[PATCH net-next v5 7/8] bpf: Convert bpf_sock_addr_kern "uaddr" to sockaddr_unsized

Kees Cook
2025-11-04T00:26:18Z

Change struct bpf_sock_addr_kern to use sockaddr_unsized for the "uaddr"
field instead of sockaddr. This improves type safety in the BPF cgroup
socket address filtering code.

The casting in __cgroup_bpf_run_filter_sock_addr() is updated to match the
new type, removing an unnecessary cast in the initialization and updating
the conditional assignment to use the appropriate sockaddr_unsized cast.

Additionally rename the "unspec" variable to "storage" to better align
with its usage.

No binary changes expected.

Signed-off-by: Kees Cook <kees@kernel.org>
---
include/linux/filter.h | 2 +-
kernel/bpf/cgroup.c | 8 ++++----
2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/include/linux/filter.h b/include/linux/filter.h
index f5c859b8131a..e116de7edc58 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -1515,7 +1515,7 @@ static inline int bpf_tell_extensions(void)

struct bpf_sock_addr_kern {
struct sock *sk;
- struct sockaddr *uaddr;
+ struct sockaddr_unsized *uaddr;
/* Temporary "register" to make indirect stores to nested structures
* defined above. We need three registers to make such a store, but
* only two (src and dst) are available at convert_ctx_access time
diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index 497aedc9afa1..69988af44b37 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -1673,10 +1673,10 @@ int __cgroup_bpf_run_filter_sock_addr(struct sock *sk,
{
struct bpf_sock_addr_kern ctx = {
.sk = sk,
- .uaddr = (struct sockaddr *)uaddr,
+ .uaddr = uaddr,
.t_ctx = t_ctx,
};
- struct sockaddr_storage unspec;
+ struct sockaddr_storage storage;
struct cgroup *cgrp;
int ret;

@@ -1688,8 +1688,8 @@ int __cgroup_bpf_run_filter_sock_addr(struct sock *sk,
return 0;

if (!ctx.uaddr) {
- memset(&unspec, 0, sizeof(unspec));
- ctx.uaddr = (struct sockaddr *)&unspec;
+ memset(&storage, 0, sizeof(storage));
+ ctx.uaddr = (struct sockaddr_unsized *)&storage;
ctx.uaddrlen = 0;
} else {
ctx.uaddrlen = *uaddrlen;
--
2.34.1