Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ecryptfs/ecryptfs-2.6

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ecryptfs/ecryptfs-2.6:
  ecryptfs: remove unnecessary decrypt when extending a file
  ecryptfs: Fix ecryptfs_printk() size_t warnings
  fs/ecryptfs: Add printf format/argument verification and fix fallout
  ecryptfs: fixed testing of file descriptor flags
  ecryptfs: test lower_file pointer when lower_file_mutex is locked
  ecryptfs: missing initialization of the superblock 'magic' field
  ecryptfs: moved ECRYPTFS_SUPER_MAGIC definition to linux/magic.h
  ecryptfs: fix truncation error in ecryptfs_read_update_atime

8 files changed, 83 insertions, 80 deletions

diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index cbadc1bee6e7..bfd8b680e648 100644
--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -348,7 +348,7 @@ static int encrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
 	BUG_ON(!crypt_stat || !crypt_stat->tfm
 	       || !(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED));
 	if (unlikely(ecryptfs_verbosity > 0)) {
-		ecryptfs_printk(KERN_DEBUG, "Key size [%d]; key:\n",
+		ecryptfs_printk(KERN_DEBUG, "Key size [%zd]; key:\n",
 				crypt_stat->key_size);
 		ecryptfs_dump_hex(crypt_stat->key,
 				  crypt_stat->key_size);
@@ -413,10 +413,9 @@ static int ecryptfs_encrypt_extent(struct page *enc_extent_page,
 	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%.16x]; "
-				"rc = [%d]\n", (extent_base + extent_offset),
-				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;
 	}
 	if (unlikely(ecryptfs_verbosity > 0)) {
@@ -443,9 +442,9 @@ static int ecryptfs_encrypt_extent(struct page *enc_extent_page,
 	}
 	rc = 0;
 	if (unlikely(ecryptfs_verbosity > 0)) {
-		ecryptfs_printk(KERN_DEBUG, "Encrypt extent [0x%.16x]; "
-				"rc = [%d]\n", (extent_base + extent_offset),
-				rc);
+		ecryptfs_printk(KERN_DEBUG, "Encrypt extent [0x%.16llx]; "
+			"rc = [%d]\n",
+			(unsigned long long)(extent_base + extent_offset), rc);
 		ecryptfs_printk(KERN_DEBUG, "First 8 bytes after "
 				"encryption:\n");
 		ecryptfs_dump_hex((char *)(page_address(enc_extent_page)), 8);
@@ -540,10 +539,9 @@ static int ecryptfs_decrypt_extent(struct page *page,
 	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%.16x]; "
-				"rc = [%d]\n", (extent_base + extent_offset),
-				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;
 	}
 	if (unlikely(ecryptfs_verbosity > 0)) {
@@ -571,9 +569,9 @@ static int ecryptfs_decrypt_extent(struct page *page,
 	}
 	rc = 0;
 	if (unlikely(ecryptfs_verbosity > 0)) {
-		ecryptfs_printk(KERN_DEBUG, "Decrypt extent [0x%.16x]; "
-				"rc = [%d]\n", (extent_base + extent_offset),
-				rc);
+		ecryptfs_printk(KERN_DEBUG, "Decrypt extent [0x%.16llx]; "
+			"rc = [%d]\n",
+			(unsigned long long)(extent_base + extent_offset), rc);
 		ecryptfs_printk(KERN_DEBUG, "First 8 bytes after "
 				"decryption:\n");
 		ecryptfs_dump_hex((char *)(page_address(page)
@@ -780,7 +778,7 @@ int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
 	}
 	ecryptfs_printk(KERN_DEBUG,
 			"Initializing cipher [%s]; strlen = [%d]; "
-			"key_size_bits = [%d]\n",
+			"key_size_bits = [%zd]\n",
 			crypt_stat->cipher, (int)strlen(crypt_stat->cipher),
 			crypt_stat->key_size << 3);
 	if (crypt_stat->tfm) {
diff --git a/fs/ecryptfs/ecryptfs_kernel.h b/fs/ecryptfs/ecryptfs_kernel.h
index 413a3c48f0bb..dbc84ed96336 100644
--- a/fs/ecryptfs/ecryptfs_kernel.h
+++ b/fs/ecryptfs/ecryptfs_kernel.h
@@ -192,7 +192,6 @@ ecryptfs_get_key_payload_data(struct key *key)
 		(((struct user_key_payload*)key->payload.data)->data);
 }
 
-#define ECRYPTFS_SUPER_MAGIC 0xf15f
 #define ECRYPTFS_MAX_KEYSET_SIZE 1024
 #define ECRYPTFS_MAX_CIPHER_NAME_SIZE 32
 #define ECRYPTFS_MAX_NUM_ENC_KEYS 64
@@ -584,6 +583,7 @@ ecryptfs_set_dentry_lower_mnt(struct dentry *dentry, struct vfsmount *lower_mnt)
 
 #define ecryptfs_printk(type, fmt, arg...) \
         __ecryptfs_printk(type "%s: " fmt, __func__, ## arg);
+__attribute__ ((format(printf, 1, 2)))
 void __ecryptfs_printk(const char *fmt, ...);
 
 extern const struct file_operations ecryptfs_main_fops;
diff --git a/fs/ecryptfs/file.c b/fs/ecryptfs/file.c
index 91da02987bff..81e10e6a9443 100644
--- a/fs/ecryptfs/file.c
+++ b/fs/ecryptfs/file.c
@@ -47,7 +47,7 @@ static ssize_t ecryptfs_read_update_atime(struct kiocb *iocb,
 				const struct iovec *iov,
 				unsigned long nr_segs, loff_t pos)
 {
-	int rc;
+	ssize_t rc;
 	struct dentry *lower_dentry;
 	struct vfsmount *lower_vfsmount;
 	struct file *file = iocb->ki_filp;
@@ -191,18 +191,16 @@ static int ecryptfs_open(struct inode *inode, struct file *file)
 				      | ECRYPTFS_ENCRYPTED);
 	}
 	mutex_unlock(&crypt_stat->cs_mutex);
-	if (!ecryptfs_inode_to_private(inode)->lower_file) {
-		rc = ecryptfs_init_persistent_file(ecryptfs_dentry);
-		if (rc) {
-			printk(KERN_ERR "%s: Error attempting to initialize "
-			       "the persistent file for the dentry with name "
-			       "[%s]; rc = [%d]\n", __func__,
-			       ecryptfs_dentry->d_name.name, rc);
-			goto out_free;
-		}
+	rc = ecryptfs_init_persistent_file(ecryptfs_dentry);
+	if (rc) {
+		printk(KERN_ERR "%s: Error attempting to initialize "
+			"the persistent file for the dentry with name "
+			"[%s]; rc = [%d]\n", __func__,
+			ecryptfs_dentry->d_name.name, rc);
+		goto out_free;
 	}
-	if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_RDONLY)
-	    && !(file->f_flags & O_RDONLY)) {
+	if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_ACCMODE)
+	    == O_RDONLY && (file->f_flags & O_ACCMODE) != O_RDONLY) {
 		rc = -EPERM;
 		printk(KERN_WARNING "%s: Lower persistent file is RO; eCryptfs "
 		       "file must hence be opened RO\n", __func__);
@@ -243,9 +241,9 @@ static int ecryptfs_open(struct inode *inode, struct file *file)
 		}
 	}
 	mutex_unlock(&crypt_stat->cs_mutex);
-	ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = [0x%.16x] "
-			"size: [0x%.16x]\n", inode, inode->i_ino,
-			i_size_read(inode));
+	ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = "
+			"[0x%.16lx] size: [0x%.16llx]\n", inode, inode->i_ino,
+			(unsigned long long)i_size_read(inode));
 	goto out;
 out_free:
 	kmem_cache_free(ecryptfs_file_info_cache,
diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index 64ff02330752..bd33f87a1907 100644
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -185,15 +185,13 @@ static int ecryptfs_initialize_file(struct dentry *ecryptfs_dentry)
 				"context; rc = [%d]\n", rc);
 		goto out;
 	}
-	if (!ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->lower_file) {
-		rc = ecryptfs_init_persistent_file(ecryptfs_dentry);
-		if (rc) {
-			printk(KERN_ERR "%s: Error attempting to initialize "
-			       "the persistent file for the dentry with name "
-			       "[%s]; rc = [%d]\n", __func__,
-			       ecryptfs_dentry->d_name.name, rc);
-			goto out;
-		}
+	rc = ecryptfs_init_persistent_file(ecryptfs_dentry);
+	if (rc) {
+		printk(KERN_ERR "%s: Error attempting to initialize "
+			"the persistent file for the dentry with name "
+			"[%s]; rc = [%d]\n", __func__,
+			ecryptfs_dentry->d_name.name, rc);
+		goto out;
 	}
 	rc = ecryptfs_write_metadata(ecryptfs_dentry);
 	if (rc) {
@@ -302,15 +300,13 @@ int ecryptfs_lookup_and_interpose_lower(struct dentry *ecryptfs_dentry,
 		rc = -ENOMEM;
 		goto out;
 	}
-	if (!ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->lower_file) {
-		rc = ecryptfs_init_persistent_file(ecryptfs_dentry);
-		if (rc) {
-			printk(KERN_ERR "%s: Error attempting to initialize "
-			       "the persistent file for the dentry with name "
-			       "[%s]; rc = [%d]\n", __func__,
-			       ecryptfs_dentry->d_name.name, rc);
-			goto out_free_kmem;
-		}
+	rc = ecryptfs_init_persistent_file(ecryptfs_dentry);
+	if (rc) {
+		printk(KERN_ERR "%s: Error attempting to initialize "
+			"the persistent file for the dentry with name "
+			"[%s]; rc = [%d]\n", __func__,
+			ecryptfs_dentry->d_name.name, rc);
+		goto out_free_kmem;
 	}
 	crypt_stat = &ecryptfs_inode_to_private(
 					ecryptfs_dentry->d_inode)->crypt_stat;
diff --git a/fs/ecryptfs/keystore.c b/fs/ecryptfs/keystore.c
index b1f6858a5223..c1436cff6f2d 100644
--- a/fs/ecryptfs/keystore.c
+++ b/fs/ecryptfs/keystore.c
@@ -59,7 +59,7 @@ static int process_request_key_err(long err_code)
 		break;
 	default:
 		ecryptfs_printk(KERN_WARNING, "Unknown error code: "
-				"[0x%.16x]\n", err_code);
+				"[0x%.16lx]\n", err_code);
 		rc = -EINVAL;
 	}
 	return rc;
@@ -130,7 +130,7 @@ int ecryptfs_write_packet_length(char *dest, size_t size,
 	} else {
 		rc = -EINVAL;
 		ecryptfs_printk(KERN_WARNING,
-				"Unsupported packet size: [%d]\n", size);
+				"Unsupported packet size: [%zd]\n", size);
 	}
 	return rc;
 }
@@ -1672,7 +1672,7 @@ decrypt_passphrase_encrypted_session_key(struct ecryptfs_auth_tok *auth_tok,
 	       auth_tok->session_key.decrypted_key_size);
 	crypt_stat->flags |= ECRYPTFS_KEY_VALID;
 	if (unlikely(ecryptfs_verbosity > 0)) {
-		ecryptfs_printk(KERN_DEBUG, "FEK of size [%d]:\n",
+		ecryptfs_printk(KERN_DEBUG, "FEK of size [%zd]:\n",
 				crypt_stat->key_size);
 		ecryptfs_dump_hex(crypt_stat->key,
 				  crypt_stat->key_size);
@@ -1754,7 +1754,7 @@ int ecryptfs_parse_packet_set(struct ecryptfs_crypt_stat *crypt_stat,
 			if (ECRYPTFS_SIG_SIZE != tag_11_contents_size) {
 				ecryptfs_printk(KERN_ERR, "Expected "
 						"signature of size [%d]; "
-						"read size [%d]\n",
+						"read size [%zd]\n",
 						ECRYPTFS_SIG_SIZE,
 						tag_11_contents_size);
 				rc = -EIO;
@@ -1787,8 +1787,8 @@ int ecryptfs_parse_packet_set(struct ecryptfs_crypt_stat *crypt_stat,
 			goto out_wipe_list;
 			break;
 		default:
-			ecryptfs_printk(KERN_DEBUG, "No packet at offset "
-					"[%d] of the file header; hex value of "
+			ecryptfs_printk(KERN_DEBUG, "No packet at offset [%zd] "
+					"of the file header; hex value of "
 					"character is [0x%.2x]\n", i, src[i]);
 			next_packet_is_auth_tok_packet = 0;
 		}
@@ -1864,8 +1864,8 @@ found_matching_auth_tok:
 				"session key for authentication token with sig "
 				"[%.*s]; rc = [%d]. Removing auth tok "
 				"candidate from the list and searching for "
-				"the next match.\n", candidate_auth_tok_sig,
-				ECRYPTFS_SIG_SIZE_HEX, rc);
+				"the next match.\n", ECRYPTFS_SIG_SIZE_HEX,
+				candidate_auth_tok_sig,	rc);
 		list_for_each_entry_safe(auth_tok_list_item,
 					 auth_tok_list_item_tmp,
 					 &auth_tok_list, list) {
@@ -2168,7 +2168,7 @@ write_tag_3_packet(char *dest, size_t *remaining_bytes,
 	if (encrypted_session_key_valid) {
 		ecryptfs_printk(KERN_DEBUG, "encrypted_session_key_valid != 0; "
 				"using auth_tok->session_key.encrypted_key, "
-				"where key_rec->enc_key_size = [%d]\n",
+				"where key_rec->enc_key_size = [%zd]\n",
 				key_rec->enc_key_size);
 		memcpy(key_rec->enc_key,
 		       auth_tok->session_key.encrypted_key,
@@ -2198,7 +2198,7 @@ write_tag_3_packet(char *dest, size_t *remaining_bytes,
 	if (rc < 1 || rc > 2) {
 		ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
 				"for crypt_stat session key; expected rc = 1; "
-				"got rc = [%d]. key_rec->enc_key_size = [%d]\n",
+				"got rc = [%d]. key_rec->enc_key_size = [%zd]\n",
 				rc, key_rec->enc_key_size);
 		rc = -ENOMEM;
 		goto out;
@@ -2209,7 +2209,7 @@ write_tag_3_packet(char *dest, size_t *remaining_bytes,
 		ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
 				"for crypt_stat encrypted session key; "
 				"expected rc = 1; got rc = [%d]. "
-				"key_rec->enc_key_size = [%d]\n", rc,
+				"key_rec->enc_key_size = [%zd]\n", rc,
 				key_rec->enc_key_size);
 		rc = -ENOMEM;
 		goto out;
@@ -2224,7 +2224,7 @@ write_tag_3_packet(char *dest, size_t *remaining_bytes,
 		goto out;
 	}
 	rc = 0;
-	ecryptfs_printk(KERN_DEBUG, "Encrypting [%d] bytes of the key\n",
+	ecryptfs_printk(KERN_DEBUG, "Encrypting [%zd] bytes of the key\n",
 			crypt_stat->key_size);
 	rc = crypto_blkcipher_encrypt(&desc, dst_sg, src_sg,
 				      (*key_rec).enc_key_size);
@@ -2235,7 +2235,7 @@ write_tag_3_packet(char *dest, size_t *remaining_bytes,
 	}
 	ecryptfs_printk(KERN_DEBUG, "This should be the encrypted key:\n");
 	if (ecryptfs_verbosity > 0) {
-		ecryptfs_printk(KERN_DEBUG, "EFEK of size [%d]:\n",
+		ecryptfs_printk(KERN_DEBUG, "EFEK of size [%zd]:\n",
 				key_rec->enc_key_size);
 		ecryptfs_dump_hex(key_rec->enc_key,
 				  key_rec->enc_key_size);
diff --git a/fs/ecryptfs/main.c b/fs/ecryptfs/main.c
index d3b28abdd6aa..758323a0f09a 100644
--- a/fs/ecryptfs/main.c
+++ b/fs/ecryptfs/main.c
@@ -36,6 +36,7 @@
 #include <linux/parser.h>
 #include <linux/fs_stack.h>
 #include <linux/slab.h>
+#include <linux/magic.h>
 #include "ecryptfs_kernel.h"
 
 /**
@@ -564,6 +565,7 @@ static struct dentry *ecryptfs_mount(struct file_system_type *fs_type, int flags
 	ecryptfs_set_superblock_lower(s, path.dentry->d_sb);
 	s->s_maxbytes = path.dentry->d_sb->s_maxbytes;
 	s->s_blocksize = path.dentry->d_sb->s_blocksize;
+	s->s_magic = ECRYPTFS_SUPER_MAGIC;
 
 	inode = ecryptfs_get_inode(path.dentry->d_inode, s);
 	rc = PTR_ERR(inode);
@@ -808,9 +810,10 @@ static int __init ecryptfs_init(void)
 		ecryptfs_printk(KERN_ERR, "The eCryptfs extent size is "
 				"larger than the host's page size, and so "
 				"eCryptfs cannot run on this system. The "
-				"default eCryptfs extent size is [%d] bytes; "
-				"the page size is [%d] bytes.\n",
-				ECRYPTFS_DEFAULT_EXTENT_SIZE, PAGE_CACHE_SIZE);
+				"default eCryptfs extent size is [%u] bytes; "
+				"the page size is [%lu] bytes.\n",
+				ECRYPTFS_DEFAULT_EXTENT_SIZE,
+				(unsigned long)PAGE_CACHE_SIZE);
 		goto out;
 	}
 	rc = ecryptfs_init_kmem_caches();
diff --git a/fs/ecryptfs/mmap.c b/fs/ecryptfs/mmap.c
index b1d82756544b..cc64fca89f8d 100644
--- a/fs/ecryptfs/mmap.c
+++ b/fs/ecryptfs/mmap.c
@@ -65,7 +65,7 @@ static int ecryptfs_writepage(struct page *page, struct writeback_control *wbc)
 	rc = ecryptfs_encrypt_page(page);
 	if (rc) {
 		ecryptfs_printk(KERN_WARNING, "Error encrypting "
-				"page (upper index [0x%.16x])\n", page->index);
+				"page (upper index [0x%.16lx])\n", page->index);
 		ClearPageUptodate(page);
 		goto out;
 	}
@@ -237,7 +237,7 @@ out:
 		ClearPageUptodate(page);
 	else
 		SetPageUptodate(page);
-	ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16x]\n",
+	ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16lx]\n",
 			page->index);
 	unlock_page(page);
 	return rc;
@@ -290,6 +290,7 @@ static int ecryptfs_write_begin(struct file *file,
 		return -ENOMEM;
 	*pagep = page;
 
+	prev_page_end_size = ((loff_t)index << PAGE_CACHE_SHIFT);
 	if (!PageUptodate(page)) {
 		struct ecryptfs_crypt_stat *crypt_stat =
 			&ecryptfs_inode_to_private(mapping->host)->crypt_stat;
@@ -335,18 +336,23 @@ static int ecryptfs_write_begin(struct file *file,
 				SetPageUptodate(page);
 			}
 		} else {
-			rc = ecryptfs_decrypt_page(page);
-			if (rc) {
-				printk(KERN_ERR "%s: Error decrypting page "
-				       "at index [%ld]; rc = [%d]\n",
-				       __func__, page->index, rc);
-				ClearPageUptodate(page);
-				goto out;
+			if (prev_page_end_size
+			    >= i_size_read(page->mapping->host)) {
+				zero_user(page, 0, PAGE_CACHE_SIZE);
+			} else {
+				rc = ecryptfs_decrypt_page(page);
+				if (rc) {
+					printk(KERN_ERR "%s: Error decrypting "
+					       "page at index [%ld]; "
+					       "rc = [%d]\n",
+					       __func__, page->index, rc);
+					ClearPageUptodate(page);
+					goto out;
+				}
 			}
 			SetPageUptodate(page);
 		}
 	}
-	prev_page_end_size = ((loff_t)index << PAGE_CACHE_SHIFT);
 	/* If creating a page or more of holes, zero them out via truncate.
 	 * Note, this will increase i_size. */
 	if (index != 0) {
@@ -488,7 +494,7 @@ static int ecryptfs_write_end(struct file *file,
 	} else
 		ecryptfs_printk(KERN_DEBUG, "Not a new file\n");
 	ecryptfs_printk(KERN_DEBUG, "Calling fill_zeros_to_end_of_page"
-			"(page w/ index = [0x%.16x], to = [%d])\n", index, to);
+			"(page w/ index = [0x%.16lx], to = [%d])\n", index, to);
 	if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
 		rc = ecryptfs_write_lower_page_segment(ecryptfs_inode, page, 0,
 						       to);
@@ -503,19 +509,20 @@ static int ecryptfs_write_end(struct file *file,
 	rc = fill_zeros_to_end_of_page(page, to);
 	if (rc) {
 		ecryptfs_printk(KERN_WARNING, "Error attempting to fill "
-			"zeros in page with index = [0x%.16x]\n", index);
+			"zeros in page with index = [0x%.16lx]\n", index);
 		goto out;
 	}
 	rc = ecryptfs_encrypt_page(page);
 	if (rc) {
 		ecryptfs_printk(KERN_WARNING, "Error encrypting page (upper "
-				"index [0x%.16x])\n", index);
+				"index [0x%.16lx])\n", index);
 		goto out;
 	}
 	if (pos + copied > i_size_read(ecryptfs_inode)) {
 		i_size_write(ecryptfs_inode, pos + copied);
 		ecryptfs_printk(KERN_DEBUG, "Expanded file size to "
-				"[0x%.16x]\n", i_size_read(ecryptfs_inode));
+			"[0x%.16llx]\n",
+			(unsigned long long)i_size_read(ecryptfs_inode));
 	}
 	rc = ecryptfs_write_inode_size_to_metadata(ecryptfs_inode);
 	if (rc)
diff --git a/include/linux/magic.h b/include/linux/magic.h
index ff690d05f129..62730ea2b56e 100644
--- a/include/linux/magic.h
+++ b/include/linux/magic.h
@@ -16,6 +16,7 @@
 #define TMPFS_MAGIC		0x01021994
 #define HUGETLBFS_MAGIC 	0x958458f6	/* some random number */
 #define SQUASHFS_MAGIC		0x73717368
+#define ECRYPTFS_SUPER_MAGIC	0xf15f
 #define EFS_SUPER_MAGIC		0x414A53
 #define EXT2_SUPER_MAGIC	0xEF53
 #define EXT3_SUPER_MAGIC	0xEF53