fs, fscrypt: add an S_ENCRYPTED inode flag

Introduce a flag S_ENCRYPTED which can be set in ->i_flags to indicate
that the inode is encrypted using the fscrypt (fs/crypto/) mechanism.

Checking this flag will give the same information that
inode->i_sb->s_cop->is_encrypted(inode) currently does, but will be more
efficient.  This will be useful for adding higher-level helper functions
for filesystems to use.  For example we'll be able to replace this:

	if (ext4_encrypted_inode(inode)) {
		ret = fscrypt_get_encryption_info(inode);
		if (ret)
			return ret;
		if (!fscrypt_has_encryption_key(inode))
			return -ENOKEY;
	}

with this:

	ret = fscrypt_require_key(inode);
	if (ret)
		return ret;

... since we'll be able to retain the fast path for unencrypted files as
a single flag check, using an inline function.  This wasn't possible
before because we'd have had to frequently call through the
->i_sb->s_cop->is_encrypted function pointer, even when the encryption
support was disabled or not being used.

Note: we don't define S_ENCRYPTED to 0 if CONFIG_FS_ENCRYPTION is
disabled because we want to continue to return an error if an encrypted
file is accessed without encryption support, rather than pretending that
it is unencrypted.

Reviewed-by: Chao Yu <[email protected]>
Acked-by: Dave Chinner <[email protected]>
Signed-off-by: Eric Biggers <[email protected]>
Signed-off-by: Theodore Ts'o <[email protected]>
This commit is contained in:
Eric Biggers 2017-10-09 12:15:35 -07:00 • committed by Theodore Ts'o
commit 2ee6a576be
7 changed files with 23 additions and 6 deletions

View file

@ -38,7 +38,8 @@ void ubifs_set_inode_flags(struct inode *inode)
{
unsigned int flags = ubifs_inode(inode)->flags;
inode->i_flags &= ~(S_SYNC | S_APPEND | S_IMMUTABLE | S_DIRSYNC);
inode->i_flags &= ~(S_SYNC | S_APPEND | S_IMMUTABLE | S_DIRSYNC |
S_ENCRYPTED);
if (flags & UBIFS_SYNC_FL)
inode->i_flags |= S_SYNC;
if (flags & UBIFS_APPEND_FL)
@ -47,6 +48,8 @@ void ubifs_set_inode_flags(struct inode *inode)
inode->i_flags |= S_IMMUTABLE;
if (flags & UBIFS_DIRSYNC_FL)
inode->i_flags |= S_DIRSYNC;
if (flags & UBIFS_CRYPT_FL)
inode->i_flags |= S_ENCRYPTED;
}
/*

View file

@ -170,6 +170,7 @@ static int create_xattr(struct ubifs_info *c, struct inode *host,
err = ubifs_jnl_update(c, host, nm, inode, 0, 1);
if (err)
goto out_cancel;
ubifs_set_inode_flags(host);
mutex_unlock(&host_ui->ui_mutex);
ubifs_release_budget(c, &req);