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From:   Jinmeng Zhou <jjjinmeng.zhou@gmail.com>
Date:   Tue, 15 Feb 2022 20:37:56 +0800
Message-ID: <CAA-qYXiUFi5atN8tGRdORbiGqWnbdquuAeKuwdpWSVFVO2FveA@mail.gmail.com>
Subject: 4 missing check bugs
To:     marcel@holtmann.org, johan.hedberg@gmail.com, davem@davemloft.net,
        Jakub Kicinski <kuba@kernel.org>
Cc:     linux-bluetooth@vger.kernel.org, netdev@vger.kernel.org,
        shenwenbosmile@gmail.com
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Dear maintainers,

Hi, our tool finds several missing check bugs on
Linux kernel v4.18.5 using static analysis.
We are looking forward to having more experts' eyes on this. Thank you!

Before calling sk_alloc() with SOCK_RAW type,
there should be a permission check, ns_capable(ns,CAP_NET_RAW).
For example,

static int xsk_create(struct net *net, struct socket *sock, int protocol,
      int kern)
{
struct xdp_sock *xs;
struct sock *sk;

if (!ns_capable(net->user_ns, CAP_NET_RAW))
return -EPERM;
if (sock->type != SOCK_RAW)
return -ESOCKTNOSUPPORT;
...
sk = sk_alloc(net, PF_XDP, GFP_KERNEL, &xsk_proto, kern);
if (!sk)
return -ENOBUFS;
...
}


We find 4 missing check bugs.
The functions that miss permission checks in v4.18.5:

net/bluetooth/hidp/sock.c
static int hidp_sock_create(struct net *net, struct socket *sock, int protocol,
    int kern)
{
struct sock *sk;

BT_DBG("sock %p", sock);

if (sock->type != SOCK_RAW)
return -ESOCKTNOSUPPORT;

sk = sk_alloc(net, PF_BLUETOOTH, GFP_ATOMIC, &hidp_proto, kern);
if (!sk)
return -ENOMEM;
...
}


net/bluetooth/cmtp/sock.c
static int cmtp_sock_create(struct net *net, struct socket *sock, int protocol,
    int kern)
{
struct sock *sk;

BT_DBG("sock %p", sock);

if (sock->type != SOCK_RAW)
return -ESOCKTNOSUPPORT;

sk = sk_alloc(net, PF_BLUETOOTH, GFP_ATOMIC, &cmtp_proto, kern);
if (!sk)
return -ENOMEM;
...
}


net/bluetooth/hci_sock.c
static int hci_sock_create(struct net *net, struct socket *sock, int protocol,
   int kern)
{
struct sock *sk;

BT_DBG("sock %p", sock);

if (sock->type != SOCK_RAW)
return -ESOCKTNOSUPPORT;

sock->ops = &hci_sock_ops;

sk = sk_alloc(net, PF_BLUETOOTH, GFP_ATOMIC, &hci_sk_proto, kern);
if (!sk)
return -ENOMEM;
...
}


/net/bluetooth/bnep/sock.c
static int bnep_sock_create(struct net *net, struct socket *sock, int protocol,
    int kern)
{
struct sock *sk;

BT_DBG("sock %p", sock);

if (sock->type != SOCK_RAW)
return -ESOCKTNOSUPPORT;

sk = sk_alloc(net, PF_BLUETOOTH, GFP_ATOMIC, &bnep_proto, kern);
if (!sk)
return -ENOMEM;
...
}


Thanks again!


Best regards,
Jinmeng Zhou