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Merge tag 'for-next-6.9' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/krisman/unicode into vfs.misc

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Merge case-insensitive updates from Gabriel Krisman Bertazi:

- Patch case-insensitive lookup by trying the case-exact comparison
  first, before falling back to costly utf8 casefolded comparison.

- Fix to forbid using a case-insensitive directory as part of an
  overlayfs mount.

- Patchset to ensure d_op are set at d_alloc time for fscrypt and
  casefold volumes, ensuring filesystem dentries will all have the
  correct ops, whether they come from a lookup or not.

* tag 'for-next-6.9' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/krisman/unicode:
  libfs: Drop generic_set_encrypted_ci_d_ops
  ubifs: Configure dentry operations at dentry-creation time
  f2fs: Configure dentry operations at dentry-creation time
  ext4: Configure dentry operations at dentry-creation time
  libfs: Add helper to choose dentry operations at mount-time
  libfs: Merge encrypted_ci_dentry_ops and ci_dentry_ops
  fscrypt: Drop d_revalidate once the key is added
  fscrypt: Drop d_revalidate for valid dentries during lookup
  fscrypt: Factor out a helper to configure the lookup dentry
  ovl: Always reject mounting over case-insensitive directories
  libfs: Attempt exact-match comparison first during casefolded lookup

Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Christian Brauner
2024-03-07 11:55:41 +01:00
parent 91e78a1eb6 101c3fad29
commit 09406ad8e5
11 changed files with 128 additions and 86 deletions
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fs/libfs.c
+40 -62
View File
@@ -1738,16 +1738,28 @@ bool is_empty_dir_inode(struct inode *inode)
static int generic_ci_d_compare(const struct dentry *dentry, unsigned int len,
const char *str, const struct qstr *name)
{
const struct dentry *parent = READ_ONCE(dentry->d_parent);
const struct inode *dir = READ_ONCE(parent->d_inode);
const struct super_block *sb = dentry->d_sb;
const struct unicode_map *um = sb->s_encoding;
struct qstr qstr = QSTR_INIT(str, len);
const struct dentry *parent;
const struct inode *dir;
char strbuf[DNAME_INLINE_LEN];
int ret;
struct qstr qstr;
/*
* Attempt a case-sensitive match first. It is cheaper and
* should cover most lookups, including all the sane
* applications that expect a case-sensitive filesystem.
*
* This comparison is safe under RCU because the caller
* guarantees the consistency between str and len. See
* __d_lookup_rcu_op_compare() for details.
*/
if (len == name->len && !memcmp(str, name->name, len))
return 0;
parent = READ_ONCE(dentry->d_parent);
dir = READ_ONCE(parent->d_inode);
if (!dir || !IS_CASEFOLDED(dir))
goto fallback;
return 1;
/*
* If the dentry name is stored in-line, then it may be concurrently
* modified by a rename. If this happens, the VFS will eventually retry
@@ -1758,20 +1770,14 @@ static int generic_ci_d_compare(const struct dentry *dentry, unsigned int len,
if (len <= DNAME_INLINE_LEN - 1) {
memcpy(strbuf, str, len);
strbuf[len] = 0;
qstr.name = strbuf;
str = strbuf;
/* prevent compiler from optimizing out the temporary buffer */
barrier();
}
ret = utf8_strncasecmp(um, name, &qstr);
if (ret >= 0)
return ret;
qstr.len = len;
qstr.name = str;
if (sb_has_strict_encoding(sb))
return -EINVAL;
fallback:
if (len != name->len)
return 1;
return !!memcmp(str, name->name, len);
return utf8_strncasecmp(dentry->d_sb->s_encoding, name, &qstr);
}
/**
@@ -1800,6 +1806,9 @@ static int generic_ci_d_hash(const struct dentry *dentry, struct qstr *str)
static const struct dentry_operations generic_ci_dentry_ops = {
.d_hash = generic_ci_d_hash,
.d_compare = generic_ci_d_compare,
#ifdef CONFIG_FS_ENCRYPTION
.d_revalidate = fscrypt_d_revalidate,
#endif
};
#endif
@@ -1809,64 +1818,33 @@ static const struct dentry_operations generic_encrypted_dentry_ops = {
};
#endif
#if defined(CONFIG_FS_ENCRYPTION) && IS_ENABLED(CONFIG_UNICODE)
static const struct dentry_operations generic_encrypted_ci_dentry_ops = {
.d_hash = generic_ci_d_hash,
.d_compare = generic_ci_d_compare,
.d_revalidate = fscrypt_d_revalidate,
};
#endif
/**
* generic_set_encrypted_ci_d_ops - helper for setting d_ops for given dentry
* @dentry: dentry to set ops on
* generic_set_sb_d_ops - helper for choosing the set of
* filesystem-wide dentry operations for the enabled features
* @sb: superblock to be configured
*
* Casefolded directories need d_hash and d_compare set, so that the dentries
* contained in them are handled case-insensitively. Note that these operations
* are needed on the parent directory rather than on the dentries in it, and
* while the casefolding flag can be toggled on and off on an empty directory,
* dentry_operations can't be changed later. As a result, if the filesystem has
* casefolding support enabled at all, we have to give all dentries the
* casefolding operations even if their inode doesn't have the casefolding flag
* currently (and thus the casefolding ops would be no-ops for now).
*
* Encryption works differently in that the only dentry operation it needs is
* d_revalidate, which it only needs on dentries that have the no-key name flag.
* The no-key flag can't be set "later", so we don't have to worry about that.
*
* Finally, to maximize compatibility with overlayfs (which isn't compatible
* with certain dentry operations) and to avoid taking an unnecessary
* performance hit, we use custom dentry_operations for each possible
* combination rather than always installing all operations.
* Filesystems supporting casefolding and/or fscrypt can call this
* helper at mount-time to configure sb->s_d_op to best set of dentry
* operations required for the enabled features. The helper must be
* called after these have been configured, but before the root dentry
* is created.
*/
void generic_set_encrypted_ci_d_ops(struct dentry *dentry)
void generic_set_sb_d_ops(struct super_block *sb)
{
#ifdef CONFIG_FS_ENCRYPTION
bool needs_encrypt_ops = dentry->d_flags & DCACHE_NOKEY_NAME;
#endif
#if IS_ENABLED(CONFIG_UNICODE)
bool needs_ci_ops = dentry->d_sb->s_encoding;
#endif
#if defined(CONFIG_FS_ENCRYPTION) && IS_ENABLED(CONFIG_UNICODE)
if (needs_encrypt_ops && needs_ci_ops) {
d_set_d_op(dentry, &generic_encrypted_ci_dentry_ops);
if (sb->s_encoding) {
sb->s_d_op = &generic_ci_dentry_ops;
return;
}
#endif
#ifdef CONFIG_FS_ENCRYPTION
if (needs_encrypt_ops) {
d_set_d_op(dentry, &generic_encrypted_dentry_ops);
return;
}
#endif
#if IS_ENABLED(CONFIG_UNICODE)
if (needs_ci_ops) {
d_set_d_op(dentry, &generic_ci_dentry_ops);
if (sb->s_cop) {
sb->s_d_op = &generic_encrypted_dentry_ops;
return;
}
#endif
}
EXPORT_SYMBOL(generic_set_encrypted_ci_d_ops);
EXPORT_SYMBOL(generic_set_sb_d_ops);
/**
* inode_maybe_inc_iversion - increments i_version