linux-ext4 - [PATCH 2/3] fscrypt: fix renaming and linking special files

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Message-Id: <1481829584-50218-2-git-send-email-ebiggers3@gmail.com>
Date:   Thu, 15 Dec 2016 11:19:43 -0800
From:   Eric Biggers <ebiggers3@...il.com>
To:     linux-fsdevel@...r.kernel.org
Cc:     "Theodore Y . Ts'o" <tytso@....edu>,
        Jaegeuk Kim <jaegeuk@...nel.org>, linux-ext4@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net,
        Richard Weinberger <richard@....at>,
        David Gstir <david@...ma-star.at>,
        Eric Biggers <ebiggers@...gle.com>
Subject: [PATCH 2/3] fscrypt: fix renaming and linking special files

From: Eric Biggers <ebiggers@...gle.com>

Attempting to link a device node, named pipe, or socket file into an
encrypted directory through rename(2) or link(2) always failed with
EPERM.  This happened because fscrypt_permitted_context() saw that the
file was unencrypted and forbid creating the link.  This behavior was
unexpected because such files are never encrypted; only regular files,
directories, and symlinks can be encrypted.

To fix this, make fscrypt_has_permitted_context() always return true on
special files.

This will be covered by a test in my encryption xfstests patchset.

Fixes: 9bd8212f981e ("ext4 crypto: add encryption policy and password salt support")
Signed-off-by: Eric Biggers <ebiggers@...gle.com>
---
 fs/crypto/policy.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c
index 5de0633..2e50cbc 100644
--- a/fs/crypto/policy.c
+++ b/fs/crypto/policy.c
@@ -198,6 +198,11 @@ int fscrypt_has_permitted_context(struct inode *parent, struct inode *child)
 	if (!cops->is_encrypted(parent))
 		return 1;
 
+	/* No restrictions on file types which are never encrypted */
+	if (!S_ISREG(child->i_mode) && !S_ISDIR(child->i_mode) &&
+	    !S_ISLNK(child->i_mode))
+		return 1;
+
 	/* Encrypted directories must not contain unencrypted files */
 	if (!cops->is_encrypted(child))
 		return 0;
-- 
2.8.0.rc3.226.g39d4020

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