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authorJamal Hadi Salim <jhs@mojatatu.com>2017-07-30 13:24:49 -0400
committerDavid S. Miller <davem@davemloft.net>2017-07-30 19:28:08 -0700
commit64c83d837329531252a1a0f0dfdd4fd607e1d8e9 (patch)
treea764214643c24db912ab942efd1aa47365d179c9 /lib/nlattr.c
parentfbbeefdd21049fcf9437c809da3828b210577f36 (diff)
downloadlinux-64c83d837329531252a1a0f0dfdd4fd607e1d8e9.tar.bz2
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>
Diffstat (limited to 'lib/nlattr.c')
-rw-r--r--lib/nlattr.c30
1 files changed, 30 insertions, 0 deletions
diff --git a/lib/nlattr.c b/lib/nlattr.c
index fb52435be42d..ee79b7a3c6b0 100644
--- a/lib/nlattr.c
+++ b/lib/nlattr.c
@@ -27,6 +27,30 @@ static const u8 nla_attr_minlen[NLA_TYPE_MAX+1] = {
[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 @@ static int validate_nla(const struct nlattr *nla, int maxtype,
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);