bpf: Add MEM_RDONLY for helper args that are pointers to rdonly mem.

Some helper functions may modify its arguments, for example,
bpf_d_path, bpf_get_stack etc. Previously, their argument types
were marked as ARG_PTR_TO_MEM, which is compatible with read-only
mem types, such as PTR_TO_RDONLY_BUF. Therefore it's legitimate,
but technically incorrect, to modify a read-only memory by passing
it into one of such helper functions.

This patch tags the bpf_args compatible with immutable memory with
MEM_RDONLY flag. The arguments that don't have this flag will be
only compatible with mutable memory types, preventing the helper
from modifying a read-only memory. The bpf_args that have
MEM_RDONLY are compatible with both mutable memory and immutable
memory.

Signed-off-by: Hao Luo <haoluo@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211217003152.48334-9-haoluo@google.com

1 files changed, 32 insertions, 32 deletions

diff --git a/net/core/filter.c b/net/core/filter.c
index 3f656391af7e..606ab5a98a1a 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -1712,7 +1712,7 @@ static const struct bpf_func_proto bpf_skb_store_bytes_proto = {
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_PTR_TO_CTX,
 	.arg2_type	= ARG_ANYTHING,
-	.arg3_type	= ARG_PTR_TO_MEM,
+	.arg3_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg4_type	= ARG_CONST_SIZE,
 	.arg5_type	= ARG_ANYTHING,
 };
@@ -2017,9 +2017,9 @@ static const struct bpf_func_proto bpf_csum_diff_proto = {
 	.gpl_only	= false,
 	.pkt_access	= true,
 	.ret_type	= RET_INTEGER,
-	.arg1_type	= ARG_PTR_TO_MEM_OR_NULL,
+	.arg1_type	= ARG_PTR_TO_MEM | PTR_MAYBE_NULL | MEM_RDONLY,
 	.arg2_type	= ARG_CONST_SIZE_OR_ZERO,
-	.arg3_type	= ARG_PTR_TO_MEM_OR_NULL,
+	.arg3_type	= ARG_PTR_TO_MEM | PTR_MAYBE_NULL | MEM_RDONLY,
 	.arg4_type	= ARG_CONST_SIZE_OR_ZERO,
 	.arg5_type	= ARG_ANYTHING,
 };
@@ -2540,7 +2540,7 @@ static const struct bpf_func_proto bpf_redirect_neigh_proto = {
 	.gpl_only	= false,
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_ANYTHING,
-	.arg2_type      = ARG_PTR_TO_MEM_OR_NULL,
+	.arg2_type      = ARG_PTR_TO_MEM | PTR_MAYBE_NULL | MEM_RDONLY,
 	.arg3_type      = ARG_CONST_SIZE_OR_ZERO,
 	.arg4_type	= ARG_ANYTHING,
 };
@@ -4173,7 +4173,7 @@ static const struct bpf_func_proto bpf_skb_event_output_proto = {
 	.arg1_type	= ARG_PTR_TO_CTX,
 	.arg2_type	= ARG_CONST_MAP_PTR,
 	.arg3_type	= ARG_ANYTHING,
-	.arg4_type	= ARG_PTR_TO_MEM,
+	.arg4_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg5_type	= ARG_CONST_SIZE_OR_ZERO,
 };
 
@@ -4187,7 +4187,7 @@ const struct bpf_func_proto bpf_skb_output_proto = {
 	.arg1_btf_id	= &bpf_skb_output_btf_ids[0],
 	.arg2_type	= ARG_CONST_MAP_PTR,
 	.arg3_type	= ARG_ANYTHING,
-	.arg4_type	= ARG_PTR_TO_MEM,
+	.arg4_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg5_type	= ARG_CONST_SIZE_OR_ZERO,
 };
 
@@ -4370,7 +4370,7 @@ static const struct bpf_func_proto bpf_skb_set_tunnel_key_proto = {
 	.gpl_only	= false,
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_PTR_TO_CTX,
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type	= ARG_CONST_SIZE,
 	.arg4_type	= ARG_ANYTHING,
 };
@@ -4396,7 +4396,7 @@ static const struct bpf_func_proto bpf_skb_set_tunnel_opt_proto = {
 	.gpl_only	= false,
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_PTR_TO_CTX,
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type	= ARG_CONST_SIZE,
 };
 
@@ -4566,7 +4566,7 @@ static const struct bpf_func_proto bpf_xdp_event_output_proto = {
 	.arg1_type	= ARG_PTR_TO_CTX,
 	.arg2_type	= ARG_CONST_MAP_PTR,
 	.arg3_type	= ARG_ANYTHING,
-	.arg4_type	= ARG_PTR_TO_MEM,
+	.arg4_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg5_type	= ARG_CONST_SIZE_OR_ZERO,
 };
 
@@ -4580,7 +4580,7 @@ const struct bpf_func_proto bpf_xdp_output_proto = {
 	.arg1_btf_id	= &bpf_xdp_output_btf_ids[0],
 	.arg2_type	= ARG_CONST_MAP_PTR,
 	.arg3_type	= ARG_ANYTHING,
-	.arg4_type	= ARG_PTR_TO_MEM,
+	.arg4_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg5_type	= ARG_CONST_SIZE_OR_ZERO,
 };
 
@@ -5066,7 +5066,7 @@ const struct bpf_func_proto bpf_sk_setsockopt_proto = {
 	.arg1_type	= ARG_PTR_TO_BTF_ID_SOCK_COMMON,
 	.arg2_type	= ARG_ANYTHING,
 	.arg3_type	= ARG_ANYTHING,
-	.arg4_type	= ARG_PTR_TO_MEM,
+	.arg4_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg5_type	= ARG_CONST_SIZE,
 };
 
@@ -5100,7 +5100,7 @@ static const struct bpf_func_proto bpf_sock_addr_setsockopt_proto = {
 	.arg1_type	= ARG_PTR_TO_CTX,
 	.arg2_type	= ARG_ANYTHING,
 	.arg3_type	= ARG_ANYTHING,
-	.arg4_type	= ARG_PTR_TO_MEM,
+	.arg4_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg5_type	= ARG_CONST_SIZE,
 };
 
@@ -5134,7 +5134,7 @@ static const struct bpf_func_proto bpf_sock_ops_setsockopt_proto = {
 	.arg1_type	= ARG_PTR_TO_CTX,
 	.arg2_type	= ARG_ANYTHING,
 	.arg3_type	= ARG_ANYTHING,
-	.arg4_type	= ARG_PTR_TO_MEM,
+	.arg4_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg5_type	= ARG_CONST_SIZE,
 };
 
@@ -5309,7 +5309,7 @@ static const struct bpf_func_proto bpf_bind_proto = {
 	.gpl_only	= false,
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_PTR_TO_CTX,
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type	= ARG_CONST_SIZE,
 };
 
@@ -5897,7 +5897,7 @@ static const struct bpf_func_proto bpf_lwt_in_push_encap_proto = {
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_PTR_TO_CTX,
 	.arg2_type	= ARG_ANYTHING,
-	.arg3_type	= ARG_PTR_TO_MEM,
+	.arg3_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg4_type	= ARG_CONST_SIZE
 };
 
@@ -5907,7 +5907,7 @@ static const struct bpf_func_proto bpf_lwt_xmit_push_encap_proto = {
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_PTR_TO_CTX,
 	.arg2_type	= ARG_ANYTHING,
-	.arg3_type	= ARG_PTR_TO_MEM,
+	.arg3_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg4_type	= ARG_CONST_SIZE
 };
 
@@ -5950,7 +5950,7 @@ static const struct bpf_func_proto bpf_lwt_seg6_store_bytes_proto = {
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_PTR_TO_CTX,
 	.arg2_type	= ARG_ANYTHING,
-	.arg3_type	= ARG_PTR_TO_MEM,
+	.arg3_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg4_type	= ARG_CONST_SIZE
 };
 
@@ -6038,7 +6038,7 @@ static const struct bpf_func_proto bpf_lwt_seg6_action_proto = {
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_PTR_TO_CTX,
 	.arg2_type	= ARG_ANYTHING,
-	.arg3_type	= ARG_PTR_TO_MEM,
+	.arg3_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg4_type	= ARG_CONST_SIZE
 };
 
@@ -6263,7 +6263,7 @@ static const struct bpf_func_proto bpf_skc_lookup_tcp_proto = {
 	.pkt_access	= true,
 	.ret_type	= RET_PTR_TO_SOCK_COMMON_OR_NULL,
 	.arg1_type	= ARG_PTR_TO_CTX,
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type	= ARG_CONST_SIZE,
 	.arg4_type	= ARG_ANYTHING,
 	.arg5_type	= ARG_ANYTHING,
@@ -6282,7 +6282,7 @@ static const struct bpf_func_proto bpf_sk_lookup_tcp_proto = {
 	.pkt_access	= true,
 	.ret_type	= RET_PTR_TO_SOCKET_OR_NULL,
 	.arg1_type	= ARG_PTR_TO_CTX,
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type	= ARG_CONST_SIZE,
 	.arg4_type	= ARG_ANYTHING,
 	.arg5_type	= ARG_ANYTHING,
@@ -6301,7 +6301,7 @@ static const struct bpf_func_proto bpf_sk_lookup_udp_proto = {
 	.pkt_access	= true,
 	.ret_type	= RET_PTR_TO_SOCKET_OR_NULL,
 	.arg1_type	= ARG_PTR_TO_CTX,
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type	= ARG_CONST_SIZE,
 	.arg4_type	= ARG_ANYTHING,
 	.arg5_type	= ARG_ANYTHING,
@@ -6338,7 +6338,7 @@ static const struct bpf_func_proto bpf_xdp_sk_lookup_udp_proto = {
 	.pkt_access     = true,
 	.ret_type       = RET_PTR_TO_SOCKET_OR_NULL,
 	.arg1_type      = ARG_PTR_TO_CTX,
-	.arg2_type      = ARG_PTR_TO_MEM,
+	.arg2_type      = ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type      = ARG_CONST_SIZE,
 	.arg4_type      = ARG_ANYTHING,
 	.arg5_type      = ARG_ANYTHING,
@@ -6361,7 +6361,7 @@ static const struct bpf_func_proto bpf_xdp_skc_lookup_tcp_proto = {
 	.pkt_access     = true,
 	.ret_type       = RET_PTR_TO_SOCK_COMMON_OR_NULL,
 	.arg1_type      = ARG_PTR_TO_CTX,
-	.arg2_type      = ARG_PTR_TO_MEM,
+	.arg2_type      = ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type      = ARG_CONST_SIZE,
 	.arg4_type      = ARG_ANYTHING,
 	.arg5_type      = ARG_ANYTHING,
@@ -6384,7 +6384,7 @@ static const struct bpf_func_proto bpf_xdp_sk_lookup_tcp_proto = {
 	.pkt_access     = true,
 	.ret_type       = RET_PTR_TO_SOCKET_OR_NULL,
 	.arg1_type      = ARG_PTR_TO_CTX,
-	.arg2_type      = ARG_PTR_TO_MEM,
+	.arg2_type      = ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type      = ARG_CONST_SIZE,
 	.arg4_type      = ARG_ANYTHING,
 	.arg5_type      = ARG_ANYTHING,
@@ -6403,7 +6403,7 @@ static const struct bpf_func_proto bpf_sock_addr_skc_lookup_tcp_proto = {
 	.gpl_only	= false,
 	.ret_type	= RET_PTR_TO_SOCK_COMMON_OR_NULL,
 	.arg1_type	= ARG_PTR_TO_CTX,
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type	= ARG_CONST_SIZE,
 	.arg4_type	= ARG_ANYTHING,
 	.arg5_type	= ARG_ANYTHING,
@@ -6422,7 +6422,7 @@ static const struct bpf_func_proto bpf_sock_addr_sk_lookup_tcp_proto = {
 	.gpl_only	= false,
 	.ret_type	= RET_PTR_TO_SOCKET_OR_NULL,
 	.arg1_type	= ARG_PTR_TO_CTX,
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type	= ARG_CONST_SIZE,
 	.arg4_type	= ARG_ANYTHING,
 	.arg5_type	= ARG_ANYTHING,
@@ -6441,7 +6441,7 @@ static const struct bpf_func_proto bpf_sock_addr_sk_lookup_udp_proto = {
 	.gpl_only	= false,
 	.ret_type	= RET_PTR_TO_SOCKET_OR_NULL,
 	.arg1_type	= ARG_PTR_TO_CTX,
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type	= ARG_CONST_SIZE,
 	.arg4_type	= ARG_ANYTHING,
 	.arg5_type	= ARG_ANYTHING,
@@ -6754,9 +6754,9 @@ static const struct bpf_func_proto bpf_tcp_check_syncookie_proto = {
 	.pkt_access	= true,
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_PTR_TO_BTF_ID_SOCK_COMMON,
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type	= ARG_CONST_SIZE,
-	.arg4_type	= ARG_PTR_TO_MEM,
+	.arg4_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg5_type	= ARG_CONST_SIZE,
 };
 
@@ -6823,9 +6823,9 @@ static const struct bpf_func_proto bpf_tcp_gen_syncookie_proto = {
 	.pkt_access	= true,
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_PTR_TO_BTF_ID_SOCK_COMMON,
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type	= ARG_CONST_SIZE,
-	.arg4_type	= ARG_PTR_TO_MEM,
+	.arg4_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg5_type	= ARG_CONST_SIZE,
 };
 
@@ -7054,7 +7054,7 @@ static const struct bpf_func_proto bpf_sock_ops_store_hdr_opt_proto = {
 	.gpl_only	= false,
 	.ret_type	= RET_INTEGER,
 	.arg1_type	= ARG_PTR_TO_CTX,
-	.arg2_type	= ARG_PTR_TO_MEM,
+	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
 	.arg3_type	= ARG_CONST_SIZE,
 	.arg4_type	= ARG_ANYTHING,
 };