On Wed, Aug 23, 2023 at 8:55 AM Sumit Garg [off-list ref] wrote:

On Tue, 22 Aug 2023 at 18:25, Jens Wiklander [off-list ref] wrote:

quoted

On Tue, Aug 22, 2023 at 04:59:33PM +0530, Sumit Garg wrote:

quoted

The OP-TEE driver using the old SMC based ABI permits overlapping shared
buffers, but with the new FF-A based ABI each physical page may only
be registered once.

As the key and blob buffer are allocated adjancently, there is no need
for redundant register shared memory invocation. Also, it is incompatibile
with FF-A based ABI limitation. So refactor register shared memory
implementation to use only single invocation to register both key and blob
buffers.

Fixes: 4615e5a34b95 ("optee: add FF-A support")
Reported-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Sumit Garg <redacted>
---
 security/keys/trusted-keys/trusted_tee.c | 64 ++++++++----------------
 1 file changed, 20 insertions(+), 44 deletions(-)

diff --git a/security/keys/trusted-keys/trusted_tee.c b/security/keys/trusted-keys/trusted_tee.c
index ac3e270ade69..aa3d477de6db 100644
--- a/security/keys/trusted-keys/trusted_tee.c
+++ b/security/keys/trusted-keys/trusted_tee.c

@@ -65,24 +65,16 @@ static int trusted_tee_seal(struct trusted_key_payload *p, char *datablob)
      int ret;
      struct tee_ioctl_invoke_arg inv_arg;
      struct tee_param param[4];
-     struct tee_shm *reg_shm_in = NULL, *reg_shm_out = NULL;
+     struct tee_shm *reg_shm = NULL;

      memset(&inv_arg, 0, sizeof(inv_arg));
      memset(&param, 0, sizeof(param));

-     reg_shm_in = tee_shm_register_kernel_buf(pvt_data.ctx, p->key,
-                                              p->key_len);
-     if (IS_ERR(reg_shm_in)) {
-             dev_err(pvt_data.dev, "key shm register failed\n");
-             return PTR_ERR(reg_shm_in);
-     }
-
-     reg_shm_out = tee_shm_register_kernel_buf(pvt_data.ctx, p->blob,
-                                               sizeof(p->blob));
-     if (IS_ERR(reg_shm_out)) {
-             dev_err(pvt_data.dev, "blob shm register failed\n");
-             ret = PTR_ERR(reg_shm_out);
-             goto out;
+     reg_shm = tee_shm_register_kernel_buf(pvt_data.ctx, p->key,
+                                           sizeof(p->key) + sizeof(p->blob));

This is somewhat fragile. What if struct trusted_key_payload has a small
unexpected change in layout?

key and blob buffers are just two adjacent fixed sized byte arrays. So
I am not worried here as long as they stay adjacent (which has been
the case since trusted keys were introduced in the kernel).

Yeah, that was my point, but fine if you don't believe it's an issue.

Thanks,
Jens

-Sumit

quoted

Thanks,
Jens

quoted

+     if (IS_ERR(reg_shm)) {
+             dev_err(pvt_data.dev, "shm register failed\n");
+             return PTR_ERR(reg_shm);
      }

      inv_arg.func = TA_CMD_SEAL;

@@ -90,13 +82,13 @@ static int trusted_tee_seal(struct trusted_key_payload *p, char *datablob)
      inv_arg.num_params = 4;

      param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INPUT;
-     param[0].u.memref.shm = reg_shm_in;
+     param[0].u.memref.shm = reg_shm;
      param[0].u.memref.size = p->key_len;
      param[0].u.memref.shm_offs = 0;
      param[1].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT;
-     param[1].u.memref.shm = reg_shm_out;
+     param[1].u.memref.shm = reg_shm;
      param[1].u.memref.size = sizeof(p->blob);
-     param[1].u.memref.shm_offs = 0;
+     param[1].u.memref.shm_offs = sizeof(p->key);

      ret = tee_client_invoke_func(pvt_data.ctx, &inv_arg, param);
      if ((ret < 0) || (inv_arg.ret != 0)) {

@@ -107,11 +99,7 @@ static int trusted_tee_seal(struct trusted_key_payload *p, char *datablob)
              p->blob_len = param[1].u.memref.size;
      }

-out:
-     if (reg_shm_out)
-             tee_shm_free(reg_shm_out);
-     if (reg_shm_in)
-             tee_shm_free(reg_shm_in);
+     tee_shm_free(reg_shm);

      return ret;
 }

@@ -124,24 +112,16 @@ static int trusted_tee_unseal(struct trusted_key_payload *p, char *datablob)
      int ret;
      struct tee_ioctl_invoke_arg inv_arg;
      struct tee_param param[4];
-     struct tee_shm *reg_shm_in = NULL, *reg_shm_out = NULL;
+     struct tee_shm *reg_shm = NULL;

      memset(&inv_arg, 0, sizeof(inv_arg));
      memset(&param, 0, sizeof(param));

-     reg_shm_in = tee_shm_register_kernel_buf(pvt_data.ctx, p->blob,
-                                              p->blob_len);
-     if (IS_ERR(reg_shm_in)) {
-             dev_err(pvt_data.dev, "blob shm register failed\n");
-             return PTR_ERR(reg_shm_in);
-     }
-
-     reg_shm_out = tee_shm_register_kernel_buf(pvt_data.ctx, p->key,
-                                               sizeof(p->key));
-     if (IS_ERR(reg_shm_out)) {
-             dev_err(pvt_data.dev, "key shm register failed\n");
-             ret = PTR_ERR(reg_shm_out);
-             goto out;
+     reg_shm = tee_shm_register_kernel_buf(pvt_data.ctx, p->key,
+                                           sizeof(p->key) + sizeof(p->blob));
+     if (IS_ERR(reg_shm)) {
+             dev_err(pvt_data.dev, "shm register failed\n");
+             return PTR_ERR(reg_shm);
      }

      inv_arg.func = TA_CMD_UNSEAL;

@@ -149,11 +129,11 @@ static int trusted_tee_unseal(struct trusted_key_payload *p, char *datablob)
      inv_arg.num_params = 4;

      param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INPUT;
-     param[0].u.memref.shm = reg_shm_in;
+     param[0].u.memref.shm = reg_shm;
      param[0].u.memref.size = p->blob_len;
-     param[0].u.memref.shm_offs = 0;
+     param[0].u.memref.shm_offs = sizeof(p->key);
      param[1].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT;
-     param[1].u.memref.shm = reg_shm_out;
+     param[1].u.memref.shm = reg_shm;
      param[1].u.memref.size = sizeof(p->key);
      param[1].u.memref.shm_offs = 0;

@@ -166,11 +146,7 @@ static int trusted_tee_unseal(struct trusted_key_payload *p, char *datablob)
              p->key_len = param[1].u.memref.size;
      }

-out:
-     if (reg_shm_out)
-             tee_shm_free(reg_shm_out);
-     if (reg_shm_in)
-             tee_shm_free(reg_shm_in);
+     tee_shm_free(reg_shm);

      return ret;
 }
--

2.34.1