From: Ruihan Li lrh2000@pku.edu.cn
commit 25c150ac103a4ebeed0319994c742a90634ddf18 upstream.
Previously, capability was checked using capable(), which verified that the caller of the ioctl system call had the required capability. In addition, the result of the check would be stored in the HCI_SOCK_TRUSTED flag, making it persistent for the socket.
However, malicious programs can abuse this approach by deliberately sharing an HCI socket with a privileged task. The HCI socket will be marked as trusted when the privileged task occasionally makes an ioctl call.
This problem can be solved by using sk_capable() to check capability, which ensures that not only the current task but also the socket opener has the specified capability, thus reducing the risk of privilege escalation through the previously identified vulnerability.
Cc: stable@vger.kernel.org Fixes: f81f5b2db869 ("Bluetooth: Send control open and close messages for HCI raw sockets") Signed-off-by: Ruihan Li lrh2000@pku.edu.cn Signed-off-by: Luiz Augusto von Dentz luiz.von.dentz@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/bluetooth/hci_sock.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
--- a/net/bluetooth/hci_sock.c +++ b/net/bluetooth/hci_sock.c @@ -996,7 +996,14 @@ static int hci_sock_ioctl(struct socket if (hci_sock_gen_cookie(sk)) { struct sk_buff *skb;
- if (capable(CAP_NET_ADMIN)) + /* Perform careful checks before setting the HCI_SOCK_TRUSTED + * flag. Make sure that not only the current task but also + * the socket opener has the required capability, since + * privileged programs can be tricked into making ioctl calls + * on HCI sockets, and the socket should not be marked as + * trusted simply because the ioctl caller is privileged. + */ + if (sk_capable(sk, CAP_NET_ADMIN)) hci_sock_set_flag(sk, HCI_SOCK_TRUSTED);
/* Send event to monitor */