CCP RSA implementation uses a hardware input buffer which size depends only
on the current RSA key length. Key modulus and a message to be processed
is then copied to this buffer based on their own lengths.
Since the price for providing too long input data is a buffer overflow and
there already has been a case when this has happened let's better reject
such oversized input data and log an error message in this case so we know
what is going on.
Signed-off-by: Maciej S. Szmigiero <[email protected]>
---
drivers/crypto/ccp/ccp-ops.c | 24 ++++++++++++++++++++----
1 file changed, 20 insertions(+), 4 deletions(-)
diff --git a/drivers/crypto/ccp/ccp-ops.c b/drivers/crypto/ccp/ccp-ops.c
index 406b95329b3d..517aeee30abf 100644
--- a/drivers/crypto/ccp/ccp-ops.c
+++ b/drivers/crypto/ccp/ccp-ops.c
@@ -1770,10 +1770,6 @@ static int ccp_run_rsa_cmd(struct ccp_cmd_queue *cmd_q, struct ccp_cmd *cmd)
if (!rsa->exp || !rsa->mod || !rsa->src || !rsa->dst)
return -EINVAL;
- memset(&op, 0, sizeof(op));
- op.cmd_q = cmd_q;
- op.jobid = CCP_NEW_JOBID(cmd_q->ccp);
-
/* The RSA modulus must precede the message being acted upon, so
* it must be copied to a DMA area where the message and the
* modulus can be concatenated. Therefore the input buffer
@@ -1785,6 +1781,26 @@ static int ccp_run_rsa_cmd(struct ccp_cmd_queue *cmd_q, struct ccp_cmd *cmd)
o_len = 32 * ((rsa->key_size + 255) / 256);
i_len = o_len * 2;
+ if (rsa->mod_len > o_len) {
+ dev_err(cmd_q->ccp->dev,
+ "RSA modulus of %u bytes too large for key size of %u bits\n",
+ (unsigned int)rsa->mod_len,
+ (unsigned int)rsa->key_size);
+ return -EINVAL;
+ }
+
+ if (rsa->src_len > o_len) {
+ dev_err(cmd_q->ccp->dev,
+ "RSA data of %u bytes too large for key size of %u bits\n",
+ (unsigned int)rsa->src_len,
+ (unsigned int)rsa->key_size);
+ return -EINVAL;
+ }
+
+ memset(&op, 0, sizeof(op));
+ op.cmd_q = cmd_q;
+ op.jobid = CCP_NEW_JOBID(cmd_q->ccp);
+
sb_count = 0;
if (cmd_q->ccp->vdata->version < CCP_VERSION(5, 0)) {
/* sb_count is the number of storage block slots required
On 02/24/2018 10:03 AM, Maciej S. Szmigiero wrote:
> CCP RSA implementation uses a hardware input buffer which size depends only
> on the current RSA key length. Key modulus and a message to be processed
> is then copied to this buffer based on their own lengths.
>
> Since the price for providing too long input data is a buffer overflow and
> there already has been a case when this has happened let's better reject
> such oversized input data and log an error message in this case so we know
> what is going on.
>
> Signed-off-by: Maciej S. Szmigiero <[email protected]>
> ---
> drivers/crypto/ccp/ccp-ops.c | 24 ++++++++++++++++++++----
> 1 file changed, 20 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/crypto/ccp/ccp-ops.c b/drivers/crypto/ccp/ccp-ops.c
> index 406b95329b3d..517aeee30abf 100644
> --- a/drivers/crypto/ccp/ccp-ops.c
> +++ b/drivers/crypto/ccp/ccp-ops.c
> @@ -1770,10 +1770,6 @@ static int ccp_run_rsa_cmd(struct ccp_cmd_queue *cmd_q, struct ccp_cmd *cmd)
> if (!rsa->exp || !rsa->mod || !rsa->src || !rsa->dst)
> return -EINVAL;
>
> - memset(&op, 0, sizeof(op));
> - op.cmd_q = cmd_q;
> - op.jobid = CCP_NEW_JOBID(cmd_q->ccp);
> -
> /* The RSA modulus must precede the message being acted upon, so
> * it must be copied to a DMA area where the message and the
> * modulus can be concatenated. Therefore the input buffer
> @@ -1785,6 +1781,26 @@ static int ccp_run_rsa_cmd(struct ccp_cmd_queue *cmd_q, struct ccp_cmd *cmd)
> o_len = 32 * ((rsa->key_size + 255) / 256);
> i_len = o_len * 2;
>
> + if (rsa->mod_len > o_len) {
> + dev_err(cmd_q->ccp->dev,
> + "RSA modulus of %u bytes too large for key size of %u bits\n",
> + (unsigned int)rsa->mod_len,
> + (unsigned int)rsa->key_size);
> + return -EINVAL;
> + }
> +
> + if (rsa->src_len > o_len) {
> + dev_err(cmd_q->ccp->dev,
> + "RSA data of %u bytes too large for key size of %u bits\n",
> + (unsigned int)rsa->src_len,
> + (unsigned int)rsa->key_size);
> + return -EINVAL;
> + }
We've talked about this, and we believe that a more central fix is
warranted. I intend to post another patch tomorrow that should address
this problem.
> +
> + memset(&op, 0, sizeof(op));
> + op.cmd_q = cmd_q;
> + op.jobid = CCP_NEW_JOBID(cmd_q->ccp);
> +
> sb_count = 0;
> if (cmd_q->ccp->vdata->version < CCP_VERSION(5, 0)) {
> /* sb_count is the number of storage block slots required
>