From e3ccaa9761200952cc269b1f4b7d7bb77a5e071b Mon Sep 17 00:00:00 2001 From: Tyler Hicks Date: Wed, 20 Jun 2012 23:50:59 -0700 Subject: eCryptfs: Initialize empty lower files when opening them Historically, eCryptfs has only initialized lower files in the ecryptfs_create() path. Lower file initialization is the act of writing the cryptographic metadata from the inode's crypt_stat to the header of the file. The ecryptfs_open() path already expects that metadata to be in the header of the file. A number of users have reported empty lower files in beneath their eCryptfs mounts. Most of the causes for those empty files being left around have been addressed, but the presence of empty files causes problems due to the lack of proper cryptographic metadata. To transparently solve this problem, this patch initializes empty lower files in the ecryptfs_open() error path. If the metadata is unreadable due to the lower inode size being 0, plaintext passthrough support is not in use, and the metadata is stored in the header of the file (as opposed to the user.ecryptfs extended attribute), the lower file will be initialized. The number of nested conditionals in ecryptfs_open() was getting out of hand, so a helper function was created. To avoid the same nested conditional problem, the conditional logic was reversed inside of the helper function. https://launchpad.net/bugs/911507 Signed-off-by: Tyler Hicks Cc: John Johansen Cc: Colin Ian King --- fs/ecryptfs/file.c | 71 ++++++++++++++++++++++++++++++++++-------------------- 1 file changed, 45 insertions(+), 26 deletions(-) (limited to 'fs/ecryptfs/file.c') diff --git a/fs/ecryptfs/file.c b/fs/ecryptfs/file.c index 2b17f2f9b121..baf8b0550391 100644 --- a/fs/ecryptfs/file.c +++ b/fs/ecryptfs/file.c @@ -161,6 +161,48 @@ static int ecryptfs_file_mmap(struct file *file, struct vm_area_struct *vma) struct kmem_cache *ecryptfs_file_info_cache; +static int read_or_initialize_metadata(struct dentry *dentry) +{ + struct inode *inode = dentry->d_inode; + struct ecryptfs_mount_crypt_stat *mount_crypt_stat; + struct ecryptfs_crypt_stat *crypt_stat; + int rc; + + crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat; + mount_crypt_stat = &ecryptfs_superblock_to_private( + inode->i_sb)->mount_crypt_stat; + mutex_lock(&crypt_stat->cs_mutex); + + if (crypt_stat->flags & ECRYPTFS_POLICY_APPLIED && + crypt_stat->flags & ECRYPTFS_KEY_VALID) { + rc = 0; + goto out; + } + + rc = ecryptfs_read_metadata(dentry); + if (!rc) + goto out; + + if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED) { + crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED + | ECRYPTFS_ENCRYPTED); + rc = 0; + goto out; + } + + if (!(mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) && + !i_size_read(ecryptfs_inode_to_lower(inode))) { + rc = ecryptfs_initialize_file(dentry, inode); + if (!rc) + goto out; + } + + rc = -EIO; +out: + mutex_unlock(&crypt_stat->cs_mutex); + return rc; +} + /** * ecryptfs_open * @inode: inode speciying file to open @@ -236,32 +278,9 @@ static int ecryptfs_open(struct inode *inode, struct file *file) rc = 0; goto out; } - mutex_lock(&crypt_stat->cs_mutex); - if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED) - || !(crypt_stat->flags & ECRYPTFS_KEY_VALID)) { - rc = ecryptfs_read_metadata(ecryptfs_dentry); - if (rc) { - ecryptfs_printk(KERN_DEBUG, - "Valid headers not found\n"); - if (!(mount_crypt_stat->flags - & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)) { - rc = -EIO; - printk(KERN_WARNING "Either the lower file " - "is not in a valid eCryptfs format, " - "or the key could not be retrieved. " - "Plaintext passthrough mode is not " - "enabled; returning -EIO\n"); - mutex_unlock(&crypt_stat->cs_mutex); - goto out_put; - } - rc = 0; - crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED - | ECRYPTFS_ENCRYPTED); - mutex_unlock(&crypt_stat->cs_mutex); - goto out; - } - } - mutex_unlock(&crypt_stat->cs_mutex); + rc = read_or_initialize_metadata(ecryptfs_dentry); + if (rc) + goto out_put; 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)); -- cgit v1.2.3 From 821f7494a77627fb1ab539591c57b22cdca702d6 Mon Sep 17 00:00:00 2001 From: Tyler Hicks Date: Tue, 3 Jul 2012 16:50:57 -0700 Subject: eCryptfs: Revert to a writethrough cache model A change was made about a year ago to get eCryptfs to better utilize its page cache during writes. The idea was to do the page encryption operations during page writeback, rather than doing them when initially writing into the page cache, to reduce the number of page encryption operations during sequential writes. This meant that the encrypted page would only be written to the lower filesystem during page writeback, which was a change from how eCryptfs had previously wrote to the lower filesystem in ecryptfs_write_end(). The change caused a few eCryptfs-internal bugs that were shook out. Unfortunately, more grave side effects have been identified that will force changes outside of eCryptfs. Because the lower filesystem isn't consulted until page writeback, eCryptfs has no way to pass lower write errors (ENOSPC, mainly) back to userspace. Additionaly, it was reported that quotas could be bypassed because of the way eCryptfs may sometimes open the lower filesystem using a privileged kthread. It would be nice to resolve the latest issues, but it is best if the eCryptfs commits be reverted to the old behavior in the meantime. This reverts: 32001d6f "eCryptfs: Flush file in vma close" 5be79de2 "eCryptfs: Flush dirty pages in setattr" 57db4e8d "ecryptfs: modify write path to encrypt page in writepage" Signed-off-by: Tyler Hicks Tested-by: Colin King Cc: Colin King Cc: Thieu Le --- fs/ecryptfs/file.c | 33 ++------------------------------- 1 file changed, 2 insertions(+), 31 deletions(-) (limited to 'fs/ecryptfs/file.c') diff --git a/fs/ecryptfs/file.c b/fs/ecryptfs/file.c index baf8b0550391..44ce5c6a541d 100644 --- a/fs/ecryptfs/file.c +++ b/fs/ecryptfs/file.c @@ -138,27 +138,6 @@ out: return rc; } -static void ecryptfs_vma_close(struct vm_area_struct *vma) -{ - filemap_write_and_wait(vma->vm_file->f_mapping); -} - -static const struct vm_operations_struct ecryptfs_file_vm_ops = { - .close = ecryptfs_vma_close, - .fault = filemap_fault, -}; - -static int ecryptfs_file_mmap(struct file *file, struct vm_area_struct *vma) -{ - int rc; - - rc = generic_file_mmap(file, vma); - if (!rc) - vma->vm_ops = &ecryptfs_file_vm_ops; - - return rc; -} - struct kmem_cache *ecryptfs_file_info_cache; static int read_or_initialize_metadata(struct dentry *dentry) @@ -311,15 +290,7 @@ static int ecryptfs_release(struct inode *inode, struct file *file) static int ecryptfs_fsync(struct file *file, loff_t start, loff_t end, int datasync) { - int rc = 0; - - rc = generic_file_fsync(file, start, end, datasync); - if (rc) - goto out; - rc = vfs_fsync_range(ecryptfs_file_to_lower(file), start, end, - datasync); -out: - return rc; + return vfs_fsync(ecryptfs_file_to_lower(file), datasync); } static int ecryptfs_fasync(int fd, struct file *file, int flag) @@ -388,7 +359,7 @@ const struct file_operations ecryptfs_main_fops = { #ifdef CONFIG_COMPAT .compat_ioctl = ecryptfs_compat_ioctl, #endif - .mmap = ecryptfs_file_mmap, + .mmap = generic_file_mmap, .open = ecryptfs_open, .flush = ecryptfs_flush, .release = ecryptfs_release, -- cgit v1.2.3