From 0091d9241ea24c5275be4a3e5a032862fd9de9ec Mon Sep 17 00:00:00 2001 From: Steven Chen Date: Mon, 21 Apr 2025 15:25:09 -0700 Subject: kexec: define functions to map and unmap segments Implement kimage_map_segment() to enable IMA to map the measurement log list to the kimage structure during the kexec 'load' stage. This function gathers the source pages within the specified address range, and maps them to a contiguous virtual address range. This is a preparation for later usage. Implement kimage_unmap_segment() for unmapping segments using vunmap(). 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 Acked-by: Baoquan He Tested-by: Stefan Berger # ppc64/kvm Signed-off-by: Mimi Zohar --- include/linux/kexec.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'include/linux') diff --git a/include/linux/kexec.h b/include/linux/kexec.h index c8971861521a..805743208d19 100644 --- a/include/linux/kexec.h +++ b/include/linux/kexec.h @@ -474,13 +474,19 @@ extern bool kexec_file_dbg_print; #define kexec_dprintk(fmt, arg...) \ do { if (kexec_file_dbg_print) pr_info(fmt, ##arg); } while (0) +extern void *kimage_map_segment(struct kimage *image, unsigned long addr, unsigned long size); +extern void kimage_unmap_segment(void *buffer); #else /* !CONFIG_KEXEC_CORE */ struct pt_regs; struct task_struct; +struct kimage; static inline void __crash_kexec(struct pt_regs *regs) { } static inline void crash_kexec(struct pt_regs *regs) { } static inline int kexec_should_crash(struct task_struct *p) { return 0; } static inline int kexec_crash_loaded(void) { return 0; } +static inline void *kimage_map_segment(struct kimage *image, unsigned long addr, unsigned long size) +{ return NULL; } +static inline void kimage_unmap_segment(void *buffer) { } #define kexec_in_progress false #endif /* CONFIG_KEXEC_CORE */ -- cgit v1.2.3 From 9ee8888a80fe2bd20ce929ffbc1dedd57607a778 Mon Sep 17 00:00:00 2001 From: Steven Chen Date: Mon, 21 Apr 2025 15:25:10 -0700 Subject: ima: kexec: skip IMA segment validation after kexec soft reboot 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 --- include/linux/kexec.h | 3 +++ kernel/kexec_file.c | 22 ++++++++++++++++++++++ security/integrity/ima/ima_kexec.c | 3 +++ 3 files changed, 28 insertions(+) (limited to 'include/linux') diff --git a/include/linux/kexec.h b/include/linux/kexec.h index 805743208d19..53ef1b6c8712 100644 --- a/include/linux/kexec.h +++ b/include/linux/kexec.h @@ -369,6 +369,9 @@ struct kimage { phys_addr_t ima_buffer_addr; size_t ima_buffer_size; + + unsigned long ima_segment_index; + bool is_ima_segment_index_set; #endif /* Core ELF header buffer */ diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c index fba686487e3b..f6e80ebc33e9 100644 --- a/kernel/kexec_file.c +++ b/kernel/kexec_file.c @@ -38,6 +38,21 @@ void set_kexec_sig_enforced(void) } #endif +#ifdef CONFIG_IMA_KEXEC +static bool check_ima_segment_index(struct kimage *image, int i) +{ + if (image->is_ima_segment_index_set && i == image->ima_segment_index) + return true; + else + return false; +} +#else +static bool check_ima_segment_index(struct kimage *image, int i) +{ + return false; +} +#endif + static int kexec_calculate_store_digests(struct kimage *image); /* Maximum size in bytes for kernel/initrd files. */ @@ -776,6 +791,13 @@ static int kexec_calculate_store_digests(struct kimage *image) if (ksegment->kbuf == pi->purgatory_buf) continue; + /* + * Skip the segment if ima_segment_index is set and matches + * the current index + */ + if (check_ima_segment_index(image, i)) + continue; + ret = crypto_shash_update(desc, ksegment->kbuf, ksegment->bufsz); if (ret) diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c index b12ac3619b8f..7e0a19c3483f 100644 --- a/security/integrity/ima/ima_kexec.c +++ b/security/integrity/ima/ima_kexec.c @@ -145,6 +145,7 @@ void ima_add_kexec_buffer(struct kimage *image) kbuf.buffer = kexec_buffer; kbuf.bufsz = kexec_buffer_size; kbuf.memsz = kexec_segment_size; + image->is_ima_segment_index_set = false; ret = kexec_add_buffer(&kbuf); if (ret) { pr_err("Error passing over kexec measurement buffer.\n"); @@ -155,6 +156,8 @@ void ima_add_kexec_buffer(struct kimage *image) image->ima_buffer_addr = kbuf.mem; image->ima_buffer_size = kexec_segment_size; image->ima_buffer = kexec_buffer; + image->ima_segment_index = image->nr_segments - 1; + image->is_ima_segment_index_set = true; kexec_dprintk("kexec measurement buffer for the loaded kernel at 0x%lx.\n", kbuf.mem); -- cgit v1.2.3 From f18e502db673c75f762d47101dafcf58f30e2733 Mon Sep 17 00:00:00 2001 From: Steven Chen Date: Mon, 21 Apr 2025 15:25:11 -0700 Subject: ima: kexec: define functions to copy IMA log at soft boot 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 --- include/linux/ima.h | 3 +++ security/integrity/ima/ima_kexec.c | 47 ++++++++++++++++++++++++++++++++++++++ 2 files changed, 50 insertions(+) (limited to 'include/linux') diff --git a/include/linux/ima.h b/include/linux/ima.h index 0bae61a15b60..8e29cb4e6a01 100644 --- a/include/linux/ima.h +++ b/include/linux/ima.h @@ -32,6 +32,9 @@ static inline void ima_appraise_parse_cmdline(void) {} #ifdef CONFIG_IMA_KEXEC extern void ima_add_kexec_buffer(struct kimage *image); +extern void ima_kexec_post_load(struct kimage *image); +#else +static inline void ima_kexec_post_load(struct kimage *image) {} #endif #else diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c index 7e0a19c3483f..e79f6caf895b 100644 --- a/security/integrity/ima/ima_kexec.c +++ b/security/integrity/ima/ima_kexec.c @@ -12,10 +12,14 @@ #include #include #include +#include +#include #include "ima.h" #ifdef CONFIG_IMA_KEXEC +static bool ima_kexec_update_registered; static struct seq_file ima_kexec_file; +static void *ima_kexec_buffer; static void ima_free_kexec_file_buf(struct seq_file *sf) { @@ -162,6 +166,49 @@ void ima_add_kexec_buffer(struct kimage *image) kexec_dprintk("kexec measurement buffer for the loaded kernel at 0x%lx.\n", kbuf.mem); } + +/* + * Called during kexec execute so that IMA can update the measurement list. + */ +static int ima_update_kexec_buffer(struct notifier_block *self, + unsigned long action, void *data) +{ + return NOTIFY_OK; +} + +static struct notifier_block update_buffer_nb = { + .notifier_call = ima_update_kexec_buffer, + .priority = INT_MIN +}; + +/* + * Create a mapping for the source pages that contain the IMA buffer + * so we can update it later. + */ +void ima_kexec_post_load(struct kimage *image) +{ + if (ima_kexec_buffer) { + kimage_unmap_segment(ima_kexec_buffer); + ima_kexec_buffer = NULL; + } + + if (!image->ima_buffer_addr) + return; + + ima_kexec_buffer = kimage_map_segment(image, + image->ima_buffer_addr, + image->ima_buffer_size); + if (!ima_kexec_buffer) { + pr_err("Could not map measurements buffer.\n"); + return; + } + + if (!ima_kexec_update_registered) { + register_reboot_notifier(&update_buffer_nb); + ima_kexec_update_registered = true; + } +} + #endif /* IMA_KEXEC */ /* -- cgit v1.2.3