[PATCH v2 3/5] ext4: consolidate fscrypt_has_permitted_context() checks

From: Eric Biggers <ebiggers3@gmail.com>
To: linux-fsdevel@vger.kernel.org
Cc: "Theodore Y . Ts'o" <tytso@mit.edu>,
	Jaegeuk Kim <jaegeuk@kernel.org>,
	Richard Weinberger <richard@nod.at>,
	Eric Biggers <ebiggers@google.com>
Subject: [PATCH v2 3/5] ext4: consolidate fscrypt_has_permitted_context() checks
Date: Mon, 19 Dec 2016 14:20:14 -0800	[thread overview]
Message-ID: <1482186016-107643-3-git-send-email-ebiggers3@gmail.com> (raw)
In-Reply-To: <1482186016-107643-1-git-send-email-ebiggers3@gmail.com>

From: Eric Biggers <ebiggers@google.com>

Now that fscrypt_has_permitted_context() compares the fscrypt_context
rather than the fscrypt_info when needed, it is no longer necessary to
delay fscrypt_has_permitted_context() from ->lookup() to ->open() for
regular files, as introduced in commit ff978b09f973 ("ext4 crypto: move
context consistency check to ext4_file_open()").  Therefore the check in
->open(), along with the dget_parent() hack, can be removed.  It's also
no longer necessary to check the file type before calling
fscrypt_has_permitted_context().

This patch should not be applied before my other two patches:

    fscrypt: fix loophole in one-encryption-policy-per-tree enforcement
    fscrypt: fix renaming and linking special files

Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 fs/ext4/file.c  | 12 ------------
 fs/ext4/namei.c | 10 ++--------
 2 files changed, 2 insertions(+), 20 deletions(-)

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index b5f1844..2123cd8 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -398,7 +398,6 @@ static int ext4_file_open(struct inode * inode, struct file * filp)
 	struct super_block *sb = inode->i_sb;
 	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 	struct vfsmount *mnt = filp->f_path.mnt;
-	struct dentry *dir;
 	struct path path;
 	char buf[64], *cp;
 	int ret;
@@ -443,17 +442,6 @@ static int ext4_file_open(struct inode * inode, struct file * filp)
 			return -ENOKEY;
 	}
 
-	dir = dget_parent(file_dentry(filp));
-	if (ext4_encrypted_inode(d_inode(dir)) &&
-			!fscrypt_has_permitted_context(d_inode(dir), inode)) {
-		ext4_warning(inode->i_sb,
-			     "Inconsistent encryption contexts: %lu/%lu",
-			     (unsigned long) d_inode(dir)->i_ino,
-			     (unsigned long) inode->i_ino);
-		dput(dir);
-		return -EPERM;
-	}
-	dput(dir);
 	/*
 	 * Set up the jbd2_inode if we are opening the inode for
 	 * writing and the journal is present
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index eadba91..eb8b064 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -1612,17 +1612,11 @@ static struct dentry *ext4_lookup(struct inode *dir, struct dentry *dentry, unsi
 			return ERR_PTR(-EFSCORRUPTED);
 		}
 		if (!IS_ERR(inode) && ext4_encrypted_inode(dir) &&
-		    (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode)) &&
 		    !fscrypt_has_permitted_context(dir, inode)) {
-			int nokey = ext4_encrypted_inode(inode) &&
-				!fscrypt_has_encryption_key(inode);
-			iput(inode);
-			if (nokey)
-				return ERR_PTR(-ENOKEY);
 			ext4_warning(inode->i_sb,
 				     "Inconsistent encryption contexts: %lu/%lu",
-				     (unsigned long) dir->i_ino,
-				     (unsigned long) inode->i_ino);
+				     dir->i_ino, inode->i_ino);
+			iput(inode);
 			return ERR_PTR(-EPERM);
 		}
 	}
-- 
2.8.0.rc3.226.g39d4020

