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Subject[PATCH bpf-next v3 1/4] bpf: sockmap: enable map_update_elem from bpf_iter
Date
Allow passing a pointer to a BTF struct sock_common* when updating
a sockmap or sockhash. Since BTF pointers can fault and therefore be
NULL at runtime we need to add an additional !sk check to
sock_map_update_elem. Since we may be passed a request or timewait
socket we also need to check sk_fullsock. Doing this allows calling
map_update_elem on sockmap from bpf_iter context, which uses
BTF pointers.

Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
---
kernel/bpf/verifier.c | 2 +-
net/core/sock_map.c | 3 +++
2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index b25ba989c2dc..cc9c90d74dc1 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -3943,7 +3943,7 @@ static int resolve_map_arg_type(struct bpf_verifier_env *env,
case BPF_MAP_TYPE_SOCKMAP:
case BPF_MAP_TYPE_SOCKHASH:
if (*arg_type == ARG_PTR_TO_MAP_VALUE) {
- *arg_type = ARG_PTR_TO_SOCKET;
+ *arg_type = ARG_PTR_TO_BTF_ID_SOCK_COMMON;
} else {
verbose(env, "invalid arg_type for sockmap/sockhash\n");
return -EINVAL;
diff --git a/net/core/sock_map.c b/net/core/sock_map.c
index e1f05e3fa1d0..08bc86f51593 100644
--- a/net/core/sock_map.c
+++ b/net/core/sock_map.c
@@ -610,6 +610,9 @@ static int sock_map_update_elem(struct bpf_map *map, void *key,
struct sock *sk = (struct sock *)value;
int ret;

+ if (unlikely(!sk || !sk_fullsock(sk)))
+ return -EINVAL;
+
if (!sock_map_sk_is_suitable(sk))
return -EOPNOTSUPP;

--
2.25.1
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