diff mbox series

[bpf-next,v1,1/6] bpf: Add check_func_arg_reg_off function

Message ID 20220301065745.1634848-2-memxor@gmail.com (mailing list archive)
State Superseded
Delegated to: BPF
Headers show
Series Fixes for bad PTR_TO_BTF_ID offset | expand

Checks

Context Check Description
netdev/tree_selection success Clearly marked for bpf-next
netdev/fixes_present success Fixes tag not required for -next series
netdev/subject_prefix success Link
netdev/cover_letter success Series has a cover letter
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 45 this patch: 45
netdev/cc_maintainers warning 6 maintainers not CCed: kpsingh@kernel.org john.fastabend@gmail.com kafai@fb.com songliubraving@fb.com yhs@fb.com netdev@vger.kernel.org
netdev/build_clang success Errors and warnings before: 18 this patch: 18
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 50 this patch: 50
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 90 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
bpf/vmtest-bpf-next-PR fail PR summary
bpf/vmtest-bpf-next fail VM_Test

Commit Message

Kumar Kartikeya Dwivedi March 1, 2022, 6:57 a.m. UTC 
Lift the list of register types allowed for having fixed and variable
offsets when passed as helper function arguments into a common helper,
so that they can be reused for kfunc checks in later commits. Keeping a
common helper aids maintainability and allows us to follow the same
consistent rules across helpers and kfuncs. Also, convert check_func_arg
to use this function.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
 include/linux/bpf_verifier.h |  3 ++
 kernel/bpf/verifier.c        | 69 +++++++++++++++++++++---------------
 2 files changed, 44 insertions(+), 28 deletions(-)
diff mbox series

Patch

diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index 7a7be8c057f2..38b24ee8d8c2 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -521,6 +521,9 @@  bpf_prog_offload_remove_insns(struct bpf_verifier_env *env, u32 off, u32 cnt);
 
 int check_ptr_off_reg(struct bpf_verifier_env *env,
 		      const struct bpf_reg_state *reg, int regno);
+int check_func_arg_reg_off(struct bpf_verifier_env *env,
+			   const struct bpf_reg_state *reg, int regno,
+			   enum bpf_arg_type arg_type);
 int check_kfunc_mem_size_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
 			     u32 regno);
 int check_mem_reg(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index d7473fee247c..a641e61767b4 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -5353,6 +5353,44 @@  static int check_reg_type(struct bpf_verifier_env *env, u32 regno,
 	return 0;
 }
 
+int check_func_arg_reg_off(struct bpf_verifier_env *env,
+			   const struct bpf_reg_state *reg, int regno,
+			   enum bpf_arg_type arg_type)
+{
+	enum bpf_reg_type type = reg->type;
+	int err;
+
+	switch ((u32)type) {
+	case SCALAR_VALUE:
+	/* Pointer types where reg offset is explicitly allowed: */
+	case PTR_TO_PACKET:
+	case PTR_TO_PACKET_META:
+	case PTR_TO_MAP_KEY:
+	case PTR_TO_MAP_VALUE:
+	case PTR_TO_MEM:
+	case PTR_TO_MEM | MEM_RDONLY:
+	case PTR_TO_MEM | MEM_ALLOC:
+	case PTR_TO_BUF:
+	case PTR_TO_BUF | MEM_RDONLY:
+	case PTR_TO_STACK:
+		/* Some of the argument types nevertheless require a
+		 * zero register offset.
+		 */
+		if (arg_type == ARG_PTR_TO_ALLOC_MEM)
+			goto force_off_check;
+		break;
+	/* All the rest must be rejected: */
+	default:
+force_off_check:
+		err = __check_ptr_off_reg(env, reg, regno,
+					  type == PTR_TO_BTF_ID);
+		if (err < 0)
+			return err;
+		break;
+	}
+	return 0;
+}
+
 static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
 			  struct bpf_call_arg_meta *meta,
 			  const struct bpf_func_proto *fn)
@@ -5402,34 +5440,9 @@  static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
 	if (err)
 		return err;
 
-	switch ((u32)type) {
-	case SCALAR_VALUE:
-	/* Pointer types where reg offset is explicitly allowed: */
-	case PTR_TO_PACKET:
-	case PTR_TO_PACKET_META:
-	case PTR_TO_MAP_KEY:
-	case PTR_TO_MAP_VALUE:
-	case PTR_TO_MEM:
-	case PTR_TO_MEM | MEM_RDONLY:
-	case PTR_TO_MEM | MEM_ALLOC:
-	case PTR_TO_BUF:
-	case PTR_TO_BUF | MEM_RDONLY:
-	case PTR_TO_STACK:
-		/* Some of the argument types nevertheless require a
-		 * zero register offset.
-		 */
-		if (arg_type == ARG_PTR_TO_ALLOC_MEM)
-			goto force_off_check;
-		break;
-	/* All the rest must be rejected: */
-	default:
-force_off_check:
-		err = __check_ptr_off_reg(env, reg, regno,
-					  type == PTR_TO_BTF_ID);
-		if (err < 0)
-			return err;
-		break;
-	}
+	err = check_func_arg_reg_off(env, reg, regno, arg_type);
+	if (err)
+		return err;
 
 skip_type_check:
 	if (reg->ref_obj_id) {