crypto: shash - Remove VLA usage in unaligned hashing
In the quest to remove all stack VLA usage from the kernel[1], this uses the newly defined max alignment to perform unaligned hashing to avoid VLAs, and drops the helper function while adding sanity checks on the resulting buffer sizes. Additionally, the __aligned_largest macro is removed since this helper was the only user. [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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@ -73,13 +73,6 @@ int crypto_shash_setkey(struct crypto_shash *tfm, const u8 *key,
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}
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}
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EXPORT_SYMBOL_GPL(crypto_shash_setkey);
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EXPORT_SYMBOL_GPL(crypto_shash_setkey);
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static inline unsigned int shash_align_buffer_size(unsigned len,
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unsigned long mask)
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{
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typedef u8 __aligned_largest u8_aligned;
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return len + (mask & ~(__alignof__(u8_aligned) - 1));
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}
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static int shash_update_unaligned(struct shash_desc *desc, const u8 *data,
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static int shash_update_unaligned(struct shash_desc *desc, const u8 *data,
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unsigned int len)
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unsigned int len)
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{
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{
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@ -88,11 +81,17 @@ static int shash_update_unaligned(struct shash_desc *desc, const u8 *data,
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unsigned long alignmask = crypto_shash_alignmask(tfm);
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unsigned long alignmask = crypto_shash_alignmask(tfm);
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unsigned int unaligned_len = alignmask + 1 -
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unsigned int unaligned_len = alignmask + 1 -
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((unsigned long)data & alignmask);
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((unsigned long)data & alignmask);
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u8 ubuf[shash_align_buffer_size(unaligned_len, alignmask)]
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/*
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__aligned_largest;
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* We cannot count on __aligned() working for large values:
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* https://patchwork.kernel.org/patch/9507697/
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*/
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u8 ubuf[MAX_ALGAPI_ALIGNMASK * 2];
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u8 *buf = PTR_ALIGN(&ubuf[0], alignmask + 1);
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u8 *buf = PTR_ALIGN(&ubuf[0], alignmask + 1);
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int err;
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int err;
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if (WARN_ON(buf + unaligned_len > ubuf + sizeof(ubuf)))
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return -EINVAL;
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if (unaligned_len > len)
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if (unaligned_len > len)
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unaligned_len = len;
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unaligned_len = len;
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@ -124,11 +123,17 @@ static int shash_final_unaligned(struct shash_desc *desc, u8 *out)
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unsigned long alignmask = crypto_shash_alignmask(tfm);
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unsigned long alignmask = crypto_shash_alignmask(tfm);
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struct shash_alg *shash = crypto_shash_alg(tfm);
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struct shash_alg *shash = crypto_shash_alg(tfm);
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unsigned int ds = crypto_shash_digestsize(tfm);
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unsigned int ds = crypto_shash_digestsize(tfm);
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u8 ubuf[shash_align_buffer_size(ds, alignmask)]
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/*
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__aligned_largest;
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* We cannot count on __aligned() working for large values:
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* https://patchwork.kernel.org/patch/9507697/
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*/
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u8 ubuf[MAX_ALGAPI_ALIGNMASK + HASH_MAX_DIGESTSIZE];
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u8 *buf = PTR_ALIGN(&ubuf[0], alignmask + 1);
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u8 *buf = PTR_ALIGN(&ubuf[0], alignmask + 1);
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int err;
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int err;
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if (WARN_ON(buf + ds > ubuf + sizeof(ubuf)))
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return -EINVAL;
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err = shash->final(desc, buf);
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err = shash->final(desc, buf);
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if (err)
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if (err)
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goto out;
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goto out;
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@ -198,7 +198,6 @@ struct ftrace_likely_data {
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*/
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*/
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#define __pure __attribute__((pure))
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#define __pure __attribute__((pure))
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#define __aligned(x) __attribute__((aligned(x)))
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#define __aligned(x) __attribute__((aligned(x)))
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#define __aligned_largest __attribute__((aligned))
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#define __printf(a, b) __attribute__((format(printf, a, b)))
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#define __printf(a, b) __attribute__((format(printf, a, b)))
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#define __scanf(a, b) __attribute__((format(scanf, a, b)))
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#define __scanf(a, b) __attribute__((format(scanf, a, b)))
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#define __maybe_unused __attribute__((unused))
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#define __maybe_unused __attribute__((unused))
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