1 files changed, 39 insertions, 0 deletions

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 2c2bfaacce66..8ee520f0ec70 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -20,9 +20,12 @@
  * Andi Kleen - Fix a few bad bugs and races.
  * Kris Katterjohn - Added many additional checks in bpf_check_classic()
  */
+
 #include <linux/filter.h>
 #include <linux/skbuff.h>
 #include <linux/vmalloc.h>
+#include <linux/random.h>
+#include <linux/moduleloader.h>
 #include <asm/unaligned.h>
 
 /* Registers */
@@ -125,6 +128,42 @@ void __bpf_prog_free(struct bpf_prog *fp)
 }
 EXPORT_SYMBOL_GPL(__bpf_prog_free);
 
+struct bpf_binary_header *
+bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr,
+                     unsigned int alignment,
+                     bpf_jit_fill_hole_t bpf_fill_ill_insns)
+{
+        struct bpf_binary_header *hdr;
+        unsigned int size, hole, start;
+
+        /* Most of BPF filters are really small, but if some of them
+         * fill a page, allow at least 128 extra bytes to insert a
+         * random section of illegal instructions.
+         */
+        size = round_up(proglen + sizeof(*hdr) + 128, PAGE_SIZE);
+        hdr = module_alloc(size);
+        if (hdr == NULL)
+                return NULL;
+
+        /* Fill space with illegal/arch-dep instructions. */
+        bpf_fill_ill_insns(hdr, size);
+
+        hdr->pages = size / PAGE_SIZE;
+        hole = min_t(unsigned int, size - (proglen + sizeof(*hdr)),
+                     PAGE_SIZE - sizeof(*hdr));
+        start = (prandom_u32() % hole) & ~(alignment - 1);
+
+        /* Leave a random number of instructions before BPF code. */
+        *image_ptr = &hdr->image[start];
+
+        return hdr;
+}
+
+void bpf_jit_binary_free(struct bpf_binary_header *hdr)
+{
+        module_free(NULL, hdr);
+}
+
 /* Base function for offset calculation. Needs to go into .text section,
  * therefore keeping it non-static as well; will also be used by JITs
  * anyway later on, so do not let the compiler omit it.