This is a note to let you know that I've just added the patch titled
bpf: don't (ab)use instructions to store state
to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: bpf-don-t-ab-use-instructions-to-store-state.patch and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From 3df126f35f88dc76eea33769f85a3c3bb8ce6c6b Mon Sep 17 00:00:00 2001
From: Jakub Kicinski jakub.kicinski@netronome.com Date: Wed, 21 Sep 2016 11:43:56 +0100 Subject: bpf: don't (ab)use instructions to store state
From: Jakub Kicinski jakub.kicinski@netronome.com
commit 3df126f35f88dc76eea33769f85a3c3bb8ce6c6b upstream.
Storing state in reserved fields of instructions makes it impossible to run verifier on programs already marked as read-only. Allocate and use an array of per-instruction state instead.
While touching the error path rename and move existing jump target.
Suggested-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Jakub Kicinski jakub.kicinski@netronome.com Acked-by: Alexei Starovoitov ast@kernel.org Acked-by: Daniel Borkmann daniel@iogearbox.net Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Jiri Slaby jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/bpf/verifier.c | 67 +++++++++++++++++++++++++++++--------------------- 1 file changed, 39 insertions(+), 28 deletions(-)
--- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -186,6 +186,10 @@ struct verifier_stack_elem { struct verifier_stack_elem *next; };
+struct bpf_insn_aux_data { + enum bpf_reg_type ptr_type; /* pointer type for load/store insns */ +}; + #define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */
/* single container for all structs @@ -200,6 +204,7 @@ struct verifier_env { struct bpf_map *used_maps[MAX_USED_MAPS]; /* array of map's used by eBPF program */ u32 used_map_cnt; /* number of used maps */ bool allow_ptr_leaks; + struct bpf_insn_aux_data *insn_aux_data; /* array of per-insn state */ };
/* verbose verifier prints what it's seeing @@ -1784,7 +1789,7 @@ static int do_check(struct verifier_env return err;
} else if (class == BPF_LDX) { - enum bpf_reg_type src_reg_type; + enum bpf_reg_type *prev_src_type, src_reg_type;
/* check for reserved fields is already done */
@@ -1813,16 +1818,18 @@ static int do_check(struct verifier_env continue; }
- if (insn->imm == 0) { + prev_src_type = &env->insn_aux_data[insn_idx].ptr_type; + + if (*prev_src_type == NOT_INIT) { /* saw a valid insn * dst_reg = *(u32 *)(src_reg + off) - * use reserved 'imm' field to mark this insn + * save type to validate intersecting paths */ - insn->imm = src_reg_type; + *prev_src_type = src_reg_type;
- } else if (src_reg_type != insn->imm && + } else if (src_reg_type != *prev_src_type && (src_reg_type == PTR_TO_CTX || - insn->imm == PTR_TO_CTX)) { + *prev_src_type == PTR_TO_CTX)) { /* ABuser program is trying to use the same insn * dst_reg = *(u32*) (src_reg + off) * with different pointer types: @@ -1835,7 +1842,7 @@ static int do_check(struct verifier_env }
} else if (class == BPF_STX) { - enum bpf_reg_type dst_reg_type; + enum bpf_reg_type *prev_dst_type, dst_reg_type;
if (BPF_MODE(insn->code) == BPF_XADD) { err = check_xadd(env, insn); @@ -1863,11 +1870,13 @@ static int do_check(struct verifier_env if (err) return err;
- if (insn->imm == 0) { - insn->imm = dst_reg_type; - } else if (dst_reg_type != insn->imm && + prev_dst_type = &env->insn_aux_data[insn_idx].ptr_type; + + if (*prev_dst_type == NOT_INIT) { + *prev_dst_type = dst_reg_type; + } else if (dst_reg_type != *prev_dst_type && (dst_reg_type == PTR_TO_CTX || - insn->imm == PTR_TO_CTX)) { + *prev_dst_type == PTR_TO_CTX)) { verbose("same insn cannot be used with different pointers\n"); return -EINVAL; } @@ -2104,17 +2113,17 @@ static void convert_pseudo_ld_imm64(stru static int convert_ctx_accesses(struct verifier_env *env) { struct bpf_insn *insn = env->prog->insnsi; - int insn_cnt = env->prog->len; + const int insn_cnt = env->prog->len; struct bpf_insn insn_buf[16]; struct bpf_prog *new_prog; enum bpf_access_type type; - int i; + int i, delta = 0;
if (!env->prog->aux->ops->convert_ctx_access) return 0;
for (i = 0; i < insn_cnt; i++, insn++) { - u32 insn_delta, cnt; + u32 cnt;
if (insn->code == (BPF_LDX | BPF_MEM | BPF_W)) type = BPF_READ; @@ -2123,11 +2132,8 @@ static int convert_ctx_accesses(struct v else continue;
- if (insn->imm != PTR_TO_CTX) { - /* clear internal mark */ - insn->imm = 0; + if (env->insn_aux_data[i].ptr_type != PTR_TO_CTX) continue; - }
cnt = env->prog->aux->ops-> convert_ctx_access(type, insn->dst_reg, insn->src_reg, @@ -2137,18 +2143,16 @@ static int convert_ctx_accesses(struct v return -EINVAL; }
- new_prog = bpf_patch_insn_single(env->prog, i, insn_buf, cnt); + new_prog = bpf_patch_insn_single(env->prog, i + delta, insn_buf, + cnt); if (!new_prog) return -ENOMEM;
- insn_delta = cnt - 1; + delta += cnt - 1;
/* keep walking new program and skip insns we just inserted */ env->prog = new_prog; - insn = new_prog->insnsi + i + insn_delta; - - insn_cnt += insn_delta; - i += insn_delta; + insn = new_prog->insnsi + i + delta; }
return 0; @@ -2192,6 +2196,11 @@ int bpf_check(struct bpf_prog **prog, un if (!env) return -ENOMEM;
+ env->insn_aux_data = vzalloc(sizeof(struct bpf_insn_aux_data) * + (*prog)->len); + ret = -ENOMEM; + if (!env->insn_aux_data) + goto err_free_env; env->prog = *prog;
/* grab the mutex to protect few globals used by verifier */ @@ -2210,12 +2219,12 @@ int bpf_check(struct bpf_prog **prog, un /* log_* values have to be sane */ if (log_size < 128 || log_size > UINT_MAX >> 8 || log_level == 0 || log_ubuf == NULL) - goto free_env; + goto err_unlock;
ret = -ENOMEM; log_buf = vmalloc(log_size); if (!log_buf) - goto free_env; + goto err_unlock; } else { log_level = 0; } @@ -2284,14 +2293,16 @@ skip_full_check: free_log_buf: if (log_level) vfree(log_buf); -free_env: if (!env->prog->aux->used_maps) /* if we didn't copy map pointers into bpf_prog_info, release * them now. Otherwise free_bpf_prog_info() will release them. */ release_maps(env); *prog = env->prog; - kfree(env); +err_unlock: mutex_unlock(&bpf_verifier_lock); + vfree(env->insn_aux_data); +err_free_env: + kfree(env); return ret; }
Patches currently in stable-queue which might be from jakub.kicinski@netronome.com are
queue-4.4/bpf-don-t-ab-use-instructions-to-store-state.patch