From: "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>
To: Karel Zak <kzak@redhat.com>
Cc: mtk.manpages@gmail.com, util-linux@vger.kernel.org,
Sami Kerola <kerolasa@iki.fi>
Subject: [PATCH] ipcs.1: ipcs no longer needs read permission on IPC resources
Date: Sat, 16 May 2020 10:10:27 +0200 [thread overview]
Message-ID: <5700d4b6-c499-0881-263c-7df96df511ff@gmail.com> (raw)
From: Michael Kerrisk <mtk.manpages@gmail.com>
Date: Sat, 16 May 2020 09:45:11 +0200
Subject: [PATCH] ipcs.1: ipcs no longer needs read permission on IPC resources
With changes starting around util-linux commit 058e81540fbb0d2b78
that switched from using IPC_STAT to parsing /proc/sysvipc/*,
ipcs now shows all IPC objects rather than just the objects for
which the user has read permission. Update the page to reflect this
fact, and also add a NOTES section describing the historical and
fallback behavior where /proc is not available.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
---
sys-utils/ipcs.1 | 22 ++++++++++++++++++++--
1 file changed, 20 insertions(+), 2 deletions(-)
diff --git a/sys-utils/ipcs.1 b/sys-utils/ipcs.1
index 93c35e323..4b3baaaa5 100644
--- a/sys-utils/ipcs.1
+++ b/sys-utils/ipcs.1
@@ -8,8 +8,7 @@ ipcs \- show information on IPC facilities
[options]
.SH DESCRIPTION
.B ipcs
-shows information on the inter-process communication facilities
-for which the calling process has read access.
+shows information on inter-process communication facilities.
By default it shows information about all three resources:
shared memory segments, message queues, and semaphore arrays.
.SH OPTIONS
@@ -76,6 +75,25 @@ Print sizes in bytes.
.TP
.B \-\-human
Print sizes in human-readable format.
+.SH NOTES
+The current implementation of
+.B ipcs
+obtains information about available IPC resources by parsing the files in
+.IR /proc/sysvipc .
+Before util-linux version v2.23, an alternate mechanism was used: the
+.BR IPC_STAT
+command of
+.BR msgctl (2),
+.BR semctl (2),
+and
+.BR shmctl (2).
+This mechanism is also used in later util-linux versions in the case where
+.I /proc
+is unavailable.
+A limitation of the
+.B IPC_STAT
+mechanism is that it can only be used to retrieve information about
+IPC resources for which the user has read permission.
.SH SEE ALSO
.BR ipcmk (1),
.BR ipcrm (1),
--
2.26.2
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
next reply other threads:[~2020-05-16 8:10 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-16 8:10 Michael Kerrisk (man-pages) [this message]
2020-05-18 11:41 ` [PATCH] ipcs.1: ipcs no longer needs read permission on IPC resources Karel Zak
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=5700d4b6-c499-0881-263c-7df96df511ff@gmail.com \
--to=mtk.manpages@gmail.com \
--cc=kerolasa@iki.fi \
--cc=kzak@redhat.com \
--cc=util-linux@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).