/** * ecryptfs_write_lower * @ecryptfs_inode: The eCryptfs inode * @data: Data to write * @offset: Byte offset in the lower file to which to write the data * @size: Number of bytes from @data to write at @offset in the lower * file * * Write data to the lower file. * * Returns bytes written on success; less than zero on error
*/ int ecryptfs_write_lower(struct inode *ecryptfs_inode, char *data,
loff_t offset, size_t size)
{ struct file *lower_file;
ssize_t rc;
/** * ecryptfs_write_lower_page_segment * @ecryptfs_inode: The eCryptfs inode * @folio_for_lower: The folio containing the data to be written to the * lower file * @offset_in_page: The offset in the @folio_for_lower from which to * start writing the data * @size: The amount of data from @folio_for_lower to write to the * lower file * * Determines the byte offset in the file for the given page and * offset within the page, maps the page, and makes the call to write * the contents of @folio_for_lower to the lower inode. * * Returns zero on success; non-zero otherwise
*/ int ecryptfs_write_lower_page_segment(struct inode *ecryptfs_inode, struct folio *folio_for_lower,
size_t offset_in_page, size_t size)
{ char *virt;
loff_t offset; int rc;
/** * ecryptfs_write * @ecryptfs_inode: The eCryptfs file into which to write * @data: Virtual address where data to write is located * @offset: Offset in the eCryptfs file at which to begin writing the * data from @data * @size: The number of bytes to write from @data * * Write an arbitrary amount of data to an arbitrary location in the * eCryptfs inode page cache. This is done on a page-by-page, and then * by an extent-by-extent, basis; individual extents are encrypted and * written to the lower page cache (via VFS writes). This function * takes care of all the address translation to locations in the lower * filesystem; it also handles truncate events, writing out zeros * where necessary. * * Returns zero on success; non-zero otherwise
*/ int ecryptfs_write(struct inode *ecryptfs_inode, char *data, loff_t offset,
size_t size)
{ struct ecryptfs_crypt_stat *crypt_stat; char *ecryptfs_page_virt;
loff_t ecryptfs_file_size = i_size_read(ecryptfs_inode);
loff_t data_offset = 0;
loff_t pos; int rc = 0;
crypt_stat = &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat; /* * if we are writing beyond current size, then start pos * at the current size - we'll fill in zeros from there.
*/ if (offset > ecryptfs_file_size)
pos = ecryptfs_file_size; else
pos = offset; while (pos < (offset + size)) { struct folio *ecryptfs_folio;
pgoff_t ecryptfs_page_idx = (pos >> PAGE_SHIFT);
size_t start_offset_in_page = (pos & ~PAGE_MASK);
size_t num_bytes = (PAGE_SIZE - start_offset_in_page);
loff_t total_remaining_bytes = ((offset + size) - pos);
if (fatal_signal_pending(current)) {
rc = -EINTR; break;
}
if (num_bytes > total_remaining_bytes)
num_bytes = total_remaining_bytes; if (pos < offset) { /* remaining zeros to write, up to destination offset */
loff_t total_remaining_zeros = (offset - pos);
/* * pos: where we're now writing, offset: where the request was * If current pos is before request, we are filling zeros * If we are at or beyond request, we are writing the *data* * If we're in a fresh page beyond eof, zero it in either case
*/ if (pos < offset || !start_offset_in_page) { /* We are extending past the previous end of the file.
* Fill in zero values to the end of the page */
memset(((char *)ecryptfs_page_virt
+ start_offset_in_page), 0,
PAGE_SIZE - start_offset_in_page);
}
/* pos >= offset, we are now writing the data request */ if (pos >= offset) {
memcpy(((char *)ecryptfs_page_virt
+ start_offset_in_page),
(data + data_offset), num_bytes);
data_offset += num_bytes;
}
kunmap_local(ecryptfs_page_virt);
flush_dcache_folio(ecryptfs_folio);
folio_mark_uptodate(ecryptfs_folio);
folio_unlock(ecryptfs_folio); if (crypt_stat->flags & ECRYPTFS_ENCRYPTED)
rc = ecryptfs_encrypt_page(ecryptfs_folio); else
rc = ecryptfs_write_lower_page_segment(ecryptfs_inode,
ecryptfs_folio,
start_offset_in_page,
data_offset);
folio_put(ecryptfs_folio); if (rc) {
printk(KERN_ERR "%s: Error encrypting " "page; rc = [%d]\n", __func__, rc); goto out;
}
pos += num_bytes;
} if (pos > ecryptfs_file_size) {
i_size_write(ecryptfs_inode, pos); if (crypt_stat->flags & ECRYPTFS_ENCRYPTED) { int rc2;
/** * ecryptfs_read_lower * @data: The read data is stored here by this function * @offset: Byte offset in the lower file from which to read the data * @size: Number of bytes to read from @offset of the lower file and * store into @data * @ecryptfs_inode: The eCryptfs inode * * Read @size bytes of data at byte offset @offset from the lower * inode into memory location @data. * * Returns bytes read on success; 0 on EOF; less than zero on error
*/ int ecryptfs_read_lower(char *data, loff_t offset, size_t size, struct inode *ecryptfs_inode)
{ struct file *lower_file;
lower_file = ecryptfs_inode_to_private(ecryptfs_inode)->lower_file; if (!lower_file) return -EIO; return kernel_read(lower_file, data, size, &offset);
}
/** * ecryptfs_read_lower_page_segment * @folio_for_ecryptfs: The folio into which data for eCryptfs will be * written * @page_index: Page index in @page_for_ecryptfs from which to start * writing * @offset_in_page: Offset in @page_for_ecryptfs from which to start * writing * @size: The number of bytes to write into @page_for_ecryptfs * @ecryptfs_inode: The eCryptfs inode * * Determines the byte offset in the file for the given page and * offset within the page, maps the page, and makes the call to read * the contents of @page_for_ecryptfs from the lower inode. * * Returns zero on success; non-zero otherwise
*/ int ecryptfs_read_lower_page_segment(struct folio *folio_for_ecryptfs,
pgoff_t page_index,
size_t offset_in_page, size_t size, struct inode *ecryptfs_inode)
{ char *virt;
loff_t offset; int rc;
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