[ovs-dev] [PATCH V3 7/9] compat: Use nla_parse deprecated functions

Greg Rose gvrose8192 at gmail.com
Wed Mar 4 23:04:18 UTC 2020

From: Johannes Berg <johannes.berg at intel.com>

Upstream commit:
    commit 8cb081746c031fb164089322e2336a0bf5b3070c
    Author: Johannes Berg <johannes.berg at intel.com>
    Date:   Fri Apr 26 14:07:28 2019 +0200

    netlink: make validation more configurable for future strictness

    We currently have two levels of strict validation:

     1) liberal (default)
         - undefined (type >= max) & NLA_UNSPEC attributes accepted
         - attribute length >= expected accepted
         - garbage at end of message accepted
     2) strict (opt-in)
         - NLA_UNSPEC attributes accepted
         - attribute length >= expected accepted

    Split out parsing strictness into four different options:
     * TRAILING     - check that there's no trailing data after parsing
                      attributes (in message or nested)
     * MAXTYPE      - reject attrs > max known type
     * UNSPEC       - reject attributes with NLA_UNSPEC policy entries
     * STRICT_ATTRS - strictly validate attribute size

    The default for future things should be *everything*.
    The current *_strict() is a combination of TRAILING and MAXTYPE,
    and is renamed to _deprecated_strict().
    The current regular parsing has none of this, and is renamed to

    Additionally it allows us to selectively set one of the new flags
    even on old policies. Notably, the UNSPEC flag could be useful in
    this case, since it can be arranged (by filling in the policy) to
    not be an incompatible userspace ABI change, but would then going
    forward prevent forgetting attribute entries. Similar can apply
    to the POLICY flag.

    We end up with the following renames:
     * nla_parse           -> nla_parse_deprecated
     * nla_parse_strict    -> nla_parse_deprecated_strict
     * nlmsg_parse         -> nlmsg_parse_deprecated
     * nlmsg_parse_strict  -> nlmsg_parse_deprecated_strict
     * nla_parse_nested    -> nla_parse_nested_deprecated
     * nla_validate_nested -> nla_validate_nested_deprecated

    Using spatch, of course:
        expression TB, MAX, HEAD, LEN, POL, EXT;
        -nla_parse(TB, MAX, HEAD, LEN, POL, EXT)
        +nla_parse_deprecated(TB, MAX, HEAD, LEN, POL, EXT)

        expression NLH, HDRLEN, TB, MAX, POL, EXT;
        -nlmsg_parse(NLH, HDRLEN, TB, MAX, POL, EXT)
        +nlmsg_parse_deprecated(NLH, HDRLEN, TB, MAX, POL, EXT)

        expression NLH, HDRLEN, TB, MAX, POL, EXT;
        -nlmsg_parse_strict(NLH, HDRLEN, TB, MAX, POL, EXT)
        +nlmsg_parse_deprecated_strict(NLH, HDRLEN, TB, MAX, POL, EXT)

        expression TB, MAX, NLA, POL, EXT;
        -nla_parse_nested(TB, MAX, NLA, POL, EXT)
        +nla_parse_nested_deprecated(TB, MAX, NLA, POL, EXT)

        expression START, MAX, POL, EXT;
        -nla_validate_nested(START, MAX, POL, EXT)
        +nla_validate_nested_deprecated(START, MAX, POL, EXT)

        expression NLH, HDRLEN, MAX, POL, EXT;
        -nlmsg_validate(NLH, HDRLEN, MAX, POL, EXT)
        +nlmsg_validate_deprecated(NLH, HDRLEN, MAX, POL, EXT)

    For this patch, don't actually add the strict, non-renamed versions
    yet so that it breaks compile if I get it wrong.

    Also, while at it, make nla_validate and nla_parse go down to a
    common __nla_validate_parse() function to avoid code duplication.

    Ultimately, this allows us to have very strict validation for every
    new caller of nla_parse()/nlmsg_parse() etc as re-introduced in the
    next patch, while existing things will continue to work as is.

    In effect then, this adds fully strict validation for any new command.

    Signed-off-by: Johannes Berg <johannes.berg at intel.com>
    Signed-off-by: David S. Miller <davem at davemloft.net>

Backport portions of this commit applicable to openvswitch and
added necessary compatibility layer changes to support older

Signed-off-by: Greg Rose <gvrose8192 at gmail.com>
V3 - As per Yi-Hung's suggestion just backport the upstream patch
     to stay in sync with upstream kernel code.
 acinclude.m4                                |  3 +++
 datapath/datapath.c                         |  4 ++--
 datapath/flow_netlink.c                     |  9 +++++----
 datapath/linux/compat/include/net/netlink.h | 12 ++++++++++--
 datapath/meter.c                            |  8 +++++---
 datapath/vport-vxlan.c                      |  4 ++--
 6 files changed, 27 insertions(+), 13 deletions(-)

diff --git a/acinclude.m4 b/acinclude.m4
index a55c905..43d1576 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -1072,6 +1072,9 @@ AC_DEFUN([OVS_CHECK_LINUX_COMPAT], [
   OVS_FIND_FIELD_IFELSE([$KSRC/include/net/genetlink.h], [genl_ops],
+  OVS_GREP_IFELSE([$KSRC/include/net/netlink.h],
+                  [nla_parse_deprecated_strict],
   if cmp -s datapath/linux/kcompat.h.new \
             datapath/linux/kcompat.h >/dev/null 2>&1; then
diff --git a/datapath/datapath.c b/datapath/datapath.c
index f0c3457..a7af784 100644
--- a/datapath/datapath.c
+++ b/datapath/datapath.c
@@ -1401,8 +1401,8 @@ static int ovs_flow_cmd_dump(struct sk_buff *skb, struct netlink_callback *cb)
 	u32 ufid_flags;
 	int err;
-	err = genlmsg_parse(cb->nlh, &dp_flow_genl_family, a,
-			    OVS_FLOW_ATTR_MAX, flow_policy, NULL);
+	err = genlmsg_parse_deprecated(cb->nlh, &dp_flow_genl_family, a,
+				       OVS_FLOW_ATTR_MAX, flow_policy, NULL);
 	if (err)
 		return err;
 	ufid_flags = ovs_nla_get_ufid_flags(a[OVS_FLOW_ATTR_UFID_FLAGS]);
diff --git a/datapath/flow_netlink.c b/datapath/flow_netlink.c
index 9fc1a19..d3fd771 100644
--- a/datapath/flow_netlink.c
+++ b/datapath/flow_netlink.c
@@ -2859,8 +2859,8 @@ static int validate_userspace(const struct nlattr *attr)
 	struct nlattr *a[OVS_USERSPACE_ATTR_MAX + 1];
 	int error;
-	error = nla_parse_nested(a, OVS_USERSPACE_ATTR_MAX, attr,
-				 userspace_policy, NULL);
+	error = nla_parse_nested_deprecated(a, OVS_USERSPACE_ATTR_MAX, attr,
+					    userspace_policy, NULL);
 	if (error)
 		return error;
@@ -2891,8 +2891,9 @@ static int validate_and_copy_check_pkt_len(struct net *net,
 	int nested_acts_start;
 	int start, err;
-	err = nla_parse_nested(a, OVS_CHECK_PKT_LEN_ATTR_MAX, attr,
-			       cpl_policy, NULL);
+	err = nla_parse_deprecated_strict(a, OVS_CHECK_PKT_LEN_ATTR_MAX,
+					  nla_data(attr), nla_len(attr),
+					  cpl_policy, NULL);
 	if (err)
 		return err;
diff --git a/datapath/linux/compat/include/net/netlink.h b/datapath/linux/compat/include/net/netlink.h
index 34fc346..84e0739 100644
--- a/datapath/linux/compat/include/net/netlink.h
+++ b/datapath/linux/compat/include/net/netlink.h
@@ -143,6 +143,11 @@ static inline int nla_put_be64(struct sk_buff *skb, int attrtype, __be64 value,
+#define nla_parse_nested_deprecated nla_parse_nested
+#define nla_parse_deprecated_strict nla_parse
+#define genlmsg_parse_deprecated genlmsg_parse
 struct netlink_ext_ack;
@@ -153,7 +158,8 @@ static inline int rpl_nla_parse_nested(struct nlattr *tb[], int maxtype,
 	return nla_parse_nested(tb, maxtype, nla, policy);
-#define nla_parse_nested rpl_nla_parse_nested
+#undef nla_parse_nested_deprecated
+#define nla_parse_nested_deprecated rpl_nla_parse_nested
 static inline int rpl_nla_parse(struct nlattr **tb, int maxtype,
 				const struct nlattr *head, int len,
@@ -162,8 +168,10 @@ static inline int rpl_nla_parse(struct nlattr **tb, int maxtype,
 	return nla_parse(tb, maxtype, head, len, policy);
-#define nla_parse rpl_nla_parse
+#undef nla_parse_deprecated_strict
+#define nla_parse_deprecated_strict rpl_nla_parse
 static inline struct nlattr *rpl_nla_nest_start_noflag(struct sk_buff *skb,
diff --git a/datapath/meter.c b/datapath/meter.c
index 8cecd5a..92c9c36 100644
--- a/datapath/meter.c
+++ b/datapath/meter.c
@@ -239,9 +239,11 @@ static struct dp_meter *dp_meter_create(struct nlattr **a)
 		struct nlattr *attr[OVS_BAND_ATTR_MAX + 1];
 		u32 band_max_delta_t;
-		err = nla_parse((struct nlattr **)&attr, OVS_BAND_ATTR_MAX,
-				nla_data(nla), nla_len(nla), band_policy,
-				NULL);
+		err = nla_parse_deprecated_strict((struct nlattr **)&attr,
+						  nla_data(nla),
+						  nla_len(nla),
+						  band_policy, NULL);
 		if (err)
 			goto exit_free_meter;
diff --git a/datapath/vport-vxlan.c b/datapath/vport-vxlan.c
index 70ed376..79331c9 100644
--- a/datapath/vport-vxlan.c
+++ b/datapath/vport-vxlan.c
@@ -99,8 +99,8 @@ static int vxlan_configure_exts(struct vport *vport, struct nlattr *attr,
 	if (nla_len(attr) < sizeof(struct nlattr))
 		return -EINVAL;
-	err = nla_parse_nested(exts, OVS_VXLAN_EXT_MAX, attr, exts_policy,
-			       NULL);
+	err = nla_parse_nested_deprecated(exts, OVS_VXLAN_EXT_MAX, attr,
+					  exts_policy, NULL);
 	if (err < 0)
 		return err;

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