linux-kernel - [PATCH 1/2] pstore: Make default pstorefs root dir perms 0750

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Message-Id: <1502397395-118652-2-git-send-email-keescook@chromium.org>
Date:   Thu, 10 Aug 2017 13:36:34 -0700
From:   Kees Cook <keescook@...omium.org>
To:     linux-kernel@...r.kernel.org
Cc:     Kees Cook <keescook@...omium.org>, Nick Kralevich <nnk@...gle.com>,
        Sebastian Schmidt <yath@...h.de>,
        Tony Luck <tony.luck@...el.com>,
        Anton Vorontsov <anton@...msg.org>,
        Colin Cross <ccross@...roid.com>,
        Petr Mladek <pmladek@...e.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Patrick Tjin <pattjin@...gle.com>,
        Mark Salyzyn <salyzyn@...gle.com>
Subject: [PATCH 1/2] pstore: Make default pstorefs root dir perms 0750

Currently only DMESG and CONSOLE record types are protected, and it isn't
obvious that they are using a capability check. Instead switch to explicit
root directory mode of 0750 to keep files private by default.  This will
allow the removal of the capability check, which was non-obvious and
forces a process to have possibly too much privilege when simple post-boot
chgrp for readers would be possible without it.

Signed-off-by: Kees Cook <keescook@...omium.org>
---
 fs/pstore/inode.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
index fefd22611cf6..f1e88b695090 100644
--- a/fs/pstore/inode.c
+++ b/fs/pstore/inode.c
@@ -471,7 +471,7 @@ static int pstore_fill_super(struct super_block *sb, void *data, int silent)
 
 	inode = pstore_get_inode(sb);
 	if (inode) {
-		inode->i_mode = S_IFDIR | 0755;
+		inode->i_mode = S_IFDIR | 0750;
 		inode->i_op = &pstore_dir_inode_operations;
 		inode->i_fop = &simple_dir_operations;
 		inc_nlink(inode);
-- 
2.7.4