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bpf: net: Consider has_current_bpf_ctx() when testing capable() in sk…
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…_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 8d650cd ("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: Stanislav Fomichev <sdf@google.com>
Reviewed-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/r/20220817061723.4175820-1-kafai@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Martin KaFai Lau authored and Alexei Starovoitov committed Aug 19, 2022
1 parent 2442665 commit e42c7be
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Showing 2 changed files with 27 additions and 13 deletions.
2 changes: 2 additions & 0 deletions include/net/sock.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand Down
38 changes: 25 additions & 13 deletions net/core/sock.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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.
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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;
}
Expand All @@ -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;
}
Expand All @@ -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;
Expand Down Expand Up @@ -1334,17 +1346,17 @@ 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;
}

__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;
}
Expand Down Expand Up @@ -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)
Expand All @@ -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)
Expand Down Expand Up @@ -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;
}
Expand Down

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