[PATCH v2 bpf-next 13/17] bpf: Change bpf_getsockopt(SOL_SOCKET) to reuse sk_getsockopt()

Martin KaFai Lau
2022-09-02T00:32:06Z

This patch changes bpf_getsockopt(SOL_SOCKET) to reuse
sk_getsockopt(). It removes all duplicated code from
bpf_getsockopt(SOL_SOCKET).

Before this patch, there were some optnames available to
bpf_setsockopt(SOL_SOCKET) but missing in bpf_getsockopt(SOL_SOCKET).
It surprises users from time to time. For example, SO_REUSEADDR,
SO_KEEPALIVE, SO_RCVLOWAT, and SO_MAX_PACING_RATE. This patch
automatically closes this gap without duplicating more code.
The only exception is SO_BINDTODEVICE because it needs to acquire a
blocking lock. Thus, SO_BINDTODEVICE is not supported.

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
---
include/net/sock.h | 2 ++
net/core/filter.c | 57 +++++++++++++++++++---------------------------
net/core/sock.c | 4 ++--
3 files changed, 27 insertions(+), 36 deletions(-)

diff --git a/include/net/sock.h b/include/net/sock.h
index ee44b424d952..ea7965524133 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1833,6 +1833,8 @@ int sk_setsockopt(struct sock *sk, int level, int optname,
int sock_setsockopt(struct socket *sock, int level, int op,
sockptr_t optval, unsigned int optlen);

+int sk_getsockopt(struct sock *sk, int level, int optname,
+ sockptr_t optval, sockptr_t optlen);
int sock_getsockopt(struct socket *sock, int level, int op,
char __user *optval, int __user *optlen);
int sock_gettstamp(struct socket *sock, void __user *userstamp,
diff --git a/net/core/filter.c b/net/core/filter.c
index 347c38da1e0c..68b52243b306 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -5013,8 +5013,9 @@ static const struct bpf_func_proto bpf_get_socket_uid_proto = {
.arg1_type = ARG_PTR_TO_CTX,
};

-static int sol_socket_setsockopt(struct sock *sk, int optname,
- char *optval, int optlen)
+static int sol_socket_sockopt(struct sock *sk, int optname,
+ char *optval, int *optlen,
+ bool getopt)
{
switch (optname) {
case SO_REUSEADDR:
@@ -5028,7 +5029,7 @@ static int sol_socket_setsockopt(struct sock *sk, int optname,
case SO_MAX_PACING_RATE:
case SO_BINDTOIFINDEX:
case SO_TXREHASH:
- if (optlen != sizeof(int))
+ if (*optlen != sizeof(int))
return -EINVAL;
break;
case SO_BINDTODEVICE:
@@ -5037,8 +5038,16 @@ static int sol_socket_setsockopt(struct sock *sk, int optname,
return -EINVAL;
}

+ if (getopt) {
+ if (optname == SO_BINDTODEVICE)
+ return -EINVAL;
+ return sk_getsockopt(sk, SOL_SOCKET, optname,
+ KERNEL_SOCKPTR(optval),
+ KERNEL_SOCKPTR(optlen));
+ }
+
return sk_setsockopt(sk, SOL_SOCKET, optname,
- KERNEL_SOCKPTR(optval), optlen);
+ KERNEL_SOCKPTR(optval), *optlen);
}

static int bpf_sol_tcp_setsockopt(struct sock *sk, int optname,
@@ -5164,7 +5173,7 @@ static int __bpf_setsockopt(struct sock *sk, int level, int optname,
return -EINVAL;

if (level == SOL_SOCKET)
- return sol_socket_setsockopt(sk, optname, optval, optlen);
+ return sol_socket_sockopt(sk, optname, optval, &optlen, false);
else if (IS_ENABLED(CONFIG_INET) && level == SOL_IP)
return sol_ip_setsockopt(sk, optname, optval, optlen);
else if (IS_ENABLED(CONFIG_IPV6) && level == SOL_IPV6)
@@ -5186,38 +5195,13 @@ static int _bpf_setsockopt(struct sock *sk, int level, int optname,
static int __bpf_getsockopt(struct sock *sk, int level, int optname,
char *optval, int optlen)
{
+ int err = 0, saved_optlen = optlen;
+
if (!sk_fullsock(sk))
goto err_clear;

if (level == SOL_SOCKET) {
- if (optlen != sizeof(int))
- goto err_clear;
-
- switch (optname) {
- case SO_RCVBUF:
- *((int *)optval) = sk->sk_rcvbuf;
- break;
- case SO_SNDBUF:
- *((int *)optval) = sk->sk_sndbuf;
- break;
- case SO_MARK:
- *((int *)optval) = sk->sk_mark;
- break;
- case SO_PRIORITY:
- *((int *)optval) = sk->sk_priority;
- break;
- case SO_BINDTOIFINDEX:
- *((int *)optval) = sk->sk_bound_dev_if;
- break;
- case SO_REUSEPORT:
- *((int *)optval) = sk->sk_reuseport;
- break;
- case SO_TXREHASH:
- *((int *)optval) = sk->sk_txrehash;
- break;
- default:
- goto err_clear;
- }
+ err = sol_socket_sockopt(sk, optname, optval, &optlen, true);
} else if (IS_ENABLED(CONFIG_INET) &&
level == SOL_TCP && sk->sk_prot->getsockopt == tcp_getsockopt) {
struct inet_connection_sock *icsk;
@@ -5274,7 +5258,12 @@ static int __bpf_getsockopt(struct sock *sk, int level, int optname,
} else {
goto err_clear;
}
- return 0;
+
+ if (err)
+ optlen = 0;
+ if (optlen < saved_optlen)
+ memset(optval + optlen, 0, saved_optlen - optlen);
+ return err;
err_clear:
memset(optval, 0, optlen);
return -EINVAL;
diff --git a/net/core/sock.c b/net/core/sock.c
index 7fa30fd4b37f..68e4662eb2eb 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1583,8 +1583,8 @@ static int groups_to_user(sockptr_t dst, const struct group_info *src)
return 0;
}

-static int sk_getsockopt(struct sock *sk, int level, int optname,
- sockptr_t optval, sockptr_t optlen)
+int sk_getsockopt(struct sock *sk, int level, int optname,
+ sockptr_t optval, sockptr_t optlen)
{
struct socket *sock = sk->sk_socket;

--
2.30.2