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Donenfeld" Subject: [PULL 14/14] x86: re-initialize RNG seed when selecting kernel Date: Thu, 29 Sep 2022 18:30:14 +0200 Message-Id: <20220929163014.16950-15-pbonzini@redhat.com> X-Mailer: git-send-email 2.37.3 In-Reply-To: <20220929163014.16950-1-pbonzini@redhat.com> References: <20220929163014.16950-1-pbonzini@redhat.com> MIME-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.08, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" From: "Jason A. Donenfeld" We don't want it to be possible to re-read the RNG seed after ingesting it, because this ruins forward secrecy. Currently, however, the setup data section can just be re-read. Since the kernel is always read after the setup data, use the selection of the kernel as a trigger to re-initialize the RNG seed, just like we do on reboot, to preserve forward secrecy. Cc: Paolo Bonzini Signed-off-by: Jason A. Donenfeld Message-Id: <20220922152847.3670513-1-Jason@zx2c4.com> Signed-off-by: Paolo Bonzini --- hw/i386/x86.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/hw/i386/x86.c b/hw/i386/x86.c index f9a4ddaa4a..1148f70c03 100644 --- a/hw/i386/x86.c +++ b/hw/i386/x86.c @@ -1112,11 +1112,14 @@ void x86_load_linux(X86MachineState *x86ms, setup_data->len = cpu_to_le32(RNG_SEED_LENGTH); qemu_guest_getrandom_nofail(setup_data->data, RNG_SEED_LENGTH); qemu_register_reset(reset_rng_seed, setup_data); + fw_cfg_add_bytes_callback(fw_cfg, FW_CFG_KERNEL_DATA, reset_rng_seed, NULL, + setup_data, kernel, kernel_size, true); + } else { + fw_cfg_add_bytes(fw_cfg, FW_CFG_KERNEL_DATA, kernel, kernel_size); } fw_cfg_add_i32(fw_cfg, FW_CFG_KERNEL_ADDR, prot_addr); fw_cfg_add_i32(fw_cfg, FW_CFG_KERNEL_SIZE, kernel_size); - fw_cfg_add_bytes(fw_cfg, FW_CFG_KERNEL_DATA, kernel, kernel_size); sev_load_ctx.kernel_data = (char *)kernel; sev_load_ctx.kernel_size = kernel_size; -- 2.37.3