net netlink: Add new type NLA_BITFIELD32
Generic bitflags attribute content sent to the kernel by user.
With this netlink attr type the user can either set or unset a
flag in the kernel.
The value is a bitmap that defines the bit values being set
The selector is a bitmask that defines which value bit is to be
considered.
A check is made to ensure the rules that a kernel subsystem always
conforms to bitflags the kernel already knows about. i.e
if the user tries to set a bit flag that is not understood then
the _it will be rejected_.
In the most basic form, the user specifies the attribute policy as:
[ATTR_GOO] = { .type = NLA_BITFIELD32, .validation_data = &myvalidflags },
where myvalidflags is the bit mask of the flags the kernel understands.
If the user _does not_ provide myvalidflags then the attribute will
also be rejected.
Examples:
value = 0x0, and selector = 0x1
implies we are selecting bit 1 and we want to set its value to 0.
value = 0x2, and selector = 0x2
implies we are selecting bit 2 and we want to set its value to 1.
Suggested-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/lib/nlattr.c b/lib/nlattr.c
index fb52435..ee79b7a 100644
--- a/lib/nlattr.c
+++ b/lib/nlattr.c
@@ -27,6 +27,30 @@
[NLA_S64] = sizeof(s64),
};
+static int validate_nla_bitfield32(const struct nlattr *nla,
+ u32 *valid_flags_allowed)
+{
+ const struct nla_bitfield32 *bf = nla_data(nla);
+ u32 *valid_flags_mask = valid_flags_allowed;
+
+ if (!valid_flags_allowed)
+ return -EINVAL;
+
+ /*disallow invalid bit selector */
+ if (bf->selector & ~*valid_flags_mask)
+ return -EINVAL;
+
+ /*disallow invalid bit values */
+ if (bf->value & ~*valid_flags_mask)
+ return -EINVAL;
+
+ /*disallow valid bit values that are not selected*/
+ if (bf->value & ~bf->selector)
+ return -EINVAL;
+
+ return 0;
+}
+
static int validate_nla(const struct nlattr *nla, int maxtype,
const struct nla_policy *policy)
{
@@ -46,6 +70,12 @@
return -ERANGE;
break;
+ case NLA_BITFIELD32:
+ if (attrlen != sizeof(struct nla_bitfield32))
+ return -ERANGE;
+
+ return validate_nla_bitfield32(nla, pt->validation_data);
+
case NLA_NUL_STRING:
if (pt->len)
minlen = min_t(int, attrlen, pt->len + 1);