bpf: Introduce bpf_arch_text_invalidate for bpf_prog_pack

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.

Song Liu committed 4 years ago

Commit fe736561 parent aadd1b63 files · +14 −0Browse files

Unified · Split

3 files

 	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 */

@@ -2365,6 +2365,7 @@ int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t, · 2364 unmodified lines
2365	void addr1, void addr2);	2365	void addr1, void addr2);
2366		2366
2367	void bpf_arch_text_copy(void dst, void *src, size_t len);	2367	void bpf_arch_text_copy(void dst, void *src, size_t len);
		2368	int bpf_arch_text_invalidate(void *dst, size_t len);
2368		2369
2369	struct btf_id_set;	2370	struct btf_id_set;
2370	bool btf_id_set_contains(const struct btf_id_set *set, u32 id);	2371	bool btf_id_set_contains(const struct btf_id_set *set, u32 id);

 	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) {
 	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);

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