On 1/22/24 13:37, Tushar Sugandhi wrote:
> 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 at linux.microsoft.com>
> ---
> 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);
> +
This series applies to v6.5. You may want to rebase to 6.7.
> #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__);
imap -> ima
> +
> + 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);
> }
> +
remove
> #endif /* IMA_KEXEC */
>
> /*