| Message ID | 20240215042654.359210-4-eugen.hristev@collabora.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [f2fs-dev,v10,1/8] ext4: Simplify the handling of cached insensitive names | expand |
Eugen Hristev <eugen.hristev@collabora.com> writes: > From: Gabriel Krisman Bertazi <krisman@collabora.com> > > generic_ci_match can be used by case-insensitive filesystems to compare > strings under lookup with dirents in a case-insensitive way. This > function is currently reimplemented by each filesystem supporting > casefolding, so this reduces code duplication in filesystem-specific > code. > > Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com> > [eugen.hristev@collabora.com: rework to first test the exact match] > Signed-off-by: Eugen Hristev <eugen.hristev@collabora.com> > --- > fs/libfs.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++ > include/linux/fs.h | 4 +++ > 2 files changed, 84 insertions(+) > > diff --git a/fs/libfs.c b/fs/libfs.c > index bb18884ff20e..82871fa1b066 100644 > --- a/fs/libfs.c > +++ b/fs/libfs.c > @@ -1773,6 +1773,86 @@ static const struct dentry_operations generic_ci_dentry_ops = { > .d_hash = generic_ci_d_hash, > .d_compare = generic_ci_d_compare, > }; > + > +/** > + * generic_ci_match() - Match a name (case-insensitively) with a dirent. > + * This is a filesystem helper for comparison with directory entries. > + * generic_ci_d_compare should be used in VFS' ->d_compare instead. > + * > + * @parent: Inode of the parent of the dirent under comparison > + * @name: name under lookup. > + * @folded_name: Optional pre-folded name under lookup > + * @de_name: Dirent name. > + * @de_name_len: dirent name length. > + * > + * Since this need a respin, mind dropping the extra empty line here? > + * Test whether a case-insensitive directory entry matches the filename > + * being searched. If @folded_name is provided, it is used instead of > + * recalculating the casefold of @name. > + * > + * Return: > 0 if the directory entry matches, 0 if it doesn't match, or > + * < 0 on error. > + */ > +int generic_ci_match(const struct inode *parent, > + const struct qstr *name, > + const struct qstr *folded_name, > + const u8 *de_name, u32 de_name_len) > +{ > + const struct super_block *sb = parent->i_sb; > + const struct unicode_map *um = sb->s_encoding; > + struct fscrypt_str decrypted_name = FSTR_INIT(NULL, de_name_len); > + struct qstr dirent = QSTR_INIT(de_name, de_name_len); > + int res; > + > + if (IS_ENCRYPTED(parent)) { > + const struct fscrypt_str encrypted_name = > + FSTR_INIT((u8 *) de_name, de_name_len); > + > + if (WARN_ON_ONCE(!fscrypt_has_encryption_key(parent))) > + return -EINVAL; > + > + decrypted_name.name = kmalloc(de_name_len, GFP_KERNEL); > + if (!decrypted_name.name) > + return -ENOMEM; > + res = fscrypt_fname_disk_to_usr(parent, 0, 0, &encrypted_name, > + &decrypted_name); > + if (res < 0) > + goto out; > + dirent.name = decrypted_name.name; > + dirent.len = decrypted_name.len; > + } > + > + /* > + * 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. > + */ This paragraph doesn't really make sense here. It is originally from the d_compare hook, which can be called under RCU, but there is no RCU here. Also, here we are comparing the dirent with the name-under-lookup, name which is already safe. > + if (folded_name->name) { > + if (dirent.len == folded_name->len && > + !memcmp(folded_name->name, dirent.name, dirent.len)) { > + res = 1; > + goto out; > + } > + res = !utf8_strncasecmp_folded(um, folded_name, &dirent); Hmm, second thought on this. This will ignore errors from utf8_strncasecmp*, which CAN happen for the first time here, if the dirent itself is corrupted on disk (exactly why we have patch 6). Yes, ext4_match will drop the error, but we want to propagate it from here, such that the warning on patch 6 can trigger. This is why I did that match dance on the original submission. Sorry for suggesting it. We really want to get the error from utf8 and propagate it if it is negative. basically: res > 0: match res == 0: no match. res < 0: propagate error and let the caller handle it > + } else { > + if (dirent.len == name->len && > + !memcmp(name->name, dirent.name, dirent.len) && > + (!sb_has_strict_encoding(sb) || !utf8_validate(um, name))) { > + res = 1; > + goto out; > + } > + res = !utf8_strncasecmp(um, name, &dirent); > + } > + > +out: > + kfree(decrypted_name.name); > + return res; > +} > +EXPORT_SYMBOL(generic_ci_match); > #endif > > #ifdef CONFIG_FS_ENCRYPTION > diff --git a/include/linux/fs.h b/include/linux/fs.h > index 820b93b2917f..7af691ff8d44 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -3296,6 +3296,10 @@ extern int generic_file_fsync(struct file *, loff_t, loff_t, int); > extern int generic_check_addressable(unsigned, u64); > > extern void generic_set_encrypted_ci_d_ops(struct dentry *dentry); > +extern int generic_ci_match(const struct inode *parent, > + const struct qstr *name, > + const struct qstr *folded_name, > + const u8 *de_name, u32 de_name_len); > > static inline bool sb_has_encoding(const struct super_block *sb) > {
On 2/16/24 18:12, Gabriel Krisman Bertazi wrote: > Eugen Hristev <eugen.hristev@collabora.com> writes: > >> From: Gabriel Krisman Bertazi <krisman@collabora.com> >> >> generic_ci_match can be used by case-insensitive filesystems to compare >> strings under lookup with dirents in a case-insensitive way. This >> function is currently reimplemented by each filesystem supporting >> casefolding, so this reduces code duplication in filesystem-specific >> code. >> >> Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com> >> [eugen.hristev@collabora.com: rework to first test the exact match] >> Signed-off-by: Eugen Hristev <eugen.hristev@collabora.com> >> --- >> fs/libfs.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++ >> include/linux/fs.h | 4 +++ >> 2 files changed, 84 insertions(+) >> >> diff --git a/fs/libfs.c b/fs/libfs.c >> index bb18884ff20e..82871fa1b066 100644 >> --- a/fs/libfs.c >> +++ b/fs/libfs.c >> @@ -1773,6 +1773,86 @@ static const struct dentry_operations generic_ci_dentry_ops = { >> .d_hash = generic_ci_d_hash, >> .d_compare = generic_ci_d_compare, >> }; >> + >> +/** >> + * generic_ci_match() - Match a name (case-insensitively) with a dirent. >> + * This is a filesystem helper for comparison with directory entries. >> + * generic_ci_d_compare should be used in VFS' ->d_compare instead. >> + * >> + * @parent: Inode of the parent of the dirent under comparison >> + * @name: name under lookup. >> + * @folded_name: Optional pre-folded name under lookup >> + * @de_name: Dirent name. >> + * @de_name_len: dirent name length. >> + * >> + * > > Since this need a respin, mind dropping the extra empty line here? > >> + * Test whether a case-insensitive directory entry matches the filename >> + * being searched. If @folded_name is provided, it is used instead of >> + * recalculating the casefold of @name. >> + * >> + * Return: > 0 if the directory entry matches, 0 if it doesn't match, or >> + * < 0 on error. >> + */ >> +int generic_ci_match(const struct inode *parent, >> + const struct qstr *name, >> + const struct qstr *folded_name, >> + const u8 *de_name, u32 de_name_len) >> +{ >> + const struct super_block *sb = parent->i_sb; >> + const struct unicode_map *um = sb->s_encoding; >> + struct fscrypt_str decrypted_name = FSTR_INIT(NULL, de_name_len); >> + struct qstr dirent = QSTR_INIT(de_name, de_name_len); >> + int res; >> + >> + if (IS_ENCRYPTED(parent)) { >> + const struct fscrypt_str encrypted_name = >> + FSTR_INIT((u8 *) de_name, de_name_len); >> + >> + if (WARN_ON_ONCE(!fscrypt_has_encryption_key(parent))) >> + return -EINVAL; >> + >> + decrypted_name.name = kmalloc(de_name_len, GFP_KERNEL); >> + if (!decrypted_name.name) >> + return -ENOMEM; >> + res = fscrypt_fname_disk_to_usr(parent, 0, 0, &encrypted_name, >> + &decrypted_name); >> + if (res < 0) >> + goto out; >> + dirent.name = decrypted_name.name; >> + dirent.len = decrypted_name.len; >> + } >> + >> + /* >> + * 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. >> + */ > > This paragraph doesn't really make sense here. It is originally from > the d_compare hook, which can be called under RCU, but there is no RCU > here. Also, here we are comparing the dirent with the > name-under-lookup, name which is already safe. > > >> + if (folded_name->name) { >> + if (dirent.len == folded_name->len && >> + !memcmp(folded_name->name, dirent.name, dirent.len)) { >> + res = 1; >> + goto out; >> + } >> + res = !utf8_strncasecmp_folded(um, folded_name, &dirent); > > Hmm, second thought on this. This will ignore errors from utf8_strncasecmp*, > which CAN happen for the first time here, if the dirent itself is > corrupted on disk (exactly why we have patch 6). Yes, ext4_match will drop the > error, but we want to propagate it from here, such that the warning on > patch 6 can trigger. > > This is why I did that match dance on the original submission. Sorry > for suggesting it. We really want to get the error from utf8 and > propagate it if it is negative. basically: > > res > 0: match > res == 0: no match. > res < 0: propagate error and let the caller handle it In that case I will revert to the original v9 implementation and send a v11 to handle that. Eugen > > >> + } else { >> + if (dirent.len == name->len && >> + !memcmp(name->name, dirent.name, dirent.len) && >> + (!sb_has_strict_encoding(sb) || !utf8_validate(um, name))) { >> + res = 1; >> + goto out; >> + } >> + res = !utf8_strncasecmp(um, name, &dirent); >> + } >> + >> +out: >> + kfree(decrypted_name.name); >> + return res; >> +} >> +EXPORT_SYMBOL(generic_ci_match); >> #endif >> >> #ifdef CONFIG_FS_ENCRYPTION >> diff --git a/include/linux/fs.h b/include/linux/fs.h >> index 820b93b2917f..7af691ff8d44 100644 >> --- a/include/linux/fs.h >> +++ b/include/linux/fs.h >> @@ -3296,6 +3296,10 @@ extern int generic_file_fsync(struct file *, loff_t, loff_t, int); >> extern int generic_check_addressable(unsigned, u64); >> >> extern void generic_set_encrypted_ci_d_ops(struct dentry *dentry); >> +extern int generic_ci_match(const struct inode *parent, >> + const struct qstr *name, >> + const struct qstr *folded_name, >> + const u8 *de_name, u32 de_name_len); >> >> static inline bool sb_has_encoding(const struct super_block *sb) >> { >
Eugen Hristev <eugen.hristev@collabora.com> writes: > On 2/16/24 18:12, Gabriel Krisman Bertazi wrote: >> Eugen Hristev <eugen.hristev@collabora.com> writes: >> >>> From: Gabriel Krisman Bertazi <krisman@collabora.com> >>> >>> generic_ci_match can be used by case-insensitive filesystems to compare >>> strings under lookup with dirents in a case-insensitive way. This >>> function is currently reimplemented by each filesystem supporting >>> casefolding, so this reduces code duplication in filesystem-specific >>> code. >>> >>> Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com> >>> [eugen.hristev@collabora.com: rework to first test the exact match] >>> Signed-off-by: Eugen Hristev <eugen.hristev@collabora.com> >>> --- >>> fs/libfs.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++ >>> include/linux/fs.h | 4 +++ >>> 2 files changed, 84 insertions(+) >>> >>> diff --git a/fs/libfs.c b/fs/libfs.c >>> index bb18884ff20e..82871fa1b066 100644 >>> --- a/fs/libfs.c >>> +++ b/fs/libfs.c >>> @@ -1773,6 +1773,86 @@ static const struct dentry_operations generic_ci_dentry_ops = { >>> .d_hash = generic_ci_d_hash, >>> .d_compare = generic_ci_d_compare, >>> }; >>> + >>> +/** >>> + * generic_ci_match() - Match a name (case-insensitively) with a dirent. >>> + * This is a filesystem helper for comparison with directory entries. >>> + * generic_ci_d_compare should be used in VFS' ->d_compare instead. >>> + * >>> + * @parent: Inode of the parent of the dirent under comparison >>> + * @name: name under lookup. >>> + * @folded_name: Optional pre-folded name under lookup >>> + * @de_name: Dirent name. >>> + * @de_name_len: dirent name length. >>> + * >>> + * >> >> Since this need a respin, mind dropping the extra empty line here? >> >>> + * Test whether a case-insensitive directory entry matches the filename >>> + * being searched. If @folded_name is provided, it is used instead of >>> + * recalculating the casefold of @name. >>> + * >>> + * Return: > 0 if the directory entry matches, 0 if it doesn't match, or >>> + * < 0 on error. >>> + */ >>> +int generic_ci_match(const struct inode *parent, >>> + const struct qstr *name, >>> + const struct qstr *folded_name, >>> + const u8 *de_name, u32 de_name_len) >>> +{ >>> + const struct super_block *sb = parent->i_sb; >>> + const struct unicode_map *um = sb->s_encoding; >>> + struct fscrypt_str decrypted_name = FSTR_INIT(NULL, de_name_len); >>> + struct qstr dirent = QSTR_INIT(de_name, de_name_len); >>> + int res; >>> + >>> + if (IS_ENCRYPTED(parent)) { >>> + const struct fscrypt_str encrypted_name = >>> + FSTR_INIT((u8 *) de_name, de_name_len); >>> + >>> + if (WARN_ON_ONCE(!fscrypt_has_encryption_key(parent))) >>> + return -EINVAL; >>> + >>> + decrypted_name.name = kmalloc(de_name_len, GFP_KERNEL); >>> + if (!decrypted_name.name) >>> + return -ENOMEM; >>> + res = fscrypt_fname_disk_to_usr(parent, 0, 0, &encrypted_name, >>> + &decrypted_name); >>> + if (res < 0) >>> + goto out; >>> + dirent.name = decrypted_name.name; >>> + dirent.len = decrypted_name.len; >>> + } >>> + >>> + /* >>> + * 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. >>> + */ >> >> This paragraph doesn't really make sense here. It is originally from >> the d_compare hook, which can be called under RCU, but there is no RCU >> here. Also, here we are comparing the dirent with the >> name-under-lookup, name which is already safe. >> >> >>> + if (folded_name->name) { >>> + if (dirent.len == folded_name->len && >>> + !memcmp(folded_name->name, dirent.name, dirent.len)) { >>> + res = 1; >>> + goto out; >>> + } >>> + res = !utf8_strncasecmp_folded(um, folded_name, &dirent); >> >> Hmm, second thought on this. This will ignore errors from utf8_strncasecmp*, >> which CAN happen for the first time here, if the dirent itself is >> corrupted on disk (exactly why we have patch 6). Yes, ext4_match will drop the >> error, but we want to propagate it from here, such that the warning on >> patch 6 can trigger. >> >> This is why I did that match dance on the original submission. Sorry >> for suggesting it. We really want to get the error from utf8 and >> propagate it if it is negative. basically: >> >> res > 0: match >> res == 0: no match. >> res < 0: propagate error and let the caller handle it > > In that case I will revert to the original v9 implementation and send a v11 to > handle that. Please, note that the memcmp optimization is still valid. On match, we know the name is valid utf8. It is just a matter of propagating the error code from utf8 to the caller if we need to call it.
On 2/19/24 16:55, Gabriel Krisman Bertazi wrote: > Eugen Hristev <eugen.hristev@collabora.com> writes: > >> On 2/16/24 18:12, Gabriel Krisman Bertazi wrote: >>> Eugen Hristev <eugen.hristev@collabora.com> writes: >>> >>>> From: Gabriel Krisman Bertazi <krisman@collabora.com> >>>> >>>> generic_ci_match can be used by case-insensitive filesystems to compare >>>> strings under lookup with dirents in a case-insensitive way. This >>>> function is currently reimplemented by each filesystem supporting >>>> casefolding, so this reduces code duplication in filesystem-specific >>>> code. >>>> >>>> Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com> >>>> [eugen.hristev@collabora.com: rework to first test the exact match] >>>> Signed-off-by: Eugen Hristev <eugen.hristev@collabora.com> >>>> --- >>>> fs/libfs.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++ >>>> include/linux/fs.h | 4 +++ >>>> 2 files changed, 84 insertions(+) >>>> >>>> diff --git a/fs/libfs.c b/fs/libfs.c >>>> index bb18884ff20e..82871fa1b066 100644 >>>> --- a/fs/libfs.c >>>> +++ b/fs/libfs.c >>>> @@ -1773,6 +1773,86 @@ static const struct dentry_operations generic_ci_dentry_ops = { >>>> .d_hash = generic_ci_d_hash, >>>> .d_compare = generic_ci_d_compare, >>>> }; >>>> + >>>> +/** >>>> + * generic_ci_match() - Match a name (case-insensitively) with a dirent. >>>> + * This is a filesystem helper for comparison with directory entries. >>>> + * generic_ci_d_compare should be used in VFS' ->d_compare instead. >>>> + * >>>> + * @parent: Inode of the parent of the dirent under comparison >>>> + * @name: name under lookup. >>>> + * @folded_name: Optional pre-folded name under lookup >>>> + * @de_name: Dirent name. >>>> + * @de_name_len: dirent name length. >>>> + * >>>> + * >>> >>> Since this need a respin, mind dropping the extra empty line here? >>> >>>> + * Test whether a case-insensitive directory entry matches the filename >>>> + * being searched. If @folded_name is provided, it is used instead of >>>> + * recalculating the casefold of @name. >>>> + * >>>> + * Return: > 0 if the directory entry matches, 0 if it doesn't match, or >>>> + * < 0 on error. >>>> + */ >>>> +int generic_ci_match(const struct inode *parent, >>>> + const struct qstr *name, >>>> + const struct qstr *folded_name, >>>> + const u8 *de_name, u32 de_name_len) >>>> +{ >>>> + const struct super_block *sb = parent->i_sb; >>>> + const struct unicode_map *um = sb->s_encoding; >>>> + struct fscrypt_str decrypted_name = FSTR_INIT(NULL, de_name_len); >>>> + struct qstr dirent = QSTR_INIT(de_name, de_name_len); >>>> + int res; >>>> + >>>> + if (IS_ENCRYPTED(parent)) { >>>> + const struct fscrypt_str encrypted_name = >>>> + FSTR_INIT((u8 *) de_name, de_name_len); >>>> + >>>> + if (WARN_ON_ONCE(!fscrypt_has_encryption_key(parent))) >>>> + return -EINVAL; >>>> + >>>> + decrypted_name.name = kmalloc(de_name_len, GFP_KERNEL); >>>> + if (!decrypted_name.name) >>>> + return -ENOMEM; >>>> + res = fscrypt_fname_disk_to_usr(parent, 0, 0, &encrypted_name, >>>> + &decrypted_name); >>>> + if (res < 0) >>>> + goto out; >>>> + dirent.name = decrypted_name.name; >>>> + dirent.len = decrypted_name.len; >>>> + } >>>> + >>>> + /* >>>> + * 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. >>>> + */ >>> >>> This paragraph doesn't really make sense here. It is originally from >>> the d_compare hook, which can be called under RCU, but there is no RCU >>> here. Also, here we are comparing the dirent with the >>> name-under-lookup, name which is already safe. >>> >>> >>>> + if (folded_name->name) { >>>> + if (dirent.len == folded_name->len && >>>> + !memcmp(folded_name->name, dirent.name, dirent.len)) { >>>> + res = 1; >>>> + goto out; >>>> + } >>>> + res = !utf8_strncasecmp_folded(um, folded_name, &dirent); >>> >>> Hmm, second thought on this. This will ignore errors from utf8_strncasecmp*, >>> which CAN happen for the first time here, if the dirent itself is >>> corrupted on disk (exactly why we have patch 6). Yes, ext4_match will drop the >>> error, but we want to propagate it from here, such that the warning on >>> patch 6 can trigger. >>> >>> This is why I did that match dance on the original submission. Sorry >>> for suggesting it. We really want to get the error from utf8 and >>> propagate it if it is negative. basically: >>> >>> res > 0: match >>> res == 0: no match. >>> res < 0: propagate error and let the caller handle it >> >> In that case I will revert to the original v9 implementation and send a v11 to >> handle that. > > Please, note that the memcmp optimization is still valid. On match, we > know the name is valid utf8. It is just a matter of propagating the > error code from utf8 to the caller if we need to call it. > Okay, I am changing it. By the way, is this supposed to work like this on case-insensitive directories ? user@debian-rockchip-rock5b-rk3588:~$ ls -la /media/CI_dir/*cuc ls: cannot access '/media/CI_dir/*cuc': No such file or directory user@debian-rockchip-rock5b-rk3588:~$ ls -la /media/CI_dir/*CUC -rw-r--r-- 1 root root 0 Feb 12 17:47 /media/CI_dir/CUC user@debian-rockchip-rock5b-rk3588:~$ ls -la /media/CI_dir/cuc -rw-r--r-- 1 root root 0 Feb 12 17:47 /media/CI_dir/cuc user@debian-rockchip-rock5b-rk3588:~$ basically wildcards don't work. Thanks, Eugen
Eugen Hristev <eugen.hristev@collabora.com> writes: > Okay, I am changing it. > > By the way, is this supposed to work like this on case-insensitive directories ? > > user@debian-rockchip-rock5b-rk3588:~$ ls -la /media/CI_dir/*cuc > ls: cannot access '/media/CI_dir/*cuc': No such file or directory > user@debian-rockchip-rock5b-rk3588:~$ ls -la /media/CI_dir/*CUC > -rw-r--r-- 1 root root 0 Feb 12 17:47 /media/CI_dir/CUC > user@debian-rockchip-rock5b-rk3588:~$ ls -la /media/CI_dir/cuc > -rw-r--r-- 1 root root 0 Feb 12 17:47 /media/CI_dir/cuc > user@debian-rockchip-rock5b-rk3588:~$ > > > basically wildcards don't work. Yes, at least from a kernel point of view. Your shell does wildcards in userspace, probably by doing getdents and then comparing with possible matches. Since the shell itself is not case-insensitive aware, its comparison is case-sensitive, and you get these apparent weird semantics. Not ideal from a user point of view. But not a kernel bug. If it pushes people away from using case-insensitive directories in their day-to-day work and leave it to only be used by Windows compatibility layers, maybe that's a win? :)
diff --git a/fs/libfs.c b/fs/libfs.c index bb18884ff20e..82871fa1b066 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -1773,6 +1773,86 @@ static const struct dentry_operations generic_ci_dentry_ops = { .d_hash = generic_ci_d_hash, .d_compare = generic_ci_d_compare, }; + +/** + * generic_ci_match() - Match a name (case-insensitively) with a dirent. + * This is a filesystem helper for comparison with directory entries. + * generic_ci_d_compare should be used in VFS' ->d_compare instead. + * + * @parent: Inode of the parent of the dirent under comparison + * @name: name under lookup. + * @folded_name: Optional pre-folded name under lookup + * @de_name: Dirent name. + * @de_name_len: dirent name length. + * + * + * Test whether a case-insensitive directory entry matches the filename + * being searched. If @folded_name is provided, it is used instead of + * recalculating the casefold of @name. + * + * Return: > 0 if the directory entry matches, 0 if it doesn't match, or + * < 0 on error. + */ +int generic_ci_match(const struct inode *parent, + const struct qstr *name, + const struct qstr *folded_name, + const u8 *de_name, u32 de_name_len) +{ + const struct super_block *sb = parent->i_sb; + const struct unicode_map *um = sb->s_encoding; + struct fscrypt_str decrypted_name = FSTR_INIT(NULL, de_name_len); + struct qstr dirent = QSTR_INIT(de_name, de_name_len); + int res; + + if (IS_ENCRYPTED(parent)) { + const struct fscrypt_str encrypted_name = + FSTR_INIT((u8 *) de_name, de_name_len); + + if (WARN_ON_ONCE(!fscrypt_has_encryption_key(parent))) + return -EINVAL; + + decrypted_name.name = kmalloc(de_name_len, GFP_KERNEL); + if (!decrypted_name.name) + return -ENOMEM; + res = fscrypt_fname_disk_to_usr(parent, 0, 0, &encrypted_name, + &decrypted_name); + if (res < 0) + goto out; + dirent.name = decrypted_name.name; + dirent.len = decrypted_name.len; + } + + /* + * 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 (folded_name->name) { + if (dirent.len == folded_name->len && + !memcmp(folded_name->name, dirent.name, dirent.len)) { + res = 1; + goto out; + } + res = !utf8_strncasecmp_folded(um, folded_name, &dirent); + } else { + if (dirent.len == name->len && + !memcmp(name->name, dirent.name, dirent.len) && + (!sb_has_strict_encoding(sb) || !utf8_validate(um, name))) { + res = 1; + goto out; + } + res = !utf8_strncasecmp(um, name, &dirent); + } + +out: + kfree(decrypted_name.name); + return res; +} +EXPORT_SYMBOL(generic_ci_match); #endif #ifdef CONFIG_FS_ENCRYPTION diff --git a/include/linux/fs.h b/include/linux/fs.h index 820b93b2917f..7af691ff8d44 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -3296,6 +3296,10 @@ extern int generic_file_fsync(struct file *, loff_t, loff_t, int); extern int generic_check_addressable(unsigned, u64); extern void generic_set_encrypted_ci_d_ops(struct dentry *dentry); +extern int generic_ci_match(const struct inode *parent, + const struct qstr *name, + const struct qstr *folded_name, + const u8 *de_name, u32 de_name_len); static inline bool sb_has_encoding(const struct super_block *sb) {