[PATCH 15/18] lib: rspdm: Support SPDM get_certificate

[alistair23]

From: Alistair Francis <alistair@xxxxxxxxxxxxx>

Support the GET_CERTIFICATE SPDM command.

Signed-off-by: Alistair Francis <alistair@xxxxxxxxxxxxx>
---
 lib/rspdm/consts.rs    |   2 +
 lib/rspdm/lib.rs       |  11 ++++
 lib/rspdm/state.rs     | 125 +++++++++++++++++++++++++++++++++++++++++
 lib/rspdm/validator.rs |  57 +++++++++++++++++++
 4 files changed, 195 insertions(+)

diff --git a/lib/rspdm/consts.rs b/lib/rspdm/consts.rs
index 092205dab74d..302bc0285478 100644
--- a/lib/rspdm/consts.rs
+++ b/lib/rspdm/consts.rs
@@ -114,6 +114,8 @@ fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
 
 pub(crate) const SPDM_GET_DIGESTS: u8 = 0x81;
 
+pub(crate) const SPDM_GET_CERTIFICATE: u8 = 0x82;
+
 // If the crypto support isn't enabled don't offer the algorithms
 // to the responder
 #[cfg(CONFIG_CRYPTO_RSA)]
diff --git a/lib/rspdm/lib.rs b/lib/rspdm/lib.rs
index e42cfdd35524..d5aee761003a 100644
--- a/lib/rspdm/lib.rs
+++ b/lib/rspdm/lib.rs
@@ -124,6 +124,17 @@
         return e.to_errno() as c_int;
     }
 
+    let mut provisioned_slots = state.provisioned_slots;
+    while (provisioned_slots as usize) > 0 {
+        let slot = provisioned_slots.trailing_zeros() as u8;
+
+        if let Err(e) = state.get_certificate(slot) {
+            return e.to_errno() as c_int;
+        }
+
+        provisioned_slots &= !(1 << slot);
+    }
+
     0
 }
 
diff --git a/lib/rspdm/state.rs b/lib/rspdm/state.rs
index bcb1cc955c4c..69b6f67a6ef5 100644
--- a/lib/rspdm/state.rs
+++ b/lib/rspdm/state.rs
@@ -55,6 +55,8 @@
 use crate::validator::{
     GetCapabilitiesReq,
     GetCapabilitiesRsp,
+    GetCertificateReq,
+    GetCertificateRsp,
     GetDigestsReq,
     GetDigestsRsp,
     GetVersionReq,
@@ -135,6 +137,14 @@ pub struct SpdmState {
     pub(crate) certs: [KVec<u8>; SPDM_SLOTS],
 }
 
+#[repr(C, packed)]
+pub(crate) struct SpdmCertChain {
+    length: u16,
+    _reserved: [u8; 2],
+    root_hash: bindings::__IncompleteArrayField<u8>,
+    certificates: bindings::__IncompleteArrayField<u8>,
+}
+
 impl SpdmState {
     pub(crate) fn new(
         dev: *mut bindings::device,
@@ -661,4 +671,119 @@ pub(crate) fn get_digests(&mut self) -> Result<(), Error> {
 
         Ok(())
     }
+
+    fn get_cert_exchange(
+        &mut self,
+        request_buf: &mut [u8],
+        response_vec: &mut KVec<u8>,
+        rsp_sz: usize,
+    ) -> Result<&mut GetCertificateRsp, Error> {
+        // SAFETY: `response_vec` is rsp_sz length, initialised, aligned
+        // and won't be mutated
+        let response_buf = unsafe { from_raw_parts_mut(response_vec.as_mut_ptr(), rsp_sz) };
+
+        let rc = self.spdm_exchange(request_buf, response_buf)?;
+
+        if rc < (core::mem::size_of::<GetCertificateReq>() as i32) {
+            pr_err!("Truncated certificate response\n");
+            to_result(-(bindings::EIO as i32))?;
+        }
+
+        // SAFETY: `rc` is the length of data read, which will be smaller
+        // then the capacity of the vector
+        unsafe { response_vec.inc_len(rc as usize) };
+
+        let response: &mut GetCertificateRsp = Untrusted::new_mut(response_vec).validate_mut()?;
+
+        if rc
+            < (core::mem::size_of::<GetCertificateRsp>() + response.portion_length as usize) as i32
+        {
+            pr_err!("Truncated certificate response\n");
+            to_result(-(bindings::EIO as i32))?;
+        }
+
+        Ok(response)
+    }
+
+    pub(crate) fn get_certificate(&mut self, slot: u8) -> Result<(), Error> {
+        let mut request = GetCertificateReq::default();
+        request.version = self.version;
+        request.param1 = slot;
+
+        let req_sz = core::mem::size_of::<GetCertificateReq>();
+        let rsp_sz = (core::mem::size_of::<GetCertificateRsp>() as u32 + u16::MAX as u32)
+            .min(self.transport_sz) as usize;
+
+        request.offset = 0;
+        request.length = (rsp_sz - core::mem::size_of::<GetCertificateRsp>()) as u16;
+
+        // SAFETY: `request` is repr(C) and packed, so we can convert it to a slice
+        let request_buf = unsafe { from_raw_parts_mut(&mut request as *mut _ as *mut u8, req_sz) };
+
+        let mut response_vec: KVec<u8> = KVec::with_capacity(rsp_sz, GFP_KERNEL)?;
+
+        let response = self.get_cert_exchange(request_buf, &mut response_vec, rsp_sz)?;
+
+        let total_cert_len =
+            ((response.portion_length + response.remainder_length) & 0xFFFF) as usize;
+
+        let mut certs_buf: KVec<u8> = KVec::new();
+
+        certs_buf.extend_from_slice(
+            &response_vec[8..(8 + response.portion_length as usize)],
+            GFP_KERNEL,
+        )?;
+
+        let mut offset: usize = response.portion_length as usize;
+        let mut remainder_length = response.remainder_length as usize;
+
+        while remainder_length > 0 {
+            request.offset = offset.to_le() as u16;
+            request.length =
+                ((remainder_length.min(rsp_sz - core::mem::size_of::<GetCertificateRsp>())) as u16)
+                    .to_le();
+
+            let request_buf =
+                unsafe { from_raw_parts_mut(&mut request as *mut _ as *mut u8, req_sz) };
+
+            let response = self.get_cert_exchange(request_buf, &mut response_vec, rsp_sz)?;
+
+            if response.portion_length == 0
+                || (response.param1 & 0xF) != slot
+                || offset as u16 + response.portion_length + response.remainder_length
+                    != total_cert_len as u16
+            {
+                pr_err!("Malformed certificate response\n");
+                to_result(-(bindings::EPROTO as i32))?;
+            }
+
+            certs_buf.extend_from_slice(
+                &response_vec[8..(8 + response.portion_length as usize)],
+                GFP_KERNEL,
+            )?;
+            offset += response.portion_length as usize;
+            remainder_length = response.remainder_length as usize;
+        }
+
+        let header_length = core::mem::size_of::<SpdmCertChain>() + self.hash_len;
+
+        let ptr = certs_buf.as_mut_ptr();
+        // SAFETY: `SpdmCertChain` is repr(C) and packed, so we can convert it from a slice
+        let ptr = ptr.cast::<SpdmCertChain>();
+        // SAFETY: `ptr` came from a reference and the cast above is valid.
+        let certs: &mut SpdmCertChain = unsafe { &mut *ptr };
+
+        if total_cert_len < header_length
+            || total_cert_len as u16 != certs.length
+            || total_cert_len != certs_buf.len()
+        {
+            pr_err!("Malformed certificate chain in slot {slot}\n");
+            to_result(-(bindings::EPROTO as i32))?;
+        }
+
+        self.certs[slot as usize].clear();
+        self.certs[slot as usize].extend_from_slice(&certs_buf, GFP_KERNEL)?;
+
+        Ok(())
+    }
 }
diff --git a/lib/rspdm/validator.rs b/lib/rspdm/validator.rs
index 1e5ee8a7582b..8b44a056b335 100644
--- a/lib/rspdm/validator.rs
+++ b/lib/rspdm/validator.rs
@@ -30,6 +30,7 @@
     SPDM_ASYM_ALGOS,
     SPDM_CTEXPONENT,
     SPDM_GET_CAPABILITIES,
+    SPDM_GET_CERTIFICATE,
     SPDM_GET_DIGESTS,
     SPDM_GET_VERSION,
     SPDM_HASH_ALGOS,
@@ -403,3 +404,59 @@ fn validate(unvalidated: &mut Unvalidated<KVec<u8>>) -> Result<Self, Self::Err>
         Ok(rsp)
     }
 }
+
+#[repr(C, packed)]
+pub(crate) struct GetCertificateReq {
+    pub(crate) version: u8,
+    pub(crate) code: u8,
+    pub(crate) param1: u8,
+    pub(crate) param2: u8,
+
+    pub(crate) offset: u16,
+    pub(crate) length: u16,
+}
+
+impl Default for GetCertificateReq {
+    fn default() -> Self {
+        GetCertificateReq {
+            version: 0,
+            code: SPDM_GET_CERTIFICATE,
+            param1: 0,
+            param2: 0,
+            offset: 0,
+            length: 0,
+        }
+    }
+}
+
+#[repr(C, packed)]
+pub(crate) struct GetCertificateRsp {
+    pub(crate) version: u8,
+    pub(crate) code: u8,
+    pub(crate) param1: u8,
+    pub(crate) param2: u8,
+
+    pub(crate) portion_length: u16,
+    pub(crate) remainder_length: u16,
+
+    pub(crate) cert_chain: __IncompleteArrayField<u8>,
+}
+
+impl Validate<&mut Unvalidated<KVec<u8>>> for &mut GetCertificateRsp {
+    type Err = Error;
+
+    fn validate(unvalidated: &mut Unvalidated<KVec<u8>>) -> Result<Self, Self::Err> {
+        let raw = unvalidated.raw_mut();
+        if raw.len() < mem::size_of::<GetCertificateRsp>() {
+            return Err(EINVAL);
+        }
+
+        let ptr = raw.as_mut_ptr();
+        // CAST: `GetCertificateRsp` only contains integers and has `repr(C)`.
+        let ptr = ptr.cast::<GetCertificateRsp>();
+        // SAFETY: `ptr` came from a reference and the cast above is valid.
+        let rsp: &mut GetCertificateRsp = unsafe { &mut *ptr };
+
+        Ok(rsp)
+    }
+}
-- 
2.52.0