linux-ext4 - [PATCH] fscrypto: add authorization check for setting encryption policy

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <1473357429-134444-1-git-send-email-ebiggers@google.com>
Date:   Thu,  8 Sep 2016 10:57:08 -0700
From:   Eric Biggers <ebiggers@...gle.com>
To:     linux-fsdevel@...r.kernel.org
Cc:     linux-ext4@...r.kernel.org, linux-f2fs@...r.kernel.org,
        tytso@....edu, jaegeuk@...nel.org,
        Eric Biggers <ebiggers@...gle.com>
Subject: [PATCH] fscrypto: add authorization check for setting encryption policy

On an ext4 or f2fs filesystem with file encryption supported, a user
could set an encryption policy on any empty directory(*) to which they
had readonly access.  This is obviously problematic, since such a
directory might be owned by another user and the new encryption policy
would prevent that other user from creating files in their own directory
(for example).

Fix this by requiring inode_owner_or_capable() permission to set an
encryption policy.  This means that either the caller must own the file,
or the caller must have the capability CAP_FOWNER.

(*) Or also on any regular file, for f2fs v4.6 and later and ext4
    v4.8-rc1 and later; a separate bug fix is coming for that.

Signed-off-by: Eric Biggers <ebiggers@...gle.com>
Cc: stable@...r.kernel.org # 4.1+; check fs/{ext4,f2fs}
---
 fs/crypto/policy.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c
index 0f9961e..c9800b1 100644
--- a/fs/crypto/policy.c
+++ b/fs/crypto/policy.c
@@ -95,6 +95,9 @@ static int create_encryption_context_from_policy(struct inode *inode,
 int fscrypt_process_policy(struct inode *inode,
 				const struct fscrypt_policy *policy)
 {
+	if (!inode_owner_or_capable(inode))
+		return -EACCES;
+
 	if (policy->version != 0)
 		return -EINVAL;
 
-- 
2.8.0.rc3.226.g39d4020

--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html