From: Alexey Tikhonov <atikhono@redhat.com>
To: Alejandro Colomar <alx@kernel.org>
Cc: linux-man@vger.kernel.org, libc-alpha@sourceware.org
Subject: UNIX(7)
Date: Fri, 1 Dec 2023 13:16:27 +0100 [thread overview]
Message-ID: <CABPeg3a9L0142gmdZZ+0hoD+Q3Vgv0BQ21g8Z+gf2kznWouErA@mail.gmail.com> (raw)
Hello.
There is a discrepancy between the man page description of
'SO_PEERCRED' and real behavior.
`man 7 unix` states:
```
SO_PEERCRED
This read-only socket option returns the credentials of
the peer process connected to this socket. The returned
credentials are those that were in effect at the time of
the call to connect(2) or socketpair(2).
```
This doesn't match real behavior in following situation (just an example):
- process starts with uid=0, gid=0
- process creates UNIX socket, binds it, listens on it
- process changes to uid=uid1, git=gid1 (using `setresuid()`, `setresgid()`)
- another process connects to the listening socket and requests
peer's credentials using `getsockopt(... SOL_SOCKET, SO_PEERCRED ...)`
According to the man page: SO_PEERCRED should report (uid1, gid1),
because peer process was running under (uid1, gid1) "at the time of
the call to connect(2)"
In reality SO_PEERCRED reports (0, 0)
Reproducing code is available in
https://bugzilla.redhat.com/show_bug.cgi?id=2247682
I'm not entirely sure if this is a real bug or rather a poor
description in the man page, but I tend to think that it's the latter.
next reply other threads:[~2023-12-01 12:16 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-01 12:16 Alexey Tikhonov [this message]
2023-12-01 12:54 ` UNIX(7) Alejandro Colomar
2023-12-01 22:07 ` UNIX(7) Kuniyuki Iwashima
2023-12-04 10:11 ` UNIX(7) Alexey Tikhonov
2023-12-20 18:05 ` [patch] unix.7: SO_PEERCRED: Mention listen(2) Alexey Tikhonov
2023-12-21 1:49 ` [PATCH] " Kuniyuki Iwashima
2023-12-21 12:15 ` Alejandro Colomar
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