| Message ID | 20220520235758.1858153-4-song@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | bpf_prog_pack followup | expand |
On Fri, May 20, 2022 at 04:57:53PM -0700, Song Liu wrote: > 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@kernel.org> > --- > 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"); Why is this a WARN? What happens if bpf_arch_text_invalidate() is implemented but returns an error? > + > 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 > >
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);
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@kernel.org> --- arch/x86/net/bpf_jit_comp.c | 5 +++++ include/linux/bpf.h | 1 + kernel/bpf/core.c | 8 ++++++++ 3 files changed, 14 insertions(+)