[PATCH 4/5] crypto: ccp: Use the stack for small SEV command buffers

Sean Christopherson
2021-04-02T23:37:43Z

For commands with small input/output buffers, use the local stack to
"allocate" the structures used to communicate with the PSP. Now that
__sev_do_cmd_locked() gracefully handles vmalloc'd buffers, there's no
reason to avoid using the stack, e.g. CONFIG_VMAP_STACK=y will just work.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
drivers/crypto/ccp/sev-dev.c | 122 ++++++++++++++---------------------
1 file changed, 47 insertions(+), 75 deletions(-)

diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index 6d5882290cfc..6a380d483fce 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -402,7 +402,7 @@ static int sev_ioctl_do_pek_csr(struct sev_issue_cmd *argp, bool writable)
{
struct sev_device *sev = psp_master->sev_data;
struct sev_user_data_pek_csr input;
- struct sev_data_pek_csr *data;
+ struct sev_data_pek_csr data;
void __user *input_address;
void *blob = NULL;
int ret;
@@ -413,29 +413,24 @@ static int sev_ioctl_do_pek_csr(struct sev_issue_cmd *argp, bool writable)
if (copy_from_user(&input, (void __user *)argp->data, sizeof(input)))
return -EFAULT;

- data = kzalloc(sizeof(*data), GFP_KERNEL);
- if (!data)
- return -ENOMEM;
-
/* userspace wants to query CSR length */
- if (!input.address || !input.length)
+ if (!input.address || !input.length) {
+ data.address = 0;
+ data.len = 0;
goto cmd;
+ }

/* allocate a physically contiguous buffer to store the CSR blob */
input_address = (void __user *)input.address;
- if (input.length > SEV_FW_BLOB_MAX_SIZE) {
- ret = -EFAULT;
- goto e_free;
- }
+ if (input.length > SEV_FW_BLOB_MAX_SIZE)
+ return -EFAULT;

blob = kmalloc(input.length, GFP_KERNEL);
- if (!blob) {
- ret = -ENOMEM;
- goto e_free;
- }
+ if (!blob)
+ return -ENOMEM;

- data->address = __psp_pa(blob);
- data->len = input.length;
+ data.address = __psp_pa(blob);
+ data.len = input.length;

cmd:
if (sev->state == SEV_STATE_UNINIT) {
@@ -444,10 +439,10 @@ static int sev_ioctl_do_pek_csr(struct sev_issue_cmd *argp, bool writable)
goto e_free_blob;
}

- ret = __sev_do_cmd_locked(SEV_CMD_PEK_CSR, data, &argp->error);
+ ret = __sev_do_cmd_locked(SEV_CMD_PEK_CSR, &data, &argp->error);

/* If we query the CSR length, FW responded with expected data. */
- input.length = data->len;
+ input.length = data.len;

if (copy_to_user((void __user *)argp->data, &input, sizeof(input))) {
ret = -EFAULT;
@@ -461,8 +456,6 @@ static int sev_ioctl_do_pek_csr(struct sev_issue_cmd *argp, bool writable)

e_free_blob:
kfree(blob);
-e_free:
- kfree(data);
return ret;
}

@@ -594,7 +587,7 @@ static int sev_ioctl_do_pek_import(struct sev_issue_cmd *argp, bool writable)
{
struct sev_device *sev = psp_master->sev_data;
struct sev_user_data_pek_cert_import input;
- struct sev_data_pek_cert_import *data;
+ struct sev_data_pek_cert_import data;
void *pek_blob, *oca_blob;
int ret;

@@ -604,19 +597,14 @@ static int sev_ioctl_do_pek_import(struct sev_issue_cmd *argp, bool writable)
if (copy_from_user(&input, (void __user *)argp->data, sizeof(input)))
return -EFAULT;

- data = kzalloc(sizeof(*data), GFP_KERNEL);
- if (!data)
- return -ENOMEM;
-
/* copy PEK certificate blobs from userspace */
pek_blob = psp_copy_user_blob(input.pek_cert_address, input.pek_cert_len);
- if (IS_ERR(pek_blob)) {
- ret = PTR_ERR(pek_blob);
- goto e_free;
- }
+ if (IS_ERR(pek_blob))
+ return PTR_ERR(pek_blob);

- data->pek_cert_address = __psp_pa(pek_blob);
- data->pek_cert_len = input.pek_cert_len;
+ data.reserved = 0;
+ data.pek_cert_address = __psp_pa(pek_blob);
+ data.pek_cert_len = input.pek_cert_len;

/* copy PEK certificate blobs from userspace */
oca_blob = psp_copy_user_blob(input.oca_cert_address, input.oca_cert_len);
@@ -625,8 +613,8 @@ static int sev_ioctl_do_pek_import(struct sev_issue_cmd *argp, bool writable)
goto e_free_pek;
}

- data->oca_cert_address = __psp_pa(oca_blob);
- data->oca_cert_len = input.oca_cert_len;
+ data.oca_cert_address = __psp_pa(oca_blob);
+ data.oca_cert_len = input.oca_cert_len;

/* If platform is not in INIT state then transition it to INIT */
if (sev->state != SEV_STATE_INIT) {
@@ -635,21 +623,19 @@ static int sev_ioctl_do_pek_import(struct sev_issue_cmd *argp, bool writable)
goto e_free_oca;
}

- ret = __sev_do_cmd_locked(SEV_CMD_PEK_CERT_IMPORT, data, &argp->error);
+ ret = __sev_do_cmd_locked(SEV_CMD_PEK_CERT_IMPORT, &data, &argp->error);

e_free_oca:
kfree(oca_blob);
e_free_pek:
kfree(pek_blob);
-e_free:
- kfree(data);
return ret;
}

static int sev_ioctl_do_get_id2(struct sev_issue_cmd *argp)
{
struct sev_user_data_get_id2 input;
- struct sev_data_get_id *data;
+ struct sev_data_get_id data;
void __user *input_address;
void *id_blob = NULL;
int ret;
@@ -663,28 +649,25 @@ static int sev_ioctl_do_get_id2(struct sev_issue_cmd *argp)

input_address = (void __user *)input.address;

- data = kzalloc(sizeof(*data), GFP_KERNEL);
- if (!data)
- return -ENOMEM;
-
if (input.address && input.length) {
id_blob = kmalloc(input.length, GFP_KERNEL);
- if (!id_blob) {
- kfree(data);
+ if (!id_blob)
return -ENOMEM;
- }

- data->address = __psp_pa(id_blob);
- data->len = input.length;
+ data.address = __psp_pa(id_blob);
+ data.len = input.length;
+ } else {
+ data.address = 0;
+ data.len = 0;
}

- ret = __sev_do_cmd_locked(SEV_CMD_GET_ID, data, &argp->error);
+ ret = __sev_do_cmd_locked(SEV_CMD_GET_ID, &data, &argp->error);

/*
* Firmware will return the length of the ID value (either the minimum
* required length or the actual length written), return it to the user.
*/
- input.length = data->len;
+ input.length = data.len;

if (copy_to_user((void __user *)argp->data, &input, sizeof(input))) {
ret = -EFAULT;
@@ -692,7 +675,7 @@ static int sev_ioctl_do_get_id2(struct sev_issue_cmd *argp)
}

if (id_blob) {
- if (copy_to_user(input_address, id_blob, data->len)) {
+ if (copy_to_user(input_address, id_blob, data.len)) {
ret = -EFAULT;
goto e_free;
}
@@ -700,7 +683,6 @@ static int sev_ioctl_do_get_id2(struct sev_issue_cmd *argp)

e_free:
kfree(id_blob);
- kfree(data);

return ret;
}
@@ -750,7 +732,7 @@ static int sev_ioctl_do_pdh_export(struct sev_issue_cmd *argp, bool writable)
struct sev_device *sev = psp_master->sev_data;
struct sev_user_data_pdh_cert_export input;
void *pdh_blob = NULL, *cert_blob = NULL;
- struct sev_data_pdh_cert_export *data;
+ struct sev_data_pdh_cert_export data;
void __user *input_cert_chain_address;
void __user *input_pdh_cert_address;
int ret;
@@ -768,9 +750,7 @@ static int sev_ioctl_do_pdh_export(struct sev_issue_cmd *argp, bool writable)
if (copy_from_user(&input, (void __user *)argp->data, sizeof(input)))
return -EFAULT;

- data = kzalloc(sizeof(*data), GFP_KERNEL);
- if (!data)
- return -ENOMEM;
+ memset(&data, 0, sizeof(data));

/* Userspace wants to query the certificate length. */
if (!input.pdh_cert_address ||
@@ -782,25 +762,19 @@ static int sev_ioctl_do_pdh_export(struct sev_issue_cmd *argp, bool writable)
input_cert_chain_address = (void __user *)input.cert_chain_address;

/* Allocate a physically contiguous buffer to store the PDH blob. */
- if (input.pdh_cert_len > SEV_FW_BLOB_MAX_SIZE) {
- ret = -EFAULT;
- goto e_free;
- }
+ if (input.pdh_cert_len > SEV_FW_BLOB_MAX_SIZE)
+ return -EFAULT;

/* Allocate a physically contiguous buffer to store the cert chain blob. */
- if (input.cert_chain_len > SEV_FW_BLOB_MAX_SIZE) {
- ret = -EFAULT;
- goto e_free;
- }
+ if (input.cert_chain_len > SEV_FW_BLOB_MAX_SIZE)
+ return -EFAULT;

pdh_blob = kmalloc(input.pdh_cert_len, GFP_KERNEL);
- if (!pdh_blob) {
- ret = -ENOMEM;
- goto e_free;
- }
+ if (!pdh_blob)
+ return -ENOMEM;

- data->pdh_cert_address = __psp_pa(pdh_blob);
- data->pdh_cert_len = input.pdh_cert_len;
+ data.pdh_cert_address = __psp_pa(pdh_blob);
+ data.pdh_cert_len = input.pdh_cert_len;

cert_blob = kmalloc(input.cert_chain_len, GFP_KERNEL);
if (!cert_blob) {
@@ -808,15 +782,15 @@ static int sev_ioctl_do_pdh_export(struct sev_issue_cmd *argp, bool writable)
goto e_free_pdh;
}

- data->cert_chain_address = __psp_pa(cert_blob);
- data->cert_chain_len = input.cert_chain_len;
+ data.cert_chain_address = __psp_pa(cert_blob);
+ data.cert_chain_len = input.cert_chain_len;

cmd:
- ret = __sev_do_cmd_locked(SEV_CMD_PDH_CERT_EXPORT, data, &argp->error);
+ ret = __sev_do_cmd_locked(SEV_CMD_PDH_CERT_EXPORT, &data, &argp->error);

/* If we query the length, FW responded with expected data. */
- input.cert_chain_len = data->cert_chain_len;
- input.pdh_cert_len = data->pdh_cert_len;
+ input.cert_chain_len = data.cert_chain_len;
+ input.pdh_cert_len = data.pdh_cert_len;

if (copy_to_user((void __user *)argp->data, &input, sizeof(input))) {
ret = -EFAULT;
@@ -841,8 +815,6 @@ static int sev_ioctl_do_pdh_export(struct sev_issue_cmd *argp, bool writable)
kfree(cert_blob);
e_free_pdh:
kfree(pdh_blob);
-e_free:
- kfree(data);
return ret;
}

--
2.31.0.208.g409f899ff0-goog