Messages in this thread | | | Subject | Re: [PATCH v4] fs: introduce is_dot_or_dotdot helper for cleanup | From | Tiezhu Yang <> | Date | Wed, 11 Dec 2019 08:56:32 +0800 |
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On 12/11/2019 03:19 AM, Eric Biggers wrote: > On Tue, Dec 10, 2019 at 08:10:01PM +0800, Tiezhu Yang wrote: >> diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c >> index 3da3707..ef7eba8 100644 >> --- a/fs/crypto/fname.c >> +++ b/fs/crypto/fname.c >> @@ -11,21 +11,11 @@ >> * This has not yet undergone a rigorous security audit. >> */ >> >> +#include <linux/namei.h> >> #include <linux/scatterlist.h> >> #include <crypto/skcipher.h> >> #include "fscrypt_private.h" >> >> -static inline bool fscrypt_is_dot_dotdot(const struct qstr *str) >> -{ >> - if (str->len == 1 && str->name[0] == '.') >> - return true; >> - >> - if (str->len == 2 && str->name[0] == '.' && str->name[1] == '.') >> - return true; >> - >> - return false; >> -} >> - >> /** >> * fname_encrypt() - encrypt a filename >> * >> @@ -255,7 +245,7 @@ int fscrypt_fname_disk_to_usr(struct inode *inode, >> const struct qstr qname = FSTR_TO_QSTR(iname); >> struct fscrypt_digested_name digested_name; >> >> - if (fscrypt_is_dot_dotdot(&qname)) { >> + if (is_dot_or_dotdot(qname.name, qname.len)) { > There's no need for the 'qname' variable anymore. Can you please remove it and > do: > > if (is_dot_or_dotdot(iname->name, iname->len)) {
Hi Eric,
Thanks for your review, I will do it in the v5 patch.
> >> diff --git a/include/linux/namei.h b/include/linux/namei.h >> index 7fe7b87..aba114a 100644 >> --- a/include/linux/namei.h >> +++ b/include/linux/namei.h >> @@ -92,4 +92,14 @@ retry_estale(const long error, const unsigned int flags) >> return error == -ESTALE && !(flags & LOOKUP_REVAL); >> } >> >> +static inline bool is_dot_or_dotdot(const unsigned char *name, size_t len) >> +{ >> + if (unlikely(name[0] == '.')) { >> + if (len < 2 || (len == 2 && name[1] == '.')) >> + return true; >> + } >> + >> + return false; >> +} > This doesn't handle the len=0 case. Did you check that none of the users pass > in zero-length names? It looks like fscrypt_fname_disk_to_usr() can, if the > directory entry on-disk has a zero-length name. Currently it will return > -EUCLEAN in that case, but with this patch it may think it's the name ".". > > So I think there needs to either be a len >= 1 check added, *or* you need to > make an argument for why it's okay to not care about the empty name case.
Anyway, let me modify the if condition "len < 2" to "len == 1".
static inline bool is_dot_or_dotdot(const unsigned char *name, size_t len) { if (unlikely(name[0] == '.')) { if (len == 1 || (len == 2 && name[1] == '.')) return true; }
return false; }
I will send v5 patch as soon as possible.
Thanks,
Tiezhu Yang
> > - Eric
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