From bdbb4e29df8b790db50cb73ce25d23543329f05f Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Mon, 5 Oct 2020 15:07:38 -0700 Subject: netlink: add mask validation We don't have good validation policy for existing unsigned int attrs which serve as flags (for new ones we could use NLA_BITFIELD32). With increased use of policy dumping having the validation be expressed as part of the policy is important. Add validation policy in form of a mask of supported/valid bits. Support u64 in the uAPI to be future-proof, but really for now the embedded mask member can only hold 32 bits, so anything with bit 32+ set will always fail validation. Signed-off-by: Jakub Kicinski Signed-off-by: David S. Miller --- lib/nlattr.c | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) (limited to 'lib/nlattr.c') diff --git a/lib/nlattr.c b/lib/nlattr.c index 80ff9fe83696..9c99f5daa4d2 100644 --- a/lib/nlattr.c +++ b/lib/nlattr.c @@ -323,6 +323,37 @@ static int nla_validate_int_range(const struct nla_policy *pt, } } +static int nla_validate_mask(const struct nla_policy *pt, + const struct nlattr *nla, + struct netlink_ext_ack *extack) +{ + u64 value; + + switch (pt->type) { + case NLA_U8: + value = nla_get_u8(nla); + break; + case NLA_U16: + value = nla_get_u16(nla); + break; + case NLA_U32: + value = nla_get_u32(nla); + break; + case NLA_U64: + value = nla_get_u64(nla); + break; + default: + return -EINVAL; + } + + if (value & ~(u64)pt->mask) { + NL_SET_ERR_MSG_ATTR(extack, nla, "reserved bit set"); + return -EINVAL; + } + + return 0; +} + static int validate_nla(const struct nlattr *nla, int maxtype, const struct nla_policy *policy, unsigned int validate, struct netlink_ext_ack *extack, unsigned int depth) @@ -503,6 +534,11 @@ static int validate_nla(const struct nlattr *nla, int maxtype, if (err) return err; break; + case NLA_VALIDATE_MASK: + err = nla_validate_mask(pt, nla, extack); + if (err) + return err; + break; case NLA_VALIDATE_FUNCTION: if (pt->validate) { err = pt->validate(nla, extack); -- cgit v1.2.3