crypto: keystone: Fix security context teardown procedure

After initiating a security context teardown, host should wait until the ownership flag is cleared by CP_ACE. Non-compliance to this procedure could create race condition when the same SCID is reused for a new context.

Signed-off-by: Sandeep Nair <sandeep_n@ti.com>

2 files changed, 37 insertions, 3 deletions

diff --git a/drivers/crypto/keystone-sa.c b/drivers/crypto/keystone-sa.c
index b59cb1f3a49..bba1025ff81 100644
--- a/drivers/crypto/keystone-sa.c
+++ b/drivers/crypto/keystone-sa.c
@@ -2015,7 +2015,7 @@ static int sa_init_sc(struct sa_ctx_info *ctx, const u8 *enc_key,
         php_f = php_e = SA_CTX_DMA_SIZE_64;
 
         /* SCCTL Owner info: 0=host, 1=CP_ACE */
-        sc_buf[0] = 0;
+        sc_buf[SA_CTX_SCCTL_OWNER_OFFSET] = 0;
         /* SCCTL F/E control */
         sc_buf[1] = SA_CTX_SCCTL_MK_DMA_INFO(php_f, eng0_f, eng1_f, php_e);
         memcpy(&sc_buf[2], &sc_id, 2); /*(optional)
@@ -2045,7 +2045,7 @@ static int sa_init_sc(struct sa_ctx_info *ctx, const u8 *enc_key,
         }
 
         /* Set the ownership of context to CP_ACE */
-        sc_buf[0] = 0x80;
+        sc_buf[SA_CTX_SCCTL_OWNER_OFFSET] = 0x80;
 
         /* swizzle the security context */
         sa_swiz_128(sc_buf, sc_buf, SA_CTX_MAX_SZ);
@@ -2077,17 +2077,20 @@ static int sa_init_sc(struct sa_ctx_info *ctx, const u8 *enc_key,
 }
 
 /* Tear down the Security Context */
+#define SA_SC_TEAR_RETRIES      5
+#define SA_SC_TEAR_DELAY        20 /* msecs */
 static int sa_tear_sc(struct sa_ctx_info *ctx,
                         struct keystone_crypto_data *pdata)
 {
+        int own_off, cnt = SA_SC_TEAR_RETRIES;
         struct dma_async_tx_descriptor *desc;
         struct sa_dma_req_ctx *dma_ctx;
         struct sa_swinfo swinfo;
         dma_cookie_t cookie;
         unsigned long flags;
         u16 queue_id;
-        u8 flow_id;
         int ret = 0;
+        u8 flow_id;
 
         dma_ctx = kmalloc(sizeof(struct sa_dma_req_ctx), 0);
         if (!dma_ctx)
@@ -2152,6 +2155,22 @@ static int sa_tear_sc(struct sa_ctx_info *ctx,
                 ret = -ENXIO;
                 goto err;
         }
+
+        /*
+         * Check that CP_ACE has released the context
+         * by making sure that the owner bit is 0
+         */
+        /*
+         * Security context had been swizzled by 128 bits
+         * before handing to CP_ACE
+         */
+        own_off = ((SA_CTX_SCCTL_OWNER_OFFSET/16) * 16)
+                + (15 - (SA_CTX_SCCTL_OWNER_OFFSET % 16));
+        while (__raw_readb(&ctx->sc[own_off])) {
+                if (!--cnt)
+                        return -EAGAIN;
+                msleep_interruptible(SA_SC_TEAR_DELAY);
+        }
         return 0;
 
 err:
@@ -2184,6 +2203,7 @@ static void sa_free_ctx_info
         if (sa_tear_sc(ctx, data)) {
                 dev_err(keystone_dev,
                         "Failed to tear down context id(%x)\n", ctx->sc_id);
+                return;
         }
 
         bn = ctx->sc_id - data->sc_id_start;
@@ -2284,6 +2304,9 @@ static int sa_init_tfm(struct crypto_tfm *tfm)
                 }
         }
 
+        dev_dbg(keystone_dev, "%s(0x%p) sc-ids(0x%x(0x%x), 0x%x(0x%x))\n",
+                        __func__, tfm, ctx->enc.sc_id, ctx->enc.sc_phys,
+                        ctx->dec.sc_id, ctx->dec.sc_phys);
         return 0;
 }
 
@@ -2312,6 +2335,10 @@ static void sa_exit_tfm(struct crypto_tfm *tfm)
         struct sa_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
         struct keystone_crypto_data *data = dev_get_drvdata(keystone_dev);
 
+        dev_dbg(keystone_dev, "%s(0x%p) sc-ids(0x%x(0x%x), 0x%x(0x%x))\n",
+                        __func__, tfm, ctx->enc.sc_id, ctx->enc.sc_phys,
+                        ctx->dec.sc_id, ctx->dec.sc_phys);
+
         if ((alg->cra_flags & CRYPTO_ALG_TYPE_MASK)
                         == CRYPTO_ALG_TYPE_AEAD) {
                 sa_free_ctx_info(&ctx->enc, data);
@@ -3084,6 +3111,7 @@ static int keystone_crypto_remove(struct platform_device *pdev)
 
         /* un-register crypto algorithms */
         sa_unregister_algos(&pdev->dev);
+        dma_pool_destroy(crypto->sc_pool);
         clk_disable_unprepare(crypto->clk);
         clk_put(crypto->clk);
         kfree(crypto);
diff --git a/drivers/crypto/keystone-sa.h b/drivers/crypto/keystone-sa.h
index 5e6420f7a18..a390892485c 100644
--- a/drivers/crypto/keystone-sa.h
+++ b/drivers/crypto/keystone-sa.h
@@ -214,6 +214,12 @@ typedef u8 SA_CTX_PE_PKT_TYPE_T;
          ((php_e) << 6))
 
 /*
+ * Byte offset of the owner word in SCCTL
+ * in the security context
+ */
+#define SA_CTX_SCCTL_OWNER_OFFSET 0
+
+/*
  * Assumption: CTX size is mutiple of 32
  */
 #define SA_CTX_SIZE_TO_DMA_SIZE(ctx_sz) \