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s=20210705; t=1747467735; bh=tNwwwS/3kfyG+r0IhuUAksmNxwZppBafE6zBouPal/s=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=USKuqWHP8ftrp4TWMROFV/WCLB+A8sj+F0mO2kr2aqFjcgOXKEF1l33LBLJqD9AJO ianSqv0enNC8Gtez3aINLhw9l8cEnHKgDdZ6GiMpb0dJNY7F+xUNqyNHLd778ZhBI2 TZYtp5aU3AYLEg8IZBeJqfrNnqJQurshpNzcN+r68AtxAMcmdPT18NoVPXWqHJrX7I Ukf0Be8I1sLsvB81EfL4aigSwO1mz79xQ9aEEoaiY2/WpW9iHAOKumn8aPvKiVOLTm 3GfQKFFylg1T7WtsW7sonB/43qYrBJHK8+xZxRKIxHQo4/4wrmhtp0YnhYwOHGerlZ IS36VqK6l0RlQ== Message-ID: Date: Sat, 17 May 2025 00:42:14 -0700 Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] apparmor: use SHA-256 library API instead of crypto_shash API To: Eric Biggers , apparmor@lists.ubuntu.com Cc: linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org References: <20250428190430.850240-1-ebiggers@kernel.org> Content-Language: en-US From: John Johansen Autocrypt: addr=john.johansen@canonical.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 4/28/25 12:04, Eric Biggers wrote: > From: Eric Biggers > > This user of SHA-256 does not support any other algorithm, so the > crypto_shash abstraction provides no value. Just use the SHA-256 > library API instead, which is much simpler and easier to use. > > Signed-off-by: Eric Biggers Acked-by: John Johansen > --- > > This patch is targeting the apparmor tree for 6.16. > > security/apparmor/Kconfig | 3 +- > security/apparmor/crypto.c | 85 ++++++-------------------------------- > 2 files changed, 13 insertions(+), 75 deletions(-) > > diff --git a/security/apparmor/Kconfig b/security/apparmor/Kconfig > index 64cc3044a42ce..1e3bd44643dac 100644 > --- a/security/apparmor/Kconfig > +++ b/security/apparmor/Kconfig > @@ -57,12 +57,11 @@ config SECURITY_APPARMOR_INTROSPECT_POLICY > cpu is paramount. > > config SECURITY_APPARMOR_HASH > bool "Enable introspection of sha256 hashes for loaded profiles" > depends on SECURITY_APPARMOR_INTROSPECT_POLICY > - select CRYPTO > - select CRYPTO_SHA256 > + select CRYPTO_LIB_SHA256 > default y > help > This option selects whether introspection of loaded policy > hashes is available to userspace via the apparmor > filesystem. This option provides a light weight means of > diff --git a/security/apparmor/crypto.c b/security/apparmor/crypto.c > index aad486b2fca65..40e17e153f1e5 100644 > --- a/security/apparmor/crypto.c > +++ b/security/apparmor/crypto.c > @@ -9,115 +9,54 @@ > * Fns to provide a checksum of policy that has been loaded this can be > * compared to userspace policy compiles to check loaded policy is what > * it should be. > */ > > -#include > +#include > > #include "include/apparmor.h" > #include "include/crypto.h" > > -static unsigned int apparmor_hash_size; > - > -static struct crypto_shash *apparmor_tfm; > - > unsigned int aa_hash_size(void) > { > - return apparmor_hash_size; > + return SHA256_DIGEST_SIZE; > } > > char *aa_calc_hash(void *data, size_t len) > { > - SHASH_DESC_ON_STACK(desc, apparmor_tfm); > char *hash; > - int error; > - > - if (!apparmor_tfm) > - return NULL; > > - hash = kzalloc(apparmor_hash_size, GFP_KERNEL); > + hash = kzalloc(SHA256_DIGEST_SIZE, GFP_KERNEL); > if (!hash) > return ERR_PTR(-ENOMEM); > > - desc->tfm = apparmor_tfm; > - > - error = crypto_shash_init(desc); > - if (error) > - goto fail; > - error = crypto_shash_update(desc, (u8 *) data, len); > - if (error) > - goto fail; > - error = crypto_shash_final(desc, hash); > - if (error) > - goto fail; > - > + sha256(data, len, hash); > return hash; > - > -fail: > - kfree(hash); > - > - return ERR_PTR(error); > } > > int aa_calc_profile_hash(struct aa_profile *profile, u32 version, void *start, > size_t len) > { > - SHASH_DESC_ON_STACK(desc, apparmor_tfm); > - int error; > + struct sha256_state state; > __le32 le32_version = cpu_to_le32(version); > > if (!aa_g_hash_policy) > return 0; > > - if (!apparmor_tfm) > - return 0; > - > - profile->hash = kzalloc(apparmor_hash_size, GFP_KERNEL); > + profile->hash = kzalloc(SHA256_DIGEST_SIZE, GFP_KERNEL); > if (!profile->hash) > return -ENOMEM; > > - desc->tfm = apparmor_tfm; > - > - error = crypto_shash_init(desc); > - if (error) > - goto fail; > - error = crypto_shash_update(desc, (u8 *) &le32_version, 4); > - if (error) > - goto fail; > - error = crypto_shash_update(desc, (u8 *) start, len); > - if (error) > - goto fail; > - error = crypto_shash_final(desc, profile->hash); > - if (error) > - goto fail; > - > + sha256_init(&state); > + sha256_update(&state, (u8 *)&le32_version, 4); > + sha256_update(&state, (u8 *)start, len); > + sha256_final(&state, profile->hash); > return 0; > - > -fail: > - kfree(profile->hash); > - profile->hash = NULL; > - > - return error; > } > > static int __init init_profile_hash(void) > { > - struct crypto_shash *tfm; > - > - if (!apparmor_initialized) > - return 0; > - > - tfm = crypto_alloc_shash("sha256", 0, 0); > - if (IS_ERR(tfm)) { > - int error = PTR_ERR(tfm); > - AA_ERROR("failed to setup profile sha256 hashing: %d\n", error); > - return error; > - } > - apparmor_tfm = tfm; > - apparmor_hash_size = crypto_shash_digestsize(apparmor_tfm); > - > - aa_info_message("AppArmor sha256 policy hashing enabled"); > - > + if (apparmor_initialized) > + aa_info_message("AppArmor sha256 policy hashing enabled"); > return 0; > } > - > late_initcall(init_profile_hash); > > base-commit: 33035b665157558254b3c21c3f049fd728e72368