From 034dd340b08be1f2f0477ad16131d609f9dbd53c Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 30 Aug 2026 09:22:00 -0700 Subject: Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace Pull tracing fixes from Steven Rostedt: - Fix error output of boot instance creation failure Currently if a boot instance creation fails, instead of printing out the name of the instance that failed, it prints "(null)". That is because it prints "cur_str" that had already been processed by strsep(). Print the saved name instead. While at it, print the error code of the failure. - Fix use-after-free for same named historgrams Histograms can be named so that they can be used in multiple events. But if the named histogram has a variable attached, the second event that uses the named histogram which duplicates it and needs to free the original after duplication leaves the old variable in place and still visible. If another histogram uses than variable, it will use the stale one which will try to reference the freed duplicate histogram and crash the kernel. Free the duplicate variables along with the duplicated histogram data. - Check return value of kthread_run() in event self test The events self tests uses a kthread for testing but does not check if it succeeded in creating a kthread. If the kthread creation were to fail, the code will still try to call kthread_stop() on the error returned. - Fix race between reading trace_pipe and updating subbuffer size If a user is reading the trace_pipe file at the same time they update the ring buffer sub-buffer size, can cause the trace_pipe read to read stale data. Add trace_access_lock() around updating the ring buffer sub-buffer size. - Fix eventfs_inode on failure path in creation of the events directory In the creation of the "events" directory, if after allocating the eventfs_inode a failure is detected, it calls cleanup_ei() which calls free_ei(). The free_ei() will test if eventfs_inode being freed has no children. It is a bug if it does. But on the failure case of the creation of the "events" directory, the children lists have not yet been initialized and the free will trigger a warning because list_empty() on an uninitialized list returns false. Move the initialization into init_ei() where it makes more sense and makes sure that a created eventfs_inode has its lists initialized upon creation. - Check return value of kthread_run() in ftrace direct sample code The sample code that shows how to use the ftrace direct calls does not test the return of kthread_run() to see if it succeeds. Return a failure if the kthread_run() doesn't succeed. - Clear user events state on fork in case of alloc failure On fork, the child gets a pointer to the parent's user events state. It makes a copy of it then updates the child's pointer to it. But if the allocation fails, the duplication function leaves the child with a pointer to its parent's descriptor. When the child cleans up its data, it will free the parent's descriptor while the parent is still using it. In the duplication function, set the child's user_event_mm to NULL before testing if the allocation succeeded, and when it exits it will not free the parent's descriptor. - Fix retry exhaustion in simple ring buffer reader swap simple_ring_buffer_swap_reader_page() starts with retry set to 8 and post-decrements it only after a failed link replacement. On the final attempt, a successful replacement leaves retry at zero, while a failed replacement leaves it at -1. But the check for success expects the retry value to be non-zero and exits with an error on zero. This is the opposite result. Fix it. - Fail nicely when the remote swap_reader_page() returns an error Currently, if the swap_reader_page() of a remote buffer fails, it triggers a WARN_ON_ONCE() and continues normally. Instead, have it exit with an error and a pr_warn() print instead of a full WARNING. * tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: ring-buffer: Stop remote reader update when page swap fails tracing: Fix retry exhaustion in simple ring buffer reader swap tracing/user_events: Clear copied tracing state before fork duplication samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify eventfs: Initialize ei->children and ei->list in init_ei() tracing: Fix use-after-free in trace_pipe read on sub-buffer order change tracing: Fix crash passing ERR_PTR to kthread_stop() tracing: Fix use-after-free with same-name named triggers tracing: Fix logged instance name on creation failure --- Documentation/driver-api/nvdimm/security.rst | 143 +++++++++++++++++++++++++++ 1 file changed, 143 insertions(+) create mode 100644 Documentation/driver-api/nvdimm/security.rst (limited to 'Documentation/driver-api/nvdimm/security.rst') diff --git a/Documentation/driver-api/nvdimm/security.rst b/Documentation/driver-api/nvdimm/security.rst new file mode 100644 index 000000000..eb3d35e6a --- /dev/null +++ b/Documentation/driver-api/nvdimm/security.rst @@ -0,0 +1,143 @@ +=============== +NVDIMM Security +=============== + +1. Introduction +--------------- + +With the introduction of Intel Device Specific Methods (DSM) v1.8 +specification [1], security DSMs are introduced. The spec added the following +security DSMs: "get security state", "set passphrase", "disable passphrase", +"unlock unit", "freeze lock", "secure erase", and "overwrite". A security_ops +data structure has been added to struct dimm in order to support the security +operations and generic APIs are exposed to allow vendor neutral operations. + +2. Sysfs Interface +------------------ +The "security" sysfs attribute is provided in the nvdimm sysfs directory. For +example: +/sys/devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0012:00/ndbus0/nmem0/security + +The "show" attribute of that attribute will display the security state for +that DIMM. The following states are available: disabled, unlocked, locked, +frozen, and overwrite. If security is not supported, the sysfs attribute +will not be visible. + +The "store" attribute takes several commands when it is being written to +in order to support some of the security functionalities: +update - enable or update passphrase. +disable - disable enabled security and remove key. +freeze - freeze changing of security states. +erase - delete existing user encryption key. +overwrite - wipe the entire nvdimm. +master_update - enable or update master passphrase. +master_erase - delete existing user encryption key. + +3. Key Management +----------------- + +The key is associated to the payload by the DIMM id. For example: +# cat /sys/devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0012:00/ndbus0/nmem0/nfit/id +8089-a2-1740-00000133 +The DIMM id would be provided along with the key payload (passphrase) to +the kernel. + +The security keys are managed on the basis of a single key per DIMM. The +key "passphrase" is expected to be 32bytes long. This is similar to the ATA +security specification [2]. A key is initially acquired via the request_key() +kernel API call during nvdimm unlock. It is up to the user to make sure that +all the keys are in the kernel user keyring for unlock. + +A nvdimm encrypted-key of format enc32 has the description format of: +nvdimm: + +See file ``Documentation/security/keys/trusted-encrypted.rst`` for creating +encrypted-keys of enc32 format. TPM usage with a master trusted key is +preferred for sealing the encrypted-keys. + +4. Unlocking +------------ +When the DIMMs are being enumerated by the kernel, the kernel will attempt to +retrieve the key from the kernel user keyring. This is the only time +a locked DIMM can be unlocked. Once unlocked, the DIMM will remain unlocked +until reboot. Typically an entity (i.e. shell script) will inject all the +relevant encrypted-keys into the kernel user keyring during the initramfs phase. +This provides the unlock function access to all the related keys that contain +the passphrase for the respective nvdimms. It is also recommended that the +keys are injected before libnvdimm is loaded by modprobe. + +5. Update +--------- +When doing an update, it is expected that the existing key is removed from +the kernel user keyring and reinjected as different (old) key. It's irrelevant +what the key description is for the old key since we are only interested in the +keyid when doing the update operation. It is also expected that the new key +is injected with the description format described from earlier in this +document. The update command written to the sysfs attribute will be with +the format: +update + +If there is no old keyid due to a security enabling, then a 0 should be +passed in. + +6. Freeze +--------- +The freeze operation does not require any keys. The security config can be +frozen by a user with root privilege. + +7. Disable +---------- +The security disable command format is: +disable + +An key with the current passphrase payload that is tied to the nvdimm should be +in the kernel user keyring. + +8. Secure Erase +--------------- +The command format for doing a secure erase is: +erase + +An key with the current passphrase payload that is tied to the nvdimm should be +in the kernel user keyring. + +9. Overwrite +------------ +The command format for doing an overwrite is: +overwrite + +Overwrite can be done without a key if security is not enabled. A key serial +of 0 can be passed in to indicate no key. + +The sysfs attribute "security" can be polled to wait on overwrite completion. +Overwrite can last tens of minutes or more depending on nvdimm size. + +An encrypted-key with the current user passphrase that is tied to the nvdimm +should be injected and its keyid should be passed in via sysfs. + +10. Master Update +----------------- +The command format for doing a master update is: +update + +The operating mechanism for master update is identical to update except the +master passphrase key is passed to the kernel. The master passphrase key +is just another encrypted-key. + +This command is only available when security is disabled. + +11. Master Erase +---------------- +The command format for doing a master erase is: +master_erase + +This command has the same operating mechanism as erase except the master +passphrase key is passed to the kernel. The master passphrase key is just +another encrypted-key. + +This command is only available when the master security is enabled, indicated +by the extended security status. + +[1]: https://pmem.io/documents/NVDIMM_DSM_Interface-V1.8.pdf + +[2]: http://www.t13.org/documents/UploadedDocuments/docs2006/e05179r4-ACS-SecurityClarifications.pdf -- cgit v1.3.1