[PATCH 4/8] man/man7/unix.7: Explain Abstract UDS scoping to the network namespace

["Günther Noack" <gnoack3000@gmail.com>]

Point out that Abstract Unix Domain Sockets are visible within the
current network namespace, unlike Named Unix Domain Sockets, where the
remote socket is looked up through the mount namespace.

To avoid confusion, remove the word "namespace" from the subsequent
paragraph, where it is used in a more colloquial form (there is no
abstract socket namespace in the sense of namespaces(7)).

This is already described in network_namespaces(7) as well, but might
be mentionworthy here too.

The lookup of Abtract addresses happens in __unix_find_socket_byname()
in linux.git net/unix/af_unix.c, where it is looked up in the network
namespace (struct net *net) in a hash table in that namespace:

	sk_for_each(s, &net->unx.table.buckets[hash]) {
		// ...
	}

Cc: Kuniyuki Iwashima <kuniyu@google.com>
Assisted-by: LLM
Signed-off-by: Günther Noack <gnoack3000@gmail.com>
---

Notes:
    Verified in code

 man/man7/unix.7 | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/man/man7/unix.7 b/man/man7/unix.7
index 4c46b54206a5..232fdbf4c3cd 100644
--- a/man/man7/unix.7
+++ b/man/man7/unix.7
@@ -257,7 +257,17 @@ has no effect on the accessibility of the socket.
 Abstract sockets automatically disappear when all open references
 to the socket are closed.
 .P
-The abstract socket namespace is a nonportable Linux extension.
+Each network namespace has its own abstract socket namespace (see
+.BR network_namespaces (7)):
+a socket can connect or send to an abstract address
+only if the socket bound to that address
+is in the same network namespace.
+In contrast,
+pathname sockets are not confined to a network namespace;
+they can be reached from any network namespace
+in which the socket file is accessible.
+.P
+Abstract sockets are a nonportable Linux extension.
 .\"
 .SS Socket options
 For historical reasons, these socket options are specified with a
-- 
2.56.0