| Message ID | a2a9b88418f3a58ef211b718f2970128ef9e3793.1608673640.git.me@pmachata.org |
|---|---|
| State | New |
| Headers | show |
| Series | [net] net: dcb: Validate netlink message in DCB handler | expand |
On Tue, 22 Dec 2020 22:49:44 +0100 Petr Machata wrote: > DCB uses the same handler function for both RTM_GETDCB and RTM_SETDCB > messages. dcb_doit() bounces RTM_SETDCB mesasges if the user does not have > the CAP_NET_ADMIN capability. > > However, the operation to be performed is not decided from the DCB message > type, but from the DCB command. Thus DCB_CMD_*_GET commands are used for > reading DCB objects, the corresponding SET and DEL commands are used for > manipulation. > > The assumption is that set-like commands will be sent via an RTM_SETDCB > message, and get-like ones via RTM_GETDCB. However, this assumption is not > enforced. > > It is therefore possible to manipulate DCB objects without CAP_NET_ADMIN > capability by sending the corresponding command in an RTM_GETDCB message. > That is a bug. Fix it by validating the type of the request message against > the type used for the response. > > Fixes: 2f90b8657ec9 ("ixgbe: this patch adds support for DCB to the kernel and ixgbe driver") > Signed-off-by: Petr Machata <me@pmachata.org> Applied, thanks!
diff --git a/net/dcb/dcbnl.c b/net/dcb/dcbnl.c index 084e159a12ba..7d49b6fd6cef 100644 --- a/net/dcb/dcbnl.c +++ b/net/dcb/dcbnl.c @@ -1765,6 +1765,8 @@ static int dcb_doit(struct sk_buff *skb, struct nlmsghdr *nlh, fn = &reply_funcs[dcb->cmd]; if (!fn->cb) return -EOPNOTSUPP; + if (fn->type != nlh->nlmsg_type) + return -EPERM; if (!tb[DCB_ATTR_IFNAME]) return -EINVAL;
DCB uses the same handler function for both RTM_GETDCB and RTM_SETDCB messages. dcb_doit() bounces RTM_SETDCB mesasges if the user does not have the CAP_NET_ADMIN capability. However, the operation to be performed is not decided from the DCB message type, but from the DCB command. Thus DCB_CMD_*_GET commands are used for reading DCB objects, the corresponding SET and DEL commands are used for manipulation. The assumption is that set-like commands will be sent via an RTM_SETDCB message, and get-like ones via RTM_GETDCB. However, this assumption is not enforced. It is therefore possible to manipulate DCB objects without CAP_NET_ADMIN capability by sending the corresponding command in an RTM_GETDCB message. That is a bug. Fix it by validating the type of the request message against the type used for the response. Fixes: 2f90b8657ec9 ("ixgbe: this patch adds support for DCB to the kernel and ixgbe driver") Signed-off-by: Petr Machata <me@pmachata.org> --- net/dcb/dcbnl.c | 2 ++ 1 file changed, 2 insertions(+)