[PATCH] eCryptfs: Generalize metadata read/write

Generalize the metadata reading and writing mechanisms, with two targets for
now: metadata in file header and metadata in the user.ecryptfs xattr of the
lower file.

[akpm@osdl.org: printk warning fix]
[bunk@stusta.de: make some needlessly global code static]
Signed-off-by: Michael Halcrow <mhalcrow@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/ecryptfs/ecryptfs_kernel.h

@@ -4,7 +4,7 @@
  *
  * Copyright (C) 1997-2003 Erez Zadok
  * Copyright (C) 2001-2003 Stony Brook University
- * Copyright (C) 2004-2006 International Business Machines Corp.
+ * Copyright (C) 2004-2007 International Business Machines Corp.
  *   Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
  *              Trevor S. Highland <trevor.highland@gmail.com>
  *              Tyler Hicks <tyhicks@ou.edu>
@@ -50,8 +50,8 @@
 #define ECRYPTFS_VERSIONING_XATTR                 0x00000010
 #define ECRYPTFS_VERSIONING_MASK (ECRYPTFS_VERSIONING_PASSPHRASE \
 				  | ECRYPTFS_VERSIONING_PLAINTEXT_PASSTHROUGH \
-				  | ECRYPTFS_VERSIONING_PUBKEY)
-
+				  | ECRYPTFS_VERSIONING_PUBKEY \
+				  | ECRYPTFS_VERSIONING_XATTR)
 #define ECRYPTFS_MAX_PASSWORD_LENGTH 64
 #define ECRYPTFS_MAX_PASSPHRASE_BYTES ECRYPTFS_MAX_PASSWORD_LENGTH
 #define ECRYPTFS_SALT_SIZE 8
@@ -83,6 +83,7 @@
 #define ECRYPTFS_TRANSPORT_CONNECTOR 1
 #define ECRYPTFS_TRANSPORT_RELAYFS 2
 #define ECRYPTFS_DEFAULT_TRANSPORT ECRYPTFS_TRANSPORT_NETLINK
+#define ECRYPTFS_XATTR_NAME "user.ecryptfs"
 
 #define RFC2440_CIPHER_DES3_EDE 0x02
 #define RFC2440_CIPHER_CAST_5 0x03
@@ -327,18 +328,6 @@ struct ecryptfs_msg_ctx {
 	struct mutex mux;
 };
 
-extern struct list_head ecryptfs_msg_ctx_free_list;
-extern struct list_head ecryptfs_msg_ctx_alloc_list;
-extern struct mutex ecryptfs_msg_ctx_lists_mux;
-
-#define ecryptfs_uid_hash(uid) \
-        hash_long((unsigned long)uid, ecryptfs_hash_buckets)
-extern struct hlist_head *ecryptfs_daemon_id_hash;
-extern struct mutex ecryptfs_daemon_id_hash_mux;
-extern int ecryptfs_hash_buckets;
-
-extern unsigned int ecryptfs_msg_counter;
-extern struct ecryptfs_msg_ctx *ecryptfs_msg_ctx_arr;
 extern unsigned int ecryptfs_transport;
 
 struct ecryptfs_daemon_id {
@@ -479,6 +468,7 @@ extern struct kmem_cache *ecryptfs_sb_info_cache;
 extern struct kmem_cache *ecryptfs_header_cache_0;
 extern struct kmem_cache *ecryptfs_header_cache_1;
 extern struct kmem_cache *ecryptfs_header_cache_2;
+extern struct kmem_cache *ecryptfs_xattr_cache;
 extern struct kmem_cache *ecryptfs_lower_page_cache;
 
 int ecryptfs_interpose(struct dentry *hidden_dentry,
@@ -505,9 +495,13 @@ int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat);
 int ecryptfs_crypto_api_algify_cipher_name(char **algified_name,
 					   char *cipher_name,
 					   char *chaining_modifier);
-int ecryptfs_write_inode_size_to_header(struct file *lower_file,
+#define ECRYPTFS_LOWER_I_MUTEX_NOT_HELD 0
+#define ECRYPTFS_LOWER_I_MUTEX_HELD 1
+int ecryptfs_write_inode_size_to_metadata(struct file *lower_file,
 					  struct inode *lower_inode,
-					struct inode *inode);
+					  struct inode *inode,
+					  struct dentry *ecryptfs_dentry,
+					  int lower_i_mutex_held);
 int ecryptfs_get_lower_page(struct page **lower_page, struct inode *lower_inode,
 			    struct file *lower_file,
 			    unsigned long lower_page_index, int byte_offset,
@@ -529,17 +523,15 @@ int ecryptfs_writepage_and_release_lower_page(struct page *lower_page,
 					      struct writeback_control *wbc);
 int ecryptfs_encrypt_page(struct ecryptfs_page_crypt_context *ctx);
 int ecryptfs_decrypt_page(struct file *file, struct page *page);
-int ecryptfs_write_headers(struct dentry *ecryptfs_dentry,
+int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry,
 			    struct file *lower_file);
-int ecryptfs_write_headers_virt(char *page_virt,
-				struct ecryptfs_crypt_stat *crypt_stat,
-				struct dentry *ecryptfs_dentry);
-int ecryptfs_read_headers(struct dentry *ecryptfs_dentry,
+int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry,
 			   struct file *lower_file);
 int ecryptfs_new_file_context(struct dentry *ecryptfs_dentry);
-int contains_ecryptfs_marker(char *data);
-int ecryptfs_read_header_region(char *data, struct dentry *dentry,
+int ecryptfs_read_and_validate_header_region(char *data, struct dentry *dentry,
 					     struct vfsmount *mnt);
+int ecryptfs_read_and_validate_xattr_region(char *page_virt,
+					    struct dentry *ecryptfs_dentry);
 u16 ecryptfs_code_for_cipher_string(struct ecryptfs_crypt_stat *crypt_stat);
 int ecryptfs_cipher_code_to_string(char *str, u16 cipher_code);
 void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat);
@@ -562,6 +554,11 @@ int ecryptfs_open_lower_file(struct file **lower_file,
 			     struct dentry *lower_dentry,
 			     struct vfsmount *lower_mnt, int flags);
 int ecryptfs_close_lower_file(struct file *lower_file);
+ssize_t ecryptfs_getxattr(struct dentry *dentry, const char *name, void *value,
+			  size_t size);
+int
+ecryptfs_setxattr(struct dentry *dentry, const char *name, const void *value,
+		  size_t size, int flags);
 
 int ecryptfs_process_helo(unsigned int transport, uid_t uid, pid_t pid);
 int ecryptfs_process_quit(uid_t uid, pid_t pid);

fs/ecryptfs/file.c

@@ -3,7 +3,7 @@
  *
  * Copyright (C) 1997-2004 Erez Zadok
  * Copyright (C) 2001-2004 Stony Brook University
- * Copyright (C) 2004-2006 International Business Machines Corp.
+ * Copyright (C) 2004-2007 International Business Machines Corp.
  *   Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
  *   		Michael C. Thompson <mcthomps@us.ibm.com>
  *
@@ -293,26 +293,11 @@ static int ecryptfs_open(struct inode *inode, struct file *file)
 		goto out;
 	}
 	mutex_lock(&crypt_stat->cs_mutex);
-	if (i_size_read(lower_inode) < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE) {
-		if (!(mount_crypt_stat->flags
-		      & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)) {
-			rc = -EIO;
-			printk(KERN_WARNING "Attempt to read file that is "
-			       "not in a valid eCryptfs format, and plaintext "
-			       "passthrough mode is not enabled; returning "
-			       "-EIO\n");
-			mutex_unlock(&crypt_stat->cs_mutex);
-			goto out_puts;
-		}
-		crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
-		rc = 0;
-		mutex_unlock(&crypt_stat->cs_mutex);
-		goto out;
-	} else if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags,
+	if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags,
 				 ECRYPTFS_POLICY_APPLIED)
 	    || !ECRYPTFS_CHECK_FLAG(crypt_stat->flags,
 				    ECRYPTFS_KEY_VALID)) {
-		rc = ecryptfs_read_headers(ecryptfs_dentry, lower_file);
+		rc = ecryptfs_read_metadata(ecryptfs_dentry, lower_file);
 		if (rc) {
 			ecryptfs_printk(KERN_DEBUG,
 					"Valid headers not found\n");

fs/ecryptfs/inode.c

@@ -3,7 +3,7 @@
  *
  * Copyright (C) 1997-2004 Erez Zadok
  * Copyright (C) 2001-2004 Stony Brook University
- * Copyright (C) 2004-2006 International Business Machines Corp.
+ * Copyright (C) 2004-2007 International Business Machines Corp.
  *   Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
  *              Michael C. Thompsion <mcthomps@us.ibm.com>
  *
@@ -169,7 +169,9 @@ static int grow_file(struct dentry *ecryptfs_dentry, struct file *lower_file,
 		goto out;
 	}
 	i_size_write(inode, 0);
-	ecryptfs_write_inode_size_to_header(lower_file, lower_inode, inode);
+	ecryptfs_write_inode_size_to_metadata(lower_file, lower_inode, inode,
+					      ecryptfs_dentry,
+					      ECRYPTFS_LOWER_I_MUTEX_NOT_HELD);
 	ECRYPTFS_SET_FLAG(ecryptfs_inode_to_private(inode)->crypt_stat.flags,
 			  ECRYPTFS_NEW_FILE);
 out:
@@ -225,7 +227,7 @@ static int ecryptfs_initialize_file(struct dentry *ecryptfs_dentry)
 				"context\n");
 		goto out_fput;
 	}
-	rc = ecryptfs_write_headers(ecryptfs_dentry, lower_file);
+	rc = ecryptfs_write_metadata(ecryptfs_dentry, lower_file);
 	if (rc) {
 		ecryptfs_printk(KERN_DEBUG, "Error writing headers\n");
 		goto out_fput;
@@ -369,25 +371,26 @@ static struct dentry *ecryptfs_lookup(struct inode *dir, struct dentry *dentry,
 				"Cannot ecryptfs_kmalloc a page\n");
 		goto out_dput;
 	}
-
-	rc = ecryptfs_read_header_region(page_virt, lower_dentry, nd->mnt);
 	crypt_stat = &ecryptfs_inode_to_private(dentry->d_inode)->crypt_stat;
 	if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_POLICY_APPLIED))
 		ecryptfs_set_default_sizes(crypt_stat);
+	rc = ecryptfs_read_and_validate_header_region(page_virt, lower_dentry,
+						      nd->mnt);
+	if (rc) {
+		rc = ecryptfs_read_and_validate_xattr_region(page_virt, dentry);
 		if (rc) {
+			printk(KERN_DEBUG "Valid metadata not found in header "
+			       "region or xattr region; treating file as "
+			       "unencrypted\n");
 			rc = 0;
-		ecryptfs_printk(KERN_WARNING, "Error reading header region;"
-				" assuming unencrypted\n");
-	} else {
-		if (!contains_ecryptfs_marker(page_virt
-					      + ECRYPTFS_FILE_SIZE_BYTES)) {
 			kmem_cache_free(ecryptfs_header_cache_2, page_virt);
 			goto out;
 		}
+		crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
+	}
 	memcpy(&file_size, page_virt, sizeof(file_size));
 	file_size = be64_to_cpu(file_size);
 	i_size_write(dentry->d_inode, (loff_t)file_size);
-	}
 	kmem_cache_free(ecryptfs_header_cache_2, page_virt);
 	goto out;
 
@@ -781,20 +784,26 @@ int ecryptfs_truncate(struct dentry *dentry, loff_t new_length)
 			goto out_fput;
 		}
 		i_size_write(inode, new_length);
-		rc = ecryptfs_write_inode_size_to_header(lower_file,
-							 lower_dentry->d_inode,
-							 inode);
+		rc = ecryptfs_write_inode_size_to_metadata(
+			lower_file, lower_dentry->d_inode, inode, dentry,
+			ECRYPTFS_LOWER_I_MUTEX_NOT_HELD);
 		if (rc) {
-			ecryptfs_printk(KERN_ERR,
-					"Problem with ecryptfs_write"
-					"_inode_size\n");
+			printk(KERN_ERR	"Problem with "
+			       "ecryptfs_write_inode_size_to_metadata; "
+			       "rc = [%d]\n", rc);
 			goto out_fput;
 		}
 	} else { /* new_length < i_size_read(inode) */
 		vmtruncate(inode, new_length);
-		ecryptfs_write_inode_size_to_header(lower_file,
-						    lower_dentry->d_inode,
-						    inode);
+		rc = ecryptfs_write_inode_size_to_metadata(
+			lower_file, lower_dentry->d_inode, inode, dentry,
+			ECRYPTFS_LOWER_I_MUTEX_NOT_HELD);
+		if (rc) {
+			printk(KERN_ERR	"Problem with "
+			       "ecryptfs_write_inode_size_to_metadata; "
+			       "rc = [%d]\n", rc);
+			goto out_fput;
+		}
 		/* We are reducing the size of the ecryptfs file, and need to
 		 * know if we need to reduce the size of the lower file. */
 		lower_size_before_truncate =
@@ -881,7 +890,7 @@ static int ecryptfs_setattr(struct dentry *dentry, struct iattr *ia)
 	return rc;
 }
 
-static int
+int
 ecryptfs_setxattr(struct dentry *dentry, const char *name, const void *value,
 		  size_t size, int flags)
 {
@@ -901,7 +910,7 @@ ecryptfs_setxattr(struct dentry *dentry, const char *name, const void *value,
 	return rc;
 }
 
-static ssize_t
+ssize_t
 ecryptfs_getxattr(struct dentry *dentry, const char *name, void *value,
 		  size_t size)
 {

fs/ecryptfs/main.c

@@ -3,7 +3,7 @@
  *
  * Copyright (C) 1997-2003 Erez Zadok
  * Copyright (C) 2001-2003 Stony Brook University
- * Copyright (C) 2004-2006 International Business Machines Corp.
+ * Copyright (C) 2004-2007 International Business Machines Corp.
  *   Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
  *              Michael C. Thompson <mcthomps@us.ibm.com>
  *              Tyler Hicks <tyhicks@ou.edu>
@@ -641,6 +641,11 @@ static struct ecryptfs_cache_info {
 		.name = "ecryptfs_headers_2",
 		.size = PAGE_CACHE_SIZE,
 	},
+	{
+		.cache = &ecryptfs_xattr_cache,
+		.name = "ecryptfs_xattr_cache",
+		.size = PAGE_CACHE_SIZE,
+	},
 	{
 		.cache = &ecryptfs_lower_page_cache,
 		.name = "ecryptfs_lower_page_cache",

fs/ecryptfs/messaging.c

@@ -22,16 +22,18 @@
 
 #include "ecryptfs_kernel.h"
 
-LIST_HEAD(ecryptfs_msg_ctx_free_list);
-LIST_HEAD(ecryptfs_msg_ctx_alloc_list);
-struct mutex ecryptfs_msg_ctx_lists_mux;
+static LIST_HEAD(ecryptfs_msg_ctx_free_list);
+static LIST_HEAD(ecryptfs_msg_ctx_alloc_list);
+static struct mutex ecryptfs_msg_ctx_lists_mux;
 
-struct hlist_head *ecryptfs_daemon_id_hash;
-struct mutex ecryptfs_daemon_id_hash_mux;
-int ecryptfs_hash_buckets;
+static struct hlist_head *ecryptfs_daemon_id_hash;
+static struct mutex ecryptfs_daemon_id_hash_mux;
+static int ecryptfs_hash_buckets;
+#define ecryptfs_uid_hash(uid) \
+        hash_long((unsigned long)uid, ecryptfs_hash_buckets)
 
-unsigned int ecryptfs_msg_counter;
-struct ecryptfs_msg_ctx *ecryptfs_msg_ctx_arr;
+static unsigned int ecryptfs_msg_counter;
+static struct ecryptfs_msg_ctx *ecryptfs_msg_ctx_arr;
 
 /**
  * ecryptfs_acquire_free_msg_ctx

fs/ecryptfs/mmap.c

@@ -6,7 +6,7 @@
  *
  * Copyright (C) 1997-2003 Erez Zadok
  * Copyright (C) 2001-2003 Stony Brook University
- * Copyright (C) 2004-2006 International Business Machines Corp.
+ * Copyright (C) 2004-2007 International Business Machines Corp.
  *   Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
  *
  * This program is free software; you can redistribute it and/or
@@ -308,6 +308,9 @@ static int ecryptfs_readpage(struct file *file, struct page *page)
 	return rc;
 }
 
+/**
+ * Called with lower inode mutex held.
+ */
 static int fill_zeros_to_end_of_page(struct page *page, unsigned int to)
 {
 	struct inode *inode = page->mapping->host;
@@ -407,8 +410,7 @@ static void ecryptfs_unmap_and_release_lower_page(struct page *lower_page)
  *
  * Returns zero on success; non-zero on error.
  */
-int
-ecryptfs_write_inode_size_to_header(struct file *lower_file,
+static int ecryptfs_write_inode_size_to_header(struct file *lower_file,
 					       struct inode *lower_inode,
 					       struct inode *inode)
 {
@@ -442,6 +444,80 @@ ecryptfs_write_inode_size_to_header(struct file *lower_file,
 	return rc;
 }
 
+static int ecryptfs_write_inode_size_to_xattr(struct inode *lower_inode,
+					      struct inode *inode,
+					      struct dentry *ecryptfs_dentry,
+					      int lower_i_mutex_held)
+{
+	ssize_t size;
+	void *xattr_virt;
+	struct dentry *lower_dentry;
+	u64 file_size;
+	int rc;
+
+	xattr_virt = kmem_cache_alloc(ecryptfs_xattr_cache, GFP_KERNEL);
+	if (!xattr_virt) {
+		printk(KERN_ERR "Out of memory whilst attempting to write "
+		       "inode size to xattr\n");
+		rc = -ENOMEM;
+		goto out;
+	}
+	lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
+	if (!lower_dentry->d_inode->i_op->getxattr) {
+		printk(KERN_WARNING
+		       "No support for setting xattr in lower filesystem\n");
+		rc = -ENOSYS;
+		kmem_cache_free(ecryptfs_xattr_cache, xattr_virt);
+		goto out;
+	}
+	if (!lower_i_mutex_held)
+		mutex_lock(&lower_dentry->d_inode->i_mutex);
+	size = lower_dentry->d_inode->i_op->getxattr(lower_dentry,
+						     ECRYPTFS_XATTR_NAME,
+						     xattr_virt,
+						     PAGE_CACHE_SIZE);
+	if (!lower_i_mutex_held)
+		mutex_unlock(&lower_dentry->d_inode->i_mutex);
+	if (size < 0)
+		size = 8;
+	file_size = (u64)i_size_read(inode);
+	file_size = cpu_to_be64(file_size);
+	memcpy(xattr_virt, &file_size, sizeof(u64));
+	if (!lower_i_mutex_held)
+		mutex_lock(&lower_dentry->d_inode->i_mutex);
+	rc = lower_dentry->d_inode->i_op->setxattr(lower_dentry,
+						   ECRYPTFS_XATTR_NAME,
+						   xattr_virt, size, 0);
+	if (!lower_i_mutex_held)
+		mutex_unlock(&lower_dentry->d_inode->i_mutex);
+	if (rc)
+		printk(KERN_ERR "Error whilst attempting to write inode size "
+		       "to lower file xattr; rc = [%d]\n", rc);
+	kmem_cache_free(ecryptfs_xattr_cache, xattr_virt);
+out:
+	return rc;
+}
+
+int
+ecryptfs_write_inode_size_to_metadata(struct file *lower_file,
+				      struct inode *lower_inode,
+				      struct inode *inode,
+				      struct dentry *ecryptfs_dentry,
+				      int lower_i_mutex_held)
+{
+	struct ecryptfs_crypt_stat *crypt_stat;
+
+	crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
+	if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
+		return ecryptfs_write_inode_size_to_xattr(lower_inode, inode,
+							  ecryptfs_dentry,
+							  lower_i_mutex_held);
+	else
+		return ecryptfs_write_inode_size_to_header(lower_file,
+							   lower_inode,
+							   inode);
+}
+
 int ecryptfs_get_lower_page(struct page **lower_page, struct inode *lower_inode,
 			    struct file *lower_file,
 			    unsigned long lower_page_index, int byte_offset,
@@ -528,6 +604,8 @@ int ecryptfs_copy_page_to_lower(struct page *page, struct inode *lower_inode,
 	return rc;
 }
 
+struct kmem_cache *ecryptfs_xattr_cache;
+
 /**
  * ecryptfs_commit_write
  * @file: The eCryptfs file object
@@ -581,7 +659,6 @@ static int ecryptfs_commit_write(struct file *file, struct page *page,
 				"index [0x%.16x])\n", page->index);
 		goto out;
 	}
-	rc = 0;
 	inode->i_blocks = lower_inode->i_blocks;
 	pos = (page->index << PAGE_CACHE_SHIFT) + to;
 	if (pos > i_size_read(inode)) {
@@ -589,7 +666,12 @@ static int ecryptfs_commit_write(struct file *file, struct page *page,
 		ecryptfs_printk(KERN_DEBUG, "Expanded file size to "
 				"[0x%.16x]\n", i_size_read(inode));
 	}
-	ecryptfs_write_inode_size_to_header(lower_file, lower_inode, inode);
+	rc = ecryptfs_write_inode_size_to_metadata(lower_file, lower_inode,
+						   inode, file->f_dentry,
+						   ECRYPTFS_LOWER_I_MUTEX_HELD);
+	if (rc)
+		printk(KERN_ERR "Error writing inode size to metadata; "
+		       "rc = [%d]\n", rc);
 	lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
 	mark_inode_dirty_sync(inode);
 out: