eCryptfs: track header bytes rather than extents

Remove internal references to header extents; just keep track of header bytes
instead.  Headers can easily span multiple pages with the recent persistent
file changes.

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>

5 files changed, 51 insertions, 84 deletions

diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index 5e7d018a3486..4d1b2b4eb79e 100644
--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -379,8 +379,7 @@ out:
 static void ecryptfs_lower_offset_for_extent(loff_t *offset, loff_t extent_num,
                                              struct ecryptfs_crypt_stat *crypt_stat)
 {
-        (*offset) = ((crypt_stat->extent_size
-                      * crypt_stat->num_header_extents_at_front)
+        (*offset) = (crypt_stat->num_header_bytes_at_front
                      + (crypt_stat->extent_size * extent_num));
 }
 
@@ -842,15 +841,13 @@ void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat)
         set_extent_mask_and_shift(crypt_stat);
         crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES;
         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
-                crypt_stat->num_header_extents_at_front = 0;
+                crypt_stat->num_header_bytes_at_front = 0;
         else {
                 if (PAGE_CACHE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)
-                        crypt_stat->num_header_extents_at_front =
-                                (ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE
-                                 / crypt_stat->extent_size);
+                        crypt_stat->num_header_bytes_at_front =
+                                ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
                 else
-                        crypt_stat->num_header_extents_at_front =
-                                (PAGE_CACHE_SIZE / crypt_stat->extent_size);
+                        crypt_stat->num_header_bytes_at_front = PAGE_CACHE_SIZE;
         }
 }
 
@@ -1236,7 +1233,8 @@ ecryptfs_write_header_metadata(char *virt,
 
         header_extent_size = (u32)crypt_stat->extent_size;
         num_header_extents_at_front =
-                (u16)crypt_stat->num_header_extents_at_front;
+                (u16)(crypt_stat->num_header_bytes_at_front
+                      / crypt_stat->extent_size);
         header_extent_size = cpu_to_be32(header_extent_size);
         memcpy(virt, &header_extent_size, 4);
         virt += 4;
@@ -1311,40 +1309,16 @@ static int ecryptfs_write_headers_virt(char *page_virt, size_t *size,
 static int
 ecryptfs_write_metadata_to_contents(struct ecryptfs_crypt_stat *crypt_stat,
                                     struct dentry *ecryptfs_dentry,
-                                    char *page_virt)
+                                    char *virt)
 {
-        int current_header_page;
-        int header_pages;
         int rc;
 
-        rc = ecryptfs_write_lower(ecryptfs_dentry->d_inode, page_virt,
-                                  0, PAGE_CACHE_SIZE);
-        if (rc) {
+        rc = ecryptfs_write_lower(ecryptfs_dentry->d_inode, virt,
+                                  0, crypt_stat->num_header_bytes_at_front);
+        if (rc)
                 printk(KERN_ERR "%s: Error attempting to write header "
                        "information to lower file; rc = [%d]\n", __FUNCTION__,
                        rc);
-                goto out;
-        }
-        header_pages = ((crypt_stat->extent_size
-                         * crypt_stat->num_header_extents_at_front)
-                        / PAGE_CACHE_SIZE);
-        memset(page_virt, 0, PAGE_CACHE_SIZE);
-        current_header_page = 1;
-        while (current_header_page < header_pages) {
-                loff_t offset;
-
-                offset = (((loff_t)current_header_page) << PAGE_CACHE_SHIFT);
-                if ((rc = ecryptfs_write_lower(ecryptfs_dentry->d_inode,
-                                               page_virt, offset,
-                                               PAGE_CACHE_SIZE))) {
-                        printk(KERN_ERR "%s: Error attempting to write header "
-                               "information to lower file; rc = [%d]\n",
-                               __FUNCTION__, rc);
-                        goto out;
-                }
-                current_header_page++;
-        }
-out:
         return rc;
 }
 
@@ -1370,15 +1344,13 @@ ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry,
  * retrieved via a prompt.  Exactly what happens at this point should
  * be policy-dependent.
  *
- * TODO: Support header information spanning multiple pages
- *
  * Returns zero on success; non-zero on error
  */
 int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry)
 {
         struct ecryptfs_crypt_stat *crypt_stat =
                 &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
-        char *page_virt;
+        char *virt;
         size_t size = 0;
         int rc = 0;
 
@@ -1389,40 +1361,39 @@ int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry)
                         goto out;
                 }
         } else {
+                printk(KERN_WARNING "%s: Encrypted flag not set\n",
+                       __FUNCTION__);
                 rc = -EINVAL;
-                ecryptfs_printk(KERN_WARNING,
-                                "Called with crypt_stat->encrypted == 0\n");
                 goto out;
         }
         /* Released in this function */
-        page_virt = kmem_cache_zalloc(ecryptfs_header_cache_0, GFP_USER);
-        if (!page_virt) {
-                ecryptfs_printk(KERN_ERR, "Out of memory\n");
+        virt = kzalloc(crypt_stat->num_header_bytes_at_front, GFP_KERNEL);
+        if (!virt) {
+                printk(KERN_ERR "%s: Out of memory\n", __FUNCTION__);
                 rc = -ENOMEM;
                 goto out;
         }
-        rc = ecryptfs_write_headers_virt(page_virt, &size, crypt_stat,
-                                         ecryptfs_dentry);
+        rc = ecryptfs_write_headers_virt(virt, &size, crypt_stat,
+                                         ecryptfs_dentry);
         if (unlikely(rc)) {
-                ecryptfs_printk(KERN_ERR, "Error whilst writing headers\n");
-                memset(page_virt, 0, PAGE_CACHE_SIZE);
+                printk(KERN_ERR "%s: Error whilst writing headers; rc = [%d]\n",
+                       __FUNCTION__, rc);
                 goto out_free;
         }
         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
                 rc = ecryptfs_write_metadata_to_xattr(ecryptfs_dentry,
-                                                      crypt_stat, page_virt,
-                                                      size);
+                                                      crypt_stat, virt, size);
         else
                 rc = ecryptfs_write_metadata_to_contents(crypt_stat,
-                                                         ecryptfs_dentry,
-                                                         page_virt);
+                                                         ecryptfs_dentry, virt);
         if (rc) {
-                printk(KERN_ERR "Error writing metadata out to lower file; "
-                       "rc = [%d]\n", rc);
+                printk(KERN_ERR "%s: Error writing metadata out to lower file; "
+                       "rc = [%d]\n", __FUNCTION__, rc);
                 goto out_free;
         }
 out_free:
-        kmem_cache_free(ecryptfs_header_cache_0, page_virt);
+        memset(virt, 0, crypt_stat->num_header_bytes_at_front);
+        kfree(virt);
 out:
         return rc;
 }
@@ -1442,16 +1413,16 @@ static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat,
         virt += sizeof(u32);
         memcpy(&num_header_extents_at_front, virt, sizeof(u16));
         num_header_extents_at_front = be16_to_cpu(num_header_extents_at_front);
-        crypt_stat->num_header_extents_at_front =
-                (int)num_header_extents_at_front;
+        crypt_stat->num_header_bytes_at_front =
+                (((size_t)num_header_extents_at_front
+                  * (size_t)header_extent_size));
         (*bytes_read) = (sizeof(u32) + sizeof(u16));
         if ((validate_header_size == ECRYPTFS_VALIDATE_HEADER_SIZE)
-            && ((crypt_stat->extent_size
-                 * crypt_stat->num_header_extents_at_front)
+            && (crypt_stat->num_header_bytes_at_front
                 < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)) {
                 rc = -EINVAL;
-                printk(KERN_WARNING "Invalid number of header extents: [%zd]\n",
-                       crypt_stat->num_header_extents_at_front);
+                printk(KERN_WARNING "Invalid header size: [%zd]\n",
+                       crypt_stat->num_header_bytes_at_front);
         }
         return rc;
 }
@@ -1466,7 +1437,8 @@ static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat,
  */
 static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
 {
-        crypt_stat->num_header_extents_at_front = 2;
+        crypt_stat->num_header_bytes_at_front =
+                ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
 }
 
 /**
diff --git a/fs/ecryptfs/ecryptfs_kernel.h b/fs/ecryptfs/ecryptfs_kernel.h
index 466661c9fb21..3d637e9ca36a 100644
--- a/fs/ecryptfs/ecryptfs_kernel.h
+++ b/fs/ecryptfs/ecryptfs_kernel.h
@@ -237,7 +237,7 @@ struct ecryptfs_crypt_stat {
         u32 flags;
         unsigned int file_version;
         size_t iv_bytes;
-        size_t num_header_extents_at_front;
+        size_t num_header_bytes_at_front;
         size_t extent_size; /* Data extent size; default is 4096 */
         size_t key_size;
         size_t extent_shift;
@@ -518,7 +518,6 @@ extern struct kmem_cache *ecryptfs_file_info_cache;
 extern struct kmem_cache *ecryptfs_dentry_info_cache;
 extern struct kmem_cache *ecryptfs_inode_info_cache;
 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;
diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index ed0ed849ee28..a2bc9df546bd 100644
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -365,8 +365,7 @@ static struct dentry *ecryptfs_lookup(struct inode *dir, struct dentry *dentry,
                 dentry->d_sb)->mount_crypt_stat;
         if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) {
                 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
-                        file_size = ((crypt_stat->extent_size
-                                      * crypt_stat->num_header_extents_at_front)
+                        file_size = (crypt_stat->num_header_bytes_at_front
                                      + i_size_read(lower_dentry->d_inode));
                 else
                         file_size = i_size_read(lower_dentry->d_inode);
@@ -685,7 +684,7 @@ ecryptfs_put_link(struct dentry *dentry, struct nameidata *nd, void *ptr)
  * @crypt_stat: Crypt_stat associated with file
  * @upper_size: Size of the upper file
  *
- * Calculate the requried size of the lower file based on the
+ * Calculate the required size of the lower file based on the
  * specified size of the upper file. This calculation is based on the
  * number of headers in the underlying file and the extent size.
  *
@@ -697,8 +696,7 @@ upper_size_to_lower_size(struct ecryptfs_crypt_stat *crypt_stat,
 {
         loff_t lower_size;
 
-        lower_size = (crypt_stat->extent_size
-                      * crypt_stat->num_header_extents_at_front);
+        lower_size = crypt_stat->num_header_bytes_at_front;
         if (upper_size != 0) {
                 loff_t num_extents;
 
diff --git a/fs/ecryptfs/main.c b/fs/ecryptfs/main.c
index d9f53c331a27..b67ce83da9fc 100644
--- a/fs/ecryptfs/main.c
+++ b/fs/ecryptfs/main.c
@@ -654,11 +654,6 @@ static struct ecryptfs_cache_info {
                 .size = sizeof(struct ecryptfs_sb_info),
         },
         {
-                .cache = &ecryptfs_header_cache_0,
-                .name = "ecryptfs_headers_0",
-                .size = PAGE_CACHE_SIZE,
-        },
-        {
                 .cache = &ecryptfs_header_cache_1,
                 .name = "ecryptfs_headers_1",
                 .size = PAGE_CACHE_SIZE,
diff --git a/fs/ecryptfs/mmap.c b/fs/ecryptfs/mmap.c
index 9a5e0d17f1c5..dc74b186145d 100644
--- a/fs/ecryptfs/mmap.c
+++ b/fs/ecryptfs/mmap.c
@@ -100,13 +100,14 @@ static void set_header_info(char *page_virt,
                             struct ecryptfs_crypt_stat *crypt_stat)
 {
         size_t written;
-        int save_num_header_extents_at_front =
-                crypt_stat->num_header_extents_at_front;
+        size_t save_num_header_bytes_at_front =
+                crypt_stat->num_header_bytes_at_front;
 
-        crypt_stat->num_header_extents_at_front = 1;
+        crypt_stat->num_header_bytes_at_front =
+                ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
         ecryptfs_write_header_metadata(page_virt + 20, crypt_stat, &written);
-        crypt_stat->num_header_extents_at_front =
-                save_num_header_extents_at_front;
+        crypt_stat->num_header_bytes_at_front =
+                save_num_header_bytes_at_front;
 }
 
 /**
@@ -132,8 +133,11 @@ ecryptfs_copy_up_encrypted_with_header(struct page *page,
                 loff_t view_extent_num = ((((loff_t)page->index)
                                            * num_extents_per_page)
                                           + extent_num_in_page);
+                size_t num_header_extents_at_front =
+                        (crypt_stat->num_header_bytes_at_front
+                         / crypt_stat->extent_size);
 
-                if (view_extent_num < crypt_stat->num_header_extents_at_front) {
+                if (view_extent_num < num_header_extents_at_front) {
                         /* This is a header extent */
                         char *page_virt;
 
@@ -155,9 +159,8 @@ ecryptfs_copy_up_encrypted_with_header(struct page *page,
                 } else {
                         /* This is an encrypted data extent */
                         loff_t lower_offset =
-                                ((view_extent_num -
-                                  crypt_stat->num_header_extents_at_front)
-                                 * crypt_stat->extent_size);
+                                ((view_extent_num * crypt_stat->extent_size)
+                                 - crypt_stat->num_header_bytes_at_front);
 
                         rc = ecryptfs_read_lower_page_segment(
                                 page, (lower_offset >> PAGE_CACHE_SHIFT),