Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [ 51/62] eCryptfs: Initialize empty lower files when opening them | Date | Thu, 18 Oct 2012 19:45:19 -0700 |
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3.4-stable review patch. If anyone has any objections, please let me know.
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From: Tyler Hicks <tyhicks@canonical.com>
commit e3ccaa9761200952cc269b1f4b7d7bb77a5e071b upstream.
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 <tyhicks@canonical.com> Cc: John Johansen <john.johansen@canonical.com> Cc: Colin Ian King <colin.king@canonical.com> Cc: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- fs/ecryptfs/ecryptfs_kernel.h | 2 + fs/ecryptfs/file.c | 71 ++++++++++++++++++++++++++---------------- fs/ecryptfs/inode.c | 4 +- 3 files changed, 49 insertions(+), 28 deletions(-)
--- a/fs/ecryptfs/ecryptfs_kernel.h +++ b/fs/ecryptfs/ecryptfs_kernel.h @@ -568,6 +568,8 @@ struct ecryptfs_open_req { struct inode *ecryptfs_get_inode(struct inode *lower_inode, struct super_block *sb); void ecryptfs_i_size_init(const char *page_virt, struct inode *inode); +int ecryptfs_initialize_file(struct dentry *ecryptfs_dentry, + struct inode *ecryptfs_inode); int ecryptfs_decode_and_decrypt_filename(char **decrypted_name, size_t *decrypted_name_size, struct dentry *ecryptfs_dentry, --- a/fs/ecryptfs/file.c +++ b/fs/ecryptfs/file.c @@ -161,6 +161,48 @@ static int ecryptfs_file_mmap(struct fil 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 *i 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)); --- a/fs/ecryptfs/inode.c +++ b/fs/ecryptfs/inode.c @@ -227,8 +227,8 @@ out: * * Returns zero on success */ -static int ecryptfs_initialize_file(struct dentry *ecryptfs_dentry, - struct inode *ecryptfs_inode) +int ecryptfs_initialize_file(struct dentry *ecryptfs_dentry, + struct inode *ecryptfs_inode) { struct ecryptfs_crypt_stat *crypt_stat = &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
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