diff mbox series

[PATCHv18,bpf-next,2/6] bpf: add a new bpf argument type ARG_CONST_MAP_PTR_OR_NULL

Message ID 20210204140317.384296-3-liuhangbin@gmail.com (mailing list archive)
State Superseded
Delegated to: BPF
Headers show
Series xdp: add a new helper for dev map multicast support | expand

Checks

Context Check Description
netdev/cover_letter success Link
netdev/fixes_present success Link
netdev/patch_count success Link
netdev/tree_selection success Clearly marked for bpf-next
netdev/subject_prefix success Link
netdev/cc_maintainers warning 5 maintainers not CCed: songliubraving@fb.com andrii@kernel.org kpsingh@kernel.org kafai@fb.com yhs@fb.com
netdev/source_inline success Was 0 now: 0
netdev/verify_signedoff success Link
netdev/module_param success Was 0 now: 0
netdev/build_32bit success Errors and warnings before: 12175 this patch: 12175
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/verify_fixes success Link
netdev/checkpatch warning WARNING: line length of 95 exceeds 80 columns
netdev/build_allmodconfig_warn success Errors and warnings before: 12823 this patch: 12823
netdev/header_inline success Link
netdev/stable success Stable not CCed

Commit Message

Hangbin Liu Feb. 4, 2021, 2:03 p.m. UTC
Add a new bpf argument type ARG_CONST_MAP_PTR_OR_NULL which could be
used when we want to allow NULL pointer for map parameter. The bpf helper
need to take care and check if the map is NULL when use this type.

Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>

v13-v18: no update
v11-v12: rebase the patch to latest bpf-next
v10: remove useless CONST_PTR_TO_MAP_OR_NULL and Copy-paste comment.
v9: merge the patch from [1] in to this series.
v1-v8: no this patch

[1] https://lore.kernel.org/bpf/20200715070001.2048207-1-liuhangbin@gmail.com/
---
 include/linux/bpf.h   |  1 +
 kernel/bpf/verifier.c | 10 ++++++----
 2 files changed, 7 insertions(+), 4 deletions(-)
diff mbox series

Patch

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 321966fc35db..b0777c8c03fd 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -296,6 +296,7 @@  enum bpf_arg_type {
 	ARG_CONST_ALLOC_SIZE_OR_ZERO,	/* number of allocated bytes requested */
 	ARG_PTR_TO_BTF_ID_SOCK_COMMON,	/* pointer to in-kernel sock_common or bpf-mirrored bpf_sock */
 	ARG_PTR_TO_PERCPU_BTF_ID,	/* pointer to in-kernel percpu type */
+	ARG_CONST_MAP_PTR_OR_NULL,	/* const argument used as pointer to bpf_map or NULL */
 	__BPF_ARG_TYPE_MAX,
 };
 
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 5e09632efddb..50a17f80358b 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -445,7 +445,8 @@  static bool arg_type_may_be_null(enum bpf_arg_type type)
 	       type == ARG_PTR_TO_MEM_OR_NULL ||
 	       type == ARG_PTR_TO_CTX_OR_NULL ||
 	       type == ARG_PTR_TO_SOCKET_OR_NULL ||
-	       type == ARG_PTR_TO_ALLOC_MEM_OR_NULL;
+	       type == ARG_PTR_TO_ALLOC_MEM_OR_NULL ||
+	       type == ARG_CONST_MAP_PTR_OR_NULL;
 }
 
 /* Determine whether the function releases some resources allocated by another
@@ -4112,6 +4113,7 @@  static const struct bpf_reg_types *compatible_reg_types[__BPF_ARG_TYPE_MAX] = {
 	[ARG_CONST_SIZE_OR_ZERO]	= &scalar_types,
 	[ARG_CONST_ALLOC_SIZE_OR_ZERO]	= &scalar_types,
 	[ARG_CONST_MAP_PTR]		= &const_map_ptr_types,
+	[ARG_CONST_MAP_PTR_OR_NULL]	= &const_map_ptr_types,
 	[ARG_PTR_TO_CTX]		= &context_types,
 	[ARG_PTR_TO_CTX_OR_NULL]	= &context_types,
 	[ARG_PTR_TO_SOCK_COMMON]	= &sock_types,
@@ -4257,9 +4259,9 @@  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) {
-		/* bpf_map_xxx(map_ptr) call: remember that map_ptr */
-		meta->map_ptr = reg->map_ptr;
+	if (arg_type == ARG_CONST_MAP_PTR ||
+	    arg_type == ARG_CONST_MAP_PTR_OR_NULL) {
+		meta->map_ptr = register_is_null(reg) ? NULL : reg->map_ptr;
 	} else if (arg_type == ARG_PTR_TO_MAP_KEY) {
 		/* bpf_map_xxx(..., map_ptr, ..., key) call:
 		 * check that [key, key + map->key_size) are within