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charset=UTF-8 Date: Mon, 01 Jun 2026 23:49:11 +0900 Message-Id: Cc: "Danilo Krummrich" , "Joel Fernandes" , "Timur Tabi" , "Alistair Popple" , "Eliot Courtney" , "Shashank Sharma" , "Zhi Wang" , "David Airlie" , "Simona Vetter" , "Bjorn Helgaas" , "Miguel Ojeda" , "Alex Gaynor" , "Boqun Feng" , "Gary Guo" , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , "Benno Lossin" , "Andreas Hindborg" , "Alice Ryhl" , "Trevor Gross" , , "LKML" Subject: Re: [PATCH v11 13/22] gpu: nova-core: Hopper/Blackwell: add FMC signature extraction From: "Alexandre Courbot" To: "John Hubbard" References: <20260530030953.740561-1-jhubbard@nvidia.com> <20260530030953.740561-14-jhubbard@nvidia.com> In-Reply-To: X-ClientProxiedBy: TYCP301CA0062.JPNP301.PROD.OUTLOOK.COM (2603:1096:405:7d::15) To CH2PR12MB3990.namprd12.prod.outlook.com (2603:10b6:610:28::18) Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH2PR12MB3990:EE_|BY5PR12MB4210:EE_ X-MS-Office365-Filtering-Correlation-Id: d82db99c-bf80-40cb-36e5-08debfecf370 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|7416014|376014|10070799003|366016|56012099006|6133799003|18002099003|22082099003|3023799007|11063799006|4143699003; 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FSP Chain of Trust verification needs >> these to validate the FMC image during boot. >> >> Co-developed-by: Alexandre Courbot >> Signed-off-by: Alexandre Courbot >> Signed-off-by: John Hubbard >> --- >> drivers/gpu/nova-core/firmware.rs | 2 +- >> drivers/gpu/nova-core/firmware/fsp.rs | 90 ++++++++++++++++++++++++++- >> 2 files changed, 88 insertions(+), 4 deletions(-) >> >> diff --git a/drivers/gpu/nova-core/firmware.rs b/drivers/gpu/nova-core/f= irmware.rs >> index 6edb50b83a29..569efee0d4ac 100644 >> --- a/drivers/gpu/nova-core/firmware.rs >> +++ b/drivers/gpu/nova-core/firmware.rs >> @@ -641,7 +641,7 @@ fn elf32_section<'a>(elf: &'a [u8], name: &str) -> O= ption<&'a [u8]> { >> } >> =20 >> /// Automatically detects ELF32 vs ELF64 based on the ELF header. >> - pub(super) fn elf_section<'a>(elf: &'a [u8], name: &str) -> Option<= &'a [u8]> { >> + pub(crate) fn elf_section<'a>(elf: &'a [u8], name: &str) -> Option<= &'a [u8]> { >> // Check ELF magic. >> if elf.len() < 5 || elf.get(0..4)? !=3D b"\x7fELF" { >> return None; >> diff --git a/drivers/gpu/nova-core/firmware/fsp.rs b/drivers/gpu/nova-co= re/firmware/fsp.rs >> index 011be1e571c2..dc28d0cc2d03 100644 >> --- a/drivers/gpu/nova-core/firmware/fsp.rs >> +++ b/drivers/gpu/nova-core/firmware/fsp.rs >> @@ -15,13 +15,35 @@ >> gpu::Chipset, // >> }; >> =20 >> +/// Size of the FSP SHA-384 hash, in bytes. >> +pub(crate) const FSP_HASH_SIZE: usize =3D 48; >> +/// Maximum size of the FSP public key (RSA-3072), in bytes. >> +/// >> +/// The FMC ELF `publickey` section may be shorter, so the remaining by= tes are zero-padded. >> +pub(crate) const FSP_PKEY_SIZE: usize =3D 384; >> +/// Maximum size of the FSP signature (RSA-3072), in bytes. >> +/// >> +/// The FMC ELF `signature` section may be shorter, so the remaining by= tes are zero-padded. >> +pub(crate) const FSP_SIG_SIZE: usize =3D 384; >> + >> +/// Structure to hold FMC signatures. >> +/// >> +/// C representation is used because this type is used for communicatio= n with the FSP. >> +#[derive(Debug, Clone, Copy)] >> +#[repr(C)] >> +pub(crate) struct FmcSignatures { >> + pub(crate) hash384: [u8; FSP_HASH_SIZE], >> + pub(crate) public_key: [u8; FSP_PKEY_SIZE], >> + pub(crate) signature: [u8; FSP_SIG_SIZE], >> +} >> + >> pub(crate) struct FspFirmware { >> /// FMC firmware image data (only the "image" ELF section). >> #[expect(dead_code)] >> pub(crate) fmc_image: Coherent<[u8]>, >> - /// Full FMC ELF for signature extraction. >> + /// FMC firmware signatures. >> #[expect(dead_code)] >> - pub(crate) fmc_elf: Firmware, >> + pub(crate) fmc_sigs: KBox, >> } >> =20 >> impl FspFirmware { >> @@ -41,7 +63,69 @@ pub(crate) fn new( >> =20 >> Ok(Self { >> fmc_image, >> - fmc_elf: fw, >> + fmc_sigs: Self::extract_fmc_signatures(&fw, dev)?, >> }) >> } >> + >> + /// Extract FMC firmware signatures for Chain of Trust verification= . >> + /// >> + /// Extracts real cryptographic signatures from FMC ELF32 firmware = sections. >> + /// Returns signatures in a heap-allocated structure to prevent sta= ck overflow. >> + fn extract_fmc_signatures( >> + fmc_fw: &Firmware, >> + dev: &device::Device, >> + ) -> Result> { >> + let get_section =3D |name: &str, max_len: usize| { >> + elf::elf_section(fmc_fw.data(), name) >> + .ok_or(EINVAL) >> + .inspect_err(|_| dev_err!(dev, "FMC firmware missing '{= }' section\n", name)) >> + .and_then(|section| { >> + if section.len() > max_len { >> + dev_err!( >> + dev, >> + "FMC {} section size {} > maximum {}\n", >> + name, >> + section.len(), >> + max_len >> + ); >> + Err(EINVAL) >> + } else { >> + Ok(section) >> + } >> + }) >> + }; >> + >> + let hash_section =3D get_section("hash", FSP_HASH_SIZE)?; >> + let pkey_section =3D get_section("publickey", FSP_PKEY_SIZE)?; >> + let sig_section =3D get_section("signature", FSP_SIG_SIZE)?; >> + >> + // The hash section is a SHA-384 output: it must be exactly FSP= _HASH_SIZE bytes. >> + if hash_section.len() !=3D FSP_HASH_SIZE { >> + dev_err!( >> + dev, >> + "FMC hash section size {} !=3D expected {}\n", >> + hash_section.len(), >> + FSP_HASH_SIZE >> + ); >> + return Err(EINVAL); >> + } >> + >> + let mut signatures =3D KBox::new( >> + FmcSignatures { >> + hash384: [0; _], >> + public_key: [0; _], >> + signature: [0; _], >> + }, >> + GFP_KERNEL, >> + )?; > > This construct may create the 816 bytes long `FmcSignatures` instance on > the stack, where space is at a premium. `KBox::init` guarantees in-place > initialization: > > let mut signatures =3D KBox::init( > init!(FmcSignatures { > hash384: [0; _], > public_key: [0; _], > signature: [0; _], > }), > )?; > GFP_KERNEL, > > And by chaining the initializer we can also avoid making `signatures` > mutable: > > let signatures =3D KBox::init( > init!(FmcSignatures { > hash384 <- Zeroable::init_zeroed(), > public_key <- Zeroable::init_zeroed(), > signature <- Zeroable::init_zeroed(), Oops, I got a bit ahead of myself. The three lines above should be: hash384: [0; _], public_key: [0; _], signature: [0; _], The rest should be working as expected.