[bpf-next,1/3] bpf: Add casts to keep sparse quiet.

Commit Message

Sebastian Andrzej Siewior June 28, 2024, 8:40 a.m. UTC

sparse complains about wrong data types within the BPF callbacks.
Functions like bpf_l3_csum_replace() are invoked with a specific set of
arguments and its further usage is based on a flag. So it can not be set
right upfront.
There is also access to variables in struct bpf_nh_params and struct
bpf_xfrm_state which should be __be32. The content comes directly
from the BPF program so conversion is already right.

Add __force casts for the right data type and update the members in
struct bpf_xfrm_state and bpf_nh_params in order to keep sparse happy.

Reported-by: kernel test robot <[e-mail]>
Closes: https://lore.kernel.org/oe-kbuild-all/[e-mail]
Signed-off-by: Sebastian Andrzej Siewior <[e-mail]>
---
 include/linux/filter.h   |  2 +-
 include/uapi/linux/bpf.h |  6 +++---
 net/core/filter.c        | 18 ++++++++++--------
 3 files changed, 14 insertions(+), 12 deletions(-)

Patch

diff --git a/include/linux/filter.h b/include/linux/filter.h
index c0349522de8fb..9a96019376b67 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -728,7 +728,7 @@  struct bpf_skb_data_end {
 struct bpf_nh_params {
 	u32 nh_family;
 	union {
-		u32 ipv4_nh;
+		__be32 ipv4_nh;
 		struct in6_addr ipv6_nh;
 	};
 };
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 25ea393cf084b..f45b03706e4e9 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -6290,12 +6290,12 @@  struct bpf_tunnel_key {
  */
 struct bpf_xfrm_state {
 	__u32 reqid;
-	__u32 spi;	/* Stored in network byte order */
+	__be32 spi;	/* Stored in network byte order */
 	__u16 family;
 	__u16 ext;	/* Padding, future use. */
 	union {
-		__u32 remote_ipv4;	/* Stored in network byte order */
-		__u32 remote_ipv6[4];	/* Stored in network byte order */
+		__be32 remote_ipv4;	/* Stored in network byte order */
+		__be32 remote_ipv6[4];	/* Stored in network byte order */
 	};
 };
 
diff --git a/net/core/filter.c b/net/core/filter.c
index eb1c4425c06f3..11939971f3c6a 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -1939,13 +1939,13 @@  BPF_CALL_5(bpf_l3_csum_replace, struct sk_buff *, skb, u32, offset,
 		if (unlikely(from != 0))
 			return -EINVAL;
 
-		csum_replace_by_diff(ptr, to);
+		csum_replace_by_diff(ptr, (__force __wsum)to);
 		break;
 	case 2:
-		csum_replace2(ptr, from, to);
+		csum_replace2(ptr, (__force __be16)from, (__force __be16)to);
 		break;
 	case 4:
-		csum_replace4(ptr, from, to);
+		csum_replace4(ptr, (__force __be32)from, (__force __be32)to);
 		break;
 	default:
 		return -EINVAL;
@@ -1990,13 +1990,15 @@  BPF_CALL_5(bpf_l4_csum_replace, struct sk_buff *, skb, u32, offset,
 		if (unlikely(from != 0))
 			return -EINVAL;
 
-		inet_proto_csum_replace_by_diff(ptr, skb, to, is_pseudo);
+		inet_proto_csum_replace_by_diff(ptr, skb, (__force __wsum)to, is_pseudo);
 		break;
 	case 2:
-		inet_proto_csum_replace2(ptr, skb, from, to, is_pseudo);
+		inet_proto_csum_replace2(ptr, skb, (__force __be16)from, (__force __be16)to,
+					 is_pseudo);
 		break;
 	case 4:
-		inet_proto_csum_replace4(ptr, skb, from, to, is_pseudo);
+		inet_proto_csum_replace4(ptr, skb, (__force __be32)from, (__force __be32)to,
+					 is_pseudo);
 		break;
 	default:
 		return -EINVAL;
@@ -2046,7 +2048,7 @@  BPF_CALL_5(bpf_csum_diff, __be32 *, from, u32, from_size,
 
 	ret = csum_partial(sp->diff, diff_size, seed);
 	local_unlock_nested_bh(&bpf_sp.bh_lock);
-	return ret;
+	return (__force __u32)ret;
 }
 
 static const struct bpf_func_proto bpf_csum_diff_proto = {
@@ -2068,7 +2070,7 @@  BPF_CALL_2(bpf_csum_update, struct sk_buff *, skb, __wsum, csum)
 	 * as emulating csum_sub() can be done from the eBPF program.
 	 */
 	if (skb->ip_summed == CHECKSUM_COMPLETE)
-		return (skb->csum = csum_add(skb->csum, csum));
+		return (__force __u32)(skb->csum = csum_add(skb->csum, csum));
 
 	return -ENOTSUPP;
 }