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authorJakub Sitnicki <jakub@cloudflare.com>2023-01-21 13:41:44 +0100
committerAlexei Starovoitov <ast@kernel.org>2023-01-24 21:32:55 -0800
commitddce1e091757d0259107c6c0c7262df201de2b66 (patch)
treee9ee36ac268a80df9bc6343b318e1510b47377d5 /net/ipv4/tcp_bpf.c
parent5b4a79ba65a1ab479903fff2e604865d229b70a9 (diff)
bpf, sockmap: Check for any of tcp_bpf_prots when cloning a listener
A listening socket linked to a sockmap has its sk_prot overridden. It points to one of the struct proto variants in tcp_bpf_prots. The variant depends on the socket's family and which sockmap programs are attached. A child socket cloned from a TCP listener initially inherits their sk_prot. But before cloning is finished, we restore the child's proto to the listener's original non-tcp_bpf_prots one. This happens in tcp_create_openreq_child -> tcp_bpf_clone. Today, in tcp_bpf_clone we detect if the child's proto should be restored by checking only for the TCP_BPF_BASE proto variant. This is not correct. The sk_prot of listening socket linked to a sockmap can point to to any variant in tcp_bpf_prots. If the listeners sk_prot happens to be not the TCP_BPF_BASE variant, then the child socket unintentionally is left if the inherited sk_prot by tcp_bpf_clone. This leads to issues like infinite recursion on close [1], because the child state is otherwise not set up for use with tcp_bpf_prot operations. Adjust the check in tcp_bpf_clone to detect all of tcp_bpf_prots variants. Note that it wouldn't be sufficient to check the socket state when overriding the sk_prot in tcp_bpf_update_proto in order to always use the TCP_BPF_BASE variant for listening sockets. Since commit b8b8315e39ff ("bpf, sockmap: Remove unhash handler for BPF sockmap usage") it is possible for a socket to transition to TCP_LISTEN state while already linked to a sockmap, e.g. connect() -> insert into map -> connect(AF_UNSPEC) -> listen(). [1]: https://lore.kernel.org/all/00000000000073b14905ef2e7401@google.com/ Fixes: e80251555f0b ("tcp_bpf: Don't let child socket inherit parent protocol ops on copy") Reported-by: syzbot+04c21ed96d861dccc5cd@syzkaller.appspotmail.com Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com> Acked-by: John Fastabend <john.fastabend@gmail.com> Link: https://lore.kernel.org/r/20230113-sockmap-fix-v2-2-1e0ee7ac2f90@cloudflare.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'net/ipv4/tcp_bpf.c')
-rw-r--r--net/ipv4/tcp_bpf.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c
index 94aad3870c5f..cf26d65ca389 100644
--- a/net/ipv4/tcp_bpf.c
+++ b/net/ipv4/tcp_bpf.c
@@ -6,6 +6,7 @@
#include <linux/bpf.h>
#include <linux/init.h>
#include <linux/wait.h>
+#include <linux/util_macros.h>
#include <net/inet_common.h>
#include <net/tls.h>
@@ -639,10 +640,9 @@ EXPORT_SYMBOL_GPL(tcp_bpf_update_proto);
*/
void tcp_bpf_clone(const struct sock *sk, struct sock *newsk)
{
- int family = sk->sk_family == AF_INET6 ? TCP_BPF_IPV6 : TCP_BPF_IPV4;
struct proto *prot = newsk->sk_prot;
- if (prot == &tcp_bpf_prots[family][TCP_BPF_BASE])
+ if (is_insidevar(prot, tcp_bpf_prots))
newsk->sk_prot = sk->sk_prot_creator;
}
#endif /* CONFIG_BPF_SYSCALL */