All of lore.kernel.org
 help / color / mirror / Atom feed
From: Joanne Koong <joannelkoong@gmail.com>
To: bpf@vger.kernel.org
Cc: andrii@kernel.org, daniel@iogearbox.net, ast@kernel.org,
	Joanne Koong <joannelkoong@gmail.com>
Subject: [PATCH bpf-next v1] bpf: Tidy up verifier check_func_arg()
Date: Tue, 12 Jul 2022 14:06:03 -0700	[thread overview]
Message-ID: <20220712210603.123791-1-joannelkoong@gmail.com> (raw)

This patch does two things:

1. For matching against the arg type, the match should be against the
base type of the arg type, since the arg type can have different
bpf_type_flags set on it.

2. Uses switch casing to improve readability + efficiency.

Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
---
 kernel/bpf/verifier.c | 66 +++++++++++++++++++++++++------------------
 1 file changed, 38 insertions(+), 28 deletions(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 328cfab3af60..26e7e787c20a 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -5533,17 +5533,6 @@ static bool arg_type_is_mem_size(enum bpf_arg_type type)
 	       type == ARG_CONST_SIZE_OR_ZERO;
 }
 
-static bool arg_type_is_alloc_size(enum bpf_arg_type type)
-{
-	return type == ARG_CONST_ALLOC_SIZE_OR_ZERO;
-}
-
-static bool arg_type_is_int_ptr(enum bpf_arg_type type)
-{
-	return type == ARG_PTR_TO_INT ||
-	       type == ARG_PTR_TO_LONG;
-}
-
 static bool arg_type_is_release(enum bpf_arg_type type)
 {
 	return type & OBJ_RELEASE;
@@ -5929,7 +5918,8 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
 		meta->ref_obj_id = reg->ref_obj_id;
 	}
 
-	if (arg_type == ARG_CONST_MAP_PTR) {
+	switch (base_type(arg_type)) {
+	case ARG_CONST_MAP_PTR:
 		/* bpf_map_xxx(map_ptr) call: remember that map_ptr */
 		if (meta->map_ptr) {
 			/* Use map_uid (which is unique id of inner map) to reject:
@@ -5954,7 +5944,8 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
 		}
 		meta->map_ptr = reg->map_ptr;
 		meta->map_uid = reg->map_uid;
-	} else if (arg_type == ARG_PTR_TO_MAP_KEY) {
+		break;
+	case ARG_PTR_TO_MAP_KEY:
 		/* bpf_map_xxx(..., map_ptr, ..., key) call:
 		 * check that [key, key + map->key_size) are within
 		 * stack limits and initialized
@@ -5971,7 +5962,8 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
 		err = check_helper_mem_access(env, regno,
 					      meta->map_ptr->key_size, false,
 					      NULL);
-	} else if (base_type(arg_type) == ARG_PTR_TO_MAP_VALUE) {
+		break;
+	case ARG_PTR_TO_MAP_VALUE:
 		if (type_may_be_null(arg_type) && register_is_null(reg))
 			return 0;
 
@@ -5987,14 +5979,16 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
 		err = check_helper_mem_access(env, regno,
 					      meta->map_ptr->value_size, false,
 					      meta);
-	} else if (arg_type == ARG_PTR_TO_PERCPU_BTF_ID) {
+		break;
+	case ARG_PTR_TO_PERCPU_BTF_ID:
 		if (!reg->btf_id) {
 			verbose(env, "Helper has invalid btf_id in R%d\n", regno);
 			return -EACCES;
 		}
 		meta->ret_btf = reg->btf;
 		meta->ret_btf_id = reg->btf_id;
-	} else if (arg_type == ARG_PTR_TO_SPIN_LOCK) {
+		break;
+	case ARG_PTR_TO_SPIN_LOCK:
 		if (meta->func_id == BPF_FUNC_spin_lock) {
 			if (process_spin_lock(env, regno, true))
 				return -EACCES;
@@ -6005,12 +5999,15 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
 			verbose(env, "verifier internal error\n");
 			return -EFAULT;
 		}
-	} else if (arg_type == ARG_PTR_TO_TIMER) {
+		break;
+	case ARG_PTR_TO_TIMER:
 		if (process_timer_func(env, regno, meta))
 			return -EACCES;
-	} else if (arg_type == ARG_PTR_TO_FUNC) {
+		break;
+	case ARG_PTR_TO_FUNC:
 		meta->subprogno = reg->subprogno;
-	} else if (base_type(arg_type) == ARG_PTR_TO_MEM) {
+		break;
+	case ARG_PTR_TO_MEM:
 		/* The access to this pointer is only checked when we hit the
 		 * next is_mem_size argument below.
 		 */
@@ -6020,11 +6017,14 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
 						      fn->arg_size[arg], false,
 						      meta);
 		}
-	} else if (arg_type_is_mem_size(arg_type)) {
-		bool zero_size_allowed = (arg_type == ARG_CONST_SIZE_OR_ZERO);
-
-		err = check_mem_size_reg(env, reg, regno, zero_size_allowed, meta);
-	} else if (arg_type_is_dynptr(arg_type)) {
+		break;
+	case ARG_CONST_SIZE:
+		err = check_mem_size_reg(env, reg, regno, false, meta);
+		break;
+	case ARG_CONST_SIZE_OR_ZERO:
+		err = check_mem_size_reg(env, reg, regno, true, meta);
+		break;
+	case ARG_PTR_TO_DYNPTR:
 		if (arg_type & MEM_UNINIT) {
 			if (!is_dynptr_reg_valid_uninit(env, reg)) {
 				verbose(env, "Dynptr has to be an uninitialized dynptr\n");
@@ -6058,21 +6058,28 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
 				err_extra, arg + 1);
 			return -EINVAL;
 		}
-	} else if (arg_type_is_alloc_size(arg_type)) {
+		break;
+	case ARG_CONST_ALLOC_SIZE_OR_ZERO:
 		if (!tnum_is_const(reg->var_off)) {
 			verbose(env, "R%d is not a known constant'\n",
 				regno);
 			return -EACCES;
 		}
 		meta->mem_size = reg->var_off.value;
-	} else if (arg_type_is_int_ptr(arg_type)) {
+		break;
+	case ARG_PTR_TO_INT:
+	case ARG_PTR_TO_LONG:
+	{
 		int size = int_ptr_type_to_size(arg_type);
 
 		err = check_helper_mem_access(env, regno, size, false, meta);
 		if (err)
 			return err;
 		err = check_ptr_alignment(env, reg, 0, size, true);
-	} else if (arg_type == ARG_PTR_TO_CONST_STR) {
+		break;
+	}
+	case ARG_PTR_TO_CONST_STR:
+	{
 		struct bpf_map *map = reg->map_ptr;
 		int map_off;
 		u64 map_addr;
@@ -6111,9 +6118,12 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
 			verbose(env, "string is not zero-terminated\n");
 			return -EINVAL;
 		}
-	} else if (arg_type == ARG_PTR_TO_KPTR) {
+		break;
+	}
+	case ARG_PTR_TO_KPTR:
 		if (process_kptr_func(env, regno, meta))
 			return -EACCES;
+		break;
 	}
 
 	return err;
-- 
2.30.2


             reply	other threads:[~2022-07-12 21:07 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-07-12 21:06 Joanne Koong [this message]
2022-07-12 22:44 ` [PATCH bpf-next v1] bpf: Tidy up verifier check_func_arg() sdf
2022-07-13  1:10   ` Joanne Koong
2022-07-13  1:20     ` Hao Luo
2022-07-13  1:25       ` Alexei Starovoitov
2022-07-13  1:38         ` Hao Luo
2022-07-13  2:10           ` Stanislav Fomichev
2022-07-13 20:09             ` Joanne Koong
2022-07-13 21:50 ` patchwork-bot+netdevbpf

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20220712210603.123791-1-joannelkoong@gmail.com \
    --to=joannelkoong@gmail.com \
    --cc=andrii@kernel.org \
    --cc=ast@kernel.org \
    --cc=bpf@vger.kernel.org \
    --cc=daniel@iogearbox.net \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.