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Message-ID: <14b8f8f9-0dac-4745-ac81-4c52631784e7@linux.intel.com>
Date: Tue, 26 Sep 2023 11:51:51 -0700
From: Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@...ux.intel.com>
To: Dan Williams <dan.j.williams@...el.com>, linux-coco@...ts.linux.dev
Cc: Borislav Petkov <bp@...en8.de>,
Tom Lendacky <thomas.lendacky@....com>,
Dionna Glaze <dionnaglaze@...gle.com>,
Brijesh Singh <brijesh.singh@....com>, peterz@...radead.org,
linux-kernel@...r.kernel.org, x86@...nel.org,
dave.hansen@...ux.intel.com
Subject: Re: [PATCH v4 3/6] virt: sevguest: Prep for kernel internal {get,
get_ext}_report()
On 9/25/2023 9:17 PM, Dan Williams wrote:
> In preparation for using the configs-tsm facility to convey attestation
> blobs to userspace, switch to using the 'sockptr' api for copying
> payloads to provided buffers where 'sockptr' handles user vs kernel
> buffers.
>
> While configfs-tsm is meant to replace existing confidential computing
> ioctl() implementations for attestation report retrieval the old ioctl()
> path needs to stick around for a deprecation period.
>
> No behavior change intended.
>
> Cc: Borislav Petkov <bp@...en8.de>
> Cc: Tom Lendacky <thomas.lendacky@....com>
> Cc: Dionna Glaze <dionnaglaze@...gle.com>
> Cc: Brijesh Singh <brijesh.singh@....com>
> Signed-off-by: Dan Williams <dan.j.williams@...el.com>
> ---
Looks good to me.
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
> drivers/virt/coco/sev-guest/sev-guest.c | 50 ++++++++++++++++++++-----------
> 1 file changed, 33 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c
> index 97dbe715e96a..c3c9e9ea691f 100644
> --- a/drivers/virt/coco/sev-guest/sev-guest.c
> +++ b/drivers/virt/coco/sev-guest/sev-guest.c
> @@ -19,6 +19,7 @@
> #include <crypto/aead.h>
> #include <linux/scatterlist.h>
> #include <linux/psp-sev.h>
> +#include <linux/sockptr.h>
> #include <uapi/linux/sev-guest.h>
> #include <uapi/linux/psp-sev.h>
>
> @@ -470,7 +471,13 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code,
> return 0;
> }
>
> -static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_ioctl *arg)
> +struct snp_req_resp {
> + sockptr_t req_data;
> + sockptr_t resp_data;
> +};
> +
> +static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_ioctl *arg,
> + struct snp_req_resp *io)
> {
> struct snp_guest_crypto *crypto = snp_dev->crypto;
> struct snp_report_resp *resp;
> @@ -479,10 +486,10 @@ static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_io
>
> lockdep_assert_held(&snp_cmd_mutex);
>
> - if (!arg->req_data || !arg->resp_data)
> + if (sockptr_is_null(io->req_data) || sockptr_is_null(io->resp_data))
> return -EINVAL;
>
> - if (copy_from_user(&req, (void __user *)arg->req_data, sizeof(req)))
> + if (copy_from_sockptr(&req, io->req_data, sizeof(req)))
> return -EFAULT;
>
> /*
> @@ -501,7 +508,7 @@ static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_io
> if (rc)
> goto e_free;
>
> - if (copy_to_user((void __user *)arg->resp_data, resp, sizeof(*resp)))
> + if (copy_to_sockptr(io->resp_data, resp, sizeof(*resp)))
> rc = -EFAULT;
>
> e_free:
> @@ -550,22 +557,25 @@ static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_reque
> return rc;
> }
>
> -static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_ioctl *arg)
> +static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_ioctl *arg,
> + struct snp_req_resp *io)
> +
> {
> struct snp_guest_crypto *crypto = snp_dev->crypto;
> struct snp_ext_report_req req;
> struct snp_report_resp *resp;
> int ret, npages = 0, resp_len;
> + sockptr_t certs_address;
>
> lockdep_assert_held(&snp_cmd_mutex);
>
> - if (!arg->req_data || !arg->resp_data)
> + if (sockptr_is_null(io->req_data) || sockptr_is_null(io->resp_data))
> return -EINVAL;
>
> - if (copy_from_user(&req, (void __user *)arg->req_data, sizeof(req)))
> + if (copy_from_sockptr(&req, io->req_data, sizeof(req)))
> return -EFAULT;
>
> - /* userspace does not want certificate data */
> + /* caller does not want certificate data */
> if (!req.certs_len || !req.certs_address)
> goto cmd;
>
> @@ -573,8 +583,13 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques
> !IS_ALIGNED(req.certs_len, PAGE_SIZE))
> return -EINVAL;
>
> - if (!access_ok((const void __user *)req.certs_address, req.certs_len))
> - return -EFAULT;
> + if (sockptr_is_kernel(io->resp_data)) {
> + certs_address = KERNEL_SOCKPTR((void *)req.certs_address);
> + } else {
> + certs_address = USER_SOCKPTR((void __user *)req.certs_address);
> + if (!access_ok(certs_address.user, req.certs_len))
> + return -EFAULT;
> + }
>
> /*
> * Initialize the intermediate buffer with all zeros. This buffer
> @@ -604,21 +619,19 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques
> if (arg->vmm_error == SNP_GUEST_VMM_ERR_INVALID_LEN) {
> req.certs_len = snp_dev->input.data_npages << PAGE_SHIFT;
>
> - if (copy_to_user((void __user *)arg->req_data, &req, sizeof(req)))
> + if (copy_to_sockptr(io->req_data, &req, sizeof(req)))
> ret = -EFAULT;
> }
>
> if (ret)
> goto e_free;
>
> - if (npages &&
> - copy_to_user((void __user *)req.certs_address, snp_dev->certs_data,
> - req.certs_len)) {
> + if (npages && copy_to_sockptr(certs_address, snp_dev->certs_data, req.certs_len)) {
> ret = -EFAULT;
> goto e_free;
> }
>
> - if (copy_to_user((void __user *)arg->resp_data, resp, sizeof(*resp)))
> + if (copy_to_sockptr(io->resp_data, resp, sizeof(*resp)))
> ret = -EFAULT;
>
> e_free:
> @@ -631,6 +644,7 @@ static long snp_guest_ioctl(struct file *file, unsigned int ioctl, unsigned long
> struct snp_guest_dev *snp_dev = to_snp_dev(file);
> void __user *argp = (void __user *)arg;
> struct snp_guest_request_ioctl input;
> + struct snp_req_resp io;
> int ret = -ENOTTY;
>
> if (copy_from_user(&input, argp, sizeof(input)))
> @@ -651,15 +665,17 @@ static long snp_guest_ioctl(struct file *file, unsigned int ioctl, unsigned long
> return -ENOTTY;
> }
>
> + io.req_data = USER_SOCKPTR((void __user *)input.req_data);
> + io.resp_data = USER_SOCKPTR((void __user *)input.resp_data);
> switch (ioctl) {
> case SNP_GET_REPORT:
> - ret = get_report(snp_dev, &input);
> + ret = get_report(snp_dev, &input, &io);
> break;
> case SNP_GET_DERIVED_KEY:
> ret = get_derived_key(snp_dev, &input);
> break;
> case SNP_GET_EXT_REPORT:
> - ret = get_ext_report(snp_dev, &input);
> + ret = get_ext_report(snp_dev, &input, &io);
> break;
> default:
> break;
>
>
--
Sathyanarayanan Kuppuswamy
Linux Kernel Developer
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