From 64c83d837329531252a1a0f0dfdd4fd607e1d8e9 Mon Sep 17 00:00:00 2001 From: Jamal Hadi Salim Date: Sun, 30 Jul 2017 13:24:49 -0400 Subject: 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 Signed-off-by: Jamal Hadi Salim Signed-off-by: David S. Miller --- lib/nlattr.c | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) (limited to 'lib') 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 @@ 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); -- cgit v1.1