| Message ID | 20240805175237.63098-2-thorsten.blum@toblux.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Herbert Xu |
| Headers | show |
| Series | crypto: chacha20poly1305 - Annotate struct chachapoly_ctx with __counted_by() | expand |
On Mon, Aug 05, 2024 at 07:52:38PM +0200, Thorsten Blum wrote: > struct poly_req { > @@ -611,8 +611,8 @@ static int chachapoly_create(struct crypto_template *tmpl, struct rtattr **tb, > poly->base.cra_priority) / 2; > inst->alg.base.cra_blocksize = 1; > inst->alg.base.cra_alignmask = chacha->base.cra_alignmask; > - inst->alg.base.cra_ctxsize = sizeof(struct chachapoly_ctx) + > - ctx->saltlen; > + inst->alg.base.cra_ctxsize = struct_size_t(struct chachapoly_ctx, salt, > + ctx->saltlen); What was wrong with the more straightforward code it had before? - Eric
On 5. Aug 2024, at 19:59, Eric Biggers <ebiggers@kernel.org> wrote: > On Mon, Aug 05, 2024 at 07:52:38PM +0200, Thorsten Blum wrote: >> struct poly_req { >> @@ -611,8 +611,8 @@ static int chachapoly_create(struct crypto_template *tmpl, struct rtattr **tb, >> poly->base.cra_priority) / 2; >> inst->alg.base.cra_blocksize = 1; >> inst->alg.base.cra_alignmask = chacha->base.cra_alignmask; >> - inst->alg.base.cra_ctxsize = sizeof(struct chachapoly_ctx) + >> - ctx->saltlen; >> + inst->alg.base.cra_ctxsize = struct_size_t(struct chachapoly_ctx, salt, >> + ctx->saltlen); > > What was wrong with the more straightforward code it had before? There's nothing wrong with it, but I find using the helper macro struct_size_t() more straightforward. It's just a refactoring; happy to take it out if there's a preference for the open coded version. Thanks, Thorsten
On Mon, Aug 05, 2024 at 07:52:38PM +0200, Thorsten Blum wrote: > Add the __counted_by compiler attribute to the flexible array member > salt to improve access bounds-checking via CONFIG_UBSAN_BOUNDS and > CONFIG_FORTIFY_SOURCE. > > Use struct_size_t() instead of manually calculating the struct's size. > > Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com> > --- > crypto/chacha20poly1305.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/crypto/chacha20poly1305.c b/crypto/chacha20poly1305.c > index 9e4651330852..b37f59a8280a 100644 > --- a/crypto/chacha20poly1305.c > +++ b/crypto/chacha20poly1305.c > @@ -27,7 +27,7 @@ struct chachapoly_ctx { > struct crypto_ahash *poly; > /* key bytes we use for the ChaCha20 IV */ > unsigned int saltlen; > - u8 salt[]; > + u8 salt[] __counted_by(saltlen); > }; AFAICT, all the allocations of struct chachapoly_ctx set "saltlen" before using "salt". Reviewed-by: Kees Cook <kees@kernel.org> > > struct poly_req { > @@ -611,8 +611,8 @@ static int chachapoly_create(struct crypto_template *tmpl, struct rtattr **tb, > poly->base.cra_priority) / 2; > inst->alg.base.cra_blocksize = 1; > inst->alg.base.cra_alignmask = chacha->base.cra_alignmask; > - inst->alg.base.cra_ctxsize = sizeof(struct chachapoly_ctx) + > - ctx->saltlen; > + inst->alg.base.cra_ctxsize = struct_size_t(struct chachapoly_ctx, salt, > + ctx->saltlen); > inst->alg.ivsize = ivsize; > inst->alg.chunksize = chacha->chunksize; > inst->alg.maxauthsize = POLY1305_DIGEST_SIZE; My instinct is to use struct_size_t() as little as possible (compared to normal struct_size), since I prefer to use it where a thing is being allocated. (In this case, it's "far away".) So given Eric already thinks this part should be dropped, I would agree: leave this as is.
diff --git a/crypto/chacha20poly1305.c b/crypto/chacha20poly1305.c index 9e4651330852..b37f59a8280a 100644 --- a/crypto/chacha20poly1305.c +++ b/crypto/chacha20poly1305.c @@ -27,7 +27,7 @@ struct chachapoly_ctx { struct crypto_ahash *poly; /* key bytes we use for the ChaCha20 IV */ unsigned int saltlen; - u8 salt[]; + u8 salt[] __counted_by(saltlen); }; struct poly_req { @@ -611,8 +611,8 @@ static int chachapoly_create(struct crypto_template *tmpl, struct rtattr **tb, poly->base.cra_priority) / 2; inst->alg.base.cra_blocksize = 1; inst->alg.base.cra_alignmask = chacha->base.cra_alignmask; - inst->alg.base.cra_ctxsize = sizeof(struct chachapoly_ctx) + - ctx->saltlen; + inst->alg.base.cra_ctxsize = struct_size_t(struct chachapoly_ctx, salt, + ctx->saltlen); inst->alg.ivsize = ivsize; inst->alg.chunksize = chacha->chunksize; inst->alg.maxauthsize = POLY1305_DIGEST_SIZE;
Add the __counted_by compiler attribute to the flexible array member salt to improve access bounds-checking via CONFIG_UBSAN_BOUNDS and CONFIG_FORTIFY_SOURCE. Use struct_size_t() instead of manually calculating the struct's size. Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com> --- crypto/chacha20poly1305.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)