kernel/security/integrity, branch linux-6.16.y

ima: do not copy measurement list to kdump kernel

2025-05-14T10:40:09Z

Kdump kernel doesn't need IMA to do integrity measurement. Hence the measurement list in 1st kernel doesn't need to be copied to kdump kernel. Here skip allocating buffer for measurement list copying if loading kdump kernel. Then there won't be the later handling related to ima_kexec_buffer. Signed-off-by: Steven Chen Tested-by: Baoquan He Acked-by: Baoquan He Signed-off-by: Mimi Zohar

ima: measure kexec load and exec events as critical data

2025-04-29T19:54:54Z

The amount of memory allocated at kexec load, even with the extra memory allocated, might not be large enough for the entire measurement list. The indeterminate interval between kexec 'load' and 'execute' could exacerbate this problem. Define two new IMA events, 'kexec_load' and 'kexec_execute', to be measured as critical data at kexec 'load' and 'execute' respectively. Report the allocated kexec segment size, IMA binary log size and the runtime measurements count as part of those events. These events, and the values reported through them, serve as markers in the IMA log to verify the IMA events are captured during kexec soft reboot. The presence of a 'kexec_load' event in between the last two 'boot_aggregate' events in the IMA log implies this is a kexec soft reboot, and not a cold-boot. And the absence of 'kexec_execute' event after kexec soft reboot implies missing events in that window which results in inconsistency with TPM PCR quotes, necessitating a cold boot for a successful remote attestation. These critical data events are displayed as hex encoded ascii in the ascii_runtime_measurement_list. Verifying the critical data hash requires calculating the hash of the decoded ascii string. For example, to verify the 'kexec_load' data hash: sudo cat /sys/kernel/security/integrity/ima/ascii_runtime_measurements | grep kexec_load | cut -d' ' -f 6 | xxd -r -p | sha256sum To verify the 'kexec_execute' data hash: sudo cat /sys/kernel/security/integrity/ima/ascii_runtime_measurements | grep kexec_execute | cut -d' ' -f 6 | xxd -r -p | sha256sum Co-developed-by: Tushar Sugandhi Signed-off-by: Tushar Sugandhi Signed-off-by: Steven Chen Reviewed-by: Stefan Berger Acked-by: Baoquan He Tested-by: Stefan Berger # ppc64/kvm Signed-off-by: Mimi Zohar

ima: make the kexec extra memory configurable

2025-04-29T19:54:54Z

The extra memory allocated for carrying the IMA measurement list across kexec is hard-coded as half a PAGE. Make it configurable. Define a Kconfig option, IMA_KEXEC_EXTRA_MEMORY_KB, to configure the extra memory (in kb) to be allocated for IMA measurements added during kexec soft reboot. Ensure the default value of the option is set such that extra half a page of memory for additional measurements is allocated for the additional measurements. Update ima_add_kexec_buffer() function to allocate memory based on the Kconfig option value, rather than the currently hard-coded one. Suggested-by: Stefan Berger Co-developed-by: Tushar Sugandhi Signed-off-by: Tushar Sugandhi Signed-off-by: Steven Chen Reviewed-by: Stefan Berger Acked-by: Baoquan He Tested-by: Stefan Berger # ppc64/kvm Signed-off-by: Mimi Zohar

ima: verify if the segment size has changed

2025-04-29T19:54:54Z

kexec 'load' may be called multiple times. Free and realloc the buffer only if the segment_size is changed from the previous kexec 'load' call. Signed-off-by: Steven Chen Reviewed-by: Stefan Berger Acked-by: Baoquan He Tested-by: Stefan Berger # ppc64/kvm Signed-off-by: Mimi Zohar

ima: kexec: move IMA log copy from kexec load to execute

2025-04-29T19:54:54Z

The IMA log is currently copied to the new kernel during kexec 'load' using ima_dump_measurement_list(). However, the IMA measurement list copied at kexec 'load' may result in loss of IMA measurements records that only occurred after the kexec 'load'. Move the IMA measurement list log copy from kexec 'load' to 'execute' Make the kexec_segment_size variable a local static variable within the file, so it can be accessed during both kexec 'load' and 'execute'. Define kexec_post_load() as a wrapper for calling ima_kexec_post_load() and machine_kexec_post_load(). Replace the existing direct call to machine_kexec_post_load() with kexec_post_load(). When there is insufficient memory to copy all the measurement logs, copy as much of the measurement list as possible. Co-developed-by: Tushar Sugandhi Signed-off-by: Tushar Sugandhi Cc: Eric Biederman Cc: Baoquan He Cc: Vivek Goyal Cc: Dave Young Signed-off-by: Steven Chen Tested-by: Stefan Berger # ppc64/kvm Signed-off-by: Mimi Zohar

ima: kexec: define functions to copy IMA log at soft boot

2025-04-29T19:54:54Z

The IMA log is currently copied to the new kernel during kexec 'load' using ima_dump_measurement_list(). However, the log copied at kexec 'load' may result in loss of IMA measurements that only occurred after kexec "load'. Setup the needed infrastructure to move the IMA log copy from kexec 'load' to 'execute'. Define a new IMA hook ima_update_kexec_buffer() as a stub function. It will be used to call ima_dump_measurement_list() during kexec 'execute'. Implement ima_kexec_post_load() function to be invoked after the new Kernel image has been loaded for kexec. ima_kexec_post_load() maps the IMA buffer to a segment in the newly loaded Kernel. It also registers the reboot notifier_block to trigger ima_update_kexec_buffer() at kexec 'execute'. Set the priority of register_reboot_notifier to INT_MIN to ensure that the IMA log copy operation will happen at the end of the operation chain, so that all the IMA measurement records extended into the TPM are copied Co-developed-by: Tushar Sugandhi Signed-off-by: Tushar Sugandhi Cc: Eric Biederman Cc: Baoquan He Cc: Vivek Goyal Cc: Dave Young Signed-off-by: Steven Chen Reviewed-by: Stefan Berger Acked-by: Baoquan He Tested-by: Stefan Berger # ppc64/kvm Signed-off-by: Mimi Zohar

ima: kexec: skip IMA segment validation after kexec soft reboot

2025-04-29T19:54:53Z

Currently, the function kexec_calculate_store_digests() calculates and stores the digest of the segment during the kexec_file_load syscall, where the IMA segment is also allocated. Later, the IMA segment will be updated with the measurement log at the kexec execute stage when a kexec reboot is initiated. Therefore, the digests should be updated for the IMA segment in the normal case. The problem is that the content of memory segments carried over to the new kernel during the kexec systemcall can be changed at kexec 'execute' stage, but the size and the location of the memory segments cannot be changed at kexec 'execute' stage. To address this, skip the calculation and storage of the digest for the IMA segment in kexec_calculate_store_digests() so that it is not added to the purgatory_sha_regions. With this change, the IMA segment is not included in the digest calculation, storage, and verification. Cc: Eric Biederman Cc: Baoquan He Cc: Vivek Goyal Cc: Dave Young Co-developed-by: Tushar Sugandhi Signed-off-by: Tushar Sugandhi Signed-off-by: Steven Chen Reviewed-by: Stefan Berger Acked-by: Baoquan He Tested-by: Stefan Berger # ppc64/kvm [zohar@linux.ibm.com: Fixed Signed-off-by tag to match author's email ] Signed-off-by: Mimi Zohar

ima: define and call ima_alloc_kexec_file_buf()

2025-04-29T19:54:53Z

In the current implementation, the ima_dump_measurement_list() API is called during the kexec "load" phase, where a buffer is allocated and the measurement records are copied. Due to this, new events added after kexec load but before kexec execute are not carried over to the new kernel during kexec operation Carrying the IMA measurement list across kexec requires allocating a buffer and copying the measurement records. Separate allocating the buffer and copying the measurement records into separate functions in order to allocate the buffer at kexec 'load' and copy the measurements at kexec 'execute'. After moving the vfree() here at this stage in the patch set, the IMA measurement list fails to verify when doing two consecutive "kexec -s -l" with/without a "kexec -s -u" in between. Only after "ima: kexec: move IMA log copy from kexec load to execute" the IMA measurement list verifies properly with the vfree() here. Co-developed-by: Tushar Sugandhi Signed-off-by: Tushar Sugandhi Signed-off-by: Steven Chen Reviewed-by: Stefan Berger Acked-by: Baoquan He Tested-by: Stefan Berger # ppc64/kvm Signed-off-by: Mimi Zohar

ima: rename variable the seq_file "file" to "ima_kexec_file"

2025-04-29T19:54:53Z

Before making the function local seq_file "file" variable file static global, rename it to "ima_kexec_file". Signed-off-by: Steven Chen Acked-by: Baoquan He Tested-by: Stefan Berger # ppc64/kvm Signed-off-by: Mimi Zohar

ima: process_measurement() needlessly takes inode_lock() on MAY_READ

2025-04-22T14:39:32Z

On IMA policy update, if a measure rule exists in the policy, IMA_MEASURE is set for ima_policy_flags which makes the violation_check variable always true. Coupled with a no-action on MAY_READ for a FILE_CHECK call, we're always taking the inode_lock(). This becomes a performance problem for extremely heavy read-only workloads. Therefore, prevent this only in the case there's no action to be taken. Signed-off-by: Frederick Lawler Acked-by: Roberto Sassu Signed-off-by: Mimi Zohar