Expand f2fs's casefolding support to include encrypted directories. To index casefolded+encrypted directories, we use the SipHash of the casefolded name, keyed by a key derived from the directory's fscrypt master key. This ensures that the dirhash doesn't leak information about the plaintext filenames.
Encryption keys are unavailable during roll-forward recovery, so we can't compute the dirhash when recovering a new dentry in an encrypted + casefolded directory. To avoid having to force a checkpoint when a new file is fsync'ed, store the dirhash on-disk appended to i_name. This patch incorporates work by Eric Biggers <ebigg...@google.com> and Jaegeuk Kim <jaeg...@kernel.org>. Co-developed-by: Eric Biggers <ebigg...@google.com> Signed-off-by: Eric Biggers <ebigg...@google.com> Signed-off-by: Daniel Rosenberg <dro...@google.com> --- fs/f2fs/dir.c | 57 +++++++++++++++++++++++++++++++++++++++------- fs/f2fs/f2fs.h | 8 ++++--- fs/f2fs/hash.c | 11 ++++++++- fs/f2fs/recovery.c | 12 +++++++++- fs/f2fs/super.c | 6 ----- 5 files changed, 75 insertions(+), 19 deletions(-) diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c index 0766e6250a88..07004eb6edf8 100644 --- a/fs/f2fs/dir.c +++ b/fs/f2fs/dir.c @@ -5,6 +5,7 @@ * Copyright (c) 2012 Samsung Electronics Co., Ltd. * http://www.samsung.com/ */ +#include <asm/unaligned.h> #include <linux/fs.h> #include <linux/f2fs_fs.h> #include <linux/sched/signal.h> @@ -218,9 +219,28 @@ static bool f2fs_match_ci_name(const struct inode *dir, const struct qstr *name, { const struct super_block *sb = dir->i_sb; const struct unicode_map *um = sb->s_encoding; + struct fscrypt_str decrypted_name = FSTR_INIT(NULL, de_name_len); struct qstr entry = QSTR_INIT(de_name, de_name_len); int res; + if (IS_ENCRYPTED(dir)) { + const struct fscrypt_str encrypted_name = + FSTR_INIT((u8 *)de_name, de_name_len); + + if (WARN_ON_ONCE(!fscrypt_has_encryption_key(dir))) + return false; + + decrypted_name.name = kmalloc(de_name_len, GFP_KERNEL); + if (!decrypted_name.name) + return false; + res = fscrypt_fname_disk_to_usr(dir, 0, 0, &encrypted_name, + &decrypted_name); + if (res < 0) + goto out; + entry.name = decrypted_name.name; + entry.len = decrypted_name.len; + } + res = utf8_strncasecmp_folded(um, name, &entry); if (res < 0) { /* @@ -228,9 +248,12 @@ static bool f2fs_match_ci_name(const struct inode *dir, const struct qstr *name, * fall back to treating them as opaque byte sequences. */ if (sb_has_strict_encoding(sb) || name->len != entry.len) - return false; - return !memcmp(name->name, entry.name, name->len); + res = 1; + else + res = memcmp(name->name, entry.name, name->len); } +out: + kfree(decrypted_name.name); return res == 0; } #endif /* CONFIG_UNICODE */ @@ -455,17 +478,39 @@ void f2fs_set_link(struct inode *dir, struct f2fs_dir_entry *de, f2fs_put_page(page, 1); } -static void init_dent_inode(const struct f2fs_filename *fname, +static void init_dent_inode(struct inode *dir, struct inode *inode, + const struct f2fs_filename *fname, struct page *ipage) { struct f2fs_inode *ri; + if (!fname) /* tmpfile case? */ + return; + f2fs_wait_on_page_writeback(ipage, NODE, true, true); /* copy name info. to this inode page */ ri = F2FS_INODE(ipage); ri->i_namelen = cpu_to_le32(fname->disk_name.len); memcpy(ri->i_name, fname->disk_name.name, fname->disk_name.len); + if (IS_ENCRYPTED(dir)) { + file_set_enc_name(inode); + /* + * Roll-forward recovery doesn't have encryption keys available, + * so it can't compute the dirhash for encrypted+casefolded + * filenames. Append it to i_name if possible. Else, disable + * roll-forward recovery of the dentry (i.e., make fsync'ing the + * file force a checkpoint) by setting LOST_PINO. + */ + if (IS_CASEFOLDED(dir)) { + if (fname->disk_name.len + sizeof(f2fs_hash_t) <= + F2FS_NAME_LEN) + put_unaligned(fname->hash, (f2fs_hash_t *) + &ri->i_name[fname->disk_name.len]); + else + file_lost_pino(inode); + } + } set_page_dirty(ipage); } @@ -548,11 +593,7 @@ struct page *f2fs_init_inode_metadata(struct inode *inode, struct inode *dir, return page; } - if (fname) { - init_dent_inode(fname, page); - if (IS_ENCRYPTED(dir)) - file_set_enc_name(inode); - } + init_dent_inode(dir, inode, fname, page); /* * This file should be checkpointed during fsync. diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index af1d469e8c1e..9d58fd5dae13 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -533,9 +533,11 @@ struct f2fs_filename { #ifdef CONFIG_UNICODE /* * For casefolded directories: the casefolded name, but it's left NULL - * if the original name is not valid Unicode or if the filesystem is - * doing an internal operation where usr_fname is also NULL. In these - * cases we fall back to treating the name as an opaque byte sequence. + * if the original name is not valid Unicode, if the directory is both + * casefolded and encrypted and its encryption key is unavailable, or if + * the filesystem is doing an internal operation where usr_fname is also + * NULL. In all these cases we fall back to treating the name as an + * opaque byte sequence. */ struct fscrypt_str cf_name; #endif diff --git a/fs/f2fs/hash.c b/fs/f2fs/hash.c index de841aaf3c43..e3beac546c63 100644 --- a/fs/f2fs/hash.c +++ b/fs/f2fs/hash.c @@ -111,7 +111,9 @@ void f2fs_hash_filename(const struct inode *dir, struct f2fs_filename *fname) * If the casefolded name is provided, hash it instead of the * on-disk name. If the casefolded name is *not* provided, that * should only be because the name wasn't valid Unicode, so fall - * back to treating the name as an opaque byte sequence. + * back to treating the name as an opaque byte sequence. Note + * that to handle encrypted directories, the fallback must use + * usr_fname (plaintext) rather than disk_name (ciphertext). */ WARN_ON_ONCE(!fname->usr_fname->name); if (fname->cf_name.name) { @@ -121,6 +123,13 @@ void f2fs_hash_filename(const struct inode *dir, struct f2fs_filename *fname) name = fname->usr_fname->name; len = fname->usr_fname->len; } + if (IS_ENCRYPTED(dir)) { + struct qstr tmp = QSTR_INIT(name, len); + + fname->hash = + cpu_to_le32(fscrypt_fname_siphash(dir, &tmp)); + return; + } } #endif fname->hash = cpu_to_le32(TEA_hash_name(name, len)); diff --git a/fs/f2fs/recovery.c b/fs/f2fs/recovery.c index 4f12ade6410a..0947d36af1a8 100644 --- a/fs/f2fs/recovery.c +++ b/fs/f2fs/recovery.c @@ -5,6 +5,7 @@ * Copyright (c) 2012 Samsung Electronics Co., Ltd. * http://www.samsung.com/ */ +#include <asm/unaligned.h> #include <linux/fs.h> #include <linux/f2fs_fs.h> #include "f2fs.h" @@ -128,7 +129,16 @@ static int init_recovered_filename(const struct inode *dir, } /* Compute the hash of the filename */ - if (IS_CASEFOLDED(dir)) { + if (IS_ENCRYPTED(dir) && IS_CASEFOLDED(dir)) { + /* + * In this case the hash isn't computable without the key, so it + * was saved on-disk. + */ + if (fname->disk_name.len + sizeof(f2fs_hash_t) > F2FS_NAME_LEN) + return -EINVAL; + fname->hash = get_unaligned((f2fs_hash_t *) + &raw_inode->i_name[fname->disk_name.len]); + } else if (IS_CASEFOLDED(dir)) { err = f2fs_init_casefolded_name(dir, fname); if (err) return err; diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c index 63c744c6aeff..c2e441b256a7 100644 --- a/fs/f2fs/super.c +++ b/fs/f2fs/super.c @@ -3382,12 +3382,6 @@ static int f2fs_setup_casefold(struct f2fs_sb_info *sbi) struct unicode_map *encoding; __u16 encoding_flags; - if (f2fs_sb_has_encrypt(sbi)) { - f2fs_err(sbi, - "Can't mount with encoding and encryption"); - return -EINVAL; - } - if (f2fs_sb_read_encoding(sbi->raw_super, &encoding_info, &encoding_flags)) { f2fs_err(sbi, -- 2.28.0.681.g6f77f65b4e-goog
