12 09:29:22 2012 (r240384) +++ head/lib/libc/sys/recv.2 Wed Sep 12 09:50:17 2012 (r240385) @@ -28,7 +28,7 @@ .\" @(#)recv.2 8.3 (Berkeley) 2/21/94 .\" $FreeBSD$ .\" -.Dd December 28, 2006 +.Dd September 12, 2012 .Dt RECV 2 .Os .Sh NAME @@ -252,8 +252,21 @@ struct cmsgcred { }; .Ed .Pp -The kernel will fill in the credential information of the sending process -and deliver it to the receiver. +If a sender supplies ancillary data with enough space for the above struct +tagged as +.Dv SCM_CREDS +control message type to the +.Fn sendmsg +system call, then kernel will fill in the credential information of the +sending process and deliver it to the receiver. +Since receiver usually has no control over a sender, this method of retrieving +credential information isn't reliable. +For reliable retrieval of remote side credentials it is advised to use the +.Dv LOCAL_CREDS +socket option on the receiving socket. +See +.Xr unix 4 +for details. .Pp The .Fa msg_flags @@ -322,7 +335,8 @@ address space. .Xr getsockopt 2 , .Xr read 2 , .Xr select 2 , -.Xr socket 2 +.Xr socket 2 , +.Xr unix 4 .Sh HISTORY The .Fn recv
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