Implement kimage_map_segment() to enable mapping of IMA buffer source
pages to the kimage structure post kexec 'load'. This function,
accepting a kimage pointer, an address, and a size, will gather the
source pages within the specified address range, create an array of page
pointers, and map these to a contiguous virtual address range. The
function returns the start of this range if successful, or NULL if
unsuccessful.
Implement kimage_unmap_segment() for unmapping segments
using vunmap(). Relocate 'for_each_kimage_entry()' macro from
kexec_core.c to kexec.h for broader accessibility.
Signed-off-by: Tushar Sugandhi <tusharsu@xxxxxxxxxxxxxxxxxxx>
---
include/linux/kexec.h | 13 +++++++
kernel/kexec_core.c | 59 +++++++++++++++++++++++++++---
security/integrity/ima/ima_kexec.c | 1 +
3 files changed, 68 insertions(+), 5 deletions(-)
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index 22b5cd24f581..e00b8101b53b 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -490,6 +490,15 @@ static inline int arch_kexec_post_alloc_pages(void *vaddr, unsigned int pages, g
static inline void arch_kexec_pre_free_pages(void *vaddr, unsigned int pages) { }
#endif
+#define for_each_kimage_entry(image, ptr, entry) \
+ for (ptr = &image->head; (entry = *ptr) && !(entry & IND_DONE); \
+ ptr = (entry & IND_INDIRECTION) ? \
+ boot_phys_to_virt((entry & PAGE_MASK)) : ptr + 1)
+
+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;
@@ -497,6 +506,10 @@ 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 */
diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index 3d578c6fefee..26978ad02676 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -594,11 +594,6 @@ void kimage_terminate(struct kimage *image)
*image->entry = IND_DONE;
}
-#define for_each_kimage_entry(image, ptr, entry) \
- for (ptr = &image->head; (entry = *ptr) && !(entry & IND_DONE); \
- ptr = (entry & IND_INDIRECTION) ? \
- boot_phys_to_virt((entry & PAGE_MASK)) : ptr + 1)
-
static void kimage_free_entry(kimage_entry_t entry)
{
struct page *page;
@@ -921,6 +916,60 @@ int kimage_load_segment(struct kimage *image,
return result;
}
+void *kimage_map_segment(struct kimage *image,
+ unsigned long addr, unsigned long size)
+{
+ unsigned long eaddr = addr + size;
+ unsigned long src_page_addr, dest_page_addr;
+ unsigned int npages;
+ struct page **src_pages;
+ int i;
+ kimage_entry_t *ptr, entry;
+ void *vaddr = NULL;
+
+ /*
+ * 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("%s: Could not allocate ima pages array.\n", __func__);
+ 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("%s: Could not map imap buffer.\n", __func__);
+
+ return vaddr;
+}
+
+void kimage_unmap_segment(void *segment_buffer)
+{
+ vunmap(segment_buffer);
+}
+
struct kexec_load_limit {
/* Mutex protects the limit count. */
struct mutex mutex;
diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
index 99daac355c70..4f944c9b4168 100644
--- a/security/integrity/ima/ima_kexec.c
+++ b/security/integrity/ima/ima_kexec.c
@@ -170,6 +170,7 @@ void ima_add_kexec_buffer(struct kimage *image)
pr_debug("kexec measurement buffer for the loaded kernel at 0x%lx.\n",
kbuf.mem);
}
+
#endif /* IMA_KEXEC */
/*
--
2.25.1
