linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Josh Hunt <johunt@akamai.com>
To: Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	<linux-kernel@vger.kernel.org>
Cc: Josh Hunt <johunt@akamai.com>
Subject: [PATCH] psi: allow unprivileged users with CAP_SYS_RESOURCE to write psi files
Date: Wed, 31 Mar 2021 23:31:56 -0400	[thread overview]
Message-ID: <20210401033156.7262-1-johunt@akamai.com> (raw)

Currently only root can write files under /proc/pressure. Relax this to
allow tasks running as unprivileged users with CAP_SYS_RESOURCE to be
able to write to these files.

Signed-off-by: Josh Hunt <johunt@akamai.com>
---
 kernel/sched/psi.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
index b1b00e9bd7ed..98ff7baf1ba8 100644
--- a/kernel/sched/psi.c
+++ b/kernel/sched/psi.c
@@ -1270,6 +1270,9 @@ static ssize_t psi_write(struct file *file, const char __user *user_buf,
 	if (!nbytes)
 		return -EINVAL;
 
+	if (!capable(CAP_SYS_RESOURCE))
+		return -EPERM;
+
 	buf_size = min(nbytes, sizeof(buf));
 	if (copy_from_user(buf, user_buf, buf_size))
 		return -EFAULT;
@@ -1353,9 +1356,9 @@ static int __init psi_proc_init(void)
 {
 	if (psi_enable) {
 		proc_mkdir("pressure", NULL);
-		proc_create("pressure/io", 0, NULL, &psi_io_proc_ops);
-		proc_create("pressure/memory", 0, NULL, &psi_memory_proc_ops);
-		proc_create("pressure/cpu", 0, NULL, &psi_cpu_proc_ops);
+		proc_create("pressure/io", 0666, NULL, &psi_io_proc_ops);
+		proc_create("pressure/memory", 0666, NULL, &psi_memory_proc_ops);
+		proc_create("pressure/cpu", 0666, NULL, &psi_cpu_proc_ops);
 	}
 	return 0;
 }
-- 
2.17.1


             reply	other threads:[~2021-04-01  4:20 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-01  3:31 Josh Hunt [this message]
2021-04-01  4:36 ` [PATCH] psi: allow unprivileged users with CAP_SYS_RESOURCE to write psi files Eric W. Biederman
2021-04-01  7:50   ` Kees Cook
2021-04-01 17:47     ` Eric W. Biederman
2021-04-01 18:10       ` Josh Hunt
2021-04-01  6:47 ` Peter Zijlstra
2021-04-01 19:47   ` Johannes Weiner

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=20210401033156.7262-1-johunt@akamai.com \
    --to=johunt@akamai.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@redhat.com \
    --cc=peterz@infradead.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).