Commit Graph

2 Commits

Author SHA1 Message Date
Edward Cree b03c9f9fdc bpf/verifier: track signed and unsigned min/max values
Allows us to, sometimes, combine information from a signed check of one
 bound and an unsigned check of the other.
We now track the full range of possible values, rather than restricting
 ourselves to [0, 1<<30) and considering anything beyond that as
 unknown.  While this is probably not necessary, it makes the code more
 straightforward and symmetrical between signed and unsigned bounds.

Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-08-08 17:51:34 -07:00
Edward Cree f1174f77b5 bpf/verifier: rework value tracking
Unifies adjusted and unadjusted register value types (e.g. FRAME_POINTER is
 now just a PTR_TO_STACK with zero offset).
Tracks value alignment by means of tracking known & unknown bits.  This
 also replaces the 'reg->imm' (leading zero bits) calculations for (what
 were) UNKNOWN_VALUEs.
If pointer leaks are allowed, and adjust_ptr_min_max_vals returns -EACCES,
 treat the pointer as an unknown scalar and try again, because we might be
 able to conclude something about the result (e.g. pointer & 0x40 is either
 0 or 0x40).
Verifier hooks in the netronome/nfp driver were changed to match the new
 data structures.

Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-08-08 17:51:34 -07:00