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| author | Ben Pfaff <blp@nicira.com> | 2011-01-31 15:47:43 -0800 |
|---|---|---|
| committer | Ben Pfaff <blp@nicira.com> | 2011-01-31 21:40:20 -0800 |
| commit | 0700107651b6a774f8f7ba873259a5d5011e3cb0 (patch) | |
| tree | bd365288aab22510517425a663d8797a5cfa9c39 /datapath | |
| parent | d2a23af25132de097060d59f94465c94138c78a1 (diff) | |
| download | openvswitch-0700107651b6a774f8f7ba873259a5d5011e3cb0.tar.gz | |
datapath: Fix behavior of NLA_NESTED for pre-2.6.29 kernels.
Before v2.6.29, a NLA_NESTED attribute, if it was present, was not allowed
to be empty. However, OVS depends on the ability to accept empty
attributes. For example, a present but empty ODP_FLOW_ATTR_ACTIONS on
ODP_FLOW_CMD_SET replaces the existing set of actions by an empty "drop"
action, whereas a missing ODP_FLOW_ATTR_ACTIONS leaves the existing
actions, if any, unchanged.
NLA_NESTED is different from NLA_UNSPEC in only two ways:
* If the size of the nested attributes is zero, no further size checks
are performed.
* If the size of the nested attributes is not zero and no length
parameter is specified the minimum size of nested attributes is
NLA_HDRLEN.
nla_parse_nested() validates that there is at least enough space for
NLA_HDRLEN, so neither of these conditions are important, and we might
as well use NLA_UNSPEC with old kernels.
Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Jesse Gross <jesse@nicira.com>
Diffstat (limited to 'datapath')
| -rw-r--r-- | datapath/linux-2.6/compat-2.6/include/net/netlink.h | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/datapath/linux-2.6/compat-2.6/include/net/netlink.h b/datapath/linux-2.6/compat-2.6/include/net/netlink.h index 0f881f1c8..aa7c09c03 100644 --- a/datapath/linux-2.6/compat-2.6/include/net/netlink.h +++ b/datapath/linux-2.6/compat-2.6/include/net/netlink.h @@ -4,6 +4,31 @@ #include <linux/version.h> #include_next <net/netlink.h> +#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,29) +/* Before v2.6.29, a NLA_NESTED attribute, if it was present, was not allowed + * to be empty. However, OVS depends on the ability to accept empty + * attributes. For example, a present but empty ODP_FLOW_ATTR_ACTIONS on + * ODP_FLOW_CMD_SET replaces the existing set of actions by an empty "drop" + * action, whereas a missing ODP_FLOW_ATTR_ACTIONS leaves the existing + * actions, if any, unchanged. + * + * NLA_NESTED is different from NLA_UNSPEC in only two ways: + * + * - If the size of the nested attributes is zero, no further size checks + * are performed. + * + * - If the size of the nested attributes is not zero and no length + * parameter is specified the minimum size of nested attributes is + * NLA_HDRLEN. + * + * nla_parse_nested() validates that there is at least enough space for + * NLA_HDRLEN, so neither of these conditions are important, and we might + * as well use NLA_UNSPEC with old kernels. + */ +#undef NLA_NESTED +#define NLA_NESTED NLA_UNSPEC +#endif + #ifndef HAVE_NLA_NUL_STRING static inline int VERIFY_NUL_STRING(struct nlattr *attr, int maxlen) { |