mac80211: move struct aead_req off the stack

Some crypto implementations (such as the generic CCM wrapper in crypto/)
use scatterlists to map fields of private data in their struct aead_req.
This means these data structures cannot live in the vmalloc area, which
means that they cannot live on the stack (with CONFIG_VMAP_STACK.)

This currently occurs only with the generic software implementation, but
the private data and usage is implementation specific, so move the whole
data structures off the stack into heap by allocating every time we need
to use them.

In addition, take care not to put any of our own stack allocations into
scatterlists. This involves reserving some extra room when allocating the
aead_request structures, and referring to those allocations in the scatter-
lists (while copying the data from the stack before the crypto operation)

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/aes_ccm.c

@@ -18,21 +18,24 @@
 #include "key.h"
 #include "aes_ccm.h"
 
-void ieee80211_aes_ccm_encrypt(struct crypto_aead *tfm, u8 *b_0, u8 *aad,
-			       u8 *data, size_t data_len, u8 *mic,
-			       size_t mic_len)
+int ieee80211_aes_ccm_encrypt(struct crypto_aead *tfm, u8 *b_0, u8 *aad,
+			      u8 *data, size_t data_len, u8 *mic,
+			      size_t mic_len)
 {
 	struct scatterlist sg[3];
+	struct aead_request *aead_req;
+	int reqsize = sizeof(*aead_req) + crypto_aead_reqsize(tfm);
+	u8 *__aad;
 
-	char aead_req_data[sizeof(struct aead_request) +
-			   crypto_aead_reqsize(tfm)]
-		__aligned(__alignof__(struct aead_request));
-	struct aead_request *aead_req = (void *) aead_req_data;
+	aead_req = kzalloc(reqsize + CCM_AAD_LEN, GFP_ATOMIC);
+	if (!aead_req)
+		return -ENOMEM;
 
-	memset(aead_req, 0, sizeof(aead_req_data));
+	__aad = (u8 *)aead_req + reqsize;
+	memcpy(__aad, aad, CCM_AAD_LEN);
 
 	sg_init_table(sg, 3);
-	sg_set_buf(&sg[0], &aad[2], be16_to_cpup((__be16 *)aad));
+	sg_set_buf(&sg[0], &__aad[2], be16_to_cpup((__be16 *)__aad));
 	sg_set_buf(&sg[1], data, data_len);
 	sg_set_buf(&sg[2], mic, mic_len);
 
@@ -41,6 +44,9 @@ void ieee80211_aes_ccm_encrypt(struct crypto_aead *tfm, u8 *b_0, u8 *aad,
 	aead_request_set_ad(aead_req, sg[0].length);
 
 	crypto_aead_encrypt(aead_req);
+	kzfree(aead_req);
+
+	return 0;
 }
 
 int ieee80211_aes_ccm_decrypt(struct crypto_aead *tfm, u8 *b_0, u8 *aad,
@@ -48,18 +54,23 @@ int ieee80211_aes_ccm_decrypt(struct crypto_aead *tfm, u8 *b_0, u8 *aad,
 			      size_t mic_len)
 {
 	struct scatterlist sg[3];
-	char aead_req_data[sizeof(struct aead_request) +
-			   crypto_aead_reqsize(tfm)]
-		__aligned(__alignof__(struct aead_request));
-	struct aead_request *aead_req = (void *) aead_req_data;
+	struct aead_request *aead_req;
+	int reqsize = sizeof(*aead_req) + crypto_aead_reqsize(tfm);
+	u8 *__aad;
+	int err;
 
 	if (data_len == 0)
 		return -EINVAL;
 
-	memset(aead_req, 0, sizeof(aead_req_data));
+	aead_req = kzalloc(reqsize + CCM_AAD_LEN, GFP_ATOMIC);
+	if (!aead_req)
+		return -ENOMEM;
+
+	__aad = (u8 *)aead_req + reqsize;
+	memcpy(__aad, aad, CCM_AAD_LEN);
 
 	sg_init_table(sg, 3);
-	sg_set_buf(&sg[0], &aad[2], be16_to_cpup((__be16 *)aad));
+	sg_set_buf(&sg[0], &__aad[2], be16_to_cpup((__be16 *)__aad));
 	sg_set_buf(&sg[1], data, data_len);
 	sg_set_buf(&sg[2], mic, mic_len);
 
@@ -67,7 +78,10 @@ int ieee80211_aes_ccm_decrypt(struct crypto_aead *tfm, u8 *b_0, u8 *aad,
 	aead_request_set_crypt(aead_req, sg, sg, data_len + mic_len, b_0);
 	aead_request_set_ad(aead_req, sg[0].length);
 
-	return crypto_aead_decrypt(aead_req);
+	err = crypto_aead_decrypt(aead_req);
+	kzfree(aead_req);
+
+	return err;
 }
 
 struct crypto_aead *ieee80211_aes_key_setup_encrypt(const u8 key[],

net/mac80211/aes_ccm.h

@@ -12,12 +12,14 @@
 
 #include <linux/crypto.h>
 
+#define CCM_AAD_LEN	32
+
 struct crypto_aead *ieee80211_aes_key_setup_encrypt(const u8 key[],
 						    size_t key_len,
 						    size_t mic_len);
-void ieee80211_aes_ccm_encrypt(struct crypto_aead *tfm, u8 *b_0, u8 *aad,
-			       u8 *data, size_t data_len, u8 *mic,
-			       size_t mic_len);
+int ieee80211_aes_ccm_encrypt(struct crypto_aead *tfm, u8 *b_0, u8 *aad,
+			      u8 *data, size_t data_len, u8 *mic,
+			      size_t mic_len);
 int ieee80211_aes_ccm_decrypt(struct crypto_aead *tfm, u8 *b_0, u8 *aad,
 			      u8 *data, size_t data_len, u8 *mic,
 			      size_t mic_len);

net/mac80211/aes_gcm.c

@@ -15,20 +15,23 @@
 #include "key.h"
 #include "aes_gcm.h"
 
-void ieee80211_aes_gcm_encrypt(struct crypto_aead *tfm, u8 *j_0, u8 *aad,
-			       u8 *data, size_t data_len, u8 *mic)
+int ieee80211_aes_gcm_encrypt(struct crypto_aead *tfm, u8 *j_0, u8 *aad,
+			      u8 *data, size_t data_len, u8 *mic)
 {
 	struct scatterlist sg[3];
+	struct aead_request *aead_req;
+	int reqsize = sizeof(*aead_req) + crypto_aead_reqsize(tfm);
+	u8 *__aad;
 
-	char aead_req_data[sizeof(struct aead_request) +
-			   crypto_aead_reqsize(tfm)]
-		__aligned(__alignof__(struct aead_request));
-	struct aead_request *aead_req = (void *)aead_req_data;
+	aead_req = kzalloc(reqsize + GCM_AAD_LEN, GFP_ATOMIC);
+	if (!aead_req)
+		return -ENOMEM;
 
-	memset(aead_req, 0, sizeof(aead_req_data));
+	__aad = (u8 *)aead_req + reqsize;
+	memcpy(__aad, aad, GCM_AAD_LEN);
 
 	sg_init_table(sg, 3);
-	sg_set_buf(&sg[0], &aad[2], be16_to_cpup((__be16 *)aad));
+	sg_set_buf(&sg[0], &__aad[2], be16_to_cpup((__be16 *)__aad));
 	sg_set_buf(&sg[1], data, data_len);
 	sg_set_buf(&sg[2], mic, IEEE80211_GCMP_MIC_LEN);
 
@@ -37,24 +40,31 @@ void ieee80211_aes_gcm_encrypt(struct crypto_aead *tfm, u8 *j_0, u8 *aad,
 	aead_request_set_ad(aead_req, sg[0].length);
 
 	crypto_aead_encrypt(aead_req);
+	kzfree(aead_req);
+	return 0;
 }
 
 int ieee80211_aes_gcm_decrypt(struct crypto_aead *tfm, u8 *j_0, u8 *aad,
 			      u8 *data, size_t data_len, u8 *mic)
 {
 	struct scatterlist sg[3];
-	char aead_req_data[sizeof(struct aead_request) +
-			   crypto_aead_reqsize(tfm)]
-		__aligned(__alignof__(struct aead_request));
-	struct aead_request *aead_req = (void *)aead_req_data;
+	struct aead_request *aead_req;
+	int reqsize = sizeof(*aead_req) + crypto_aead_reqsize(tfm);
+	u8 *__aad;
+	int err;
 
 	if (data_len == 0)
 		return -EINVAL;
 
-	memset(aead_req, 0, sizeof(aead_req_data));
+	aead_req = kzalloc(reqsize + GCM_AAD_LEN, GFP_ATOMIC);
+	if (!aead_req)
+		return -ENOMEM;
+
+	__aad = (u8 *)aead_req + reqsize;
+	memcpy(__aad, aad, GCM_AAD_LEN);
 
 	sg_init_table(sg, 3);
-	sg_set_buf(&sg[0], &aad[2], be16_to_cpup((__be16 *)aad));
+	sg_set_buf(&sg[0], &__aad[2], be16_to_cpup((__be16 *)__aad));
 	sg_set_buf(&sg[1], data, data_len);
 	sg_set_buf(&sg[2], mic, IEEE80211_GCMP_MIC_LEN);
 
@@ -63,7 +73,10 @@ int ieee80211_aes_gcm_decrypt(struct crypto_aead *tfm, u8 *j_0, u8 *aad,
 			       data_len + IEEE80211_GCMP_MIC_LEN, j_0);
 	aead_request_set_ad(aead_req, sg[0].length);
 
-	return crypto_aead_decrypt(aead_req);
+	err = crypto_aead_decrypt(aead_req);
+	kzfree(aead_req);
+
+	return err;
 }
 
 struct crypto_aead *ieee80211_aes_gcm_key_setup_encrypt(const u8 key[],

net/mac80211/aes_gcm.h

@@ -11,8 +11,10 @@
 
 #include <linux/crypto.h>
 
-void ieee80211_aes_gcm_encrypt(struct crypto_aead *tfm, u8 *j_0, u8 *aad,
-			       u8 *data, size_t data_len, u8 *mic);
+#define GCM_AAD_LEN	32
+
+int ieee80211_aes_gcm_encrypt(struct crypto_aead *tfm, u8 *j_0, u8 *aad,
+			      u8 *data, size_t data_len, u8 *mic);
 int ieee80211_aes_gcm_decrypt(struct crypto_aead *tfm, u8 *j_0, u8 *aad,
 			      u8 *data, size_t data_len, u8 *mic);
 struct crypto_aead *ieee80211_aes_gcm_key_setup_encrypt(const u8 key[],

net/mac80211/aes_gmac.c

@@ -17,28 +17,27 @@
 #include "key.h"
 #include "aes_gmac.h"
 
-#define GMAC_MIC_LEN 16
-#define GMAC_NONCE_LEN 12
-#define AAD_LEN 20
-
 int ieee80211_aes_gmac(struct crypto_aead *tfm, const u8 *aad, u8 *nonce,
 		       const u8 *data, size_t data_len, u8 *mic)
 {
 	struct scatterlist sg[4];
-	char aead_req_data[sizeof(struct aead_request) +
-			   crypto_aead_reqsize(tfm)]
-		__aligned(__alignof__(struct aead_request));
-	struct aead_request *aead_req = (void *)aead_req_data;
-	u8 zero[GMAC_MIC_LEN], iv[AES_BLOCK_SIZE];
+	u8 *zero, *__aad, iv[AES_BLOCK_SIZE];
+	struct aead_request *aead_req;
+	int reqsize = sizeof(*aead_req) + crypto_aead_reqsize(tfm);
 
 	if (data_len < GMAC_MIC_LEN)
 		return -EINVAL;
 
-	memset(aead_req, 0, sizeof(aead_req_data));
+	aead_req = kzalloc(reqsize + GMAC_MIC_LEN + GMAC_AAD_LEN, GFP_ATOMIC);
+	if (!aead_req)
+		return -ENOMEM;
+
+	zero = (u8 *)aead_req + reqsize;
+	__aad = zero + GMAC_MIC_LEN;
+	memcpy(__aad, aad, GMAC_AAD_LEN);
 
-	memset(zero, 0, GMAC_MIC_LEN);
 	sg_init_table(sg, 4);
-	sg_set_buf(&sg[0], aad, AAD_LEN);
+	sg_set_buf(&sg[0], __aad, GMAC_AAD_LEN);
 	sg_set_buf(&sg[1], data, data_len - GMAC_MIC_LEN);
 	sg_set_buf(&sg[2], zero, GMAC_MIC_LEN);
 	sg_set_buf(&sg[3], mic, GMAC_MIC_LEN);
@@ -49,9 +48,10 @@ int ieee80211_aes_gmac(struct crypto_aead *tfm, const u8 *aad, u8 *nonce,
 
 	aead_request_set_tfm(aead_req, tfm);
 	aead_request_set_crypt(aead_req, sg, sg, 0, iv);
-	aead_request_set_ad(aead_req, AAD_LEN + data_len);
+	aead_request_set_ad(aead_req, GMAC_AAD_LEN + data_len);
 
 	crypto_aead_encrypt(aead_req);
+	kzfree(aead_req);
 
 	return 0;
 }

net/mac80211/aes_gmac.h

@@ -11,6 +11,10 @@
 
 #include <linux/crypto.h>
 
+#define GMAC_AAD_LEN	20
+#define GMAC_MIC_LEN	16
+#define GMAC_NONCE_LEN	12
+
 struct crypto_aead *ieee80211_aes_gmac_key_setup(const u8 key[],
 						 size_t key_len);
 int ieee80211_aes_gmac(struct crypto_aead *tfm, const u8 *aad, u8 *nonce,

net/mac80211/wpa.c

@@ -405,7 +405,7 @@ static int ccmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb,
 	u8 *pos;
 	u8 pn[6];
 	u64 pn64;
-	u8 aad[2 * AES_BLOCK_SIZE];
+	u8 aad[CCM_AAD_LEN];
 	u8 b_0[AES_BLOCK_SIZE];
 
 	if (info->control.hw_key &&
@@ -461,10 +461,8 @@ static int ccmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb,
 
 	pos += IEEE80211_CCMP_HDR_LEN;
 	ccmp_special_blocks(skb, pn, b_0, aad);
-	ieee80211_aes_ccm_encrypt(key->u.ccmp.tfm, b_0, aad, pos, len,
-				  skb_put(skb, mic_len), mic_len);
-
-	return 0;
+	return ieee80211_aes_ccm_encrypt(key->u.ccmp.tfm, b_0, aad, pos, len,
+					 skb_put(skb, mic_len), mic_len);
 }
 
 
@@ -639,7 +637,7 @@ static int gcmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
 	u8 *pos;
 	u8 pn[6];
 	u64 pn64;
-	u8 aad[2 * AES_BLOCK_SIZE];
+	u8 aad[GCM_AAD_LEN];
 	u8 j_0[AES_BLOCK_SIZE];
 
 	if (info->control.hw_key &&
@@ -696,10 +694,8 @@ static int gcmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
 
 	pos += IEEE80211_GCMP_HDR_LEN;
 	gcmp_special_blocks(skb, pn, j_0, aad);
-	ieee80211_aes_gcm_encrypt(key->u.gcmp.tfm, j_0, aad, pos, len,
-				  skb_put(skb, IEEE80211_GCMP_MIC_LEN));
-
-	return 0;
+	return ieee80211_aes_gcm_encrypt(key->u.gcmp.tfm, j_0, aad, pos, len,
+					 skb_put(skb, IEEE80211_GCMP_MIC_LEN));
 }
 
 ieee80211_tx_result
@@ -1123,9 +1119,9 @@ ieee80211_crypto_aes_gmac_encrypt(struct ieee80211_tx_data *tx)
 	struct ieee80211_key *key = tx->key;
 	struct ieee80211_mmie_16 *mmie;
 	struct ieee80211_hdr *hdr;
-	u8 aad[20];
+	u8 aad[GMAC_AAD_LEN];
 	u64 pn64;
-	u8 nonce[12];
+	u8 nonce[GMAC_NONCE_LEN];
 
 	if (WARN_ON(skb_queue_len(&tx->skbs) != 1))
 		return TX_DROP;
@@ -1171,7 +1167,7 @@ ieee80211_crypto_aes_gmac_decrypt(struct ieee80211_rx_data *rx)
 	struct ieee80211_rx_status *status = IEEE80211_SKB_RXCB(skb);
 	struct ieee80211_key *key = rx->key;
 	struct ieee80211_mmie_16 *mmie;
-	u8 aad[20], mic[16], ipn[6], nonce[12];
+	u8 aad[GMAC_AAD_LEN], mic[GMAC_MIC_LEN], ipn[6], nonce[GMAC_NONCE_LEN];
 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
 
 	if (!ieee80211_is_mgmt(hdr->frame_control))