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linuxkm/lkcapi_glue.c: add LINUXKM_LKCAPI_NEED_AES_COMMON_FUNCS and

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LINUXKM_LKCAPI_NEED_AES_SKCIPHER_COMMON_FUNCS helper macros (peer review
  suggestion).

wolfcrypt/src/aes.c: add lengthy comment in software wc_AesSetKeyLocal()
  explaining the dynamics of aes->use_aesni (peer review suggestion), and in the
  !haveAESNI && WC_C_DYNAMIC_FALLBACK case, return with immediate success rather
  than following through to the redundant AesSetKey_C().
This commit is contained in:
Daniel Pouzzner
2025-04-02 17:30:19 -05:00
parent 8705d28d48
commit 13c73a9691
3 changed files with 65 additions and 25 deletions
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51
linuxkm/lkcapi_glue.c
View File

@@ -210,6 +210,29 @@ static int disable_setkey_warnings = 0;
static int linuxkm_test_aesecb(void);
#endif
#if defined(LINUXKM_LKCAPI_REGISTER_AESCBC) || \
defined(LINUXKM_LKCAPI_REGISTER_AESCFB) || \
defined(LINUXKM_LKCAPI_REGISTER_AESCTR) || \
defined(LINUXKM_LKCAPI_REGISTER_AESOFB) || \
defined(LINUXKM_LKCAPI_REGISTER_AESECB) || \
defined(LINUXKM_LKCAPI_REGISTER_AESGCM) || \
defined(LINUXKM_LKCAPI_REGISTER_AESGCM_RFC4106)
#define LINUXKM_LKCAPI_NEED_AES_COMMON_FUNCS
#endif
#if defined(LINUXKM_LKCAPI_REGISTER_AESCBC) || \
defined(LINUXKM_LKCAPI_REGISTER_AESCFB) || \
defined(LINUXKM_LKCAPI_REGISTER_AESCTR) || \
defined(LINUXKM_LKCAPI_REGISTER_AESOFB) || \
defined(LINUXKM_LKCAPI_REGISTER_AESECB)
#define LINUXKM_LKCAPI_NEED_AES_SKCIPHER_COMMON_FUNCS
#endif
#if defined(LINUXKM_LKCAPI_REGISTER_AESGCM) || \
defined(LINUXKM_LKCAPI_REGISTER_AESGCM_RFC4106)
#define LINUXKM_LKCAPI_REGISTER_AEADS
#endif
/* km_AesX(): wrappers to wolfcrypt wc_AesX functions and
* structures. */
@@ -312,13 +335,7 @@ struct km_AesCtx {
#endif
};
#if defined(LINUXKM_LKCAPI_REGISTER_AESCBC) || \
defined(LINUXKM_LKCAPI_REGISTER_AESCFB) || \
defined(LINUXKM_LKCAPI_REGISTER_AESGCM) || \
defined(LINUXKM_LKCAPI_REGISTER_AESGCM_RFC4106) || \
defined(LINUXKM_LKCAPI_REGISTER_AESCTR) || \
defined(LINUXKM_LKCAPI_REGISTER_AESOFB) || \
defined(LINUXKM_LKCAPI_REGISTER_AESECB)
#ifdef LINUXKM_LKCAPI_NEED_AES_COMMON_FUNCS
static void km_AesExitCommon(struct km_AesCtx * ctx);
@@ -518,11 +535,7 @@ static void km_AesExitCommon(struct km_AesCtx * ctx)
#endif
}
#if defined(LINUXKM_LKCAPI_REGISTER_AESCBC) || \
defined(LINUXKM_LKCAPI_REGISTER_AESCFB) || \
defined(LINUXKM_LKCAPI_REGISTER_AESCTR) || \
defined(LINUXKM_LKCAPI_REGISTER_AESOFB) || \
defined(LINUXKM_LKCAPI_REGISTER_AESECB)
#ifdef LINUXKM_LKCAPI_NEED_AES_SKCIPHER_COMMON_FUNCS
static int km_AesSetKeyCommon(struct km_AesCtx * ctx, const u8 *in_key,
unsigned int key_len, const char * name)
@@ -595,19 +608,9 @@ static void km_AesExit(struct crypto_skcipher *tfm)
km_AesExitCommon(ctx);
}
#endif /* LINUXKM_LKCAPI_REGISTER_AESCBC ||
* LINUXKM_LKCAPI_REGISTER_AESCFB ||
* LINUXKM_LKCAPI_REGISTER_AESCTR ||
* LINUXKM_LKCAPI_REGISTER_AESOFB ||
* LINUXKM_LKCAPI_REGISTER_AESECB
*/
#endif /* LINUXKM_LKCAPI_NEED_AES_SKCIPHER_COMMON_FUNCS */
#endif /* LINUXKM_LKCAPI_REGISTER_AESCBC ||
* LINUXKM_LKCAPI_REGISTER_AESCFB || LINUXKM_LKCAPI_REGISTER_AESGCM ||
* LINUXKM_LKCAPI_REGISTER_AESGCM_RFC4106 ||
* LINUXKM_LKCAPI_REGISTER_AESCTR || LINUXKM_LKCAPI_REGISTER_AESOFB ||
* LINUXKM_LKCAPI_REGISTER_AESECB
*/
#endif /* LINUXKM_LKCAPI_NEED_AES_COMMON_FUNCS */
#ifdef LINUXKM_LKCAPI_REGISTER_AESCBC

36
wolfcrypt/src/aes.c
View File

@@ -4575,6 +4575,36 @@ static void AesSetKey_C(Aes* aes, const byte* key, word32 keySz, int dir)
#endif /* WC_C_DYNAMIC_FALLBACK */
#ifdef WOLFSSL_AESNI
/* The dynamics for determining whether AES-NI will be used are tricky.
*
* First, we check for CPU support and cache the result -- if AES-NI is
* missing, we always shortcut to the AesSetKey_C() path.
*
* Second, if the CPU supports AES-NI, we confirm on a per-call basis
* that it's safe to use in the caller context, using
* SAVE_VECTOR_REGISTERS2(). This is an always-true no-op in user-space
* builds, but has substantive logic behind it in kernel module builds.
*
* The outcome when SAVE_VECTOR_REGISTERS2() fails depends on
* WC_C_DYNAMIC_FALLBACK -- if that's defined, we return immediately with
* success but with AES-NI disabled (the earlier AesSetKey_C() allows
* future encrypt/decrypt calls to succeed), otherwise we fail.
*
* Upon successful return, aes->use_aesni will have a zero value if
* AES-NI is disabled, and a nonzero value if it's enabled.
*
* An additional, optional semantic is available via
* WC_FLAG_DONT_USE_AESNI, and is used in some kernel module builds to
* let the caller inhibit AES-NI. When this macro is defined,
* wc_AesInit() before wc_AesSetKey() is imperative, to avoid a read of
* uninitialized data in aes->use_aesni. That's why support for
* WC_FLAG_DONT_USE_AESNI must remain optional -- wc_AesInit() was only
* added in release 3.11.0, so legacy applications inevitably call
* wc_AesSetKey() on uninitialized Aes contexts. This must continue to
* function correctly with default build settings.
*/
if (checkedAESNI == 0) {
haveAESNI = Check_CPU_support_AES();
checkedAESNI = 1;
@@ -4627,6 +4657,12 @@ static void AesSetKey_C(Aes* aes, const byte* key, word32 keySz, int dir)
}
else {
aes->use_aesni = 0;
#ifdef WC_C_DYNAMIC_FALLBACK
/* If WC_C_DYNAMIC_FALLBACK, we already called AesSetKey_C()
* above.
*/
return 0;
#endif
}
#endif /* WOLFSSL_AESNI */

3
wolfssl/wolfcrypt/aes.h
View File

@@ -306,7 +306,8 @@ struct Aes {
#if defined(WOLFSSL_LINUXKM) || defined(WC_WANT_FLAG_DONT_USE_AESNI)
/* Note, we can't support WC_FLAG_DONT_USE_AESNI by default because we
* need to support legacy applications that call wc_AesSetKey() on
* uninited struct Aes.
* uninited struct Aes. For details see the software implementation of
* wc_AesSetKeyLocal() (aes.c).
*/
#define WC_FLAG_DONT_USE_AESNI 2
#endif