• Johannes Berg's avatar
    netlink: add attribute range validation to policy · 3e48be05
    Johannes Berg authored
    Without further bloating the policy structs, we can overload
    the `validation_data' pointer with a struct of s16 min, max
    and use those to validate ranges in NLA_{U,S}{8,16,32,64}
    attributes.
    
    It may sound strange to validate NLA_U32 with a s16 max, but
    in many cases NLA_U32 is used for enums etc. since there's no
    size benefit in using a smaller attribute width anyway, due
    to netlink attribute alignment; in cases like that it's still
    useful, particularly when the attribute really transports an
    enum value.
    
    Doing so lets us remove quite a bit of validation code, if we
    can be sure that these attributes aren't used by userspace in
    places where they're ignored today.
    
    To achieve all this, split the 'type' field and introduce a
    new 'validation_type' field which indicates what further
    validation (beyond the validation prescribed by the type of
    the attribute) is done. This currently allows for no further
    validation (the default), as well as min, max and range checks.
    Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    3e48be05
netlink.h 44.4 KB