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bpf: Change bpf_getsockopt(SOL_TCP) to reuse do_tcp_getsockopt()

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This patch changes bpf_getsockopt(SOL_TCP) to reuse
do_tcp_getsockopt().  It removes the duplicated code from
bpf_getsockopt(SOL_TCP).

Before this patch, there were some optnames available to
bpf_setsockopt(SOL_TCP) but missing in bpf_getsockopt(SOL_TCP).
For example, TCP_NODELAY, TCP_MAXSEG, TCP_KEEPIDLE, TCP_KEEPINTVL,
and a few more.  It surprises users from time to time.  This patch
automatically closes this gap without duplicating more code.

bpf_getsockopt(TCP_SAVED_SYN) does not free the saved_syn,
so it stays in sol_tcp_sockopt().

For string name value like TCP_CONGESTION, bpf expects it
is always null terminated, so sol_tcp_sockopt() decrements
optlen by one before calling do_tcp_getsockopt() and
the 'if (optlen < saved_optlen) memset(..,0,..);'
in __bpf_getsockopt() will always do a null termination.

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20220902002918.2894511-1-kafai@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Martin KaFai Lau 2022-09-01 17:29:18 -07:00 committed by Alexei Starovoitov
parent 65ddc82d3b
commit 273b7f0fb4
3 changed files with 47 additions and 33 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/net/tcp.h
View File

@ -402,6 +402,8 @@ void tcp_init_sock(struct sock *sk);
void tcp_init_transfer(struct sock *sk, int bpf_op, struct sk_buff *skb);
__poll_t tcp_poll(struct file *file, struct socket *sock,
struct poll_table_struct *wait);
int do_tcp_getsockopt(struct sock *sk, int level,
int optname, sockptr_t optval, sockptr_t optlen);
int tcp_getsockopt(struct sock *sk, int level, int optname,
char __user *optval, int __user *optlen);
bool tcp_bpf_bypass_getsockopt(int level, int optname);

74
net/core/filter.c
View File

@ -5100,8 +5100,9 @@ static int bpf_sol_tcp_setsockopt(struct sock *sk, int optname,
return 0;
}
static int sol_tcp_setsockopt(struct sock *sk, int optname,
char *optval, int optlen)
static int sol_tcp_sockopt(struct sock *sk, int optname,
char *optval, int *optlen,
bool getopt)
{
if (sk->sk_prot->setsockopt != tcp_setsockopt)
return -EINVAL;
@ -5118,17 +5119,51 @@ static int sol_tcp_setsockopt(struct sock *sk, int optname,
case TCP_USER_TIMEOUT:
case TCP_NOTSENT_LOWAT:
case TCP_SAVE_SYN:
if (optlen != sizeof(int))
if (*optlen != sizeof(int))
return -EINVAL;
break;
case TCP_CONGESTION:
if (*optlen < 2)
return -EINVAL;
break;
case TCP_SAVED_SYN:
if (*optlen < 1)
return -EINVAL;
break;
default:
return bpf_sol_tcp_setsockopt(sk, optname, optval, optlen);
if (getopt)
return -EINVAL;
return bpf_sol_tcp_setsockopt(sk, optname, optval, *optlen);
}
if (getopt) {
if (optname == TCP_SAVED_SYN) {
struct tcp_sock *tp = tcp_sk(sk);
if (!tp->saved_syn ||
*optlen > tcp_saved_syn_len(tp->saved_syn))
return -EINVAL;
memcpy(optval, tp->saved_syn->data, *optlen);
/* It cannot free tp->saved_syn here because it
* does not know if the user space still needs it.
*/
return 0;
}
if (optname == TCP_CONGESTION) {
if (!inet_csk(sk)->icsk_ca_ops)
return -EINVAL;
/* BPF expects NULL-terminated tcp-cc string */
optval[--(*optlen)] = '\0';
}
return do_tcp_getsockopt(sk, SOL_TCP, optname,
KERNEL_SOCKPTR(optval),
KERNEL_SOCKPTR(optlen));
}
return do_tcp_setsockopt(sk, SOL_TCP, optname,
KERNEL_SOCKPTR(optval), optlen);
KERNEL_SOCKPTR(optval), *optlen);
}
static int sol_ip_setsockopt(struct sock *sk, int optname,
@ -5183,7 +5218,7 @@ static int __bpf_setsockopt(struct sock *sk, int level, int optname,
else if (IS_ENABLED(CONFIG_IPV6) && level == SOL_IPV6)
return sol_ipv6_setsockopt(sk, optname, optval, optlen);
else if (IS_ENABLED(CONFIG_INET) && level == SOL_TCP)
return sol_tcp_setsockopt(sk, optname, optval, optlen);
return sol_tcp_sockopt(sk, optname, optval, &optlen, false);
return -EINVAL;
}
@ -5206,31 +5241,8 @@ static int __bpf_getsockopt(struct sock *sk, int level, int optname,
if (level == SOL_SOCKET) {
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;
struct tcp_sock *tp;
switch (optname) {
case TCP_CONGESTION:
icsk = inet_csk(sk);
if (!icsk->icsk_ca_ops || optlen <= 1)
goto err_clear;
strncpy(optval, icsk->icsk_ca_ops->name, optlen);
optval[optlen - 1] = 0;
break;
case TCP_SAVED_SYN:
tp = tcp_sk(sk);
if (optlen <= 0 || !tp->saved_syn ||
optlen > tcp_saved_syn_len(tp->saved_syn))
goto err_clear;
memcpy(optval, tp->saved_syn->data, optlen);
break;
default:
goto err_clear;
}
} else if (IS_ENABLED(CONFIG_INET) && level == SOL_TCP) {
err = sol_tcp_sockopt(sk, optname, optval, &optlen, true);
} else if (IS_ENABLED(CONFIG_INET) && level == SOL_IP) {
struct inet_sock *inet = inet_sk(sk);

4
net/ipv4/tcp.c
View File

@ -4043,8 +4043,8 @@ struct sk_buff *tcp_get_timestamping_opt_stats(const struct sock *sk,
return stats;
}
static int do_tcp_getsockopt(struct sock *sk, int level,
int optname, sockptr_t optval, sockptr_t optlen)
int do_tcp_getsockopt(struct sock *sk, int level,
int optname, sockptr_t optval, sockptr_t optlen)
{
struct inet_connection_sock *icsk = inet_csk(sk);
struct tcp_sock *tp = tcp_sk(sk);