Commit 802bfb19 authored by Paolo Abeni's avatar Paolo Abeni Committed by David S. Miller
Browse files

net/sched: user-space can't set unknown tcfa_action values 



Currently, when initializing an action, the user-space can specify
and use arbitrary values for the tcfa_action field. If the value
is unknown by the kernel, is implicitly threaded as TC_ACT_UNSPEC.

This change explicitly checks for unknown values at action creation
time, and explicitly convert them to TC_ACT_UNSPEC. No functional
changes are introduced, but this will allow introducing tcfa_action
values not exposed to user-space in a later patch.

Note: we can't use the above to hide TC_ACT_REDIRECT from user-space,
as the latter is already part of uAPI.

v3 -> v4:
 - use an helper to check for action validity (JiriP)
 - emit an extack for invalid actions (JiriP)
v4 -> v5:
 - keep messages on a single line, drop net_warn (Marcelo)

Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
Acked-by: default avatarJiri Pirko <jiri@mellanox.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent c87fffc5

include/uapi/linux/pkt_cls.h

+4 −2
Original line number Diff line number Diff line
@@ -45,6 +45,7 @@ enum { 
				   * the skb and act like everything

				   * is alright.

				   */

#define TC_ACT_VALUE_MAX	TC_ACT_TRAP



/* There is a special kind of actions called "extended actions",

 * which need a value parameter. These have a local opcode located in
@@ -55,11 +56,12 @@ enum { 
#define __TC_ACT_EXT_SHIFT 28

#define __TC_ACT_EXT(local) ((local) << __TC_ACT_EXT_SHIFT)

#define TC_ACT_EXT_VAL_MASK ((1 << __TC_ACT_EXT_SHIFT) - 1)

#define TC_ACT_EXT_CMP(combined, opcode) \

	(((combined) & (~TC_ACT_EXT_VAL_MASK)) == opcode)

#define TC_ACT_EXT_OPCODE(combined) ((combined) & (~TC_ACT_EXT_VAL_MASK))

#define TC_ACT_EXT_CMP(combined, opcode) (TC_ACT_EXT_OPCODE(combined) == opcode)



#define TC_ACT_JUMP __TC_ACT_EXT(1)

#define TC_ACT_GOTO_CHAIN __TC_ACT_EXT(2)

#define TC_ACT_EXT_OPCODE_MAX	TC_ACT_GOTO_CHAIN



/* Action type identifiers*/

enum {

net/sched/act_api.c

+14 −0
Original line number Diff line number Diff line
@@ -786,6 +786,15 @@ static struct tc_cookie *nla_memdup_cookie(struct nlattr **tb) 
	return c;

}



static bool tcf_action_valid(int action)

{

	int opcode = TC_ACT_EXT_OPCODE(action);



	if (!opcode)

		return action <= TC_ACT_VALUE_MAX;

	return opcode <= TC_ACT_EXT_OPCODE_MAX || action == TC_ACT_UNSPEC;

}



struct tc_action *tcf_action_init_1(struct net *net, struct tcf_proto *tp,

				    struct nlattr *nla, struct nlattr *est,

				    char *name, int ovr, int bind,
@@ -895,6 +904,11 @@ struct tc_action *tcf_action_init_1(struct net *net, struct tcf_proto *tp, 
		}

	}



	if (!tcf_action_valid(a->tcfa_action)) {

		NL_SET_ERR_MSG(extack, "invalid action value, using TC_ACT_UNSPEC instead");

		a->tcfa_action = TC_ACT_UNSPEC;

	}



	return a;



err_mod:

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