[PATCH AUTOSEL 5.4 06/37] bpf: Make dst_port field in struct bpf_sock 16-bit wide

[PATCH AUTOSEL 5.4 06/37] bpf: Make dst_port field in struct bpf_sock 16-bit wide

[Sasha Levin]

From: Jakub Sitnicki <jakub@cloudflare.com>

[ Upstream commit 4421a582718ab81608d8486734c18083b822390d ]

Menglong Dong reports that the documentation for the dst_port field in
struct bpf_sock is inaccurate and confusing. From the BPF program PoV, the
field is a zero-padded 16-bit integer in network byte order. The value
appears to the BPF user as if laid out in memory as so:

  offsetof(struct bpf_sock, dst_port) + 0  <port MSB>
                                      + 8  <port LSB>
                                      +16  0x00
                                      +24  0x00

32-, 16-, and 8-bit wide loads from the field are all allowed, but only if
the offset into the field is 0.

32-bit wide loads from dst_port are especially confusing. The loaded value,
after converting to host byte order with bpf_ntohl(dst_port), contains the
port number in the upper 16-bits.

Remove the confusion by splitting the field into two 16-bit fields. For
backward compatibility, allow 32-bit wide loads from offsetof(struct
bpf_sock, dst_port).

While at it, allow loads 8-bit loads at offset [0] and [1] from dst_port.

Reported-by: Menglong Dong <imagedong@tencent.com>
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/r/20220130115518.213259-2-jakub@cloudflare.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 include/uapi/linux/bpf.h |  3 ++-
 net/core/filter.c        | 10 +++++++++-
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 63038eb23560..4d0d932a7017 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -3068,7 +3068,8 @@ struct bpf_sock {
 	__u32 src_ip4;
 	__u32 src_ip6[4];
 	__u32 src_port;		/* host byte order */
-	__u32 dst_port;		/* network byte order */
+	__be16 dst_port;	/* network byte order */
+	__u16 :16;		/* zero padding */
 	__u32 dst_ip4;
 	__u32 dst_ip6[4];
 	__u32 state;
diff --git a/net/core/filter.c b/net/core/filter.c
index d39518f691b4..54c5e3c379f6 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -6708,6 +6708,7 @@ bool bpf_sock_is_valid_access(int off, int size, enum bpf_access_type type,
 			      struct bpf_insn_access_aux *info)
 {
 	const int size_default = sizeof(__u32);
+	int field_size;
 
 	if (off < 0 || off >= sizeof(struct bpf_sock))
 		return false;
@@ -6719,7 +6720,6 @@ bool bpf_sock_is_valid_access(int off, int size, enum bpf_access_type type,
 	case offsetof(struct bpf_sock, family):
 	case offsetof(struct bpf_sock, type):
 	case offsetof(struct bpf_sock, protocol):
-	case offsetof(struct bpf_sock, dst_port):
 	case offsetof(struct bpf_sock, src_port):
 	case bpf_ctx_range(struct bpf_sock, src_ip4):
 	case bpf_ctx_range_till(struct bpf_sock, src_ip6[0], src_ip6[3]):
@@ -6727,6 +6727,14 @@ bool bpf_sock_is_valid_access(int off, int size, enum bpf_access_type type,
 	case bpf_ctx_range_till(struct bpf_sock, dst_ip6[0], dst_ip6[3]):
 		bpf_ctx_record_field_size(info, size_default);
 		return bpf_ctx_narrow_access_ok(off, size, size_default);
+	case bpf_ctx_range(struct bpf_sock, dst_port):
+		field_size = size == size_default ?
+			size_default : sizeof_field(struct bpf_sock, dst_port);
+		bpf_ctx_record_field_size(info, field_size);
+		return bpf_ctx_narrow_access_ok(off, size, field_size);
+	case offsetofend(struct bpf_sock, dst_port) ...
+	     offsetof(struct bpf_sock, dst_ip4) - 1:
+		return false;
 	}
 
 	return size == size_default;
-- 
2.34.1

[PATCH AUTOSEL 5.4 26/37] tuntap: add sanity checks about msg_controllen in sendmsg

[Sasha Levin]

From: Harold Huang <baymaxhuang@gmail.com>

[ Upstream commit 74a335a07a17d131b9263bfdbdcb5e40673ca9ca ]

In patch [1], tun_msg_ctl was added to allow pass batched xdp buffers to
tun_sendmsg. Although we donot use msg_controllen in this path, we should
check msg_controllen to make sure the caller pass a valid msg_ctl.

[1]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=fe8dd45bb7556246c6b76277b1ba4296c91c2505

Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
Suggested-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Harold Huang <baymaxhuang@gmail.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20220303022441.383865-1-baymaxhuang@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/tap.c   | 3 ++-
 drivers/net/tun.c   | 3 ++-
 drivers/vhost/net.c | 1 +
 3 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/net/tap.c b/drivers/net/tap.c
index f285422a8071..f870d08bb1f8 100644
--- a/drivers/net/tap.c
+++ b/drivers/net/tap.c
@@ -1214,7 +1214,8 @@ static int tap_sendmsg(struct socket *sock, struct msghdr *m,
 	struct xdp_buff *xdp;
 	int i;
 
-	if (ctl && (ctl->type == TUN_MSG_PTR)) {
+	if (m->msg_controllen == sizeof(struct tun_msg_ctl) &&
+	    ctl && ctl->type == TUN_MSG_PTR) {
 		for (i = 0; i < ctl->num; i++) {
 			xdp = &((struct xdp_buff *)ctl->ptr)[i];
 			tap_get_user_xdp(q, xdp);
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 10211ea60514..d9993884a97d 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -2561,7 +2561,8 @@ static int tun_sendmsg(struct socket *sock, struct msghdr *m, size_t total_len)
 	if (!tun)
 		return -EBADFD;
 
-	if (ctl && (ctl->type == TUN_MSG_PTR)) {
+	if (m->msg_controllen == sizeof(struct tun_msg_ctl) &&
+	    ctl && ctl->type == TUN_MSG_PTR) {
 		struct tun_page tpage;
 		int n = ctl->num;
 		int flush = 0;
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index cec9173aac6f..1058aba8d573 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -472,6 +472,7 @@ static void vhost_tx_batch(struct vhost_net *net,
 		goto signal_used;
 
 	msghdr->msg_control = &ctl;
+	msghdr->msg_controllen = sizeof(ctl);
 	err = sock->ops->sendmsg(sock, msghdr, 0);
 	if (unlikely(err < 0)) {
 		vq_err(&nvq->vq, "Fail to batch sending packets\n");
-- 
2.34.1