mirror of https://github.com/acidanthera/audk.git
efb0f16e98
If OVMF was built with -D SMM_REQUIRE, that implies that the runtime OS is not trusted and we should defend against it tampering with the firmware's data. One such datum is the PEI firmware volume (PEIFV). Normally PEIFV is decompressed on the first boot by SEC, then the OS preserves it across S3 suspend-resume cycles; at S3 resume SEC just reuses the originally decompressed PEIFV. However, if we don't trust the OS, then SEC must decompress PEIFV from the pristine flash every time, lest we execute OS-injected code or work with OS-injected data. Due to how FVMAIN_COMPACT is organized, we can't decompress just PEIFV; the decompression brings DXEFV with itself, plus it uses a temporary output buffer and a scratch buffer too, which even reach above the end of the finally installed DXEFV. For this reason we must keep away a non-malicious OS from DXEFV too, plus the memory up to PcdOvmfDecomprScratchEnd. The delay introduced by the LZMA decompression on S3 resume is negligible. If -D SMM_REQUIRE is not specified, then PcdSmmSmramRequire remains FALSE (from the DEC file), and then this patch has no effect (not counting some changed debug messages). If QEMU doesn't support S3 (or the user disabled it on the QEMU command line), then this patch has no effect also. Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Jordan Justen <jordan.l.justen@intel.com> git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19037 6f19259b-4bc3-4df7-8a09-765794883524 |
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| Ia32 | ||
| X64 | ||
| SecMain.c | ||
| SecMain.inf | ||