Commit e42c7bee authored by Martin KaFai Lau's avatar Martin KaFai Lau Committed by Alexei Starovoitov
Browse files

bpf: net: Consider has_current_bpf_ctx() when testing capable() in sk_setsockopt() 



When bpf program calling bpf_setsockopt(SOL_SOCKET),
it could be run in softirq and doesn't make sense to do the capable
check.  There was a similar situation in bpf_setsockopt(TCP_CONGESTION).
In commit 8d650cde ("tcp: fix tcp_set_congestion_control() use from bpf hook"),
tcp_set_congestion_control(..., cap_net_admin) was added to skip
the cap check for bpf prog.

This patch adds sockopt_ns_capable() and sockopt_capable() for
the sk_setsockopt() to use.  They will consider the
has_current_bpf_ctx() before doing the ns_capable() and capable() test.
They are in EXPORT_SYMBOL for the ipv6 module to use in a latter patch.

Suggested-by: default avatarStanislav Fomichev <sdf@google.com>
Reviewed-by: default avatarStanislav Fomichev <sdf@google.com>
Signed-off-by: default avatarMartin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/r/20220817061723.4175820-1-kafai@fb.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 24426654

include/net/sock.h

+2 −0
Original line number Diff line number Diff line
@@ -1751,6 +1751,8 @@ static inline void unlock_sock_fast(struct sock *sk, bool slow) 


void sockopt_lock_sock(struct sock *sk);

void sockopt_release_sock(struct sock *sk);

bool sockopt_ns_capable(struct user_namespace *ns, int cap);

bool sockopt_capable(int cap);



/* Used by processes to "lock" a socket state, so that

 * interrupts and bottom half handlers won't change it

net/core/sock.c

+25 −13
Original line number Diff line number Diff line
@@ -1060,6 +1060,18 @@ void sockopt_release_sock(struct sock *sk) 
}

EXPORT_SYMBOL(sockopt_release_sock);



bool sockopt_ns_capable(struct user_namespace *ns, int cap)

{

	return has_current_bpf_ctx() || ns_capable(ns, cap);

}

EXPORT_SYMBOL(sockopt_ns_capable);



bool sockopt_capable(int cap)

{

	return has_current_bpf_ctx() || capable(cap);

}

EXPORT_SYMBOL(sockopt_capable);



/*

 *	This is meant for all protocols to use and covers goings on

 *	at the socket level. Everything here is generic.
@@ -1095,7 +1107,7 @@ static int sk_setsockopt(struct sock *sk, int level, int optname, 


	switch (optname) {

	case SO_DEBUG:

		if (val && !capable(CAP_NET_ADMIN))

		if (val && !sockopt_capable(CAP_NET_ADMIN))

			ret = -EACCES;

		else

			sock_valbool_flag(sk, SOCK_DBG, valbool);
@@ -1139,7 +1151,7 @@ static int sk_setsockopt(struct sock *sk, int level, int optname, 
		break;



	case SO_SNDBUFFORCE:

		if (!capable(CAP_NET_ADMIN)) {

		if (!sockopt_capable(CAP_NET_ADMIN)) {

			ret = -EPERM;

			break;

		}
@@ -1161,7 +1173,7 @@ static int sk_setsockopt(struct sock *sk, int level, int optname, 
		break;



	case SO_RCVBUFFORCE:

		if (!capable(CAP_NET_ADMIN)) {

		if (!sockopt_capable(CAP_NET_ADMIN)) {

			ret = -EPERM;

			break;

		}
@@ -1188,8 +1200,8 @@ static int sk_setsockopt(struct sock *sk, int level, int optname, 


	case SO_PRIORITY:

		if ((val >= 0 && val <= 6) ||

		    ns_capable(sock_net(sk)->user_ns, CAP_NET_RAW) ||

		    ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))

		    sockopt_ns_capable(sock_net(sk)->user_ns, CAP_NET_RAW) ||

		    sockopt_ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))

			sk->sk_priority = val;

		else

			ret = -EPERM;
@@ -1334,8 +1346,8 @@ static int sk_setsockopt(struct sock *sk, int level, int optname, 
			clear_bit(SOCK_PASSSEC, &sock->flags);

		break;

	case SO_MARK:

		if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_RAW) &&

		    !ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN)) {

		if (!sockopt_ns_capable(sock_net(sk)->user_ns, CAP_NET_RAW) &&

		    !sockopt_ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN)) {

			ret = -EPERM;

			break;

		}
@@ -1343,8 +1355,8 @@ static int sk_setsockopt(struct sock *sk, int level, int optname, 
		__sock_set_mark(sk, val);

		break;

	case SO_RCVMARK:

		if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_RAW) &&

		    !ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN)) {

		if (!sockopt_ns_capable(sock_net(sk)->user_ns, CAP_NET_RAW) &&

		    !sockopt_ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN)) {

			ret = -EPERM;

			break;

		}
@@ -1378,7 +1390,7 @@ static int sk_setsockopt(struct sock *sk, int level, int optname, 
#ifdef CONFIG_NET_RX_BUSY_POLL

	case SO_BUSY_POLL:

		/* allow unprivileged users to decrease the value */

		if ((val > sk->sk_ll_usec) && !capable(CAP_NET_ADMIN))

		if ((val > sk->sk_ll_usec) && !sockopt_capable(CAP_NET_ADMIN))

			ret = -EPERM;

		else {

			if (val < 0)
@@ -1388,13 +1400,13 @@ static int sk_setsockopt(struct sock *sk, int level, int optname, 
		}

		break;

	case SO_PREFER_BUSY_POLL:

		if (valbool && !capable(CAP_NET_ADMIN))

		if (valbool && !sockopt_capable(CAP_NET_ADMIN))

			ret = -EPERM;

		else

			WRITE_ONCE(sk->sk_prefer_busy_poll, valbool);

		break;

	case SO_BUSY_POLL_BUDGET:

		if (val > READ_ONCE(sk->sk_busy_poll_budget) && !capable(CAP_NET_ADMIN)) {

		if (val > READ_ONCE(sk->sk_busy_poll_budget) && !sockopt_capable(CAP_NET_ADMIN)) {

			ret = -EPERM;

		} else {

			if (val < 0 || val > U16_MAX)
@@ -1465,7 +1477,7 @@ static int sk_setsockopt(struct sock *sk, int level, int optname, 
		 * scheduler has enough safe guards.

		 */

		if (sk_txtime.clockid != CLOCK_MONOTONIC &&

		    !ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN)) {

		    !sockopt_ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN)) {

			ret = -EPERM;

			break;

		}