From: Eric Biggers <ebigg...@google.com> 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. [Based on patches from Daniel Rosenberg <dro...@google.com> and Jaegeuk Kim <jaeg...@kernel.org>. This patch is incomplete as it doesn't include the generic_set_encrypted_ci_d_ops(). This patch just shows the other changes based on top of the f2fs_filename rework.] Signed-off-by: Eric Biggers <ebigg...@google.com> --- fs/f2fs/dir.c | 63 ++++++++++++++++++++++++++++++++++++++-------- fs/f2fs/f2fs.h | 8 +++--- fs/f2fs/hash.c | 11 +++++++- fs/f2fs/recovery.c | 12 ++++++++- 4 files changed, 79 insertions(+), 15 deletions(-) diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c index 29f70f2295cce8..eea9458a37b384 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> @@ -217,9 +218,28 @@ static bool f2fs_match_ci_name(const struct inode *dir, const struct qstr *name, { const struct f2fs_sb_info *sbi = F2FS_SB(dir->i_sb); const struct unicode_map *um = sbi->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) { /* @@ -227,9 +247,12 @@ static bool f2fs_match_ci_name(const struct inode *dir, const struct qstr *name, * fall back to treating them as opaque byte sequences. */ if (f2fs_has_strict_mode(sbi) || 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 */ @@ -454,17 +477,39 @@ 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, + &ri->i_name[fname->disk_name.len]); + else + file_lost_pino(inode); + } + } set_page_dirty(ipage); } @@ -547,11 +592,7 @@ 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. @@ -1116,7 +1157,8 @@ static int f2fs_d_compare(const struct dentry *dentry, unsigned int len, struct qstr entry = QSTR_INIT(str, len); int res; - if (!dir || !IS_CASEFOLDED(dir)) + if (!dir || !IS_CASEFOLDED(dir) || + (IS_ENCRYPTED(dir) && !fscrypt_has_encryption_key(dir))) goto fallback; res = utf8_strncasecmp(sbi->s_encoding, name, &entry); @@ -1139,7 +1181,8 @@ static int f2fs_d_hash(const struct dentry *dentry, struct qstr *str) unsigned char *norm; int len, ret = 0; - if (!inode || !IS_CASEFOLDED(inode)) + if (!inode || !IS_CASEFOLDED(inode) || + (IS_ENCRYPTED(inode) && !fscrypt_has_encryption_key(inode))) return 0; norm = f2fs_kmalloc(sbi, PATH_MAX, GFP_ATOMIC); diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index 1df50d9224bb71..1c01d6b87e936f 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -534,9 +534,11 @@ 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 e5997919472d4f..f9b706495d1d62 100644 --- a/fs/f2fs/hash.c +++ b/fs/f2fs/hash.c @@ -112,7 +112,9 @@ 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) { @@ -122,6 +124,13 @@ 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 ae5310f02e7ff1..c762a9e4300620 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; -- 2.26.2 _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
