Hello Stephen, On 9/14/20 8:07 PM, Stephen Smalley wrote: > SO_PEERSEC was introduced for AF_UNIX stream sockets connected via > connect(2) in Linux 2.6.2 [1] and later augmented to support AF_UNIX stream > and datagram sockets created via socketpair(2) in Linux 4.18 [2]. Document > SO_PEERSEC in the socket.7 and unix.7 man pages following the example > of the existing SO_PEERCRED descriptions. SO_PEERSEC is also supported > on AF_INET sockets when using labeled IPSEC or NetLabel but defer > adding a description of that support to a separate patch. > > The module-independent description of the security context returned > by SO_PEERSEC is from Simon McVittie <smcv@xxxxxxxxxxxxx>. > > [1] https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/?id=da6e57a2e6bd7939f610d957afacaf6a131e75ed > > [2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=0b811db2cb2aabc910e53d34ebb95a15997c33e7 > > Signed-off-by: Stephen Smalley <stephen.smalley.work@xxxxxxxxx> > --- > v2 adds kernel commit info to the description and man page and uses > the suggested text from Simon McVittie for the description of > the security context string in a module-neutral way. Thanks. I've applied this patch, and added Serge's Reviewed-by. Cheers, Michael > > man7/socket.7 | 5 +++++ > man7/unix.7 | 46 ++++++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 51 insertions(+) > > diff --git a/man7/socket.7 b/man7/socket.7 > index 21e891791..c3635f95b 100644 > --- a/man7/socket.7 > +++ b/man7/socket.7 > @@ -690,6 +690,11 @@ Return the credentials of the peer process connected to this socket. > For further details, see > .BR unix (7). > .TP > +.BR SO_PEERSEC " (since Linux 2.6.2)" > +Return the security context of the peer socket connected to this socket. > +For further details, see > +.BR unix (7). > +.TP > .B SO_PRIORITY > Set the protocol-defined priority for all packets to be sent on > this socket. > diff --git a/man7/unix.7 b/man7/unix.7 > index 50828a5bc..298521d4a 100644 > --- a/man7/unix.7 > +++ b/man7/unix.7 > @@ -349,6 +349,52 @@ stream sockets and for > .B AF_UNIX > stream and datagram socket pairs created using > .BR socketpair (2). > +.TP > +.B SO_PEERSEC > +This read-only socket option returns the > +security context of the peer socket connected to this socket. > +By default, this will be the same as the security context of > +the process that created the peer socket unless overridden > +by the policy or by a process with the required permissions. > +.IP > +The argument to > +.BR getsockopt (2) > +is a pointer to a > +buffer of the specified length in bytes > +into which the security context string will be copied. > +If the buffer length is less than the length of the security > +context string, then > +.BR getsockopt (2) > +will return the required length > +via > +.I optlen > +and return \-1 and sets > +.I errno > +to > +.BR ERANGE . > +The caller should allocate at least > +.BR NAME_MAX > +bytes for the buffer initially although this is not guaranteed > +to be sufficient. Resizing the buffer to the returned length > +and retrying may be necessary. > +.IP > +The security context string may include a terminating null character > +in the returned length, but is not guaranteed to do so: a security > +context "foo" might be represented as either {'f','o','o'} of length 3 > +or {'f','o','o','\\0'} of length 4, which are considered to be > +interchangeable. It is printable, does not contain non-terminating > +null characters, and is in an unspecified encoding (in particular it > +is not guaranteed to be ASCII or UTF-8). > +.IP > +The use of this option for sockets in the > +.B AF_UNIX > +address family > +is supported since Linux 2.6.2 for connected stream sockets and > +since Linux 4.18, > +.\" commit 0b811db2cb2aabc910e53d34ebb95a15997c33e7 > +also for stream and datagram socket pairs created > +using > +.BR socketpair (2). > .\" > .SS Autobind feature > If a > -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/
