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: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/bpf/20230404045029.82870-5-alexei.starovoitov@gmail.com

diff --git a/kernel/bpf/bpf_cgrp_storage.c b/kernel/bpf/bpf_cgrp_storage.c
index d17d5b6..d44fe8d 100644 (file)
--- a/kernel/bpf/bpf_cgrp_storage.c
+++ b/kernel/bpf/bpf_cgrp_storage.c
@@ -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],
 };

diff --git a/kernel/bpf/bpf_inode_storage.c b/kernel/bpf/bpf_inode_storage.c
index e17ad58..a4d93df 100644 (file)
--- a/kernel/bpf/bpf_inode_storage.c
+++ b/kernel/bpf/bpf_inode_storage.c
@@ -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],
 };

diff --git a/kernel/bpf/bpf_task_storage.c b/kernel/bpf/bpf_task_storage.c
index d1af0c8..adf6dfe 100644 (file)
--- a/kernel/bpf/bpf_task_storage.c
+++ b/kernel/bpf/bpf_task_storage.c
@@ -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],
 };

diff --git a/net/core/bpf_sk_storage.c b/net/core/bpf_sk_storage.c
index 085025c..d417253 100644 (file)
--- a/net/core/bpf_sk_storage.c
+++ b/net/core/bpf_sk_storage.c
@@ -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,
 };

diff --git a/net/core/filter.c b/net/core/filter.c
index 1f2abf0..727c526 100644 (file)
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -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)