evie/android_kernel_oneplus_msm8998
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f2fs: require key for truncate(2) of encrypted file

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Currently, filesystems allow truncate(2) on an encrypted file without
the encryption key.  However, it's impossible to correctly handle the
case where the size being truncated to is not a multiple of the
filesystem block size, because that would require decrypting the final
block, zeroing the part beyond i_size, then encrypting the block.

As other modifications to encrypted file contents are prohibited without
the key, just prohibit truncate(2) as well, making it fail with ENOKEY.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Acked-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This commit is contained in:
Eric Biggers 2017-06-13 16:47:54 -07:00 • committed by Jaegeuk Kim
parent 06fc88a60d
commit 4e968ec7cb
1 changed files with 7 additions and 3 deletions
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10
fs/f2fs/file.c
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@ -692,9 +692,13 @@ int f2fs_setattr(struct dentry *dentry, struct iattr *attr)
return err;
if (attr->ia_valid & ATTR_SIZE) {
if (f2fs_encrypted_inode(inode) &&
fscrypt_get_encryption_info(inode))
return -EACCES;
if (f2fs_encrypted_inode(inode)) {
err = fscrypt_get_encryption_info(inode);
if (err)
return err;
if (!fscrypt_has_encryption_key(inode))
return -ENOKEY;
}
if (attr->ia_size <= i_size_read(inode)) {
down_write(&F2FS_I(inode)->i_mmap_sem);