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Unlike other SET type commands, modifying netdev features is required to
provide a reply telling userspace what was actually changed, compared to
what was requested. For that purpose, the "modified" flag provided by
ethnl_update_bitset() is not sufficient, we need full information which
bits were requested to change.
Therefore provide ethnl_parse_bitset() returning effective value and mask
bitmaps equivalent to the contents of a bitset nested attribute.
v2: use non-atomic __set_bit() (suggested by David Miller)
Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Syzbot reported that ethnl_compact_sanity_checks() can be tricked into
reading past the end of ETHTOOL_A_BITSET_VALUE and ETHTOOL_A_BITSET_MASK
attributes and even the message by passing a value between (u32)(-31)
and (u32)(-1) as ETHTOOL_A_BITSET_SIZE.
The problem is that DIV_ROUND_UP(attr_nbits, 32) is 0 for such values so
that zero length ETHTOOL_A_BITSET_VALUE will pass the length check but
ethnl_bitmap32_not_zero() check would try to access up to 512 MB of
attribute "payload".
Prevent this overflow byt limiting the bitset size. Technically, compact
bitset format would allow bitset sizes up to almost 2^18 (so that the
nest size does not exceed U16_MAX) but bitsets used by ethtool are much
shorter. S16_MAX, the largest value which can be directly used as an
upper limit in policy, should be a reasonable compromise.
Fixes: 10b518d4e6dd ("ethtool: netlink bitset handling")
Reported-by: syzbot+7fd4ed5b4234ab1fdccd@syzkaller.appspotmail.com
Reported-by: syzbot+709b7a64d57978247e44@syzkaller.appspotmail.com
Reported-by: syzbot+983cb8fb2d17a7af549d@syzkaller.appspotmail.com
Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>
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The ethtool netlink code uses common framework for passing arbitrary
length bit sets to allow future extensions. A bitset can be a list (only
one bitmap) or can consist of value and mask pair (used e.g. when client
want to modify only some bits). A bitset can use one of two formats:
verbose (bit by bit) or compact.
Verbose format consists of bitset size (number of bits), list flag and
an array of bit nests, telling which bits are part of the list or which
bits are in the mask and which of them are to be set. In requests, bits
can be identified by index (position) or by name. In replies, kernel
provides both index and name. Verbose format is suitable for "one shot"
applications like standard ethtool command as it avoids the need to
either keep bit names (e.g. link modes) in sync with kernel or having to
add an extra roundtrip for string set request (e.g. for private flags).
Compact format uses one (list) or two (value/mask) arrays of 32-bit
words to store the bitmap(s). It is more suitable for long running
applications (ethtool in monitor mode or network management daemons)
which can retrieve the names once and then pass only compact bitmaps to
save space.
Userspace requests can use either format; ETHTOOL_FLAG_COMPACT_BITSETS
flag in request header tells kernel which format to use in reply.
Notifications always use compact format.
As some code uses arrays of unsigned long for internal representation and
some arrays of u32 (or even a single u32), two sets of parse/compose
helpers are introduced. To avoid code duplication, helpers for unsigned
long arrays are implemented as wrappers around helpers for u32 arrays.
There are two reasons for this choice: (1) u32 arrays are more frequent in
ethtool code and (2) unsigned long array can be always interpreted as an
u32 array on little endian 64-bit and all 32-bit architectures while we
would need special handling for odd number of u32 words in the opposite
direction.
Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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