[PATCH AUTOSEL 6.4 24/41] netlink: convert nlk->flags to atomic flags

Sasha Levin
2023-09-08T18:20:33Z

From: Eric Dumazet <edumazet@google.com>

[ Upstream commit 8fe08d70a2b61b35a0a1235c78cf321e7528351f ]

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>
---
net/netlink/af_netlink.c | 90 ++++++++++++++--------------------------
net/netlink/af_netlink.h | 22 ++++++----
net/netlink/diag.c | 10 ++---
3 files changed, 48 insertions(+), 74 deletions(-)

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 5968b6450d828..4cbe6df6ac36f 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -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;
@@ -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;
@@ -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);

@@ -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))
@@ -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;
}
@@ -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;
@@ -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;
}
@@ -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;
@@ -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);
@@ -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,
@@ -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))
@@ -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));
@@ -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) {
@@ -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);
@@ -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;

@@ -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) {
ret = control->start(cb);
@@ -2400,7 +2370,7 @@ 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;
@@ -2472,7 +2442,7 @@ 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;
diff --git a/net/netlink/af_netlink.h b/net/netlink/af_netlink.h
index 90a3198a9b7f7..3dbd38aef50a4 100644
--- a/net/netlink/af_netlink.h
+++ b/net/netlink/af_netlink.h
@@ -8,14 +8,16 @@
#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))
@@ -23,10 +25,10 @@
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;
@@ -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;
diff --git a/net/netlink/diag.c b/net/netlink/diag.c
index e4f21b1067bcc..9c4f231be2757 100644
--- a/net/netlink/diag.c
+++ b/net/netlink/diag.c
@@ -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);
--
2.40.1