Commit 91571a51 authored by Alexei Starovoitov's avatar Alexei Starovoitov Committed by Andrii Nakryiko
Browse files

bpf: Teach verifier that certain helpers accept NULL pointer. 



bpf_[sk|inode|task|cgrp]_storage_[get|delete]() and bpf_get_socket_cookie() helpers
perform run-time check that sk|inode|task|cgrp pointer != NULL.
Teach verifier about this fact and allow bpf programs to pass
PTR_TO_BTF_ID | PTR_MAYBE_NULL into such helpers.
It will be used in the subsequent patch that will do
bpf_sk_storage_get(.., skb->sk, ...);
Even when 'skb' pointer is trusted the 'sk' pointer may be NULL.

Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Acked-by: default avatarDavid Vernet <void@manifault.com>
Link: https://lore.kernel.org/bpf/20230404045029.82870-5-alexei.starovoitov@gmail.com
parent 63260df1

kernel/bpf/bpf_cgrp_storage.c

+2 −2
Original line number Diff line number Diff line
@@ -224,7 +224,7 @@ const struct bpf_func_proto bpf_cgrp_storage_get_proto = { 
	.gpl_only	= false,

	.ret_type	= RET_PTR_TO_MAP_VALUE_OR_NULL,

	.arg1_type	= ARG_CONST_MAP_PTR,

	.arg2_type	= ARG_PTR_TO_BTF_ID,

	.arg2_type	= ARG_PTR_TO_BTF_ID_OR_NULL,

	.arg2_btf_id	= &bpf_cgroup_btf_id[0],

	.arg3_type	= ARG_PTR_TO_MAP_VALUE_OR_NULL,

	.arg4_type	= ARG_ANYTHING,
@@ -235,6 +235,6 @@ const struct bpf_func_proto bpf_cgrp_storage_delete_proto = { 
	.gpl_only	= false,

	.ret_type	= RET_INTEGER,

	.arg1_type	= ARG_CONST_MAP_PTR,

	.arg2_type	= ARG_PTR_TO_BTF_ID,

	.arg2_type	= ARG_PTR_TO_BTF_ID_OR_NULL,

	.arg2_btf_id	= &bpf_cgroup_btf_id[0],

};

kernel/bpf/bpf_inode_storage.c

+2 −2
Original line number Diff line number Diff line
@@ -229,7 +229,7 @@ const struct bpf_func_proto bpf_inode_storage_get_proto = { 
	.gpl_only	= false,

	.ret_type	= RET_PTR_TO_MAP_VALUE_OR_NULL,

	.arg1_type	= ARG_CONST_MAP_PTR,

	.arg2_type	= ARG_PTR_TO_BTF_ID,

	.arg2_type	= ARG_PTR_TO_BTF_ID_OR_NULL,

	.arg2_btf_id	= &bpf_inode_storage_btf_ids[0],

	.arg3_type	= ARG_PTR_TO_MAP_VALUE_OR_NULL,

	.arg4_type	= ARG_ANYTHING,
@@ -240,6 +240,6 @@ const struct bpf_func_proto bpf_inode_storage_delete_proto = { 
	.gpl_only	= false,

	.ret_type	= RET_INTEGER,

	.arg1_type	= ARG_CONST_MAP_PTR,

	.arg2_type	= ARG_PTR_TO_BTF_ID,

	.arg2_type	= ARG_PTR_TO_BTF_ID_OR_NULL,

	.arg2_btf_id	= &bpf_inode_storage_btf_ids[0],

};

kernel/bpf/bpf_task_storage.c

+4 −4
Original line number Diff line number Diff line
@@ -338,7 +338,7 @@ const struct bpf_func_proto bpf_task_storage_get_recur_proto = { 
	.gpl_only = false,

	.ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,

	.arg1_type = ARG_CONST_MAP_PTR,

	.arg2_type = ARG_PTR_TO_BTF_ID,

	.arg2_type = ARG_PTR_TO_BTF_ID_OR_NULL,

	.arg2_btf_id = &btf_tracing_ids[BTF_TRACING_TYPE_TASK],

	.arg3_type = ARG_PTR_TO_MAP_VALUE_OR_NULL,

	.arg4_type = ARG_ANYTHING,
@@ -349,7 +349,7 @@ const struct bpf_func_proto bpf_task_storage_get_proto = { 
	.gpl_only = false,

	.ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,

	.arg1_type = ARG_CONST_MAP_PTR,

	.arg2_type = ARG_PTR_TO_BTF_ID,

	.arg2_type = ARG_PTR_TO_BTF_ID_OR_NULL,

	.arg2_btf_id = &btf_tracing_ids[BTF_TRACING_TYPE_TASK],

	.arg3_type = ARG_PTR_TO_MAP_VALUE_OR_NULL,

	.arg4_type = ARG_ANYTHING,
@@ -360,7 +360,7 @@ const struct bpf_func_proto bpf_task_storage_delete_recur_proto = { 
	.gpl_only = false,

	.ret_type = RET_INTEGER,

	.arg1_type = ARG_CONST_MAP_PTR,

	.arg2_type = ARG_PTR_TO_BTF_ID,

	.arg2_type = ARG_PTR_TO_BTF_ID_OR_NULL,

	.arg2_btf_id = &btf_tracing_ids[BTF_TRACING_TYPE_TASK],

};
@@ -369,6 +369,6 @@ const struct bpf_func_proto bpf_task_storage_delete_proto = { 
	.gpl_only = false,

	.ret_type = RET_INTEGER,

	.arg1_type = ARG_CONST_MAP_PTR,

	.arg2_type = ARG_PTR_TO_BTF_ID,

	.arg2_type = ARG_PTR_TO_BTF_ID_OR_NULL,

	.arg2_btf_id = &btf_tracing_ids[BTF_TRACING_TYPE_TASK],

};

net/core/bpf_sk_storage.c

+2 −2
Original line number Diff line number Diff line
@@ -412,7 +412,7 @@ const struct bpf_func_proto bpf_sk_storage_get_tracing_proto = { 
	.gpl_only	= false,

	.ret_type	= RET_PTR_TO_MAP_VALUE_OR_NULL,

	.arg1_type	= ARG_CONST_MAP_PTR,

	.arg2_type	= ARG_PTR_TO_BTF_ID,

	.arg2_type	= ARG_PTR_TO_BTF_ID_OR_NULL,

	.arg2_btf_id	= &btf_sock_ids[BTF_SOCK_TYPE_SOCK_COMMON],

	.arg3_type	= ARG_PTR_TO_MAP_VALUE_OR_NULL,

	.arg4_type	= ARG_ANYTHING,
@@ -424,7 +424,7 @@ const struct bpf_func_proto bpf_sk_storage_delete_tracing_proto = { 
	.gpl_only	= false,

	.ret_type	= RET_INTEGER,

	.arg1_type	= ARG_CONST_MAP_PTR,

	.arg2_type	= ARG_PTR_TO_BTF_ID,

	.arg2_type	= ARG_PTR_TO_BTF_ID_OR_NULL,

	.arg2_btf_id	= &btf_sock_ids[BTF_SOCK_TYPE_SOCK_COMMON],

	.allowed	= bpf_sk_storage_tracing_allowed,

};

net/core/filter.c

+1 −1
Original line number Diff line number Diff line
@@ -4998,7 +4998,7 @@ const struct bpf_func_proto bpf_get_socket_ptr_cookie_proto = { 
	.func		= bpf_get_socket_ptr_cookie,

	.gpl_only	= false,

	.ret_type	= RET_INTEGER,

	.arg1_type	= ARG_PTR_TO_BTF_ID_SOCK_COMMON,

	.arg1_type	= ARG_PTR_TO_BTF_ID_SOCK_COMMON | PTR_MAYBE_NULL,

};



BPF_CALL_1(bpf_get_socket_cookie_sock_ops, struct bpf_sock_ops_kern *, ctx)