On Mon, Jul 27, 2020 at 02:47:00PM -0700, Jacob Keller wrote:
> The ethtool netlink API can send bitsets without an associated bitmask.
> These do not get displayed properly, because the dump_link_modes, and
> bitset_get_bit to not check whether the provided bitset is a NOMASK
> bitset. This results in the inability to display peer advertised link
> modes.
>
> The dump_link_modes and bitset_get_bit functions are designed so they
> can print either the values or the mask. For a nomask bitmap, this
> doesn't make sense. There is no mask.
>
> Modify dump_link_modes to check ETHTOOL_A_BITSET_NOMASK. For compact
> bitmaps, always check and print the ETHTOOL_A_BITSET_VALUE bits,
> regardless of the request to display the mask or the value. For full
> size bitmaps, the set of provided bits indicates the valid values,
> without using ETHTOOL_A_BITSET_VALUE fields. Thus, do not skip printing
> bits without this attribute if nomask is set. This essentially means
> that dump_link_modes will treat a NOMASK bitset as having a mask
> equivalent to all of its set bits.
>
> For bitset_get_bit, also check for ETHTOOL_A_BITSET_NOMASK. For compact
> bitmaps, always use ETHTOOL_A_BITSET_BIT_VALUE as in dump_link_modes.
> For full bitmaps, if nomask is set, then always return true of the bit
> is in the set, rather than only if it provides an
> ETHTOOL_A_BITSET_BIT_VALUE. This will then correctly report the set
> bits.
>
> This fixes display of link partner advertised fields when using the
> netlink API.
>
> Reported-by: Jamie Gloudon <jamie.glou...@gmx.fr>
> Signed-off-by: Jacob Keller <jacob.e.kel...@intel.com>
> ---
> netlink/bitset.c | 9 ++++++---
> netlink/settings.c | 8 +++++---
> 2 files changed, 11 insertions(+), 6 deletions(-)
>
> diff --git a/netlink/bitset.c b/netlink/bitset.c
> index 130bcdb5b52c..ba5d3ea77ff7 100644
> --- a/netlink/bitset.c
> +++ b/netlink/bitset.c
> @@ -50,6 +50,7 @@ bool bitset_get_bit(const struct nlattr *bitset, bool mask,
> unsigned int idx,
> DECLARE_ATTR_TB_INFO(bitset_tb);
> const struct nlattr *bits;
> const struct nlattr *bit;
> + bool nomask;
> int ret;
>
> *retptr = 0;
> @@ -57,8 +58,10 @@ bool bitset_get_bit(const struct nlattr *bitset, bool
> mask, unsigned int idx,
> if (ret < 0)
> goto err;
>
> - bits = mask ? bitset_tb[ETHTOOL_A_BITSET_MASK] :
> - bitset_tb[ETHTOOL_A_BITSET_VALUE];
> + nomask = bitset_tb[ETHTOOL_A_BITSET_NOMASK];
> +
> + bits = mask && !nomask ? bitset_tb[ETHTOOL_A_BITSET_MASK] :
> + bitset_tb[ETHTOOL_A_BITSET_VALUE];
> if (bits) {
> const uint32_t *bitmap =
> (const uint32_t *)mnl_attr_get_payload(bits);
I don't like this part: (mask && nomask) is a situation which should
never happen as it would mean we are trying to get mask value from
a bitmap which does not any. In other words, if we ever see such
combination, it is a result of a bug either on ethtool side or on kernel
side.
Rather than silently returning something else than asked, we should
IMHO report an error. Which is easy in dump_link_modes() but it would
require rewriting bitset_get_bit().
Michal
> @@ -87,7 +90,7 @@ bool bitset_get_bit(const struct nlattr *bitset, bool mask,
> unsigned int idx,
>
> my_idx = mnl_attr_get_u32(tb[ETHTOOL_A_BITSET_BIT_INDEX]);
> if (my_idx == idx)
> - return mask || tb[ETHTOOL_A_BITSET_BIT_VALUE];
> + return mask || nomask || tb[ETHTOOL_A_BITSET_BIT_VALUE];
> }
>
> return false;
> diff --git a/netlink/settings.c b/netlink/settings.c
> index 35ba2f5dd6d5..29557653336e 100644
> --- a/netlink/settings.c
> +++ b/netlink/settings.c
> @@ -280,9 +280,11 @@ int dump_link_modes(struct nl_context *nlctx, const
> struct nlattr *bitset,
> const struct nlattr *bit;
> bool first = true;
> int prev = -2;
> + bool nomask;
> int ret;
>
> ret = mnl_attr_parse_nested(bitset, attr_cb, &bitset_tb_info);
> + nomask = bitset_tb[ETHTOOL_A_BITSET_NOMASK];
> bits = bitset_tb[ETHTOOL_A_BITSET_BITS];
> if (ret < 0)
> goto err_nonl;
> @@ -297,8 +299,8 @@ int dump_link_modes(struct nl_context *nlctx, const
> struct nlattr *bitset,
> goto err_nonl;
> lm_strings = global_stringset(ETH_SS_LINK_MODES,
> nlctx->ethnl2_socket);
> - bits = mask ? bitset_tb[ETHTOOL_A_BITSET_MASK] :
> - bitset_tb[ETHTOOL_A_BITSET_VALUE];
> + bits = mask && !nomask ? bitset_tb[ETHTOOL_A_BITSET_MASK] :
> + bitset_tb[ETHTOOL_A_BITSET_VALUE];
> ret = -EFAULT;
> if (!bits || !bitset_tb[ETHTOOL_A_BITSET_SIZE])
> goto err_nonl;
> @@ -354,7 +356,7 @@ int dump_link_modes(struct nl_context *nlctx, const
> struct nlattr *bitset,
> if (!tb[ETHTOOL_A_BITSET_BIT_INDEX] ||
> !tb[ETHTOOL_A_BITSET_BIT_NAME])
> goto err;
> - if (!mask && !tb[ETHTOOL_A_BITSET_BIT_VALUE])
> + if (!mask && !nomask && !tb[ETHTOOL_A_BITSET_BIT_VALUE])
> continue;
>
> idx = mnl_attr_get_u32(tb[ETHTOOL_A_BITSET_BIT_INDEX]);
> --
> 2.26.2
>
