Introduce bpf_arch_text_invalidate and use it to fill unused part of the
bpf_prog_pack with illegal instructions when a BPF program is freed.
Signed-off-by: Song Liu <song@xxxxxxxxxx>
---
arch/x86/net/bpf_jit_comp.c | 5 +++++
include/linux/bpf.h | 1 +
kernel/bpf/core.c | 8 ++++++++
3 files changed, 14 insertions(+)
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index a2b6d197c226..f298b18a9a3d 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -228,6 +228,11 @@ static void jit_fill_hole(void *area, unsigned int size)
memset(area, 0xcc, size);
}
+int bpf_arch_text_invalidate(void *dst, size_t len)
+{
+ return IS_ERR_OR_NULL(text_poke_set(dst, 0xcc, len));
+}
+
struct jit_context {
int cleanup_addr; /* Epilogue code offset */
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index cc4d5e394031..a9b1875212f6 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -2365,6 +2365,7 @@ int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t,
void *addr1, void *addr2);
void *bpf_arch_text_copy(void *dst, void *src, size_t len);
+int bpf_arch_text_invalidate(void *dst, size_t len);
struct btf_id_set;
bool btf_id_set_contains(const struct btf_id_set *set, u32 id);
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 2d0c9d4696ad..cacd8684c3c4 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -968,6 +968,9 @@ static void bpf_prog_pack_free(struct bpf_binary_header *hdr)
nbits = BPF_PROG_SIZE_TO_NBITS(hdr->size);
pos = ((unsigned long)hdr - (unsigned long)pack_ptr) >> BPF_PROG_CHUNK_SHIFT;
+ WARN_ONCE(bpf_arch_text_invalidate(hdr, hdr->size),
+ "bpf_prog_pack bug: missing bpf_arch_text_invalidate?\n");
+
bitmap_clear(pack->bitmap, pos, nbits);
if (bitmap_find_next_zero_area(pack->bitmap, bpf_prog_chunk_count(), 0,
bpf_prog_chunk_count(), 0) == 0) {
@@ -2740,6 +2743,11 @@ void * __weak bpf_arch_text_copy(void *dst, void *src, size_t len)
return ERR_PTR(-ENOTSUPP);
}
+int __weak bpf_arch_text_invalidate(void *dst, size_t len)
+{
+ return -ENOTSUPP;
+}
+
DEFINE_STATIC_KEY_FALSE(bpf_stats_enabled_key);
EXPORT_SYMBOL(bpf_stats_enabled_key);
--
2.30.2
