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-rw-r--r--fs/ecryptfs/mmap.c557
1 files changed, 557 insertions, 0 deletions
diff --git a/fs/ecryptfs/mmap.c b/fs/ecryptfs/mmap.c
new file mode 100644
index 000000000..19af229eb
--- /dev/null
+++ b/fs/ecryptfs/mmap.c
@@ -0,0 +1,557 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * eCryptfs: Linux filesystem encryption layer
+ * This is where eCryptfs coordinates the symmetric encryption and
+ * decryption of the file data as it passes between the lower
+ * encrypted file and the upper decrypted file.
+ *
+ * Copyright (C) 1997-2003 Erez Zadok
+ * Copyright (C) 2001-2003 Stony Brook University
+ * Copyright (C) 2004-2007 International Business Machines Corp.
+ * Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
+ */
+
+#include <linux/pagemap.h>
+#include <linux/writeback.h>
+#include <linux/page-flags.h>
+#include <linux/mount.h>
+#include <linux/file.h>
+#include <linux/scatterlist.h>
+#include <linux/slab.h>
+#include <linux/xattr.h>
+#include <asm/unaligned.h>
+#include "ecryptfs_kernel.h"
+
+/*
+ * ecryptfs_get_locked_page
+ *
+ * Get one page from cache or lower f/s, return error otherwise.
+ *
+ * Returns locked and up-to-date page (if ok), with increased
+ * refcnt.
+ */
+struct page *ecryptfs_get_locked_page(struct inode *inode, loff_t index)
+{
+ struct page *page = read_mapping_page(inode->i_mapping, index, NULL);
+ if (!IS_ERR(page))
+ lock_page(page);
+ return page;
+}
+
+/**
+ * ecryptfs_writepage
+ * @page: Page that is locked before this call is made
+ * @wbc: Write-back control structure
+ *
+ * Returns zero on success; non-zero otherwise
+ *
+ * This is where we encrypt the data and pass the encrypted data to
+ * the lower filesystem. In OpenPGP-compatible mode, we operate on
+ * entire underlying packets.
+ */
+static int ecryptfs_writepage(struct page *page, struct writeback_control *wbc)
+{
+ int rc;
+
+ rc = ecryptfs_encrypt_page(page);
+ if (rc) {
+ ecryptfs_printk(KERN_WARNING, "Error encrypting "
+ "page (upper index [0x%.16lx])\n", page->index);
+ ClearPageUptodate(page);
+ goto out;
+ }
+ SetPageUptodate(page);
+out:
+ unlock_page(page);
+ return rc;
+}
+
+static void strip_xattr_flag(char *page_virt,
+ struct ecryptfs_crypt_stat *crypt_stat)
+{
+ if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) {
+ size_t written;
+
+ crypt_stat->flags &= ~ECRYPTFS_METADATA_IN_XATTR;
+ ecryptfs_write_crypt_stat_flags(page_virt, crypt_stat,
+ &written);
+ crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
+ }
+}
+
+/*
+ * Header Extent:
+ * Octets 0-7: Unencrypted file size (big-endian)
+ * Octets 8-15: eCryptfs special marker
+ * Octets 16-19: Flags
+ * Octet 16: File format version number (between 0 and 255)
+ * Octets 17-18: Reserved
+ * Octet 19: Bit 1 (lsb): Reserved
+ * Bit 2: Encrypted?
+ * Bits 3-8: Reserved
+ * Octets 20-23: Header extent size (big-endian)
+ * Octets 24-25: Number of header extents at front of file
+ * (big-endian)
+ * Octet 26: Begin RFC 2440 authentication token packet set
+ */
+
+/**
+ * ecryptfs_copy_up_encrypted_with_header
+ * @page: Sort of a ``virtual'' representation of the encrypted lower
+ * file. The actual lower file does not have the metadata in
+ * the header. This is locked.
+ * @crypt_stat: The eCryptfs inode's cryptographic context
+ *
+ * The ``view'' is the version of the file that userspace winds up
+ * seeing, with the header information inserted.
+ */
+static int
+ecryptfs_copy_up_encrypted_with_header(struct page *page,
+ struct ecryptfs_crypt_stat *crypt_stat)
+{
+ loff_t extent_num_in_page = 0;
+ loff_t num_extents_per_page = (PAGE_SIZE
+ / crypt_stat->extent_size);
+ int rc = 0;
+
+ while (extent_num_in_page < num_extents_per_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->metadata_size / crypt_stat->extent_size);
+
+ if (view_extent_num < num_header_extents_at_front) {
+ /* This is a header extent */
+ char *page_virt;
+
+ page_virt = kmap_atomic(page);
+ memset(page_virt, 0, PAGE_SIZE);
+ /* TODO: Support more than one header extent */
+ if (view_extent_num == 0) {
+ size_t written;
+
+ rc = ecryptfs_read_xattr_region(
+ page_virt, page->mapping->host);
+ strip_xattr_flag(page_virt + 16, crypt_stat);
+ ecryptfs_write_header_metadata(page_virt + 20,
+ crypt_stat,
+ &written);
+ }
+ kunmap_atomic(page_virt);
+ flush_dcache_page(page);
+ if (rc) {
+ printk(KERN_ERR "%s: Error reading xattr "
+ "region; rc = [%d]\n", __func__, rc);
+ goto out;
+ }
+ } else {
+ /* This is an encrypted data extent */
+ loff_t lower_offset =
+ ((view_extent_num * crypt_stat->extent_size)
+ - crypt_stat->metadata_size);
+
+ rc = ecryptfs_read_lower_page_segment(
+ page, (lower_offset >> PAGE_SHIFT),
+ (lower_offset & ~PAGE_MASK),
+ crypt_stat->extent_size, page->mapping->host);
+ if (rc) {
+ printk(KERN_ERR "%s: Error attempting to read "
+ "extent at offset [%lld] in the lower "
+ "file; rc = [%d]\n", __func__,
+ lower_offset, rc);
+ goto out;
+ }
+ }
+ extent_num_in_page++;
+ }
+out:
+ return rc;
+}
+
+/**
+ * ecryptfs_read_folio
+ * @file: An eCryptfs file
+ * @folio: Folio from eCryptfs inode mapping into which to stick the read data
+ *
+ * Read in a folio, decrypting if necessary.
+ *
+ * Returns zero on success; non-zero on error.
+ */
+static int ecryptfs_read_folio(struct file *file, struct folio *folio)
+{
+ struct page *page = &folio->page;
+ struct ecryptfs_crypt_stat *crypt_stat =
+ &ecryptfs_inode_to_private(page->mapping->host)->crypt_stat;
+ int rc = 0;
+
+ if (!crypt_stat || !(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
+ rc = ecryptfs_read_lower_page_segment(page, page->index, 0,
+ PAGE_SIZE,
+ page->mapping->host);
+ } else if (crypt_stat->flags & ECRYPTFS_VIEW_AS_ENCRYPTED) {
+ if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) {
+ rc = ecryptfs_copy_up_encrypted_with_header(page,
+ crypt_stat);
+ if (rc) {
+ printk(KERN_ERR "%s: Error attempting to copy "
+ "the encrypted content from the lower "
+ "file whilst inserting the metadata "
+ "from the xattr into the header; rc = "
+ "[%d]\n", __func__, rc);
+ goto out;
+ }
+
+ } else {
+ rc = ecryptfs_read_lower_page_segment(
+ page, page->index, 0, PAGE_SIZE,
+ page->mapping->host);
+ if (rc) {
+ printk(KERN_ERR "Error reading page; rc = "
+ "[%d]\n", rc);
+ goto out;
+ }
+ }
+ } else {
+ rc = ecryptfs_decrypt_page(page);
+ if (rc) {
+ ecryptfs_printk(KERN_ERR, "Error decrypting page; "
+ "rc = [%d]\n", rc);
+ goto out;
+ }
+ }
+out:
+ if (rc)
+ ClearPageUptodate(page);
+ else
+ SetPageUptodate(page);
+ ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16lx]\n",
+ page->index);
+ unlock_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;
+ int end_byte_in_page;
+
+ if ((i_size_read(inode) / PAGE_SIZE) != page->index)
+ goto out;
+ end_byte_in_page = i_size_read(inode) % PAGE_SIZE;
+ if (to > end_byte_in_page)
+ end_byte_in_page = to;
+ zero_user_segment(page, end_byte_in_page, PAGE_SIZE);
+out:
+ return 0;
+}
+
+/**
+ * ecryptfs_write_begin
+ * @file: The eCryptfs file
+ * @mapping: The eCryptfs object
+ * @pos: The file offset at which to start writing
+ * @len: Length of the write
+ * @flags: Various flags
+ * @pagep: Pointer to return the page
+ * @fsdata: Pointer to return fs data (unused)
+ *
+ * This function must zero any hole we create
+ *
+ * Returns zero on success; non-zero otherwise
+ */
+static int ecryptfs_write_begin(struct file *file,
+ struct address_space *mapping,
+ loff_t pos, unsigned len,
+ struct page **pagep, void **fsdata)
+{
+ pgoff_t index = pos >> PAGE_SHIFT;
+ struct page *page;
+ loff_t prev_page_end_size;
+ int rc = 0;
+
+ page = grab_cache_page_write_begin(mapping, index);
+ if (!page)
+ return -ENOMEM;
+ *pagep = page;
+
+ prev_page_end_size = ((loff_t)index << PAGE_SHIFT);
+ if (!PageUptodate(page)) {
+ struct ecryptfs_crypt_stat *crypt_stat =
+ &ecryptfs_inode_to_private(mapping->host)->crypt_stat;
+
+ if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
+ rc = ecryptfs_read_lower_page_segment(
+ page, index, 0, PAGE_SIZE, mapping->host);
+ if (rc) {
+ printk(KERN_ERR "%s: Error attempting to read "
+ "lower page segment; rc = [%d]\n",
+ __func__, rc);
+ ClearPageUptodate(page);
+ goto out;
+ } else
+ SetPageUptodate(page);
+ } else if (crypt_stat->flags & ECRYPTFS_VIEW_AS_ENCRYPTED) {
+ if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) {
+ rc = ecryptfs_copy_up_encrypted_with_header(
+ page, crypt_stat);
+ if (rc) {
+ printk(KERN_ERR "%s: Error attempting "
+ "to copy the encrypted content "
+ "from the lower file whilst "
+ "inserting the metadata from "
+ "the xattr into the header; rc "
+ "= [%d]\n", __func__, rc);
+ ClearPageUptodate(page);
+ goto out;
+ }
+ SetPageUptodate(page);
+ } else {
+ rc = ecryptfs_read_lower_page_segment(
+ page, index, 0, PAGE_SIZE,
+ mapping->host);
+ if (rc) {
+ printk(KERN_ERR "%s: Error reading "
+ "page; rc = [%d]\n",
+ __func__, rc);
+ ClearPageUptodate(page);
+ goto out;
+ }
+ SetPageUptodate(page);
+ }
+ } else {
+ if (prev_page_end_size
+ >= i_size_read(page->mapping->host)) {
+ zero_user(page, 0, PAGE_SIZE);
+ SetPageUptodate(page);
+ } else if (len < PAGE_SIZE) {
+ 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);
+ }
+ }
+ }
+ /* If creating a page or more of holes, zero them out via truncate.
+ * Note, this will increase i_size. */
+ if (index != 0) {
+ if (prev_page_end_size > i_size_read(page->mapping->host)) {
+ rc = ecryptfs_truncate(file->f_path.dentry,
+ prev_page_end_size);
+ if (rc) {
+ printk(KERN_ERR "%s: Error on attempt to "
+ "truncate to (higher) offset [%lld];"
+ " rc = [%d]\n", __func__,
+ prev_page_end_size, rc);
+ goto out;
+ }
+ }
+ }
+ /* Writing to a new page, and creating a small hole from start
+ * of page? Zero it out. */
+ if ((i_size_read(mapping->host) == prev_page_end_size)
+ && (pos != 0))
+ zero_user(page, 0, PAGE_SIZE);
+out:
+ if (unlikely(rc)) {
+ unlock_page(page);
+ put_page(page);
+ *pagep = NULL;
+ }
+ return rc;
+}
+
+/*
+ * ecryptfs_write_inode_size_to_header
+ *
+ * Writes the lower file size to the first 8 bytes of the header.
+ *
+ * Returns zero on success; non-zero on error.
+ */
+static int ecryptfs_write_inode_size_to_header(struct inode *ecryptfs_inode)
+{
+ char *file_size_virt;
+ int rc;
+
+ file_size_virt = kmalloc(sizeof(u64), GFP_KERNEL);
+ if (!file_size_virt) {
+ rc = -ENOMEM;
+ goto out;
+ }
+ put_unaligned_be64(i_size_read(ecryptfs_inode), file_size_virt);
+ rc = ecryptfs_write_lower(ecryptfs_inode, file_size_virt, 0,
+ sizeof(u64));
+ kfree(file_size_virt);
+ if (rc < 0)
+ printk(KERN_ERR "%s: Error writing file size to header; "
+ "rc = [%d]\n", __func__, rc);
+ else
+ rc = 0;
+out:
+ return rc;
+}
+
+struct kmem_cache *ecryptfs_xattr_cache;
+
+static int ecryptfs_write_inode_size_to_xattr(struct inode *ecryptfs_inode)
+{
+ ssize_t size;
+ void *xattr_virt;
+ struct dentry *lower_dentry =
+ ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_path.dentry;
+ struct inode *lower_inode = d_inode(lower_dentry);
+ int rc;
+
+ if (!(lower_inode->i_opflags & IOP_XATTR)) {
+ printk(KERN_WARNING
+ "No support for setting xattr in lower filesystem\n");
+ rc = -ENOSYS;
+ goto out;
+ }
+ xattr_virt = kmem_cache_alloc(ecryptfs_xattr_cache, GFP_KERNEL);
+ if (!xattr_virt) {
+ rc = -ENOMEM;
+ goto out;
+ }
+ inode_lock(lower_inode);
+ size = __vfs_getxattr(lower_dentry, lower_inode, ECRYPTFS_XATTR_NAME,
+ xattr_virt, PAGE_SIZE);
+ if (size < 0)
+ size = 8;
+ put_unaligned_be64(i_size_read(ecryptfs_inode), xattr_virt);
+ rc = __vfs_setxattr(&init_user_ns, lower_dentry, lower_inode,
+ ECRYPTFS_XATTR_NAME, xattr_virt, size, 0);
+ inode_unlock(lower_inode);
+ 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 inode *ecryptfs_inode)
+{
+ struct ecryptfs_crypt_stat *crypt_stat;
+
+ crypt_stat = &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
+ BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
+ if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
+ return ecryptfs_write_inode_size_to_xattr(ecryptfs_inode);
+ else
+ return ecryptfs_write_inode_size_to_header(ecryptfs_inode);
+}
+
+/**
+ * ecryptfs_write_end
+ * @file: The eCryptfs file object
+ * @mapping: The eCryptfs object
+ * @pos: The file position
+ * @len: The length of the data (unused)
+ * @copied: The amount of data copied
+ * @page: The eCryptfs page
+ * @fsdata: The fsdata (unused)
+ */
+static int ecryptfs_write_end(struct file *file,
+ struct address_space *mapping,
+ loff_t pos, unsigned len, unsigned copied,
+ struct page *page, void *fsdata)
+{
+ pgoff_t index = pos >> PAGE_SHIFT;
+ unsigned from = pos & (PAGE_SIZE - 1);
+ unsigned to = from + copied;
+ struct inode *ecryptfs_inode = mapping->host;
+ struct ecryptfs_crypt_stat *crypt_stat =
+ &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
+ int rc;
+
+ ecryptfs_printk(KERN_DEBUG, "Calling fill_zeros_to_end_of_page"
+ "(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);
+ if (!rc) {
+ rc = copied;
+ fsstack_copy_inode_size(ecryptfs_inode,
+ ecryptfs_inode_to_lower(ecryptfs_inode));
+ }
+ goto out;
+ }
+ if (!PageUptodate(page)) {
+ if (copied < PAGE_SIZE) {
+ rc = 0;
+ goto out;
+ }
+ SetPageUptodate(page);
+ }
+ /* Fills in zeros if 'to' goes beyond inode size */
+ 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%.16lx]\n", index);
+ goto out;
+ }
+ rc = ecryptfs_encrypt_page(page);
+ if (rc) {
+ ecryptfs_printk(KERN_WARNING, "Error encrypting page (upper "
+ "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%.16llx]\n",
+ (unsigned long long)i_size_read(ecryptfs_inode));
+ }
+ rc = ecryptfs_write_inode_size_to_metadata(ecryptfs_inode);
+ if (rc)
+ printk(KERN_ERR "Error writing inode size to metadata; "
+ "rc = [%d]\n", rc);
+ else
+ rc = copied;
+out:
+ unlock_page(page);
+ put_page(page);
+ return rc;
+}
+
+static sector_t ecryptfs_bmap(struct address_space *mapping, sector_t block)
+{
+ struct inode *lower_inode = ecryptfs_inode_to_lower(mapping->host);
+ int ret = bmap(lower_inode, &block);
+
+ if (ret)
+ return 0;
+ return block;
+}
+
+#include <linux/buffer_head.h>
+
+const struct address_space_operations ecryptfs_aops = {
+ /*
+ * XXX: This is pretty broken for multiple reasons: ecryptfs does not
+ * actually use buffer_heads, and ecryptfs will crash without
+ * CONFIG_BLOCK. But it matches the behavior before the default for
+ * address_space_operations without the ->dirty_folio method was
+ * cleaned up, so this is the best we can do without maintainer
+ * feedback.
+ */
+#ifdef CONFIG_BLOCK
+ .dirty_folio = block_dirty_folio,
+ .invalidate_folio = block_invalidate_folio,
+#endif
+ .writepage = ecryptfs_writepage,
+ .read_folio = ecryptfs_read_folio,
+ .write_begin = ecryptfs_write_begin,
+ .write_end = ecryptfs_write_end,
+ .bmap = ecryptfs_bmap,
+};
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