Re: [PATCH v4 2/7] kexec: define functions to map and unmap segments

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Thanks Stefan for taking a look.

On 1/23/24 09:03, Stefan Berger wrote:


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@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);
+

This series applies to v6.5. You may want to rebase to 6.7.

Will rebase. Thanks for catching this.
  #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

Good eye catching this.
Will fix.
+
+    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

Will do.

~Tushar

  #endif /* IMA_KEXEC */
  /*

_______________________________________________
kexec mailing list
kexec@xxxxxxxxxxxxxxxxxxx
http://lists.infradead.org/mailman/listinfo/kexec




[Index of Archives]     [LM Sensors]     [Linux Sound]     [ALSA Users]     [ALSA Devel]     [Linux Audio Users]     [Linux Media]     [Kernel]     [Gimp]     [Yosemite News]     [Linux Media]

  Powered by Linux