[PATCH v2 bpf-next 11/17] bpf: net: Avoid do_ipv6_getsockopt() taking sk lock when called from bpf

Martin KaFai Lau
2022-09-02T00:35:56Z

Similar to the earlier patch that changes sk_getsockopt() to
use sockopt_{lock,release}_sock() such that it can avoid taking the
lock when called from bpf. This patch also changes do_ipv6_getsockopt()
to use sockopt_{lock,release}_sock() such that bpf_getsockopt(SOL_IPV6)
can reuse do_ipv6_getsockopt().

Although bpf_getsockopt(SOL_IPV6) currently does not support optname
that requires lock_sock(), using sockopt_{lock,release}_sock()
consistently across *_getsockopt() will make future optname addition
harder to miss the sockopt_{lock,release}_sock() usage. eg. when
adding new optname that requires a lock and the new optname is
needed in bpf_getsockopt() also.

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
---
net/ipv6/ipv6_sockglue.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
index 4d9fadef2d3e..d9887e3a6077 100644
--- a/net/ipv6/ipv6_sockglue.c
+++ b/net/ipv6/ipv6_sockglue.c
@@ -1078,7 +1078,7 @@ static int ipv6_get_msfilter(struct sock *sk, sockptr_t optval,
if (gsf.gf_group.ss_family != AF_INET6)
return -EADDRNOTAVAIL;
num = gsf.gf_numsrc;
- lock_sock(sk);
+ sockopt_lock_sock(sk);
err = ip6_mc_msfget(sk, &gsf, optval, size0);
if (!err) {
if (num > gsf.gf_numsrc)
@@ -1088,7 +1088,7 @@ static int ipv6_get_msfilter(struct sock *sk, sockptr_t optval,
copy_to_sockptr(optval, &gsf, size0))
err = -EFAULT;
}
- release_sock(sk);
+ sockopt_release_sock(sk);
return err;
}

@@ -1114,9 +1114,9 @@ static int compat_ipv6_get_msfilter(struct sock *sk, sockptr_t optval,
if (gf.gf_group.ss_family != AF_INET6)
return -EADDRNOTAVAIL;

- lock_sock(sk);
+ sockopt_lock_sock(sk);
err = ip6_mc_msfget(sk, &gf, optval, size0);
- release_sock(sk);
+ sockopt_release_sock(sk);
if (err)
return err;
if (num > gf.gf_numsrc)
@@ -1175,11 +1175,11 @@ static int do_ipv6_getsockopt(struct sock *sk, int level, int optname,
msg.msg_controllen = len;
msg.msg_flags = 0;

- lock_sock(sk);
+ sockopt_lock_sock(sk);
skb = np->pktoptions;
if (skb)
ip6_datagram_recv_ctl(sk, &msg, skb);
- release_sock(sk);
+ sockopt_release_sock(sk);
if (!skb) {
if (np->rxopt.bits.rxinfo) {
struct in6_pktinfo src_info;
@@ -1268,11 +1268,11 @@ static int do_ipv6_getsockopt(struct sock *sk, int level, int optname,
{
struct ipv6_txoptions *opt;

- lock_sock(sk);
+ sockopt_lock_sock(sk);
opt = rcu_dereference_protected(np->opt,
lockdep_sock_is_held(sk));
len = ipv6_getsockopt_sticky(sk, opt, optname, optval, len);
- release_sock(sk);
+ sockopt_release_sock(sk);
/* check if ipv6_getsockopt_sticky() returns err code */
if (len < 0)
return len;
--
2.30.2