LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Alexey Dobriyan <adobriyan@openvz.org>
To: akpm@osdl.org
Cc: pasky@suse.cz, linux-kernel@vger.kernel.org, devel@openvz.org,
	oleg@tv-sign.ru
Subject: [PATCH v3] Allow access to /proc/$PID/fd after setuid()
Date: Fri, 9 Feb 2007 18:09:51 +0300	[thread overview]
Message-ID: <20070209150951.GA6026@localhost.sw.ru> (raw)

/proc/$PID/fd has r-x------ permissions, so if process does setuid(), it
will not be able to access /proc/*/fd/. This breaks fstatat() emulation
in glibc.

open("foo", O_RDONLY|O_DIRECTORY)       = 4
setuid32(65534)                         = 0
stat64("/proc/self/fd/4/bar", 0xbfafb298) = -1 EACCES (Permission denied)

Comments and suggestions from Andrew Morton and Oleg Nesterov.

Signed-off-by: Alexey Dobriyan <adobriyan@openvz.org>
---

 fs/proc/base.c |   18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1414,10 +1414,28 @@ static struct file_operations proc_fd_op
 };
 
 /*
+ * /proc/pid/fd needs a special permission handler so that a process can still
+ * access /proc/self/fd after it has executed a setuid().
+ */
+static int proc_fd_permission(struct inode *inode, int mask,
+				struct nameidata *nd)
+{
+	int rv;
+
+	rv = generic_permission(inode, mask, NULL);
+	if (rv == 0)
+		return 0;
+	if (task_pid(current) == proc_pid(inode))
+		rv = 0;
+	return rv;
+}
+
+/*
  * proc directories can do almost nothing..
  */
 static struct inode_operations proc_fd_inode_operations = {
 	.lookup		= proc_lookupfd,
+	.permission	= proc_fd_permission,
 	.setattr	= proc_setattr,
 };
 


                 reply	other threads:[~2007-02-09 15:03 UTC|newest]

Thread overview: [no followups] expand[flat|nested]  mbox.gz  Atom feed

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=20070209150951.GA6026@localhost.sw.ru \
    --to=adobriyan@openvz.org \
    --cc=akpm@osdl.org \
    --cc=devel@openvz.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=oleg@tv-sign.ru \
    --cc=pasky@suse.cz \
    --subject='Re: [PATCH v3] Allow access to /proc/$PID/fd after setuid()' \
    /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

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).