1 files changed, 207 insertions, 280 deletions

diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index 68b19ab0481..2f6735dbf1a 100644
--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -37,16 +37,8 @@
 #include <asm/unaligned.h>
 #include "ecryptfs_kernel.h"
 
-static int
-ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
-			     struct page *dst_page, int dst_offset,
-			     struct page *src_page, int src_offset, int size,
-			     unsigned char *iv);
-static int
-ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
-			     struct page *dst_page, int dst_offset,
-			     struct page *src_page, int src_offset, int size,
-			     unsigned char *iv);
+#define DECRYPT		0
+#define ENCRYPT		1
 
 /**
  * ecryptfs_to_hex
@@ -243,7 +235,7 @@ void ecryptfs_destroy_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
 	struct ecryptfs_key_sig *key_sig, *key_sig_tmp;
 
 	if (crypt_stat->tfm)
-		crypto_free_blkcipher(crypt_stat->tfm);
+		crypto_free_ablkcipher(crypt_stat->tfm);
 	if (crypt_stat->hash_tfm)
 		crypto_free_hash(crypt_stat->hash_tfm);
 	list_for_each_entry_safe(key_sig, key_sig_tmp,
@@ -301,17 +293,14 @@ int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg,
 	while (size > 0 && i < sg_size) {
 		pg = virt_to_page(addr);
 		offset = offset_in_page(addr);
-		if (sg)
-			sg_set_page(&sg[i], pg, 0, offset);
+		sg_set_page(&sg[i], pg, 0, offset);
 		remainder_of_page = PAGE_CACHE_SIZE - offset;
 		if (size >= remainder_of_page) {
-			if (sg)
-				sg[i].length = remainder_of_page;
+			sg[i].length = remainder_of_page;
 			addr += remainder_of_page;
 			size -= remainder_of_page;
 		} else {
-			if (sg)
-				sg[i].length = size;
+			sg[i].length = size;
 			addr += size;
 			size = 0;
 		}
@@ -322,26 +311,40 @@ int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg,
 	return i;
 }
 
+struct extent_crypt_result {
+	struct completion completion;
+	int rc;
+};
+
+static void extent_crypt_complete(struct crypto_async_request *req, int rc)
+{
+	struct extent_crypt_result *ecr = req->data;
+
+	if (rc == -EINPROGRESS)
+		return;
+
+	ecr->rc = rc;
+	complete(&ecr->completion);
+}
+
 /**
- * encrypt_scatterlist
+ * crypt_scatterlist
  * @crypt_stat: Pointer to the crypt_stat struct to initialize.
- * @dest_sg: Destination of encrypted data
- * @src_sg: Data to be encrypted
- * @size: Length of data to be encrypted
- * @iv: iv to use during encryption
+ * @dst_sg: Destination of the data after performing the crypto operation
+ * @src_sg: Data to be encrypted or decrypted
+ * @size: Length of data
+ * @iv: IV to use
+ * @op: ENCRYPT or DECRYPT to indicate the desired operation
  *
- * Returns the number of bytes encrypted; negative value on error
+ * Returns the number of bytes encrypted or decrypted; negative value on error
  */
-static int encrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
-			       struct scatterlist *dest_sg,
-			       struct scatterlist *src_sg, int size,
-			       unsigned char *iv)
+static int crypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
+			     struct scatterlist *dst_sg,
+			     struct scatterlist *src_sg, int size,
+			     unsigned char *iv, int op)
 {
-	struct blkcipher_desc desc = {
-		.tfm = crypt_stat->tfm,
-		.info = iv,
-		.flags = CRYPTO_TFM_REQ_MAY_SLEEP
-	};
+	struct ablkcipher_request *req = NULL;
+	struct extent_crypt_result ecr;
 	int rc = 0;
 
 	BUG_ON(!crypt_stat || !crypt_stat->tfm
@@ -352,63 +355,88 @@ static int encrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
 		ecryptfs_dump_hex(crypt_stat->key,
 				  crypt_stat->key_size);
 	}
-	/* Consider doing this once, when the file is opened */
+
+	init_completion(&ecr.completion);
+
 	mutex_lock(&crypt_stat->cs_tfm_mutex);
-	if (!(crypt_stat->flags & ECRYPTFS_KEY_SET)) {
-		rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
-					     crypt_stat->key_size);
-		crypt_stat->flags |= ECRYPTFS_KEY_SET;
-	}
-	if (rc) {
-		ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
-				rc);
+	req = ablkcipher_request_alloc(crypt_stat->tfm, GFP_NOFS);
+	if (!req) {
 		mutex_unlock(&crypt_stat->cs_tfm_mutex);
-		rc = -EINVAL;
+		rc = -ENOMEM;
 		goto out;
 	}
-	ecryptfs_printk(KERN_DEBUG, "Encrypting [%d] bytes.\n", size);
-	crypto_blkcipher_encrypt_iv(&desc, dest_sg, src_sg, size);
+
+	ablkcipher_request_set_callback(req,
+			CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
+			extent_crypt_complete, &ecr);
+	/* Consider doing this once, when the file is opened */
+	if (!(crypt_stat->flags & ECRYPTFS_KEY_SET)) {
+		rc = crypto_ablkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
+					      crypt_stat->key_size);
+		if (rc) {
+			ecryptfs_printk(KERN_ERR,
+					"Error setting key; rc = [%d]\n",
+					rc);
+			mutex_unlock(&crypt_stat->cs_tfm_mutex);
+			rc = -EINVAL;
+			goto out;
+		}
+		crypt_stat->flags |= ECRYPTFS_KEY_SET;
+	}
 	mutex_unlock(&crypt_stat->cs_tfm_mutex);
+	ablkcipher_request_set_crypt(req, src_sg, dst_sg, size, iv);
+	rc = op == ENCRYPT ? crypto_ablkcipher_encrypt(req) :
+			     crypto_ablkcipher_decrypt(req);
+	if (rc == -EINPROGRESS || rc == -EBUSY) {
+		struct extent_crypt_result *ecr = req->base.data;
+
+		wait_for_completion(&ecr->completion);
+		rc = ecr->rc;
+		reinit_completion(&ecr->completion);
+	}
 out:
+	ablkcipher_request_free(req);
 	return rc;
 }
 
 /**
- * ecryptfs_lower_offset_for_extent
+ * lower_offset_for_page
  *
  * Convert an eCryptfs page index into a lower byte offset
  */
-static void ecryptfs_lower_offset_for_extent(loff_t *offset, loff_t extent_num,
-					     struct ecryptfs_crypt_stat *crypt_stat)
+static loff_t lower_offset_for_page(struct ecryptfs_crypt_stat *crypt_stat,
+				    struct page *page)
 {
-	(*offset) = ecryptfs_lower_header_size(crypt_stat)
-		    + (crypt_stat->extent_size * extent_num);
+	return ecryptfs_lower_header_size(crypt_stat) +
+	       ((loff_t)page->index << PAGE_CACHE_SHIFT);
 }
 
 /**
- * ecryptfs_encrypt_extent
- * @enc_extent_page: Allocated page into which to encrypt the data in
- *                   @page
+ * crypt_extent
  * @crypt_stat: crypt_stat containing cryptographic context for the
  *              encryption operation
- * @page: Page containing plaintext data extent to encrypt
+ * @dst_page: The page to write the result into
+ * @src_page: The page to read from
  * @extent_offset: Page extent offset for use in generating IV
+ * @op: ENCRYPT or DECRYPT to indicate the desired operation
  *
- * Encrypts one extent of data.
+ * Encrypts or decrypts one extent of data.
  *
  * Return zero on success; non-zero otherwise
  */
-static int ecryptfs_encrypt_extent(struct page *enc_extent_page,
-				   struct ecryptfs_crypt_stat *crypt_stat,
-				   struct page *page,
-				   unsigned long extent_offset)
+static int crypt_extent(struct ecryptfs_crypt_stat *crypt_stat,
+			struct page *dst_page,
+			struct page *src_page,
+			unsigned long extent_offset, int op)
 {
+	pgoff_t page_index = op == ENCRYPT ? src_page->index : dst_page->index;
 	loff_t extent_base;
 	char extent_iv[ECRYPTFS_MAX_IV_BYTES];
+	struct scatterlist src_sg, dst_sg;
+	size_t extent_size = crypt_stat->extent_size;
 	int rc;
 
-	extent_base = (((loff_t)page->index)
-		       * (PAGE_CACHE_SIZE / crypt_stat->extent_size));
+	extent_base = (((loff_t)page_index) * (PAGE_CACHE_SIZE / extent_size));
 	rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
 				(extent_base + extent_offset));
 	if (rc) {
@@ -417,15 +445,21 @@ static int ecryptfs_encrypt_extent(struct page *enc_extent_page,
 			(unsigned long long)(extent_base + extent_offset), rc);
 		goto out;
 	}
-	rc = ecryptfs_encrypt_page_offset(crypt_stat, enc_extent_page, 0,
-					  page, (extent_offset
-						 * crypt_stat->extent_size),
-					  crypt_stat->extent_size, extent_iv);
+
+	sg_init_table(&src_sg, 1);
+	sg_init_table(&dst_sg, 1);
+
+	sg_set_page(&src_sg, src_page, extent_size,
+		    extent_offset * extent_size);
+	sg_set_page(&dst_sg, dst_page, extent_size,
+		    extent_offset * extent_size);
+
+	rc = crypt_scatterlist(crypt_stat, &dst_sg, &src_sg, extent_size,
+			       extent_iv, op);
 	if (rc < 0) {
-		printk(KERN_ERR "%s: Error attempting to encrypt page with "
-		       "page->index = [%ld], extent_offset = [%ld]; "
-		       "rc = [%d]\n", __func__, page->index, extent_offset,
-		       rc);
+		printk(KERN_ERR "%s: Error attempting to crypt page with "
+		       "page_index = [%ld], extent_offset = [%ld]; "
+		       "rc = [%d]\n", __func__, page_index, extent_offset, rc);
 		goto out;
 	}
 	rc = 0;
@@ -456,6 +490,7 @@ int ecryptfs_encrypt_page(struct page *page)
 	char *enc_extent_virt;
 	struct page *enc_extent_page = NULL;
 	loff_t extent_offset;
+	loff_t lower_offset;
 	int rc = 0;
 
 	ecryptfs_inode = page->mapping->host;
@@ -469,75 +504,35 @@ int ecryptfs_encrypt_page(struct page *page)
 				"encrypted extent\n");
 		goto out;
 	}
-	enc_extent_virt = kmap(enc_extent_page);
+
 	for (extent_offset = 0;
 	     extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
 	     extent_offset++) {
-		loff_t offset;
-
-		rc = ecryptfs_encrypt_extent(enc_extent_page, crypt_stat, page,
-					     extent_offset);
+		rc = crypt_extent(crypt_stat, enc_extent_page, page,
+				  extent_offset, ENCRYPT);
 		if (rc) {
 			printk(KERN_ERR "%s: Error encrypting extent; "
 			       "rc = [%d]\n", __func__, rc);
 			goto out;
 		}
-		ecryptfs_lower_offset_for_extent(
-			&offset, ((((loff_t)page->index)
-				   * (PAGE_CACHE_SIZE
-				      / crypt_stat->extent_size))
-				  + extent_offset), crypt_stat);
-		rc = ecryptfs_write_lower(ecryptfs_inode, enc_extent_virt,
-					  offset, crypt_stat->extent_size);
-		if (rc < 0) {
-			ecryptfs_printk(KERN_ERR, "Error attempting "
-					"to write lower page; rc = [%d]"
-					"\n", rc);
-			goto out;
-		}
 	}
-	rc = 0;
-out:
-	if (enc_extent_page) {
-		kunmap(enc_extent_page);
-		__free_page(enc_extent_page);
-	}
-	return rc;
-}
-
-static int ecryptfs_decrypt_extent(struct page *page,
-				   struct ecryptfs_crypt_stat *crypt_stat,
-				   struct page *enc_extent_page,
-				   unsigned long extent_offset)
-{
-	loff_t extent_base;
-	char extent_iv[ECRYPTFS_MAX_IV_BYTES];
-	int rc;
 
-	extent_base = (((loff_t)page->index)
-		       * (PAGE_CACHE_SIZE / crypt_stat->extent_size));
-	rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
-				(extent_base + extent_offset));
-	if (rc) {
-		ecryptfs_printk(KERN_ERR, "Error attempting to derive IV for "
-			"extent [0x%.16llx]; rc = [%d]\n",
-			(unsigned long long)(extent_base + extent_offset), rc);
-		goto out;
-	}
-	rc = ecryptfs_decrypt_page_offset(crypt_stat, page,
-					  (extent_offset
-					   * crypt_stat->extent_size),
-					  enc_extent_page, 0,
-					  crypt_stat->extent_size, extent_iv);
+	lower_offset = lower_offset_for_page(crypt_stat, page);
+	enc_extent_virt = kmap(enc_extent_page);
+	rc = ecryptfs_write_lower(ecryptfs_inode, enc_extent_virt, lower_offset,
+				  PAGE_CACHE_SIZE);
+	kunmap(enc_extent_page);
 	if (rc < 0) {
-		printk(KERN_ERR "%s: Error attempting to decrypt to page with "
-		       "page->index = [%ld], extent_offset = [%ld]; "
-		       "rc = [%d]\n", __func__, page->index, extent_offset,
-		       rc);
+		ecryptfs_printk(KERN_ERR,
+			"Error attempting to write lower page; rc = [%d]\n",
+			rc);
 		goto out;
 	}
 	rc = 0;
 out:
+	if (enc_extent_page) {
+		__free_page(enc_extent_page);
+	}
 	return rc;
 }
 
@@ -561,43 +556,33 @@ int ecryptfs_decrypt_page(struct page *page)
 {
 	struct inode *ecryptfs_inode;
 	struct ecryptfs_crypt_stat *crypt_stat;
-	char *enc_extent_virt;
-	struct page *enc_extent_page = NULL;
+	char *page_virt;
 	unsigned long extent_offset;
+	loff_t lower_offset;
 	int rc = 0;
 
 	ecryptfs_inode = page->mapping->host;
 	crypt_stat =
 		&(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
 	BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
-	enc_extent_page = alloc_page(GFP_USER);
-	if (!enc_extent_page) {
-		rc = -ENOMEM;
-		ecryptfs_printk(KERN_ERR, "Error allocating memory for "
-				"encrypted extent\n");
+
+	lower_offset = lower_offset_for_page(crypt_stat, page);
+	page_virt = kmap(page);
+	rc = ecryptfs_read_lower(page_virt, lower_offset, PAGE_CACHE_SIZE,
+				 ecryptfs_inode);
+	kunmap(page);
+	if (rc < 0) {
+		ecryptfs_printk(KERN_ERR,
+			"Error attempting to read lower page; rc = [%d]\n",
+			rc);
 		goto out;
 	}
-	enc_extent_virt = kmap(enc_extent_page);
+
 	for (extent_offset = 0;
 	     extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
 	     extent_offset++) {
-		loff_t offset;
-
-		ecryptfs_lower_offset_for_extent(
-			&offset, ((page->index * (PAGE_CACHE_SIZE
-						  / crypt_stat->extent_size))
-				  + extent_offset), crypt_stat);
-		rc = ecryptfs_read_lower(enc_extent_virt, offset,
-					 crypt_stat->extent_size,
-					 ecryptfs_inode);
-		if (rc < 0) {
-			ecryptfs_printk(KERN_ERR, "Error attempting "
-					"to read lower page; rc = [%d]"
-					"\n", rc);
-			goto out;
-		}
-		rc = ecryptfs_decrypt_extent(page, crypt_stat, enc_extent_page,
-					     extent_offset);
+		rc = crypt_extent(crypt_stat, page, page,
+				  extent_offset, DECRYPT);
 		if (rc) {
 			printk(KERN_ERR "%s: Error encrypting extent; "
 			       "rc = [%d]\n", __func__, rc);
@@ -605,116 +590,9 @@ int ecryptfs_decrypt_page(struct page *page)
 		}
 	}
 out:
-	if (enc_extent_page) {
-		kunmap(enc_extent_page);
-		__free_page(enc_extent_page);
-	}
 	return rc;
 }
 
-/**
- * decrypt_scatterlist
- * @crypt_stat: Cryptographic context
- * @dest_sg: The destination scatterlist to decrypt into
- * @src_sg: The source scatterlist to decrypt from
- * @size: The number of bytes to decrypt
- * @iv: The initialization vector to use for the decryption
- *
- * Returns the number of bytes decrypted; negative value on error
- */
-static int decrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
-			       struct scatterlist *dest_sg,
-			       struct scatterlist *src_sg, int size,
-			       unsigned char *iv)
-{
-	struct blkcipher_desc desc = {
-		.tfm = crypt_stat->tfm,
-		.info = iv,
-		.flags = CRYPTO_TFM_REQ_MAY_SLEEP
-	};
-	int rc = 0;
-
-	/* Consider doing this once, when the file is opened */
-	mutex_lock(&crypt_stat->cs_tfm_mutex);
-	rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
-				     crypt_stat->key_size);
-	if (rc) {
-		ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
-				rc);
-		mutex_unlock(&crypt_stat->cs_tfm_mutex);
-		rc = -EINVAL;
-		goto out;
-	}
-	ecryptfs_printk(KERN_DEBUG, "Decrypting [%d] bytes.\n", size);
-	rc = crypto_blkcipher_decrypt_iv(&desc, dest_sg, src_sg, size);
-	mutex_unlock(&crypt_stat->cs_tfm_mutex);
-	if (rc) {
-		ecryptfs_printk(KERN_ERR, "Error decrypting; rc = [%d]\n",
-				rc);
-		goto out;
-	}
-	rc = size;
-out:
-	return rc;
-}
-
-/**
- * ecryptfs_encrypt_page_offset
- * @crypt_stat: The cryptographic context
- * @dst_page: The page to encrypt into
- * @dst_offset: The offset in the page to encrypt into
- * @src_page: The page to encrypt from
- * @src_offset: The offset in the page to encrypt from
- * @size: The number of bytes to encrypt
- * @iv: The initialization vector to use for the encryption
- *
- * Returns the number of bytes encrypted
- */
-static int
-ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
-			     struct page *dst_page, int dst_offset,
-			     struct page *src_page, int src_offset, int size,
-			     unsigned char *iv)
-{
-	struct scatterlist src_sg, dst_sg;
-
-	sg_init_table(&src_sg, 1);
-	sg_init_table(&dst_sg, 1);
-
-	sg_set_page(&src_sg, src_page, size, src_offset);
-	sg_set_page(&dst_sg, dst_page, size, dst_offset);
-	return encrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
-}
-
-/**
- * ecryptfs_decrypt_page_offset
- * @crypt_stat: The cryptographic context
- * @dst_page: The page to decrypt into
- * @dst_offset: The offset in the page to decrypt into
- * @src_page: The page to decrypt from
- * @src_offset: The offset in the page to decrypt from
- * @size: The number of bytes to decrypt
- * @iv: The initialization vector to use for the decryption
- *
- * Returns the number of bytes decrypted
- */
-static int
-ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
-			     struct page *dst_page, int dst_offset,
-			     struct page *src_page, int src_offset, int size,
-			     unsigned char *iv)
-{
-	struct scatterlist src_sg, dst_sg;
-
-	sg_init_table(&src_sg, 1);
-	sg_set_page(&src_sg, src_page, size, src_offset);
-
-	sg_init_table(&dst_sg, 1);
-	sg_set_page(&dst_sg, dst_page, size, dst_offset);
-
-	return decrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
-}
-
 #define ECRYPTFS_MAX_SCATTERLIST_LEN 4
 
 /**
@@ -731,40 +609,35 @@ int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
 	char *full_alg_name;
 	int rc = -EINVAL;
 
-	if (!crypt_stat->cipher) {
-		ecryptfs_printk(KERN_ERR, "No cipher specified\n");
-		goto out;
-	}
 	ecryptfs_printk(KERN_DEBUG,
 			"Initializing cipher [%s]; strlen = [%d]; "
 			"key_size_bits = [%zd]\n",
 			crypt_stat->cipher, (int)strlen(crypt_stat->cipher),
 			crypt_stat->key_size << 3);
+	mutex_lock(&crypt_stat->cs_tfm_mutex);
 	if (crypt_stat->tfm) {
 		rc = 0;
-		goto out;
+		goto out_unlock;
 	}
-	mutex_lock(&crypt_stat->cs_tfm_mutex);
 	rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name,
 						    crypt_stat->cipher, "cbc");
 	if (rc)
 		goto out_unlock;
-	crypt_stat->tfm = crypto_alloc_blkcipher(full_alg_name, 0,
-						 CRYPTO_ALG_ASYNC);
-	kfree(full_alg_name);
+	crypt_stat->tfm = crypto_alloc_ablkcipher(full_alg_name, 0, 0);
 	if (IS_ERR(crypt_stat->tfm)) {
 		rc = PTR_ERR(crypt_stat->tfm);
 		crypt_stat->tfm = NULL;
 		ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): "
 				"Error initializing cipher [%s]\n",
-				crypt_stat->cipher);
-		goto out_unlock;
+				full_alg_name);
+		goto out_free;
 	}
-	crypto_blkcipher_set_flags(crypt_stat->tfm, CRYPTO_TFM_REQ_WEAK_KEY);
+	crypto_ablkcipher_set_flags(crypt_stat->tfm, CRYPTO_TFM_REQ_WEAK_KEY);
 	rc = 0;
+out_free:
+	kfree(full_alg_name);
 out_unlock:
 	mutex_unlock(&crypt_stat->cs_tfm_mutex);
-out:
 	return rc;
 }
 
@@ -1550,8 +1423,8 @@ int ecryptfs_read_and_validate_xattr_region(struct dentry *dentry,
  */
 int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry)
 {
-	int rc = 0;
-	char *page_virt = NULL;
+	int rc;
+	char *page_virt;
 	struct inode *ecryptfs_inode = ecryptfs_dentry->d_inode;
 	struct ecryptfs_crypt_stat *crypt_stat =
 	    &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
@@ -1576,6 +1449,7 @@ int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry)
 						ecryptfs_dentry,
 						ECRYPTFS_VALIDATE_HEADER_SIZE);
 	if (rc) {
+		/* metadata is not in the file header, so try xattrs */
 		memset(page_virt, 0, PAGE_CACHE_SIZE);
 		rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_inode);
 		if (rc) {
@@ -1934,7 +1808,7 @@ static const unsigned char filename_rev_map[256] = {
  * @src: Source location for the filename to encode
  * @src_size: Size of the source in bytes
  */
-void ecryptfs_encode_for_filename(unsigned char *dst, size_t *dst_size,
+static void ecryptfs_encode_for_filename(unsigned char *dst, size_t *dst_size,
 				  unsigned char *src, size_t src_size)
 {
 	size_t num_blocks;
@@ -1989,6 +1863,17 @@ out:
 	return;
 }
 
+static size_t ecryptfs_max_decoded_size(size_t encoded_size)
+{
+	/* Not exact; conservatively long. Every block of 4
+	 * encoded characters decodes into a block of 3
+	 * decoded characters. This segment of code provides
+	 * the caller with the maximum amount of allocated
+	 * space that @dst will need to point to in a
+	 * subsequent call. */
+	return ((encoded_size + 1) * 3) / 4;
+}
+
 /**
  * ecryptfs_decode_from_filename
  * @dst: If NULL, this function only sets @dst_size and returns. If
@@ -2007,13 +1892,7 @@ ecryptfs_decode_from_filename(unsigned char *dst, size_t *dst_size,
 	size_t dst_byte_offset = 0;
 
 	if (dst == NULL) {
-		/* Not exact; conservatively long. Every block of 4
-		 * encoded characters decodes into a block of 3
-		 * decoded characters. This segment of code provides
-		 * the caller with the maximum amount of allocated
-		 * space that @dst will need to point to in a
-		 * subsequent call. */
-		(*dst_size) = (((src_size + 1) * 3) / 4);
+		(*dst_size) = ecryptfs_max_decoded_size(src_size);
 		goto out;
 	}
 	while (src_byte_offset < src_size) {
@@ -2179,12 +2058,11 @@ out:
  */
 int ecryptfs_decode_and_decrypt_filename(char **plaintext_name,
 					 size_t *plaintext_name_size,
-					 struct dentry *ecryptfs_dir_dentry,
+					 struct super_block *sb,
 					 const char *name, size_t name_size)
 {
 	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
-		&ecryptfs_superblock_to_private(
-			ecryptfs_dir_dentry->d_sb)->mount_crypt_stat;
+		&ecryptfs_superblock_to_private(sb)->mount_crypt_stat;
 	char *decoded_name;
 	size_t decoded_name_size;
 	size_t packet_size;
@@ -2238,3 +2116,52 @@ out_free:
 out:
 	return rc;
 }
+
+#define ENC_NAME_MAX_BLOCKLEN_8_OR_16	143
+
+int ecryptfs_set_f_namelen(long *namelen, long lower_namelen,
+			   struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
+{
+	struct blkcipher_desc desc;
+	struct mutex *tfm_mutex;
+	size_t cipher_blocksize;
+	int rc;
+
+	if (!(mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) {
+		(*namelen) = lower_namelen;
+		return 0;
+	}
+
+	rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&desc.tfm, &tfm_mutex,
+			mount_crypt_stat->global_default_fn_cipher_name);
+	if (unlikely(rc)) {
+		(*namelen) = 0;
+		return rc;
+	}
+
+	mutex_lock(tfm_mutex);
+	cipher_blocksize = crypto_blkcipher_blocksize(desc.tfm);
+	mutex_unlock(tfm_mutex);
+
+	/* Return an exact amount for the common cases */
+	if (lower_namelen == NAME_MAX
+	    && (cipher_blocksize == 8 || cipher_blocksize == 16)) {
+		(*namelen) = ENC_NAME_MAX_BLOCKLEN_8_OR_16;
+		return 0;
+	}
+
+	/* Return a safe estimate for the uncommon cases */
+	(*namelen) = lower_namelen;
+	(*namelen) -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
+	/* Since this is the max decoded size, subtract 1 "decoded block" len */
+	(*namelen) = ecryptfs_max_decoded_size(*namelen) - 3;
+	(*namelen) -= ECRYPTFS_TAG_70_MAX_METADATA_SIZE;
+	(*namelen) -= ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES;
+	/* Worst case is that the filename is padded nearly a full block size */
+	(*namelen) -= cipher_blocksize - 1;
+
+	if ((*namelen) < 0)
+		(*namelen) = 0;
+
+	return 0;
+}