From 9342bf3d670b1b3d3cfc77a9dc1cd0d6574e5cc6 Mon Sep 17 00:00:00 2001 From: Kuppuswamy Sathyanarayanan Date: Tue, 10 Feb 2026 16:17:11 -0800 Subject: [PATCH] configfs-tsm-report: Increase TSM_REPORT_OUTBLOB_MAX to 16MB Confidential Computing (CoCo) attestation is evolving toward standardized models such as DICE (Device Identifier Composition Engine) and Post-Quantum Cryptography (PQC), which rely on layered certificate chains and larger cryptographic signatures. A typical PQC certificate can range from 5KB to 15KB, and DICE-based architectures accumulate these certificates across multiple boot stages. In such configurations, the total attestation evidence can reach several megabytes, exceeding the current 32KB limit. Increase TSM_REPORT_OUTBLOB_MAX to 16MB to accommodate these larger certificate chains. This provides sufficient headroom to handle evolving requirements without requiring frequent updates to the limit. TSM_REPORT_OUTBLOB_MAX is used by the configfs read interface to cap the maximum allowed binary blob size for outblob, auxblob and manifestblob attributes. Hence, the per-open-file worst case memory allocation increases from 32KB to 16MB. Multiple concurrent readers multiply this cost (e.g., N readers of an M-byte blob incur NxM bytes of vmalloc-backed memory). However, allocations are performed on demand and remain proportional to the actual blob length, not the configured maximum. Reviewed-by: Fang Peter Signed-off-by: Kuppuswamy Sathyanarayanan Link: https://patch.msgid.link/20260211001712.1531955-3-sathyanarayanan.kuppuswamy@linux.intel.com Signed-off-by: Dan Williams --- include/linux/tsm.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/tsm.h b/include/linux/tsm.h index a3b7ab668efff..7f72a154b6b20 100644 --- a/include/linux/tsm.h +++ b/include/linux/tsm.h @@ -8,7 +8,7 @@ #include #define TSM_REPORT_INBLOB_MAX 64 -#define TSM_REPORT_OUTBLOB_MAX SZ_32K +#define TSM_REPORT_OUTBLOB_MAX SZ_16M /* * Privilege level is a nested permission concept to allow confidential -- 2.47.3