9324cc3f5322e0977264ad87c71098cba5679542bbec55bd2995618e.patch

From 5d14096425298d69adb66c7dc975cf5ee064ebdf Mon Sep 17 00:00:00 2001
From: Sarthak Kukreti <sarthakkukreti@google.com>
Date: Wed, 19 Jun 2019 18:36:11 -0700
Subject: [PATCH] CHROMIUM: Revert "eCryptfs: don't pass up plaintext names
 when using filename encryption"

This reverts commit e86281e700cca8a773f9a572fa406adf2784ba5c.

Commit e86281e700cc ("eCryptfs: don't pass up plaintext names
when using filename encryption") introduces a regression
preventing lookups on plaintext files in the lower directory.

BUG=chromium:974368
TEST=MyFiles/Downloads shows in Files app after revert.

Change-Id: I234b3fa8036c6b90a40d738d3a1031f35013bdea
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/1668671
Reviewed-by: Guenter Roeck <groeck@chromium.org>
Reviewed-by: Gwendal Grignou <gwendal@chromium.org>
Commit-Queue: Sarthak Kukreti <sarthakkukreti@chromium.org>
Tested-by: Sarthak Kukreti <sarthakkukreti@chromium.org>
(cherry picked from commit aad4b948cf78cc4e1b2abf7d4c6101b3c41fec1c)
Signed-off-by: Guenter Roeck <groeck@chromium.org>
---
 fs/ecryptfs/crypto.c | 41 +++++++++++++----------------------------
 fs/ecryptfs/file.c   | 22 ++++++----------------
 2 files changed, 19 insertions(+), 44 deletions(-)

diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index 9df18a08c5275733836c0af65abe5b5eac8550ab..437ddfb9cd07da031a998dee4de3f55e42142c22 100644
--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -1977,16 +1977,6 @@ int ecryptfs_encrypt_and_encode_filename(
 	return rc;
 }
 
-static bool is_dot_dotdot(const char *name, size_t name_size)
-{
-	if (name_size == 1 && name[0] == '.')
-		return true;
-	else if (name_size == 2 && name[0] == '.' && name[1] == '.')
-		return true;
-
-	return false;
-}
-
 /**
  * ecryptfs_decode_and_decrypt_filename - converts the encoded cipher text name to decoded plaintext
  * @plaintext_name: The plaintext name
@@ -2011,21 +2001,13 @@ int ecryptfs_decode_and_decrypt_filename(char **plaintext_name,
 	size_t packet_size;
 	int rc = 0;
 
-	if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) &&
-	    !(mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)) {
-		if (is_dot_dotdot(name, name_size)) {
-			rc = ecryptfs_copy_filename(plaintext_name,
-						    plaintext_name_size,
-						    name, name_size);
-			goto out;
-		}
-
-		if (name_size <= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE ||
-		    strncmp(name, ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
-			    ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE)) {
-			rc = -EINVAL;
-			goto out;
-		}
+	if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)
+	    && !(mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
+	    && (name_size > ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE)
+	    && (strncmp(name, ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
+			ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE) == 0)) {
+		const char *orig_name = name;
+		size_t orig_name_size = name_size;
 
 		name += ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
 		name_size -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
@@ -2045,9 +2027,12 @@ int ecryptfs_decode_and_decrypt_filename(char **plaintext_name,
 						  decoded_name,
 						  decoded_name_size);
 		if (rc) {
-			ecryptfs_printk(KERN_DEBUG,
-					"%s: Could not parse tag 70 packet from filename\n",
-					__func__);
+			printk(KERN_INFO "%s: Could not parse tag 70 packet "
+			       "from filename; copying through filename "
+			       "as-is\n", __func__);
+			rc = ecryptfs_copy_filename(plaintext_name,
+						    plaintext_name_size,
+						    orig_name, orig_name_size);
 			goto out_free;
 		}
 	} else {
diff --git a/fs/ecryptfs/file.c b/fs/ecryptfs/file.c
index 268b74499c28c7c76f8e3230b66d86fec2394ee6..89e2c4648b906877c885af8d316302b6387b71ee 100644
--- a/fs/ecryptfs/file.c
+++ b/fs/ecryptfs/file.c
@@ -66,23 +66,13 @@ ecryptfs_filldir(struct dir_context *ctx, const char *lower_name,
 
 	buf->filldir_called++;
 	err = ecryptfs_decode_and_decrypt_filename(&name, &name_size,
-						   buf->sb, lower_name,
-						   lower_namelen);
+						  buf->sb, lower_name,
+						  lower_namelen);
 	if (err) {
-		if (err != -EINVAL) {
-			ecryptfs_printk(KERN_DEBUG,
-					"%s: Error attempting to decode and decrypt filename [%s]; rc = [%d]\n",
-					__func__, lower_name, err);
-			return false;
-		}
-
-		/* Mask -EINVAL errors as these are most likely due a plaintext
-		 * filename present in the lower filesystem despite filename
-		 * encryption being enabled. One unavoidable example would be
-		 * the "lost+found" dentry in the root directory of an Ext4
-		 * filesystem.
-		 */
-		return true;
+		printk(KERN_ERR "%s: Error attempting to decode and decrypt "
+		       "filename [%s]; err = [%d]\n", __func__, lower_name,
+		       err);
+		return false;
 	}
 
 	buf->caller->pos = buf->ctx.pos;
-- 
2.38.1.584.g0f3c55d4c2-goog