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Message-Id: <1386656190-6021-1-git-send-email-qiaowei.ren@intel.com> Date: Tue, 10 Dec 2013 14:16:30 +0800 From: Qiaowei Ren <qiaowei.ren@...el.com> To: Rob Landley <rob@...dley.net>, Gang Wei <gang.wei@...el.com> Cc: linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org, tboot-devel@...ts.sourceforge.net, Qiaowei Ren <qiaowei.ren@...el.com> Subject: [PATCH] Documentation: move intel_txt.txt to Documentation/x86 Documentation/x86 is a more fitting place for intel_txt.txt. Signed-off-by: Qiaowei Ren <qiaowei.ren@...el.com> --- Documentation/intel_txt.txt | 210 --------------------------------------- Documentation/x86/intel_txt.txt | 210 +++++++++++++++++++++++++++++++++++++++ 2 files changed, 210 insertions(+), 210 deletions(-) delete mode 100644 Documentation/intel_txt.txt create mode 100644 Documentation/x86/intel_txt.txt diff --git a/Documentation/intel_txt.txt b/Documentation/intel_txt.txt deleted file mode 100644 index 91d89c5..0000000 --- a/Documentation/intel_txt.txt +++ /dev/null @@ -1,210 +0,0 @@ -Intel(R) TXT Overview: -===================== - -Intel's technology for safer computing, Intel(R) Trusted Execution -Technology (Intel(R) TXT), defines platform-level enhancements that -provide the building blocks for creating trusted platforms. - -Intel TXT was formerly known by the code name LaGrande Technology (LT). - -Intel TXT in Brief: -o Provides dynamic root of trust for measurement (DRTM) -o Data protection in case of improper shutdown -o Measurement and verification of launched environment - -Intel TXT is part of the vPro(TM) brand and is also available some -non-vPro systems. It is currently available on desktop systems -based on the Q35, X38, Q45, and Q43 Express chipsets (e.g. Dell -Optiplex 755, HP dc7800, etc.) and mobile systems based on the GM45, -PM45, and GS45 Express chipsets. - -For more information, see http://www.intel.com/technology/security/. -This site also has a link to the Intel TXT MLE Developers Manual, -which has been updated for the new released platforms. - -Intel TXT has been presented at various events over the past few -years, some of which are: - LinuxTAG 2008: - http://www.linuxtag.org/2008/en/conf/events/vp-donnerstag.html - TRUST2008: - http://www.trust-conference.eu/downloads/Keynote-Speakers/ - 3_David-Grawrock_The-Front-Door-of-Trusted-Computing.pdf - IDF, Shanghai: - http://www.prcidf.com.cn/index_en.html - IDFs 2006, 2007 (I'm not sure if/where they are online) - -Trusted Boot Project Overview: -============================= - -Trusted Boot (tboot) is an open source, pre-kernel/VMM module that -uses Intel TXT to perform a measured and verified launch of an OS -kernel/VMM. - -It is hosted on SourceForge at http://sourceforge.net/projects/tboot. -The mercurial source repo is available at http://www.bughost.org/ -repos.hg/tboot.hg. - -Tboot currently supports launching Xen (open source VMM/hypervisor -w/ TXT support since v3.2), and now Linux kernels. - - -Value Proposition for Linux or "Why should you care?" -===================================================== - -While there are many products and technologies that attempt to -measure or protect the integrity of a running kernel, they all -assume the kernel is "good" to begin with. The Integrity -Measurement Architecture (IMA) and Linux Integrity Module interface -are examples of such solutions. - -To get trust in the initial kernel without using Intel TXT, a -static root of trust must be used. This bases trust in BIOS -starting at system reset and requires measurement of all code -executed between system reset through the completion of the kernel -boot as well as data objects used by that code. In the case of a -Linux kernel, this means all of BIOS, any option ROMs, the -bootloader and the boot config. In practice, this is a lot of -code/data, much of which is subject to change from boot to boot -(e.g. changing NICs may change option ROMs). Without reference -hashes, these measurement changes are difficult to assess or -confirm as benign. This process also does not provide DMA -protection, memory configuration/alias checks and locks, crash -protection, or policy support. - -By using the hardware-based root of trust that Intel TXT provides, -many of these issues can be mitigated. Specifically: many -pre-launch components can be removed from the trust chain, DMA -protection is provided to all launched components, a large number -of platform configuration checks are performed and values locked, -protection is provided for any data in the event of an improper -shutdown, and there is support for policy-based execution/verification. -This provides a more stable measurement and a higher assurance of -system configuration and initial state than would be otherwise -possible. Since the tboot project is open source, source code for -almost all parts of the trust chain is available (excepting SMM and -Intel-provided firmware). - -How Does it Work? -================= - -o Tboot is an executable that is launched by the bootloader as - the "kernel" (the binary the bootloader executes). -o It performs all of the work necessary to determine if the - platform supports Intel TXT and, if so, executes the GETSEC[SENTER] - processor instruction that initiates the dynamic root of trust. - - If tboot determines that the system does not support Intel TXT - or is not configured correctly (e.g. the SINIT AC Module was - incorrect), it will directly launch the kernel with no changes - to any state. - - Tboot will output various information about its progress to the - terminal, serial port, and/or an in-memory log; the output - locations can be configured with a command line switch. -o The GETSEC[SENTER] instruction will return control to tboot and - tboot then verifies certain aspects of the environment (e.g. TPM NV - lock, e820 table does not have invalid entries, etc.). -o It will wake the APs from the special sleep state the GETSEC[SENTER] - instruction had put them in and place them into a wait-for-SIPI - state. - - Because the processors will not respond to an INIT or SIPI when - in the TXT environment, it is necessary to create a small VT-x - guest for the APs. When they run in this guest, they will - simply wait for the INIT-SIPI-SIPI sequence, which will cause - VMEXITs, and then disable VT and jump to the SIPI vector. This - approach seemed like a better choice than having to insert - special code into the kernel's MP wakeup sequence. -o Tboot then applies an (optional) user-defined launch policy to - verify the kernel and initrd. - - This policy is rooted in TPM NV and is described in the tboot - project. The tboot project also contains code for tools to - create and provision the policy. - - Policies are completely under user control and if not present - then any kernel will be launched. - - Policy action is flexible and can include halting on failures - or simply logging them and continuing. -o Tboot adjusts the e820 table provided by the bootloader to reserve - its own location in memory as well as to reserve certain other - TXT-related regions. -o As part of its launch, tboot DMA protects all of RAM (using the - VT-d PMRs). Thus, the kernel must be booted with 'intel_iommu=on' - in order to remove this blanket protection and use VT-d's - page-level protection. -o Tboot will populate a shared page with some data about itself and - pass this to the Linux kernel as it transfers control. - - The location of the shared page is passed via the boot_params - struct as a physical address. -o The kernel will look for the tboot shared page address and, if it - exists, map it. -o As one of the checks/protections provided by TXT, it makes a copy - of the VT-d DMARs in a DMA-protected region of memory and verifies - them for correctness. The VT-d code will detect if the kernel was - launched with tboot and use this copy instead of the one in the - ACPI table. -o At this point, tboot and TXT are out of the picture until a - shutdown (S<n>) -o In order to put a system into any of the sleep states after a TXT - launch, TXT must first be exited. This is to prevent attacks that - attempt to crash the system to gain control on reboot and steal - data left in memory. - - The kernel will perform all of its sleep preparation and - populate the shared page with the ACPI data needed to put the - platform in the desired sleep state. - - Then the kernel jumps into tboot via the vector specified in the - shared page. - - Tboot will clean up the environment and disable TXT, then use the - kernel-provided ACPI information to actually place the platform - into the desired sleep state. - - In the case of S3, tboot will also register itself as the resume - vector. This is necessary because it must re-establish the - measured environment upon resume. Once the TXT environment - has been restored, it will restore the TPM PCRs and then - transfer control back to the kernel's S3 resume vector. - In order to preserve system integrity across S3, the kernel - provides tboot with a set of memory ranges (RAM and RESERVED_KERN - in the e820 table, but not any memory that BIOS might alter over - the S3 transition) that tboot will calculate a MAC (message - authentication code) over and then seal with the TPM. On resume - and once the measured environment has been re-established, tboot - will re-calculate the MAC and verify it against the sealed value. - Tboot's policy determines what happens if the verification fails. - Note that the c/s 194 of tboot which has the new MAC code supports - this. - -That's pretty much it for TXT support. - - -Configuring the System: -====================== - -This code works with 32bit, 32bit PAE, and 64bit (x86_64) kernels. - -In BIOS, the user must enable: TPM, TXT, VT-x, VT-d. Not all BIOSes -allow these to be individually enabled/disabled and the screens in -which to find them are BIOS-specific. - -grub.conf needs to be modified as follows: - title Linux 2.6.29-tip w/ tboot - root (hd0,0) - kernel /tboot.gz logging=serial,vga,memory - module /vmlinuz-2.6.29-tip intel_iommu=on ro - root=LABEL=/ rhgb console=ttyS0,115200 3 - module /initrd-2.6.29-tip.img - module /Q35_SINIT_17.BIN - -The kernel option for enabling Intel TXT support is found under the -Security top-level menu and is called "Enable Intel(R) Trusted -Execution Technology (TXT)". It is considered EXPERIMENTAL and -depends on the generic x86 support (to allow maximum flexibility in -kernel build options), since the tboot code will detect whether the -platform actually supports Intel TXT and thus whether any of the -kernel code is executed. - -The Q35_SINIT_17.BIN file is what Intel TXT refers to as an -Authenticated Code Module. It is specific to the chipset in the -system and can also be found on the Trusted Boot site. It is an -(unencrypted) module signed by Intel that is used as part of the -DRTM process to verify and configure the system. It is signed -because it operates at a higher privilege level in the system than -any other macrocode and its correct operation is critical to the -establishment of the DRTM. The process for determining the correct -SINIT ACM for a system is documented in the SINIT-guide.txt file -that is on the tboot SourceForge site under the SINIT ACM downloads. diff --git a/Documentation/x86/intel_txt.txt b/Documentation/x86/intel_txt.txt new file mode 100644 index 0000000..91d89c5 --- /dev/null +++ b/Documentation/x86/intel_txt.txt @@ -0,0 +1,210 @@ +Intel(R) TXT Overview: +===================== + +Intel's technology for safer computing, Intel(R) Trusted Execution +Technology (Intel(R) TXT), defines platform-level enhancements that +provide the building blocks for creating trusted platforms. + +Intel TXT was formerly known by the code name LaGrande Technology (LT). + +Intel TXT in Brief: +o Provides dynamic root of trust for measurement (DRTM) +o Data protection in case of improper shutdown +o Measurement and verification of launched environment + +Intel TXT is part of the vPro(TM) brand and is also available some +non-vPro systems. It is currently available on desktop systems +based on the Q35, X38, Q45, and Q43 Express chipsets (e.g. Dell +Optiplex 755, HP dc7800, etc.) and mobile systems based on the GM45, +PM45, and GS45 Express chipsets. + +For more information, see http://www.intel.com/technology/security/. +This site also has a link to the Intel TXT MLE Developers Manual, +which has been updated for the new released platforms. + +Intel TXT has been presented at various events over the past few +years, some of which are: + LinuxTAG 2008: + http://www.linuxtag.org/2008/en/conf/events/vp-donnerstag.html + TRUST2008: + http://www.trust-conference.eu/downloads/Keynote-Speakers/ + 3_David-Grawrock_The-Front-Door-of-Trusted-Computing.pdf + IDF, Shanghai: + http://www.prcidf.com.cn/index_en.html + IDFs 2006, 2007 (I'm not sure if/where they are online) + +Trusted Boot Project Overview: +============================= + +Trusted Boot (tboot) is an open source, pre-kernel/VMM module that +uses Intel TXT to perform a measured and verified launch of an OS +kernel/VMM. + +It is hosted on SourceForge at http://sourceforge.net/projects/tboot. +The mercurial source repo is available at http://www.bughost.org/ +repos.hg/tboot.hg. + +Tboot currently supports launching Xen (open source VMM/hypervisor +w/ TXT support since v3.2), and now Linux kernels. + + +Value Proposition for Linux or "Why should you care?" +===================================================== + +While there are many products and technologies that attempt to +measure or protect the integrity of a running kernel, they all +assume the kernel is "good" to begin with. The Integrity +Measurement Architecture (IMA) and Linux Integrity Module interface +are examples of such solutions. + +To get trust in the initial kernel without using Intel TXT, a +static root of trust must be used. This bases trust in BIOS +starting at system reset and requires measurement of all code +executed between system reset through the completion of the kernel +boot as well as data objects used by that code. In the case of a +Linux kernel, this means all of BIOS, any option ROMs, the +bootloader and the boot config. In practice, this is a lot of +code/data, much of which is subject to change from boot to boot +(e.g. changing NICs may change option ROMs). Without reference +hashes, these measurement changes are difficult to assess or +confirm as benign. This process also does not provide DMA +protection, memory configuration/alias checks and locks, crash +protection, or policy support. + +By using the hardware-based root of trust that Intel TXT provides, +many of these issues can be mitigated. Specifically: many +pre-launch components can be removed from the trust chain, DMA +protection is provided to all launched components, a large number +of platform configuration checks are performed and values locked, +protection is provided for any data in the event of an improper +shutdown, and there is support for policy-based execution/verification. +This provides a more stable measurement and a higher assurance of +system configuration and initial state than would be otherwise +possible. Since the tboot project is open source, source code for +almost all parts of the trust chain is available (excepting SMM and +Intel-provided firmware). + +How Does it Work? +================= + +o Tboot is an executable that is launched by the bootloader as + the "kernel" (the binary the bootloader executes). +o It performs all of the work necessary to determine if the + platform supports Intel TXT and, if so, executes the GETSEC[SENTER] + processor instruction that initiates the dynamic root of trust. + - If tboot determines that the system does not support Intel TXT + or is not configured correctly (e.g. the SINIT AC Module was + incorrect), it will directly launch the kernel with no changes + to any state. + - Tboot will output various information about its progress to the + terminal, serial port, and/or an in-memory log; the output + locations can be configured with a command line switch. +o The GETSEC[SENTER] instruction will return control to tboot and + tboot then verifies certain aspects of the environment (e.g. TPM NV + lock, e820 table does not have invalid entries, etc.). +o It will wake the APs from the special sleep state the GETSEC[SENTER] + instruction had put them in and place them into a wait-for-SIPI + state. + - Because the processors will not respond to an INIT or SIPI when + in the TXT environment, it is necessary to create a small VT-x + guest for the APs. When they run in this guest, they will + simply wait for the INIT-SIPI-SIPI sequence, which will cause + VMEXITs, and then disable VT and jump to the SIPI vector. This + approach seemed like a better choice than having to insert + special code into the kernel's MP wakeup sequence. +o Tboot then applies an (optional) user-defined launch policy to + verify the kernel and initrd. + - This policy is rooted in TPM NV and is described in the tboot + project. The tboot project also contains code for tools to + create and provision the policy. + - Policies are completely under user control and if not present + then any kernel will be launched. + - Policy action is flexible and can include halting on failures + or simply logging them and continuing. +o Tboot adjusts the e820 table provided by the bootloader to reserve + its own location in memory as well as to reserve certain other + TXT-related regions. +o As part of its launch, tboot DMA protects all of RAM (using the + VT-d PMRs). Thus, the kernel must be booted with 'intel_iommu=on' + in order to remove this blanket protection and use VT-d's + page-level protection. +o Tboot will populate a shared page with some data about itself and + pass this to the Linux kernel as it transfers control. + - The location of the shared page is passed via the boot_params + struct as a physical address. +o The kernel will look for the tboot shared page address and, if it + exists, map it. +o As one of the checks/protections provided by TXT, it makes a copy + of the VT-d DMARs in a DMA-protected region of memory and verifies + them for correctness. The VT-d code will detect if the kernel was + launched with tboot and use this copy instead of the one in the + ACPI table. +o At this point, tboot and TXT are out of the picture until a + shutdown (S<n>) +o In order to put a system into any of the sleep states after a TXT + launch, TXT must first be exited. This is to prevent attacks that + attempt to crash the system to gain control on reboot and steal + data left in memory. + - The kernel will perform all of its sleep preparation and + populate the shared page with the ACPI data needed to put the + platform in the desired sleep state. + - Then the kernel jumps into tboot via the vector specified in the + shared page. + - Tboot will clean up the environment and disable TXT, then use the + kernel-provided ACPI information to actually place the platform + into the desired sleep state. + - In the case of S3, tboot will also register itself as the resume + vector. This is necessary because it must re-establish the + measured environment upon resume. Once the TXT environment + has been restored, it will restore the TPM PCRs and then + transfer control back to the kernel's S3 resume vector. + In order to preserve system integrity across S3, the kernel + provides tboot with a set of memory ranges (RAM and RESERVED_KERN + in the e820 table, but not any memory that BIOS might alter over + the S3 transition) that tboot will calculate a MAC (message + authentication code) over and then seal with the TPM. On resume + and once the measured environment has been re-established, tboot + will re-calculate the MAC and verify it against the sealed value. + Tboot's policy determines what happens if the verification fails. + Note that the c/s 194 of tboot which has the new MAC code supports + this. + +That's pretty much it for TXT support. + + +Configuring the System: +====================== + +This code works with 32bit, 32bit PAE, and 64bit (x86_64) kernels. + +In BIOS, the user must enable: TPM, TXT, VT-x, VT-d. Not all BIOSes +allow these to be individually enabled/disabled and the screens in +which to find them are BIOS-specific. + +grub.conf needs to be modified as follows: + title Linux 2.6.29-tip w/ tboot + root (hd0,0) + kernel /tboot.gz logging=serial,vga,memory + module /vmlinuz-2.6.29-tip intel_iommu=on ro + root=LABEL=/ rhgb console=ttyS0,115200 3 + module /initrd-2.6.29-tip.img + module /Q35_SINIT_17.BIN + +The kernel option for enabling Intel TXT support is found under the +Security top-level menu and is called "Enable Intel(R) Trusted +Execution Technology (TXT)". It is considered EXPERIMENTAL and +depends on the generic x86 support (to allow maximum flexibility in +kernel build options), since the tboot code will detect whether the +platform actually supports Intel TXT and thus whether any of the +kernel code is executed. + +The Q35_SINIT_17.BIN file is what Intel TXT refers to as an +Authenticated Code Module. It is specific to the chipset in the +system and can also be found on the Trusted Boot site. It is an +(unencrypted) module signed by Intel that is used as part of the +DRTM process to verify and configure the system. It is signed +because it operates at a higher privilege level in the system than +any other macrocode and its correct operation is critical to the +establishment of the DRTM. The process for determining the correct +SINIT ACM for a system is documented in the SINIT-guide.txt file +that is on the tboot SourceForge site under the SINIT ACM downloads. -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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