From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiederm@xmission.com (Eric W. Biederman) Subject: Re: [RFC PATCH 0/5] net: socket bind to file descriptor introduced Date: Wed, 15 Aug 2012 14:25:42 -0700 Message-ID: <87k3wzalux.fsf@xmission.com> References: <20120815161141.7598.16682.stgit@localhost.localdomain> <87a9xwc4vr.fsf@xmission.com> <502C0D7C.2040707@zytor.com> Mime-Version: 1.0 Content-Type: text/plain Cc: Stanislav Kinsbursky , tglx@linutronix.de, mingo@redhat.com, davem@davemloft.net, thierry.reding@avionic-design.de, bfields@redhat.com, eric.dumazet@gmail.com, xemul@parallels.com, neilb@suse.de, netdev@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, paul.gortmaker@windriver.com, viro@zeniv.linux.org.uk, gorcunov@openvz.org, akpm@linux-foundation.org, tim.c.chen@linux.intel.com, devel@openvz.org To: "H. Peter Anvin" Return-path: In-Reply-To: <502C0D7C.2040707@zytor.com> (H. Peter Anvin's message of "Wed, 15 Aug 2012 13:58:36 -0700") Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org "H. Peter Anvin" writes: > On 08/15/2012 12:49 PM, Eric W. Biederman wrote: >> >> There is also the trick of getting a shorter directory name using >> /proc/self/fd if you are threaded and can't change the directory. >> >> The obvious choices at this point are >> - Teach bind and connect and af_unix sockets to take longer AF_UNIX >> socket path names. >> >> - introduce sockaddr_fd that can be applied to AF_UNIX sockets, >> and teach unix_bind and unix_connect how to deal with a second type of sockaddr. >> struct sockaddr_fd { short fd_family; short pad; int fd; }; >> >> - introduce sockaddr_unix_at that takes a directory file descriptor >> as well as a unix path, and teach unix_bind and unix_connect to deal with a >> second sockaddr type. >> struct sockaddr_unix_at { short family; short pad; int dfd; char path[102]; } >> AF_UNIX_AT >> >> I don't know what the implications of for breaking connect up into 3 >> system calls and changing the semantics are and I would really rather >> not have to think about it. >> >> But it certainly does not look to me like you introduce new systems >> calls to do what you want. >> > > How would you distinguish the new sockaddr types from the traditional > one? New AF_? Yeah. AF_FD or AF_UNIX_AT is what I was thinking. The way the code falls out that should be compartively simple to implement. recvmsg etc would give you sockaddr_un sockets when they come from the kernel. Eric