linux-toradex.git/samples/bpf, branch v4.9-rc2

bpf: allow access into map value arrays

2016-09-29T05:35:35+00:00

Suppose you have a map array value that is something like this

struct foo {
	unsigned iter;
	int array[SOME_CONSTANT];
};

You can easily insert this into an array, but you cannot modify the contents of
foo->array[] after the fact.  This is because we have no way to verify we won't
go off the end of the array at verification time.  This patch provides a start
for this work.  We accomplish this by keeping track of a minimum and maximum
value a register could be while we're checking the code.  Then at the time we
try to do an access into a MAP_VALUE we verify that the maximum offset into that
region is a valid access into that memory region.  So in practice, code such as
this

unsigned index = 0;

if (foo->iter >= SOME_CONSTANT)
	foo->iter = index;
else
	index = foo->iter++;
foo->array[index] = bar;

would be allowed, as we can verify that index will always be between 0 and
SOME_CONSTANT-1.  If you wish to use signed values you'll have to have an extra
check to make sure the index isn't less than 0, or do something like index %=
SOME_CONSTANT.

Signed-off-by: Josef Bacik 
Acked-by: Alexei Starovoitov 
Signed-off-by: David S. Miller

bpf samples: update tracex5 sample to use __seccomp_filter

2016-09-27T07:48:58+00:00

seccomp_phase1() does not exist anymore. Instead, update sample to use
__seccomp_filter(). While at it, set max locked memory to unlimited.

Signed-off-by: Naveen N. Rao 
Acked-by: Alexei Starovoitov 
Signed-off-by: David S. Miller

bpf samples: fix compiler errors with sockex2 and sockex3

2016-09-27T07:48:58+00:00

These samples fail to compile as 'struct flow_keys' conflicts with
definition in net/flow_dissector.h. Fix the same by renaming the
structure used in the sample.

Signed-off-by: Naveen N. Rao 
Acked-by: Alexei Starovoitov 
Signed-off-by: David S. Miller

bpf: add test cases for direct packet access

2016-09-21T03:32:11+00:00

Add couple of test cases for direct write and the negative size issue, and
also adjust the direct packet access test4 since it asserts that writes are
not possible, but since we've just added support for writes, we need to
invert the verdict to ACCEPT, of course. Summary: 133 PASSED, 0 FAILED.

Signed-off-by: Daniel Borkmann 
Acked-by: Alexei Starovoitov 
Signed-off-by: David S. Miller

samples/bpf: add comprehensive ipip, ipip6, ip6ip6 test

2016-09-17T14:13:07+00:00

the test creates 3 namespaces with veth connected via bridge.
First two namespaces simulate two different hosts with the same
IPv4 and IPv6 addresses configured on the tunnel interface and they
communicate with outside world via standard tunnels.
Third namespace creates collect_md tunnel that is driven by BPF
program which selects different remote host (either first or
second namespace) based on tcp dest port number while tcp dst
ip is the same.
This scenario is rough approximation of load balancer use case.
The tests check both traditional tunnel configuration and collect_md mode.

Signed-off-by: Alexei Starovoitov 
Signed-off-by: David S. Miller

samples/bpf: extend test_tunnel_bpf.sh with IPIP test

2016-09-17T14:13:07+00:00

extend existing tests for vxlan, geneve, gre to include IPIP tunnel.
It tests both traditional tunnel configuration and
dynamic via bpf helpers.

Signed-off-by: Alexei Starovoitov 
Signed-off-by: David S. Miller

bpf: fix range propagation on direct packet access

2016-09-09T00:28:37+00:00

LLVM can generate code that tests for direct packet access via
skb->data/data_end in a way that currently gets rejected by the
verifier, example:

  [...]
   7: (61) r3 = *(u32 *)(r6 +80)
   8: (61) r9 = *(u32 *)(r6 +76)
   9: (bf) r2 = r9
  10: (07) r2 += 54
  11: (3d) if r3 >= r2 goto pc+12
   R1=inv R2=pkt(id=0,off=54,r=0) R3=pkt_end R4=inv R6=ctx
   R9=pkt(id=0,off=0,r=0) R10=fp
  12: (18) r4 = 0xffffff7a
  14: (05) goto pc+430
  [...]

  from 11 to 24: R1=inv R2=pkt(id=0,off=54,r=0) R3=pkt_end R4=inv
                 R6=ctx R9=pkt(id=0,off=0,r=0) R10=fp
  24: (7b) *(u64 *)(r10 -40) = r1
  25: (b7) r1 = 0
  26: (63) *(u32 *)(r6 +56) = r1
  27: (b7) r2 = 40
  28: (71) r8 = *(u8 *)(r9 +20)
  invalid access to packet, off=20 size=1, R9(id=0,off=0,r=0)

The reason why this gets rejected despite a proper test is that we
currently call find_good_pkt_pointers() only in case where we detect
tests like rX > pkt_end, where rX is of type pkt(id=Y,off=Z,r=0) and
derived, for example, from a register of type pkt(id=Y,off=0,r=0)
pointing to skb->data. find_good_pkt_pointers() then fills the range
in the current branch to pkt(id=Y,off=0,r=Z) on success.

For above case, we need to extend that to recognize pkt_end >= rX
pattern and mark the other branch that is taken on success with the
appropriate pkt(id=Y,off=0,r=Z) type via find_good_pkt_pointers().
Since eBPF operates on BPF_JGT (>) and BPF_JGE (>=), these are the
only two practical options to test for from what LLVM could have
generated, since there's no such thing as BPF_JLT (<) or BPF_JLE (<=)
that we would need to take into account as well.

After the fix:

  [...]
   7: (61) r3 = *(u32 *)(r6 +80)
   8: (61) r9 = *(u32 *)(r6 +76)
   9: (bf) r2 = r9
  10: (07) r2 += 54
  11: (3d) if r3 >= r2 goto pc+12
   R1=inv R2=pkt(id=0,off=54,r=0) R3=pkt_end R4=inv R6=ctx
   R9=pkt(id=0,off=0,r=0) R10=fp
  12: (18) r4 = 0xffffff7a
  14: (05) goto pc+430
  [...]

  from 11 to 24: R1=inv R2=pkt(id=0,off=54,r=54) R3=pkt_end R4=inv
                 R6=ctx R9=pkt(id=0,off=0,r=54) R10=fp
  24: (7b) *(u64 *)(r10 -40) = r1
  25: (b7) r1 = 0
  26: (63) *(u32 *)(r6 +56) = r1
  27: (b7) r2 = 40
  28: (71) r8 = *(u8 *)(r9 +20)
  29: (bf) r1 = r8
  30: (25) if r8 > 0x3c goto pc+47
   R1=inv56 R2=imm40 R3=pkt_end R4=inv R6=ctx R8=inv56
   R9=pkt(id=0,off=0,r=54) R10=fp
  31: (b7) r1 = 1
  [...]

Verifier test cases are also added in this work, one that demonstrates
the mentioned example here and one that tries a bad packet access for
the current/fall-through branch (the one with types pkt(id=X,off=Y,r=0),
pkt(id=X,off=0,r=0)), then a case with good and bad accesses, and two
with both test variants (>, >=).

Fixes: 969bf05eb3ce ("bpf: direct packet access")
Signed-off-by: Daniel Borkmann 
Acked-by: Alexei Starovoitov 
Signed-off-by: David S. Miller

samples/bpf: add sampleip example

2016-09-02T17:46:45+00:00

sample instruction pointer and frequency count in a BPF map

Signed-off-by: Brendan Gregg 
Signed-off-by: Alexei Starovoitov 
Signed-off-by: David S. Miller

samples/bpf: add perf_event+bpf example

2016-09-02T17:46:45+00:00

The bpf program is called 50 times a second and does hashmap[kern&user_stackid]++
It's primary purpose to check that key bpf helpers like map lookup, update,
get_stackid, trace_printk and ctx access are all working.
It checks:
- PERF_COUNT_HW_CPU_CYCLES on all cpus
- PERF_COUNT_HW_CPU_CYCLES for current process and inherited perf_events to children
- PERF_COUNT_SW_CPU_CLOCK on all cpus
- PERF_COUNT_SW_CPU_CLOCK for current process

Signed-off-by: Alexei Starovoitov 
Signed-off-by: David S. Miller

samples/bpf: Add tunnel set/get tests.

2016-08-20T05:42:44+00:00

The patch creates sample code exercising bpf_skb_{set,get}_tunnel_key,
and bpf_skb_{set,get}_tunnel_opt for GRE, VXLAN, and GENEVE.  A native
tunnel device is created in a namespace to interact with a lwtunnel
device out of the namespace, with metadata enabled.  The bpf_skb_set_*
program is attached to tc egress and bpf_skb_get_* is attached to egress
qdisc.  A ping between two tunnels is used to verify correctness and
the result of bpf_skb_get_* printed by bpf_trace_printk.

Signed-off-by: William Tu 
Signed-off-by: David S. Miller