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netlink: convert nlk->flags to atomic flags
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[ Upstream commit 8fe08d7 ]

sk_diag_put_flags(), netlink_setsockopt(), netlink_getsockopt()
and others use nlk->flags without correct locking.

Use set_bit(), clear_bit(), test_bit(), assign_bit() to remove
data-races.

Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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@gregkh
Eric Dumazet authored and gregkh committed Sep 23, 2023
1 parent 8cf6ed2 commit 59285cb
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Showing 3 changed files with 48 additions and 74 deletions.
90 changes: 30 additions & 60 deletions net/netlink/af_netlink.c
View file
Expand Up @@ -84,7 +84,7 @@ struct listeners {

static inline int netlink_is_kernel(struct sock *sk)
{
return nlk_sk(sk)->flags & NETLINK_F_KERNEL_SOCKET;
return nlk_test_bit(KERNEL_SOCKET, sk);
}

struct netlink_table *nl_table __read_mostly;
Expand Down Expand Up @@ -349,9 +349,7 @@ static void netlink_deliver_tap_kernel(struct sock *dst, struct sock *src,

static void netlink_overrun(struct sock *sk)
{
struct netlink_sock *nlk = nlk_sk(sk);

if (!(nlk->flags & NETLINK_F_RECV_NO_ENOBUFS)) {
if (!nlk_test_bit(RECV_NO_ENOBUFS, sk)) {
if (!test_and_set_bit(NETLINK_S_CONGESTED,
&nlk_sk(sk)->state)) {
sk->sk_err = ENOBUFS;
Expand Down Expand Up @@ -1402,9 +1400,7 @@ EXPORT_SYMBOL_GPL(netlink_has_listeners);

bool netlink_strict_get_check(struct sk_buff *skb)
{
const struct netlink_sock *nlk = nlk_sk(NETLINK_CB(skb).sk);

return nlk->flags & NETLINK_F_STRICT_CHK;
return nlk_test_bit(STRICT_CHK, NETLINK_CB(skb).sk);
}
EXPORT_SYMBOL_GPL(netlink_strict_get_check);

Expand Down Expand Up @@ -1448,7 +1444,7 @@ static void do_one_broadcast(struct sock *sk,
return;

if (!net_eq(sock_net(sk), p->net)) {
if (!(nlk->flags & NETLINK_F_LISTEN_ALL_NSID))
if (!nlk_test_bit(LISTEN_ALL_NSID, sk))
return;

if (!peernet_has_id(sock_net(sk), p->net))
Expand Down Expand Up @@ -1481,7 +1477,7 @@ static void do_one_broadcast(struct sock *sk,
netlink_overrun(sk);
/* Clone failed. Notify ALL listeners. */
p->failure = 1;
if (nlk->flags & NETLINK_F_BROADCAST_SEND_ERROR)
if (nlk_test_bit(BROADCAST_SEND_ERROR, sk))
p->delivery_failure = 1;
goto out;
}
Expand All @@ -1496,7 +1492,7 @@ static void do_one_broadcast(struct sock *sk,
val = netlink_broadcast_deliver(sk, p->skb2);
if (val < 0) {
netlink_overrun(sk);
if (nlk->flags & NETLINK_F_BROADCAST_SEND_ERROR)
if (nlk_test_bit(BROADCAST_SEND_ERROR, sk))
p->delivery_failure = 1;
} else {
p->congested |= val;
Expand Down Expand Up @@ -1576,7 +1572,7 @@ static int do_one_set_err(struct sock *sk, struct netlink_set_err_data *p)
!test_bit(p->group - 1, nlk->groups))
goto out;

if (p->code == ENOBUFS && nlk->flags & NETLINK_F_RECV_NO_ENOBUFS) {
if (p->code == ENOBUFS && nlk_test_bit(RECV_NO_ENOBUFS, sk)) {
ret = 1;
goto out;
}
Expand Down Expand Up @@ -1643,7 +1639,7 @@ static int netlink_setsockopt(struct socket *sock, int level, int optname,
struct sock *sk = sock->sk;
struct netlink_sock *nlk = nlk_sk(sk);
unsigned int val = 0;
int err;
int nr = -1;

if (level != SOL_NETLINK)
return -ENOPROTOOPT;
Expand All @@ -1654,14 +1650,12 @@ static int netlink_setsockopt(struct socket *sock, int level, int optname,

switch (optname) {
case NETLINK_PKTINFO:
if (val)
nlk->flags |= NETLINK_F_RECV_PKTINFO;
else
nlk->flags &= ~NETLINK_F_RECV_PKTINFO;
err = 0;
nr = NETLINK_F_RECV_PKTINFO;
break;
case NETLINK_ADD_MEMBERSHIP:
case NETLINK_DROP_MEMBERSHIP: {
int err;

if (!netlink_allowed(sock, NL_CFG_F_NONROOT_RECV))
return -EPERM;
err = netlink_realloc_groups(sk);
Expand All @@ -1681,61 +1675,38 @@ static int netlink_setsockopt(struct socket *sock, int level, int optname,
if (optname == NETLINK_DROP_MEMBERSHIP && nlk->netlink_unbind)
nlk->netlink_unbind(sock_net(sk), val);

err = 0;
break;
}
case NETLINK_BROADCAST_ERROR:
if (val)
nlk->flags |= NETLINK_F_BROADCAST_SEND_ERROR;
else
nlk->flags &= ~NETLINK_F_BROADCAST_SEND_ERROR;
err = 0;
nr = NETLINK_F_BROADCAST_SEND_ERROR;
break;
case NETLINK_NO_ENOBUFS:
assign_bit(NETLINK_F_RECV_NO_ENOBUFS, &nlk->flags, val);
if (val) {
nlk->flags |= NETLINK_F_RECV_NO_ENOBUFS;
clear_bit(NETLINK_S_CONGESTED, &nlk->state);
wake_up_interruptible(&nlk->wait);
} else {
nlk->flags &= ~NETLINK_F_RECV_NO_ENOBUFS;
}
err = 0;
break;
case NETLINK_LISTEN_ALL_NSID:
if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_BROADCAST))
return -EPERM;

if (val)
nlk->flags |= NETLINK_F_LISTEN_ALL_NSID;
else
nlk->flags &= ~NETLINK_F_LISTEN_ALL_NSID;
err = 0;
nr = NETLINK_F_LISTEN_ALL_NSID;
break;
case NETLINK_CAP_ACK:
if (val)
nlk->flags |= NETLINK_F_CAP_ACK;
else
nlk->flags &= ~NETLINK_F_CAP_ACK;
err = 0;
nr = NETLINK_F_CAP_ACK;
break;
case NETLINK_EXT_ACK:
if (val)
nlk->flags |= NETLINK_F_EXT_ACK;
else
nlk->flags &= ~NETLINK_F_EXT_ACK;
err = 0;
nr = NETLINK_F_EXT_ACK;
break;
case NETLINK_GET_STRICT_CHK:
if (val)
nlk->flags |= NETLINK_F_STRICT_CHK;
else
nlk->flags &= ~NETLINK_F_STRICT_CHK;
err = 0;
nr = NETLINK_F_STRICT_CHK;
break;
default:
err = -ENOPROTOOPT;
return -ENOPROTOOPT;
}
return err;
if (nr >= 0)
assign_bit(nr, &nlk->flags, val);
return 0;
}

static int netlink_getsockopt(struct socket *sock, int level, int optname,
Expand Down Expand Up @@ -1802,7 +1773,7 @@ static int netlink_getsockopt(struct socket *sock, int level, int optname,
return -EINVAL;

len = sizeof(int);
val = nlk->flags & flag ? 1 : 0;
val = test_bit(flag, &nlk->flags);

if (put_user(len, optlen) ||
copy_to_user(optval, &val, len))
Expand Down Expand Up @@ -1979,9 +1950,9 @@ static int netlink_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
msg->msg_namelen = sizeof(*addr);
}

if (nlk->flags & NETLINK_F_RECV_PKTINFO)
if (nlk_test_bit(RECV_PKTINFO, sk))
netlink_cmsg_recv_pktinfo(msg, skb);
if (nlk->flags & NETLINK_F_LISTEN_ALL_NSID)
if (nlk_test_bit(LISTEN_ALL_NSID, sk))
netlink_cmsg_listen_all_nsid(sk, msg, skb);

memset(&scm, 0, sizeof(scm));
Expand Down Expand Up @@ -2058,7 +2029,7 @@ __netlink_kernel_create(struct net *net, int unit, struct module *module,
goto out_sock_release;

nlk = nlk_sk(sk);
nlk->flags |= NETLINK_F_KERNEL_SOCKET;
set_bit(NETLINK_F_KERNEL_SOCKET, &nlk->flags);

netlink_table_grab();
if (!nl_table[unit].registered) {
Expand Down Expand Up @@ -2192,7 +2163,7 @@ static int netlink_dump_done(struct netlink_sock *nlk, struct sk_buff *skb,
nl_dump_check_consistent(cb, nlh);
memcpy(nlmsg_data(nlh), &nlk->dump_done_errno, sizeof(nlk->dump_done_errno));

if (extack->_msg && nlk->flags & NETLINK_F_EXT_ACK) {
if (extack->_msg && test_bit(NETLINK_F_EXT_ACK, &nlk->flags)) {
nlh->nlmsg_flags |= NLM_F_ACK_TLVS;
if (!nla_put_string(skb, NLMSGERR_ATTR_MSG, extack->_msg))
nlmsg_end(skb, nlh);
Expand Down Expand Up @@ -2321,8 +2292,8 @@ int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
const struct nlmsghdr *nlh,
struct netlink_dump_control *control)
{
struct netlink_sock *nlk, *nlk2;
struct netlink_callback *cb;
struct netlink_sock *nlk;
struct sock *sk;
int ret;

Expand Down Expand Up @@ -2357,8 +2328,7 @@ int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
cb->min_dump_alloc = control->min_dump_alloc;
cb->skb = skb;

nlk2 = nlk_sk(NETLINK_CB(skb).sk);
cb->strict_check = !!(nlk2->flags & NETLINK_F_STRICT_CHK);
cb->strict_check = nlk_test_bit(STRICT_CHK, NETLINK_CB(skb).sk);

if (control->start) {
cb->extack = control->extack;
Expand Down Expand Up @@ -2402,7 +2372,7 @@ netlink_ack_tlv_len(struct netlink_sock *nlk, int err,
{
size_t tlvlen;

if (!extack || !(nlk->flags & NETLINK_F_EXT_ACK))
if (!extack || !test_bit(NETLINK_F_EXT_ACK, &nlk->flags))
return 0;

tlvlen = 0;
Expand Down Expand Up @@ -2474,7 +2444,7 @@ void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,
* requests to cap the error message, and get extra error data if
* requested.
*/
if (err && !(nlk->flags & NETLINK_F_CAP_ACK))
if (err && !test_bit(NETLINK_F_CAP_ACK, &nlk->flags))
payload += nlmsg_len(nlh);
else
flags |= NLM_F_CAPPED;
Expand Down
22 changes: 13 additions & 9 deletions net/netlink/af_netlink.h
View file
Expand Up @@ -8,25 +8,27 @@
#include <net/sock.h>

/* flags */
#define NETLINK_F_KERNEL_SOCKET 0x1
#define NETLINK_F_RECV_PKTINFO 0x2
#define NETLINK_F_BROADCAST_SEND_ERROR 0x4
#define NETLINK_F_RECV_NO_ENOBUFS 0x8
#define NETLINK_F_LISTEN_ALL_NSID 0x10
#define NETLINK_F_CAP_ACK 0x20
#define NETLINK_F_EXT_ACK 0x40
#define NETLINK_F_STRICT_CHK 0x80
enum {
NETLINK_F_KERNEL_SOCKET,
NETLINK_F_RECV_PKTINFO,
NETLINK_F_BROADCAST_SEND_ERROR,
NETLINK_F_RECV_NO_ENOBUFS,
NETLINK_F_LISTEN_ALL_NSID,
NETLINK_F_CAP_ACK,
NETLINK_F_EXT_ACK,
NETLINK_F_STRICT_CHK,
};

#define NLGRPSZ(x) (ALIGN(x, sizeof(unsigned long) * 8) / 8)
#define NLGRPLONGS(x) (NLGRPSZ(x)/sizeof(unsigned long))

struct netlink_sock {
/* struct sock has to be the first member of netlink_sock */
struct sock sk;
unsigned long flags;
u32 portid;
u32 dst_portid;
u32 dst_group;
u32 flags;
u32 subscriptions;
u32 ngroups;
unsigned long *groups;
Expand Down Expand Up @@ -54,6 +56,8 @@ static inline struct netlink_sock *nlk_sk(struct sock *sk)
return container_of(sk, struct netlink_sock, sk);
}

#define nlk_test_bit(nr, sk) test_bit(NETLINK_F_##nr, &nlk_sk(sk)->flags)

struct netlink_table {
struct rhashtable hash;
struct hlist_head mc_list;
Expand Down
10 changes: 5 additions & 5 deletions net/netlink/diag.c
View file
Expand Up @@ -27,15 +27,15 @@ static int sk_diag_put_flags(struct sock *sk, struct sk_buff *skb)

if (nlk->cb_running)
flags |= NDIAG_FLAG_CB_RUNNING;
if (nlk->flags & NETLINK_F_RECV_PKTINFO)
if (nlk_test_bit(RECV_PKTINFO, sk))
flags |= NDIAG_FLAG_PKTINFO;
if (nlk->flags & NETLINK_F_BROADCAST_SEND_ERROR)
if (nlk_test_bit(BROADCAST_SEND_ERROR, sk))
flags |= NDIAG_FLAG_BROADCAST_ERROR;
if (nlk->flags & NETLINK_F_RECV_NO_ENOBUFS)
if (nlk_test_bit(RECV_NO_ENOBUFS, sk))
flags |= NDIAG_FLAG_NO_ENOBUFS;
if (nlk->flags & NETLINK_F_LISTEN_ALL_NSID)
if (nlk_test_bit(LISTEN_ALL_NSID, sk))
flags |= NDIAG_FLAG_LISTEN_ALL_NSID;
if (nlk->flags & NETLINK_F_CAP_ACK)
if (nlk_test_bit(CAP_ACK, sk))
flags |= NDIAG_FLAG_CAP_ACK;

return nla_put_u32(skb, NETLINK_DIAG_FLAGS, flags);
Expand Down

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