Messages in this thread | | | From | Peter Gonda <> | Date | Wed, 27 Sep 2023 10:14:39 -0600 | Subject | Re: [PATCH v4 6/6] virt: tdx-guest: Add Quote generation support using TSM_REPORTS |
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On Mon, Sep 25, 2023 at 10:17 PM Dan Williams <dan.j.williams@intel.com> wrote: > > From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> > > In TDX guest, the attestation process is used to verify the TDX guest > trustworthiness to other entities before provisioning secrets to the > guest. The first step in the attestation process is TDREPORT > generation, which involves getting the guest measurement data in the > format of TDREPORT, which is further used to validate the authenticity > of the TDX guest. TDREPORT by design is integrity-protected and can > only be verified on the local machine. > > To support remote verification of the TDREPORT in a SGX-based > attestation, the TDREPORT needs to be sent to the SGX Quoting Enclave > (QE) to convert it to a remotely verifiable Quote. SGX QE by design can > only run outside of the TDX guest (i.e. in a host process or in a > normal VM) and guest can use communication channels like vsock or > TCP/IP to send the TDREPORT to the QE. But for security concerns, the > TDX guest may not support these communication channels. To handle such > cases, TDX defines a GetQuote hypercall which can be used by the guest > to request the host VMM to communicate with the SGX QE. More details > about GetQuote hypercall can be found in TDX Guest-Host Communication > Interface (GHCI) for Intel TDX 1.0, section titled > "TDG.VP.VMCALL<GetQuote>". > > Trusted Security Module (TSM) [1] exposes a common ABI for Confidential > Computing Guest platforms to get the measurement data via ConfigFS. > Extend the TSM framework and add support to allow an attestation agent > to get the TDX Quote data (included usage example below). > > report=/sys/kernel/config/tsm/report/report0 > mkdir $report > dd if=/dev/urandom bs=64 count=1 > $report/inblob > hexdump -C $report/outblob > rmdir $report > > GetQuote TDVMCALL requires TD guest pass a 4K aligned shared buffer > with TDREPORT data as input, which is further used by the VMM to copy > the TD Quote result after successful Quote generation. To create the > shared buffer, allocate a large enough memory and mark it shared using > set_memory_decrypted() in tdx_guest_init(). This buffer will be re-used > for GetQuote requests in the TDX TSM handler. > > Although this method reserves a fixed chunk of memory for GetQuote > requests, such one time allocation can help avoid memory fragmentation > related allocation failures later in the uptime of the guest. > > Since the Quote generation process is not time-critical or frequently > used, the current version uses a polling model for Quote requests and > it also does not support parallel GetQuote requests. > > Link: https://lore.kernel.org/lkml/169342399185.3934343.3035845348326944519.stgit@dwillia2-xfh.jf.intel.com/ [1] > Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> > Reviewed-by: Erdem Aktas <erdemaktas@google.com> > Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Hey Dan,
I tried running your test commands on an SNP enabled guest. To build the kernel I just checked out linus/master and applied your series. I haven't done any debugging yet, so I will update with what I find.
root@Ubuntu2004:~# hexdump -C $report/outblob [ 219.871875] ------------[ cut here ]------------ [ 219.876642] kernel BUG at include/linux/scatterlist.h:187! [ 219.882280] invalid opcode: 0000 [#1] PREEMPT SMP NOPTI [ 219.887628] CPU: 0 PID: 1317 Comm: hexdump Not tainted 6.6.0-rc3-xfstests-000 44-gf636850ddfc7 #1 [ 219.896530] Hardware name: Google Google Compute Engine/Google Compute Engine , BIOS Google 09/26/2023 [ 219.905859] RIP: 0010:enc_dec_message+0x4ed/0x570 [ 219.910673] Code: c7 c0 00 00 00 80 48 2b 05 b8 4f 99 00 e9 dc fd ff ff 0f 0b bb f4 ff ff ff eb b5 0f 0b 0f 0b 0f 0b e8 e7 47 ce ff 89 c3 eb 94 <0f> 0b 0f 0b 0f 0b 0f 0b 48 8d 7c 24 38 e8 11 6b 23 00 8b 5c 24 58 [ 219.929547] RSP: 0018:ffffc90000e27a18 EFLAGS: 00010246 [ 219.934893] RAX: 0000000000000000 RBX: ffffc90000e27bf8 RCX: 0000000000081000 [ 219.942134] RDX: 0000000000000000 RSI: 0000000000080000 RDI: ffffc90080e27bf8 [ 219.949378] RBP: ffff8881018980a0 R08: 0000000000000000 R09: ffffc90000e27a78 [ 219.956621] R10: 0000000000026680 R11: 0000000000000008 R12: ffff888111a3c400 [ 219.963864] R13: ffff8881018980d0 R14: ffff8881003e7000 R15: 0000000000000060 [ 219.971106] FS: 00007fd7e75f5740(0000) GS:ffff888237c00000(0000) knlGS:00000 00000000000 [ 219.979303] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 219.985160] CR2: 00005563500e8808 CR3: 0008000111986001 CR4: 0000000000370ef0 [ 219.992401] Call Trace: [ 219.994955] <TASK> [ 219.997160] ? die+0x36/0x80 [ 220.000149] ? do_trap+0xf4/0x100 [ 220.003574] ? enc_dec_message+0x4ed/0x570 [ 220.007777] ? do_error_trap+0x65/0x80 [ 220.011632] ? enc_dec_message+0x4ed/0x570 [ 220.015842] ? exc_invalid_op+0x50/0x70 [ 220.019788] ? enc_dec_message+0x4ed/0x570 [ 220.023994] ? asm_exc_invalid_op+0x1a/0x20 [ 220.028288] ? enc_dec_message+0x4ed/0x570 [ 220.032505] ? enc_dec_message+0x16f/0x570 [ 220.036711] ? srso_alias_return_thunk+0x5/0x7f [ 220.041352] ? srso_alias_return_thunk+0x5/0x7f [ 220.045994] handle_guest_request+0xc6/0x330 [ 220.050375] get_ext_report+0x1e0/0x3d0 [ 220.054323] sev_report_new+0x159/0x460 [ 220.058267] tsm_report_read.part.0+0x96/0x120 [ 220.062818] configfs_bin_read_iter+0xe1/0x1e0 [ 220.067377] vfs_read+0x1db/0x310 [ 220.070813] ksys_read+0x6f/0xf0 [ 220.074152] do_syscall_64+0x3f/0x90 [ 220.077843] entry_SYSCALL_64_after_hwframe+0x6e/0xd8 [ 220.083007] RIP: 0033:0x7fd7e7705fd2 [ 220.086695] Code: c0 e9 c2 fe ff ff 50 48 8d 3d aa cb 0a 00 e8 d5 1a 02 00 0f 1f 44 00 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 0f 05 <48> 3d 00 f0 ff ff 77 56 c3 0f 1f 44 00 00 48 83 ec 28 48 89 54 24 [ 220.105572] RSP: 002b:00007fff9bc8fc18 EFLAGS: 00000246 ORIG_RAX: 00000000000 00000 [ 220.113252] RAX: ffffffffffffffda RBX: 00007fd7e77e4980 RCX: 00007fd7e7705fd2 [ 220.120496] RDX: 0000000000001000 RSI: 00005563500e7800 RDI: 0000000000000000 [ 220.127742] RBP: 00007fd7e77e14a0 R08: 0000000000000000 R09: 000000000000007c [ 220.134988] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000010 [ 220.142232] R13: 00007fd7e77e08a0 R14: 0000000000000d68 R15: 0000000000000d68 [ 220.149479] </TASK> [ 220.151865] ---[ end trace 0000000000000000 ]--- [ 220.156629] RIP: 0010:enc_dec_message+0x4ed/0x570 [ 220.161479] Code: c7 c0 00 00 00 80 48 2b 05 b8 4f 99 00 e9 dc fd ff ff 0f 0b bb f4 ff ff ff eb b5 0f 0b 0f 0b 0f 0b e8 e7 47 ce ff 89 c3 eb 94 <0f> 0b 0f 0b 0f 0b 0f 0b 48 8d 7c 24 38 e8 11 6b 23 00 8b 5c 24 58 [ 220.180379] RSP: 0018:ffffc90000e27a18 EFLAGS: 00010246 [ 220.185743] RAX: 0000000000000000 RBX: ffffc90000e27bf8 RCX: 0000000000081000 [ 220.193012] RDX: 0000000000000000 RSI: 0000000000080000 RDI: ffffc90080e27bf8 [ 220.200280] RBP: ffff8881018980a0 R08: 0000000000000000 R09: ffffc90000e27a78 [ 220.207551] R10: 0000000000026680 R11: 0000000000000008 R12: ffff888111a3c400 [ 220.214822] R13: ffff8881018980d0 R14: ffff8881003e7000 R15: 0000000000000060 [ 220.222094] FS: 00007fd7e75f5740(0000) GS:ffff888237c00000(0000) knlGS:00000 00000000000 [ 220.230329] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 220.236210] CR2: 00005563500e8808 CR3: 0008000111986001 CR4: 0000000000370ef0
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