bpf: Convert bpf_sock_addr_kern "uaddr" to sockaddr_unsized

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>
Link: https://patch.msgid.link/20251104002617.2752303-7-kees@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/linux/filter.h b/include/linux/filter.h
index f5c859b8131a3e5fa5111b60cc291cedd44f096d..e116de7edc58715171762b6aa6d7ca32344c5768 100644 (file)
--- 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 497aedc9afa1c589b59825dedcc7903706cd7465..69988af44b3782a560cc96830ba65ff83be74c16 100644 (file)
--- 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;