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 --- kernel/kexec_core.c | 54 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 54 insertions(+) (limited to 'kernel') diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c index 3e62b944c883..9c59fa480b0b 100644 --- a/kernel/kexec_core.c +++ b/kernel/kexec_core.c @@ -877,6 +877,60 @@ int kimage_load_segment(struct kimage *image, return result; } +void *kimage_map_segment(struct kimage *image, + unsigned long addr, unsigned long size) +{ + unsigned long src_page_addr, dest_page_addr = 0; + unsigned long eaddr = addr + size; + kimage_entry_t *ptr, entry; + struct page **src_pages; + unsigned int npages; + void *vaddr = NULL; + int i; + + /* + * Collect the source pages and map them in a contiguous VA range. + */ + npages = PFN_UP(eaddr) - PFN_DOWN(addr); + src_pages = kmalloc_array(npages, sizeof(*src_pages), GFP_KERNEL); + if (!src_pages) { + pr_err("Could not allocate ima pages array.\n"); + return NULL; + } + + i = 0; + for_each_kimage_entry(image, ptr, entry) { + if (entry & IND_DESTINATION) { + dest_page_addr = entry & PAGE_MASK; + } else if (entry & IND_SOURCE) { + if (dest_page_addr >= addr && dest_page_addr < eaddr) { + src_page_addr = entry & PAGE_MASK; + src_pages[i++] = + virt_to_page(__va(src_page_addr)); + if (i == npages) + break; + dest_page_addr += PAGE_SIZE; + } + } + } + + /* Sanity check. */ + WARN_ON(i < npages); + + vaddr = vmap(src_pages, npages, VM_MAP, PAGE_KERNEL); + kfree(src_pages); + + if (!vaddr) + pr_err("Could not map ima buffer.\n"); + + return vaddr; +} + +void kimage_unmap_segment(void *segment_buffer) +{ + vunmap(segment_buffer); +} + struct kexec_load_limit { /* Mutex protects the limit count. */ struct mutex mutex; -- cgit v1.2.3-59-g8ed1b 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 'kernel') 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 v1.2.3-59-g8ed1b From 9f0ec4b16f2b41d663f688a8012e9e52b2657eba Mon Sep 17 00:00:00 2001 From: Steven Chen Date: Mon, 21 Apr 2025 15:25:12 -0700 Subject: ima: kexec: move IMA log copy from kexec load to execute 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 --- kernel/kexec_file.c | 11 +++++++++- security/integrity/ima/ima_kexec.c | 43 +++++++++++++++++++++++++------------- 2 files changed, 39 insertions(+), 15 deletions(-) (limited to 'kernel') diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c index f6e80ebc33e9..0adb645072aa 100644 --- a/kernel/kexec_file.c +++ b/kernel/kexec_file.c @@ -201,6 +201,15 @@ kimage_validate_signature(struct kimage *image) } #endif +static int kexec_post_load(struct kimage *image, unsigned long flags) +{ +#ifdef CONFIG_IMA_KEXEC + if (!(flags & KEXEC_FILE_ON_CRASH)) + ima_kexec_post_load(image); +#endif + return machine_kexec_post_load(image); +} + /* * In file mode list of segments is prepared by kernel. Copy relevant * data from user space, do error checking, prepare segment list @@ -428,7 +437,7 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd, kimage_terminate(image); - ret = machine_kexec_post_load(image); + ret = kexec_post_load(image, flags); if (ret) goto out; diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c index e79f6caf895b..5c3b3e0b2186 100644 --- a/security/integrity/ima/ima_kexec.c +++ b/security/integrity/ima/ima_kexec.c @@ -19,6 +19,7 @@ #ifdef CONFIG_IMA_KEXEC static bool ima_kexec_update_registered; static struct seq_file ima_kexec_file; +static size_t kexec_segment_size; static void *ima_kexec_buffer; static void ima_free_kexec_file_buf(struct seq_file *sf) @@ -72,9 +73,6 @@ static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer, } } - if (ret < 0) - goto out; - /* * fill in reserved space with some buffer details * (eg. version, buffer size, number of measurements) @@ -94,7 +92,7 @@ static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer, *buffer_size = ima_kexec_file.count; *buffer = ima_kexec_file.buf; -out: + return ret; } @@ -112,9 +110,8 @@ void ima_add_kexec_buffer(struct kimage *image) unsigned long binary_runtime_size; /* use more understandable variable names than defined in kbuf */ + size_t kexec_buffer_size = 0; void *kexec_buffer = NULL; - size_t kexec_buffer_size; - size_t kexec_segment_size; int ret; /* @@ -139,13 +136,6 @@ void ima_add_kexec_buffer(struct kimage *image) return; } - ima_dump_measurement_list(&kexec_buffer_size, &kexec_buffer, - kexec_segment_size); - if (!kexec_buffer) { - pr_err("Not enough memory for the kexec measurement buffer.\n"); - return; - } - kbuf.buffer = kexec_buffer; kbuf.bufsz = kexec_buffer_size; kbuf.memsz = kexec_segment_size; @@ -173,7 +163,32 @@ void ima_add_kexec_buffer(struct kimage *image) static int ima_update_kexec_buffer(struct notifier_block *self, unsigned long action, void *data) { - return NOTIFY_OK; + size_t buf_size = 0; + int ret = NOTIFY_OK; + void *buf = NULL; + + if (!kexec_in_progress) { + pr_info("No kexec in progress.\n"); + return ret; + } + + if (!ima_kexec_buffer) { + pr_err("Kexec buffer not set.\n"); + return ret; + } + + ret = ima_dump_measurement_list(&buf_size, &buf, kexec_segment_size); + + if (ret) + pr_err("Dump measurements failed. Error:%d\n", ret); + + if (buf_size != 0) + memcpy(ima_kexec_buffer, buf, buf_size); + + kimage_unmap_segment(ima_kexec_buffer); + ima_kexec_buffer = NULL; + + return ret; } static struct notifier_block update_buffer_nb = { -- cgit v1.2.3-59-g8ed1b