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

@@ -228,6 +228,11 @@ static void jit_fill_hole(void *area, unsigned int size) · 227 unmodified lines
228	228	memset(area, 0xcc, size);
229	229	}
230	230
	231	+int bpf_arch_text_invalidate(void *dst, size_t len)
	232	+{
	233	+ return IS_ERR_OR_NULL(text_poke_set(dst, 0xcc, len));
	234	+}
	235	+
231	236	struct jit_context {
232	237	int cleanup_addr; /* Epilogue code offset */
233	238

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

@@ -968,6 +968,9 @@ static void bpf_prog_pack_free(struct bpf_binary_header *hdr) · 967 unmodified lines
968	968	nbits = BPF_PROG_SIZE_TO_NBITS(hdr->size);
969	969	pos = ((unsigned long)hdr - (unsigned long)pack_ptr) >> BPF_PROG_CHUNK_SHIFT;
970	970
	971	+ WARN_ONCE(bpf_arch_text_invalidate(hdr, hdr->size),
	972	+ "bpf_prog_pack bug: missing bpf_arch_text_invalidate?\n");
	973	+
971	974	bitmap_clear(pack->bitmap, pos, nbits);
972	975	if (bitmap_find_next_zero_area(pack->bitmap, bpf_prog_chunk_count(), 0,
973	976	bpf_prog_chunk_count(), 0) == 0) {
@@ -2740,6 +2743,11 @@ void * __weak bpf_arch_text_copy(void dst, void src, size_t len) · 1766 unmodified lines
2740	2743	return ERR_PTR(-ENOTSUPP);
2741	2744	}
2742	2745
	2746	+int __weak bpf_arch_text_invalidate(void *dst, size_t len)
	2747	+{
	2748	+ return -ENOTSUPP;
	2749	+}
	2750	+
2743	2751	DEFINE_STATIC_KEY_FALSE(bpf_stats_enabled_key);
2744	2752	EXPORT_SYMBOL(bpf_stats_enabled_key);
2745	2753

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