- 07 Jul, 2022 20 commits
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Reinette Chatre authored
The page reclaimer ensures availability of EPC pages across all enclaves. In support of this it runs independently from the individual enclaves in order to take locks from the different enclaves as it writes pages to swap. When needing to load a page from swap an EPC page needs to be available for its contents to be loaded into. Loading an existing enclave page from swap does not reclaim EPC pages directly if none are available, instead the reclaimer is woken when the available EPC pages are found to be below a watermark. When iterating over a large number of pages in an oversubscribed environment there is a race between the reclaimer woken up and EPC pages reclaimed fast enough for the page operations to proceed. Ensure there are EPC pages available before attempting to load a page that may potentially be pulled from swap into an available EPC page. Signed-off-by:
Reinette Chatre <reinette.chatre@intel.com> Signed-off-by:
Dave Hansen <dave.hansen@linux.intel.com> Acked-by:
Jarkko Sakkinen <jarkko@kernel.org> Link: https://lkml.kernel.org/r/a0d8f037c4a075d56bf79f432438412985f7ff7a.1652137848.git.reinette.chatre@intel.com
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Reinette Chatre authored
The SGX2 page removal flow was introduced in previous patch and is as follows: 1) Change the type of the pages to be removed to SGX_PAGE_TYPE_TRIM using the ioctl() SGX_IOC_ENCLAVE_MODIFY_TYPES introduced in previous patch. 2) Approve the page removal by running ENCLU[EACCEPT] from within the enclave. 3) Initiate actual page removal using the ioctl() SGX_IOC_ENCLAVE_REMOVE_PAGES introduced here. Support the final step of the SGX2 page removal flow with ioctl() SGX_IOC_ENCLAVE_REMOVE_PAGES. With this ioctl() the user specifies a page range that should be removed. All pages in the provided range should have the SGX_PAGE_TYPE_TRIM page type and the request will fail with EPERM (Operation not permitted) if a page that does not have the correct type is encountered. Page removal can fail on any page within the provided range. Support partial success by returning the number of pages that were successfully removed. Since actual page removal will succeed even if ENCLU[EACCEPT] was not run from within the enclave the ENCLU[EMODPR] instruction with RWX permissions is used as a no-op mechanism to ensure ENCLU[EACCEPT] was successfully run from within the enclave before the enclave page is removed. If the user omits running SGX_IOC_ENCLAVE_REMOVE_PAGES the pages will still be removed when the enclave is unloaded. Signed-off-by:
Haitao Huang <haitao.huang@intel.com> Tested-by:
Vijay Dhanraj <vijay.dhanraj@intel.com> Tested-by:
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Reinette Chatre authored
Every enclave contains one or more Thread Control Structures (TCS). The TCS contains meta-data used by the hardware to save and restore thread specific information when entering/exiting the enclave. With SGX1 an enclave needs to be created with enough TCSs to support the largest number of threads expecting to use the enclave and enough enclave pages to meet all its anticipated memory demands. In SGX1 all pages remain in the enclave until the enclave is unloaded. SGX2 introduces a new function, ENCLS[EMODT], that is used to change the type of an enclave page from a regular (SGX_PAGE_TYPE_REG) enclave page to a TCS (SGX_PAGE_TYPE_TCS) page or change the type from a regular (SGX_PAGE_TYPE_REG) or TCS (SGX_PAGE_TYPE_TCS) page to a trimmed (SGX_PAGE_TYPE_TRIM) page (setting it up for later removal). With the existing support of dynamically adding regular enclave pages to an initialized enclave and changing the page type to TCS it is possible to dynamically increase the number of threads supported by an enclave. Changing the enclave page type to SGX_PAGE_TYPE_TRIM is the first step of dynamically removing pages from an initialized enclave. The complete page removal flow is: 1) Change the type of the pages to be removed to SGX_PAGE_TYPE_TRIM using the SGX_IOC_ENCLAVE_MODIFY_TYPES ioctl() introduced here. 2) Approve the page removal by running ENCLU[EACCEPT] from within the enclave. 3) Initiate actual page removal using the ioctl() introduced in the following patch. Add ioctl() SGX_IOC_ENCLAVE_MODIFY_TYPES to support changing SGX enclave page types within an initialized enclave. With SGX_IOC_ENCLAVE_MODIFY_TYPES the user specifies a page range and the enclave page type to be applied to all pages in the provided range. The ioctl() itself can return an error code based on failures encountered by the kernel. It is also possible for SGX specific failures to be encountered. Add a result output parameter to communicate the SGX return code. It is possible for the enclave page type change request to fail on any page within the provided range. Support partial success by returning the number of pages that were successfully changed. After the page type is changed the page continues to be accessible from the kernel perspective with page table entries and internal state. The page may be moved to swap. Any access until ENCLU[EACCEPT] will encounter a page fault with SGX flag set in error code. Signed-off-by:
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Reinette Chatre authored
Before an enclave is initialized the enclave's memory range is unknown. The enclave's memory range is learned at the time it is created via the SGX_IOC_ENCLAVE_CREATE ioctl() where the provided memory range is obtained from an earlier mmap() of /dev/sgx_enclave. After an enclave is initialized its memory can be mapped into user space (mmap()) from where it can be entered at its defined entry points. With the enclave's memory range known after it is initialized there is no reason why it should be possible to map memory outside this range. Lock down access to the initialized enclave's memory range by denying any attempt to map memory outside its memory range. Locking down the memory range also makes adding pages to an initialized enclave more efficient. Pages are added to an initialized enclave by accessing memory that belongs to the enclave's memory range but not yet backed by an enclave page. If it is possible for user space to map memory that does not form part of the enclave then an access to this memory would eventually fail. Failures range from a prompt general protection fault if the access was an ENCLU[EACCEPT] from within the enclave, or a page fault via the vDSO if it was another access from within the enclave, or a SIGBUS (also resulting from a page fault) if the access was from outside the enclave. Disallowing invalid memory to be mapped in the first place avoids preventable failures. Signed-off-by:
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Reinette Chatre authored
With SGX1 an enclave needs to be created with its maximum memory demands allocated. Pages cannot be added to an enclave after it is initialized. SGX2 introduces a new function, ENCLS[EAUG], that can be used to add pages to an initialized enclave. With SGX2 the enclave still needs to set aside address space for its maximum memory demands during enclave creation, but all pages need not be added before enclave initialization. Pages can be added during enclave runtime. Add support for dynamically adding pages to an initialized enclave, architecturally limited to RW permission at creation but allowed to obtain RWX permissions after trusted enclave runs EMODPE. Add pages via the page fault handler at the time an enclave address without a backing enclave page is accessed, potentially directly reclaiming pages if no free pages are available. The enclave is still required to run ENCLU[EACCEPT] on the page before it can be used. A useful flow is for the enclave to run ENCLU[EACCEPT] on an uninitialized address. This will trigger the page fault handler that will add the enclave page and return execution to the enclave to repeat the ENCLU[EACCEPT] instruction, this time successful. If the enclave accesses an uninitialized address in another way, for example by expanding the enclave stack to a page that has not yet been added, then the page fault handler would add the page on the first write but upon returning to the enclave the instruction that triggered the page fault would be repeated and since ENCLU[EACCEPT] was not run yet it would trigger a second page fault, this time with the SGX flag set in the page fault error code. This can only be recovered by entering the enclave again and directly running the ENCLU[EACCEPT] instruction on the now initialized address. Accessing an uninitialized address from outside the enclave also triggers this flow but the page will remain inaccessible (access will result in #PF) until accepted from within the enclave via ENCLU[EACCEPT]. Signed-off-by:
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Reinette Chatre authored
In the initial (SGX1) version of SGX, pages in an enclave need to be created with permissions that support all usages of the pages, from the time the enclave is initialized until it is unloaded. For example, pages used by a JIT compiler or when code needs to otherwise be relocated need to always have RWX permissions. SGX2 includes a new function ENCLS[EMODPR] that is run from the kernel and can be used to restrict the EPCM permissions of regular enclave pages within an initialized enclave. Introduce ioctl() SGX_IOC_ENCLAVE_RESTRICT_PERMISSIONS to support restricting EPCM permissions. With this ioctl() the user specifies a page range and the EPCM permissions to be applied to all pages in the provided range. ENCLS[EMODPR] is run to restrict the EPCM permissions followed by the ENCLS[ETRACK] flow that will ensure no cached linear-to-physical address mappings to the changed pages remain. It is possible for the permission change request to fail on any page within the provided range, either with an error encountered by the kernel or by the SGX hardware while running ENCLS[EMODPR]. To support partial success the ioctl() returns an error code based on failures encountered by the kernel as well as two result output parameters: one for the number of pages that were successfully changed and one for the SGX return code. The page table entry permissions are not impacted by the EPCM permission changes. VMAs and PTEs will continue to allow the maximum vetted permissions determined at the time the pages are added to the enclave. The SGX error code in a page fault will indicate if it was an EPCM permission check that prevented an access attempt. No checking is done to ensure that the permissions are actually being restricted. This is because the enclave may have relaxed the EPCM permissions from within the enclave without the kernel knowing. An attempt to relax permissions using this call will be ignored by the hardware. Signed-off-by:
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Reinette Chatre authored
struct sgx_encl should be protected with the mutex sgx_encl->lock. One exception is sgx_encl->page_cnt that is incremented (in sgx_encl_grow()) when an enclave page is added to the enclave. The reason the mutex is not held is to allow the reclaimer to be called directly if there are no EPC pages (in support of a new VA page) available at the time. Incrementing sgx_encl->page_cnt without sgc_encl->lock held is currently (before SGX2) safe from concurrent updates because all paths in which sgx_encl_grow() is called occur before enclave initialization and are protected with an atomic operation on SGX_ENCL_IOCTL. SGX2 includes support for dynamically adding pages after enclave initialization where the protection of SGX_ENCL_IOCTL is not available. Make direct reclaim of EPC pages optional when new VA pages are added to the enclave. Essentially the existing "reclaim" flag used when regular EPC pages are added to an enclave becomes available to the caller when used to allocate VA pages instead of always being "true". When adding pages without invoking the reclaimer it is possible to do so with sgx_encl->lock held, gaining its protection against concurrent updates to sgx_encl->page_cnt after enclave initialization. No functional change. Reported-by:
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Jarkko Sakkinen authored
Move sgx_encl_page_alloc() to encl.c and export it so that it can be used in the implementation for support of adding pages to initialized enclaves, which requires to allocate new enclave pages. Signed-off-by:
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Reinette Chatre authored
In order to use sgx_encl_{grow,shrink}() in the page augmentation code located in encl.c, export these functions. Suggested-by: -
Reinette Chatre authored
SGX2 functions are not allowed on all page types. For example, ENCLS[EMODPR] is only allowed on regular SGX enclave pages and ENCLS[EMODPT] is only allowed on TCS and regular pages. If these functions are attempted on another type of page the hardware would trigger a fault. Keep a record of the SGX page type so that there is more certainty whether an SGX2 instruction can succeed and faults can be treated as real failures. The page type is a property of struct sgx_encl_page and thus does not cover the VA page type. VA pages are maintained in separate structures and their type can be determined in a different way. The SGX2 instructions needing the page type do not operate on VA pages and this is thus not a scenario needing to be covered at this time. struct sgx_encl_page hosting this information is maintained for each enclave page so the space consumed by the struct is important. The existing sgx_encl_page->vm_max_prot_bits is already unsigned long while only using three bits. Transition to a bitfield for the two members to support the additional information without increasing the space consumed by the struct. Signed-off-by:
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Reinette Chatre authored
User provided offset and length is validated when parsing the parameters of the SGX_IOC_ENCLAVE_ADD_PAGES ioctl(). Extract this validation (with consistent use of IS_ALIGNED) into a utility that can be used by the SGX2 ioctl()s that will also provide these values. Signed-off-by:
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Reinette Chatre authored
The ETRACK function followed by an IPI to all CPUs within an enclave is a common pattern with more frequent use in support of SGX2. Make the (empty) IPI callback function available internally in preparation for usage by SGX2. Signed-off-by:
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Reinette Chatre authored
The SGX reclaimer removes page table entries pointing to pages that are moved to swap. SGX2 enables changes to pages belonging to an initialized enclave, thus enclave pages may have their permission or type changed while the page is being accessed by an enclave. Supporting SGX2 requires page table entries to be removed so that any cached mappings to changed pages are removed. For example, with the ability to change enclave page types a regular enclave page may be changed to a Thread Control Structure (TCS) page that may not be accessed by an enclave. Factor out the code removing page table entries to a separate function sgx_zap_enclave_ptes(), fixing accuracy of comments in the process, and make it available to the upcoming SGX2 code. Place sgx_zap_enclave_ptes() with the rest of the enclave code in encl.c interacting with the page table since this code is no longer unique to the reclaimer. Signed-off-by:
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Reinette Chatre authored
sgx_encl_ewb_cpumask() is no longer unique to the reclaimer where it is used during the EWB ENCLS leaf function when EPC pages are written out to main memory and sgx_encl_ewb_cpumask() is used to learn which CPUs might have executed the enclave to ensure that TLBs are cleared. Upcoming SGX2 enabling will use sgx_encl_ewb_cpumask() during the EMODPR and EMODT ENCLS leaf functions that make changes to enclave pages. The function is needed for the same reason it is used now: to learn which CPUs might have executed the enclave to ensure that TLBs no longer point to the changed pages. Rename sgx_encl_ewb_cpumask() to sgx_encl_cpumask() to reflect the broader usage. Signed-off-by:
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Reinette Chatre authored
Using sgx_encl_ewb_cpumask() to learn which CPUs might have executed an enclave is useful to ensure that TLBs are cleared when changes are made to enclave pages. sgx_encl_ewb_cpumask() is used within the reclaimer when an enclave page is evicted. The upcoming SGX2 support enables changes to be made to enclave pages and will require TLBs to not refer to the changed pages and thus will be needing sgx_encl_ewb_cpumask(). Relocate sgx_encl_ewb_cpumask() to be with the rest of the enclave code in encl.c now that it is no longer unique to the reclaimer. Take care to ensure that any future usage maintains the current context requirement that ETRACK has been called first. Expand the existing comments to highlight this while moving them to a more prominent location before the function. No functional change. Signed-off-by:
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Reinette Chatre authored
sgx_encl_load_page() is used to find and load an enclave page into enclave (EPC) memory, potentially loading it from the backing storage. Both usages of sgx_encl_load_page() are during an access to the enclave page from a VMA and thus the permissions of the VMA are considered before the enclave page is loaded. SGX2 functions operating on enclave pages belonging to an initialized enclave requiring the page to be in EPC. It is thus required to support loading enclave pages into the EPC independent from a VMA. Split the current sgx_encl_load_page() to support the two usages: A new call, sgx_encl_load_page_in_vma(), behaves exactly like the current sgx_encl_load_page() that takes VMA permissions into account, while sgx_encl_load_page() just loads an enclave page into EPC. VMA, PTE, and EPCM permissions continue to dictate whether the pages can be accessed from within an enclave. Signed-off-by:
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Reinette Chatre authored
Add a wrapper for the EAUG ENCLS leaf function used to add a page to an initialized enclave. EAUG: 1) Stores all properties of the new enclave page in the SGX hardware's Enclave Page Cache Map (EPCM). 2) Sets the PENDING bit in the EPCM entry of the enclave page. This bit is cleared by the enclave by invoking ENCLU leaf function EACCEPT or EACCEPTCOPY. Access from within the enclave to the new enclave page is not possible until the PENDING bit is cleared. Signed-off-by:
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Reinette Chatre authored
Add a wrapper for the EMODT ENCLS leaf function used to change the type of an enclave page as maintained in the SGX hardware's Enclave Page Cache Map (EPCM). EMODT: 1) Updates the EPCM page type of the enclave page. 2) Sets the MODIFIED bit in the EPCM entry of the enclave page. This bit is reset by the enclave by invoking ENCLU leaf function EACCEPT or EACCEPTCOPY. Access from within the enclave to the enclave page is not possible while the MODIFIED bit is set. After changing the enclave page type by issuing EMODT the kernel needs to collaborate with the hardware to ensure that no logical processor continues to hold a reference to the changed page. This is required to ensure no required security checks are circumvented and is required for the enclave's EACCEPT/EACCEPTCOPY to succeed. Ensuring that no references to the changed page remain is accomplished with the ETRACK flow. Signed-off-by:
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Reinette Chatre authored
Add a wrapper for the EMODPR ENCLS leaf function used to restrict enclave page permissions as maintained in the SGX hardware's Enclave Page Cache Map (EPCM). EMODPR: 1) Updates the EPCM permissions of an enclave page by treating the new permissions as a mask. Supplying a value that attempts to relax EPCM permissions has no effect on EPCM permissions (PR bit, see below, is changed). 2) Sets the PR bit in the EPCM entry of the enclave page to indicate that permission restriction is in progress. The bit is reset by the enclave by invoking ENCLU leaf function EACCEPT or EACCEPTCOPY. The enclave may access the page throughout the entire process if conforming to the EPCM permissions for the enclave page. After performing the permission restriction by issuing EMODPR the kernel needs to collaborate with the hardware to ensure that all logical processors sees the new restricted permissions. This is required for the enclave's EACCEPT/EACCEPTCOPY to succeed and is accomplished with the ETRACK flow. Expand enum sgx_return_code with the possible EMODPR return values. Signed-off-by:
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Reinette Chatre authored
The SGX ENCLS instruction uses EAX to specify an SGX function and may require additional registers, depending on the SGX function. ENCLS invokes the specified privileged SGX function for managing and debugging enclaves. Macros are used to wrap the ENCLS functionality and several wrappers are used to wrap the macros to make the different SGX functions accessible in the code. The wrappers of the supported SGX functions are cryptic. Add short descriptions of each as a comment. Suggested-by:
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- 16 May, 2022 6 commits
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Reinette Chatre authored
A PCMD (Paging Crypto MetaData) page contains the PCMD structures of enclave pages that have been encrypted and moved to the shmem backing store. When all enclave pages sharing a PCMD page are loaded in the enclave, there is no need for the PCMD page and it can be truncated from the backing store. A few issues appeared around the truncation of PCMD pages. The known issues have been addressed but the PCMD handling code could be made more robust by loudly complaining if any new issue appears in this area. Add a check that will complain with a warning if the PCMD page is not actually empty after it has been truncated. There should never be data in the PCMD page at this point since it is was just checked to be empty and truncated with enclave mutex held and is updated with the enclave mutex held. Suggested-by:
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Reinette Chatre authored
Haitao reported encountering a WARN triggered by the ENCLS[ELDU] instruction faulting with a #GP. The WARN is encountered when the reclaimer evicts a range of pages from the enclave when the same pages are faulted back right away. Consider two enclave pages (ENCLAVE_A and ENCLAVE_B) sharing a PCMD page (PCMD_AB). ENCLAVE_A is in the enclave memory and ENCLAVE_B is in the backing store. PCMD_AB contains just one entry, that of ENCLAVE_B. Scenario proceeds where ENCLAVE_A is being evicted from the enclave while ENCLAVE_B is faulted in. sgx_reclaim_pages() { ... /* * Reclaim ENCLAVE_A */ mutex_lock(&encl->lock); /* * Get a reference to ENCLAVE_A's * shmem page where enclave page * encrypted data will be stored * as well as a reference to the * enclave page's PCMD data page, * PCMD_AB. * Release mutex before writing * any data to the shmem pages. */ sgx_encl_get_backing(...); encl_page->desc |= SGX_ENCL_PAGE_BEING_RECLAIMED; mutex_unlock(&encl->lock); /* * Fault ENCLAVE_B */ sgx_vma_fault() { mutex_lock(&encl->lock); /* * Get reference to * ENCLAVE_B's shmem page * as well as PCMD_AB. */ sgx_encl_get_backing(...) /* * Load page back into * enclave via ELDU. */ /* * Release reference to * ENCLAVE_B' shmem page and * PCMD_AB. */ sgx_encl_put_backing(...); /* * PCMD_AB is found empty so * it and ENCLAVE_B's shmem page * are truncated. */ /* Truncate ENCLAVE_B backing page */ sgx_encl_truncate_backing_page(); /* Truncate PCMD_AB */ sgx_encl_truncate_backing_page(); mutex_unlock(&encl->lock); ... } mutex_lock(&encl->lock); encl_page->desc &= ~SGX_ENCL_PAGE_BEING_RECLAIMED; /* * Write encrypted contents of * ENCLAVE_A to ENCLAVE_A shmem * page and its PCMD data to * PCMD_AB. */ sgx_encl_put_backing(...) /* * Reference to PCMD_AB is * dropped and it is truncated. * ENCLAVE_A's PCMD data is lost. */ mutex_unlock(&encl->lock); } What happens next depends on whether it is ENCLAVE_A being faulted in or ENCLAVE_B being evicted - but both end up with ENCLS[ELDU] faulting with a #GP. If ENCLAVE_A is faulted then at the time sgx_encl_get_backing() is called a new PCMD page is allocated and providing the empty PCMD data for ENCLAVE_A would cause ENCLS[ELDU] to #GP If ENCLAVE_B is evicted first then a new PCMD_AB would be allocated by the reclaimer but later when ENCLAVE_A is faulted the ENCLS[ELDU] instruction would #GP during its checks of the PCMD value and the WARN would be encountered. Noting that the reclaimer sets SGX_ENCL_PAGE_BEING_RECLAIMED at the time it obtains a reference to the backing store pages of an enclave page it is in the process of reclaiming, fix the race by only truncating the PCMD page after ensuring that no page sharing the PCMD page is in the process of being reclaimed. Cc: stable@vger.kernel.org Fixes: 08999b24 ("x86/sgx: Free backing memory after faulting the enclave page") Reported-by: -
Reinette Chatre authored
Haitao reported encountering a WARN triggered by the ENCLS[ELDU] instruction faulting with a #GP. The WARN is encountered when the reclaimer evicts a range of pages from the enclave when the same pages are faulted back right away. The SGX backing storage is accessed on two paths: when there are insufficient free pages in the EPC the reclaimer works to move enclave pages to the backing storage and as enclaves access pages that have been moved to the backing storage they are retrieved from there as part of page fault handling. An oversubscribed SGX system will often run the reclaimer and page fault handler concurrently and needs to ensure that the backing store is accessed safely between the reclaimer and the page fault handler. This is not the case because the reclaimer accesses the backing store without the enclave mutex while the page fault handler accesses the backing store with the enclave mutex. Consider the scenario where a page is faulted while a page sharing a PCMD page with the faulted page is being reclaimed. The consequence is a race between the reclaimer and page fault handler, the reclaimer attempting to access a PCMD at the same time it is truncated by the page fault handler. This could result in lost PCMD data. Data may still be lost if the reclaimer wins the race, this is addressed in the following patch. The reclaimer accesses pages from the backing storage without holding the enclave mutex and runs the risk of concurrently accessing the backing storage with the page fault handler that does access the backing storage with the enclave mutex held. In the scenario below a PCMD page is truncated from the backing store after all its pages have been loaded in to the enclave at the same time the PCMD page is loaded from the backing store when one of its pages are reclaimed: sgx_reclaim_pages() { sgx_vma_fault() { ... mutex_lock(&encl->lock); ... __sgx_encl_eldu() { ... if (pcmd_page_empty) { /* * EPC page being reclaimed /* * shares a PCMD page with an * PCMD page truncated * enclave page that is being * while requested from * faulted in. * reclaimer. */ */ sgx_encl_get_backing() <----------> sgx_encl_truncate_backing_page() } mutex_unlock(&encl->lock); } } In this scenario there is a race between the reclaimer and the page fault handler when the reclaimer attempts to get access to the same PCMD page that is being truncated. This could result in the reclaimer writing to the PCMD page that is then truncated, causing the PCMD data to be lost, or in a new PCMD page being allocated. The lost PCMD data may still occur after protecting the backing store access with the mutex - this is fixed in the next patch. By ensuring the backing store is accessed with the mutex held the enclave page state can be made accurate with the SGX_ENCL_PAGE_BEING_RECLAIMED flag accurately reflecting that a page is in the process of being reclaimed. Consistently protect the reclaimer's backing store access with the enclave's mutex to ensure that it can safely run concurrently with the page fault handler. Cc: stable@vger.kernel.org Fixes: 1728ab54 ("x86/sgx: Add a page reclaimer") Reported-by: -
Reinette Chatre authored
Recent commit 08999b24 ("x86/sgx: Free backing memory after faulting the enclave page") expanded __sgx_encl_eldu() to clear an enclave page's PCMD (Paging Crypto MetaData) from the PCMD page in the backing store after the enclave page is restored to the enclave. Since the PCMD page in the backing store is modified the page should be marked as dirty to ensure the modified data is retained. Cc: stable@vger.kernel.org Fixes: 08999b24 ("x86/sgx: Free backing memory after faulting the enclave page") Signed-off-by:
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Reinette Chatre authored
SGX uses shmem backing storage to store encrypted enclave pages and their crypto metadata when enclave pages are moved out of enclave memory. Two shmem backing storage pages are associated with each enclave page - one backing page to contain the encrypted enclave page data and one backing page (shared by a few enclave pages) to contain the crypto metadata used by the processor to verify the enclave page when it is loaded back into the enclave. sgx_encl_put_backing() is used to release references to the backing storage and, optionally, mark both backing store pages as dirty. Managing references and dirty status together in this way results in both backing store pages marked as dirty, even if only one of the backing store pages are changed. Additionally, waiting until the page reference is dropped to set the page dirty risks a race with the page fault handler that may load outdated data into the enclave when a page is faulted right after it is reclaimed. Consider what happens if the reclaimer writes a page to the backing store and the page is immediately faulted back, before the reclaimer is able to set the dirty bit of the page: sgx_reclaim_pages() { sgx_vma_fault() { ... sgx_encl_get_backing(); ... ... sgx_reclaimer_write() { mutex_lock(&encl->lock); /* Write data to backing store */ mutex_unlock(&encl->lock); } mutex_lock(&encl->lock); __sgx_encl_eldu() { ... /* * Enclave backing store * page not released * nor marked dirty - * contents may not be * up to date. */ sgx_encl_get_backing(); ... /* * Enclave data restored * from backing store * and PCMD pages that * are not up to date. * ENCLS[ELDU] faults * because of MAC or PCMD * checking failure. */ sgx_encl_put_backing(); } ... /* set page dirty */ sgx_encl_put_backing(); ... mutex_unlock(&encl->lock); } } Remove the option to sgx_encl_put_backing() to set the backing pages as dirty and set the needed pages as dirty right after receiving important data while enclave mutex is held. This ensures that the page fault handler can get up to date data from a page and prepares the code for a following change where only one of the backing pages need to be marked as dirty. Cc: stable@vger.kernel.org Fixes: 1728ab54 ("x86/sgx: Add a page reclaimer") Suggested-by: -
Linus Torvalds authored
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- 15 May, 2022 8 commits
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Linus Torvalds authored
Merge tag 'driver-core-5.18-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core Pull driver core fixes from Greg KH: "Here is one fix, and three documentation updates for 5.18-rc7. The fix is for the firmware loader which resolves a long-reported problem where the credentials of the firmware loader could be set to a userspace process without enough permissions to actually load the firmware image. Many Android vendors have been reporting this for quite some time. The documentation updates are for the embargoed-hardware-issues.rst file to add a new entry, change an existing one, and sort the list to make changes easier in the future. All of these have been in linux-next for a while with no reported issues" * tag 'driver-core-5.18-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: Documentation/process: Update ARM contact for embargoed hardware issues Documentation/process: Add embargoed HW contact for Ampere Computing Documentation/process: Make groups alphabetical and use tabs consistently firmware_loader: use kernel credentials when reading firmware
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git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-miscLinus Torvalds authored
Pull char/misc driver fixes from Greg KH: "Here are two small driver fixes for 5.18-rc7 that resolve reported problems: - slimbus driver irq bugfix - interconnect sync state bugfix Both of these have been in linux-next with no reported problems" * tag 'char-misc-5.18-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: slimbus: qcom: Fix IRQ check in qcom_slim_probe interconnect: Restore sync state by ignoring ipa-virt in provider count
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git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/ttyLinus Torvalds authored
Pull tty/serial driver fixes from Greg KH: "Here are some small tty n_gsm and serial driver fixes for 5.18-rc7 that resolve reported problems. They include: - n_gsm fixes for reported issues - 8250_mtk driver fixes for some platforms - fsl_lpuart driver fix for reported problem. - digicolor driver fix for reported problem. All have been in linux-next for a while with no reported problems" * tag 'tty-5.18-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: fsl_lpuart: Don't enable interrupts too early tty: n_gsm: fix invalid gsmtty_write_room() result tty: n_gsm: fix mux activation issues in gsm_config() tty: n_gsm: fix buffer over-read in gsm_dlci_data() serial: 8250_mtk: Fix register address for XON/XOFF character serial: 8250_mtk: Make sure to select the right FEATURE_SEL serial: 8250_mtk: Fix UART_EFR register address tty/serial: digicolor: fix possible null-ptr-deref in digicolor_uart_probe()
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git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usbLinus Torvalds authored
Pull USB fixes from Greg KH: "Here are some small fixes for reported issues with some USB drivers. They include: - xhci fixes for xhci-mtk platform driver - typec driver fixes for reported problems. - cdc-wdm read-stuck fix - gadget driver fix for reported race condition - new usb-serial driver ids All of these have been in linux-next with no reported problems" * tag 'usb-5.18-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb: usb: xhci-mtk: remove bandwidth budget table usb: xhci-mtk: fix fs isoc's transfer error usb: gadget: fix race when gadget driver register via ioctl usb: typec: tcpci_mt6360: Update for BMC PHY setting usb: gadget: uvc: allow for application to cleanly shutdown usb: typec: tcpci: Don't skip cleanup in .remove() on error usb: cdc-wdm: fix reading stuck on device close USB: serial: qcserial: add support for Sierra Wireless EM7590 USB: serial: option: add Fibocom MA510 modem USB: serial: option: add Fibocom L610 modem USB: serial: pl2303: add device id for HP LM930 Display
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git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linuxLinus Torvalds authored
Pull powerpc fix from Michael Ellerman: - Fix KVM PR on 32-bit, which was broken by some MMU code refactoring. Thanks to: Alexander Graf, and Matt Evans. * tag 'powerpc-5.18-5' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: KVM: PPC: Book3S PR: Enable MSR_DR for switch_mmu_context()
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds authored
Pull x86 fix from Thomas Gleixner: "A single fix for the handling of unpopulated sub-pmd spaces. The copy & pasta from the corresponding s390 code screwed up the address calculation for marking the sub-pmd ranges via memset by omitting the ALIGN_DOWN() to calculate the proper start address. It's a mystery why this code is not generic and shared because there is nothing architecture specific in there, but that's too intrusive for a backportable fix" * tag 'x86-urgent-2022-05-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/mm: Fix marking of unused sub-pmd ranges
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds authored
Pull scheduler fix from Thomas Gleixner: "The recent expansion of the sched switch tracepoint inserted a new argument in the middle of the arguments. This reordering broke BPF programs which relied on the old argument list. While tracepoints are not considered stable ABI, it's not trivial to make BPF cope with such a change, but it's being worked on. For now restore the original argument order and move the new argument to the end of the argument list" * tag 'sched-urgent-2022-05-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/tracing: Append prev_state to tp args instead
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds authored
Pull irq fix from Thomas Gleixner: "A single fix for a recent (introduced in 5.16) regression in the core interrupt code. The consolidation of the interrupt handler invocation code added an unconditional warning when generic_handle_domain_irq() is invoked from outside hard interrupt context. That's overbroad as the requirement for invoking these handlers in hard interrupt context is only required for certain interrupt types. The subsequently called code already contains a warning which triggers conditionally for interrupt chips which indicate this requirement in their properties. Remove the overbroad one" * tag 'irq-urgent-2022-05-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: genirq: Remove WARN_ON_ONCE() in generic_handle_domain_irq()
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- 14 May, 2022 1 commit
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Linus Torvalds authored
Merge tag 'perf-tools-fixes-for-v5.18-2022-05-14' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux Pull perf tools fixes from Arnaldo Carvalho de Melo: - Fix two NDEBUG warnings in 'perf bench numa' - Fix ARM coresight `perf test` failure - Sync linux/kvm.h with the kernel sources - Add James and Mike as Arm64 performance events reviewers * tag 'perf-tools-fixes-for-v5.18-2022-05-14' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux: MAINTAINERS: Add James and Mike as Arm64 performance events reviewers tools headers UAPI: Sync linux/kvm.h with the kernel sources perf tests: Fix coresight `perf test` failure. perf bench: Fix two numa NDEBUG warnings
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- 13 May, 2022 5 commits
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git://anongit.freedesktop.org/drm/drmLinus Torvalds authored
Pull more drm fixes from Dave Airlie: "Turns out I was right, some fixes hadn't made it to me yet. The vmwgfx ones also popped up later, but all seem like bad enough things to fix. The dma-buf, vc4 and nouveau ones are all pretty small. The fbdev fixes are a bit more complicated: a fix to cleanup fbdev devices properly, uncovered some use-after-free bugs in existing drivers. Then the fix for those bugs wasn't correct. This reverts that fix, and puts the proper fixes in place in the drivers to avoid the use-after-frees. This has had a fair number of eyes on it at this stage, and I'm confident enough that it puts things in the right place, and is less dangerous than reverting our way out of the initial change at this stage. fbdev: - revert NULL deref fix that turned into a use-after-free - prevent use-after-free in fbdev - efifb/simplefb/vesafb: fix cleanup paths to avoid use-after-frees dma-buf: - fix panic in stats setup vc4: - fix hdmi build nouveau: - tegra iommu present fix - fix leak in backlight name vmwgfx: - Black screen due to fences using FIFO checks on SVGA3 - Random black screens on boot due to uninitialized drm_mode_fb_cmd2 - Hangs on SVGA3 due to command buffers being used with gbobjects" * tag 'drm-fixes-2022-05-14' of git://anongit.freedesktop.org/drm/drm: drm/vmwgfx: Disable command buffers on svga3 without gbobjects drm/vmwgfx: Initialize drm_mode_fb_cmd2 drm/vmwgfx: Fix fencing on SVGAv3 drm/vc4: hdmi: Fix build error for implicit function declaration dma-buf: call dma_buf_stats_setup after dmabuf is in valid list fbdev: efifb: Fix a use-after-free due early fb_info cleanup drm/nouveau: Fix a potential theorical leak in nouveau_get_backlight_name() drm/nouveau/tegra: Stop using iommu_present() fbdev: vesafb: Cleanup fb_info in .fb_destroy rather than .remove fbdev: efifb: Cleanup fb_info in .fb_destroy rather than .remove fbdev: simplefb: Cleanup fb_info in .fb_destroy rather than .remove fbdev: Prevent possible use-after-free in fb_release() Revert "fbdev: Make fb_release() return -ENODEV if fbdev was unregistered"
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git://anongit.freedesktop.org/drm/drm-miscDave Airlie authored
Multiple fixes to fbdev to address a regression at unregistration, an iommu detection improvement for nouveau, a memory leak fix for nouveau, pointer dereference fix for dma_buf_file_release(), and a build breakage fix for vc4 Signed-off-by:
Dave Airlie <airlied@redhat.com> From: Maxime Ripard <maxime@cerno.tech> Link: https://patchwork.freedesktop.org/patch/msgid/20220513073044.ymayac7x7bzatrt7@houat
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Dave Airlie authored
Merge tag 'vmwgfx-drm-fixes-5.18-2022-05-13' of https://gitlab.freedesktop.org/zack/vmwgfx into drm-fixes vmwgfx fixes for: - Black screen due to fences using FIFO checks on SVGA3 - Random black screens on boot due to uninitialized drm_mode_fb_cmd2 - Hangs on SVGA3 due to command buffers being used with gbobjects Signed-off-by:
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git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2Linus Torvalds authored
Pull gfs2 fixes from Andreas Gruenbacher: "We've finally identified commit dc732906 ("gfs2: Introduce flag for glock holder auto-demotion") to be the other cause of the filesystem corruption we've been seeing. This feature isn't strictly necessary anymore, so we've decided to stop using it for now. With this and the gfs_iomap_end rounding fix you've already seen ("gfs2: Fix filesystem block deallocation for short writes" in this pull request), we're corruption free again now. - Fix filesystem block deallocation for short writes. - Stop using glock holder auto-demotion for now. - Get rid of buffered writes inefficiencies due to page faults being disabled. - Minor other cleanups" * tag 'gfs2-v5.18-rc4-fix3' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2: gfs2: Stop using glock holder auto-demotion for now gfs2: buffered write prefaulting gfs2: Align read and write chunks to the page cache gfs2: Pull return value test out of should_fault_in_pages gfs2: Clean up use of fault_in_iov_iter_{read,write}able gfs2: Variable rename gfs2: Fix filesystem block deallocation for short writes
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Andreas Gruenbacher authored
We're having unresolved issues with the glock holder auto-demotion mechanism introduced in commit dc732906. This mechanism was assumed to be essential for avoiding frequent short reads and writes until commit 296abc0d ("gfs2: No short reads or writes upon glock contention"). Since then, when the inode glock is lost, it is simply re-acquired and the operation is resumed. This means that apart from the performance penalty, we might as well drop the inode glock before faulting in pages, and re-acquire it afterwards. Signed-off-by:
Andreas Gruenbacher <agruenba@redhat.com>
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