linux-toradex.git/lib/test_bpf.c, branch v4.4.129

bpf: introduce BPF_JIT_ALWAYS_ON config

2018-02-03T16:04:24+00:00

[ upstream commit 290af86629b25ffd1ed6232c4e9107da031705cb ]

The BPF interpreter has been used as part of the spectre 2 attack CVE-2017-5715.

A quote from goolge project zero blog:
"At this point, it would normally be necessary to locate gadgets in
the host kernel code that can be used to actually leak data by reading
from an attacker-controlled location, shifting and masking the result
appropriately and then using the result of that as offset to an
attacker-controlled address for a load. But piecing gadgets together
and figuring out which ones work in a speculation context seems annoying.
So instead, we decided to use the eBPF interpreter, which is built into
the host kernel - while there is no legitimate way to invoke it from inside
a VM, the presence of the code in the host kernel's text section is sufficient
to make it usable for the attack, just like with ordinary ROP gadgets."

To make attacker job harder introduce BPF_JIT_ALWAYS_ON config
option that removes interpreter from the kernel in favor of JIT-only mode.
So far eBPF JIT is supported by:
x64, arm64, arm32, sparc64, s390, powerpc64, mips64

The start of JITed program is randomized and code page is marked as read-only.
In addition "constant blinding" can be turned on with net.core.bpf_jit_harden

v2->v3:
- move __bpf_prog_ret0 under ifdef (Daniel)

v1->v2:
- fix init order, test_bpf and cBPF (Daniel's feedback)
- fix offloaded bpf (Jakub's feedback)
- add 'return 0' dummy in case something can invoke prog->bpf_func
- retarget bpf tree. For bpf-next the patch would need one extra hunk.
  It will be sent when the trees are merged back to net-next

Considered doing:
  int bpf_jit_enable __read_mostly = BPF_EBPF_JIT_DEFAULT;
but it seems better to land the patch as-is and in bpf-next remove
bpf_jit_enable global variable from all JITs, consolidate in one place
and remove this jit_init() function.

Signed-off-by: Alexei Starovoitov 
Signed-off-by: Daniel Borkmann 
Signed-off-by: Greg Kroah-Hartman

bpf, arm64: fix jit branch offset related to ldimm64

2017-05-14T11:32:58+00:00

[ Upstream commit ddc665a4bb4b728b4e6ecec8db1b64efa9184b9c ]

When the instruction right before the branch destination is
a 64 bit load immediate, we currently calculate the wrong
jump offset in the ctx->offset[] array as we only account
one instruction slot for the 64 bit load immediate although
it uses two BPF instructions. Fix it up by setting the offset
into the right slot after we incremented the index.

Before (ldimm64 test 1):

  [...]
  00000020:  52800007  mov w7, #0x0 // #0
  00000024:  d2800060  mov x0, #0x3 // #3
  00000028:  d2800041  mov x1, #0x2 // #2
  0000002c:  eb01001f  cmp x0, x1
  00000030:  54ffff82  b.cs 0x00000020
  00000034:  d29fffe7  mov x7, #0xffff // #65535
  00000038:  f2bfffe7  movk x7, #0xffff, lsl #16
  0000003c:  f2dfffe7  movk x7, #0xffff, lsl #32
  00000040:  f2ffffe7  movk x7, #0xffff, lsl #48
  00000044:  d29dddc7  mov x7, #0xeeee // #61166
  00000048:  f2bdddc7  movk x7, #0xeeee, lsl #16
  0000004c:  f2ddddc7  movk x7, #0xeeee, lsl #32
  00000050:  f2fdddc7  movk x7, #0xeeee, lsl #48
  [...]

After (ldimm64 test 1):

  [...]
  00000020:  52800007  mov w7, #0x0 // #0
  00000024:  d2800060  mov x0, #0x3 // #3
  00000028:  d2800041  mov x1, #0x2 // #2
  0000002c:  eb01001f  cmp x0, x1
  00000030:  540000a2  b.cs 0x00000044
  00000034:  d29fffe7  mov x7, #0xffff // #65535
  00000038:  f2bfffe7  movk x7, #0xffff, lsl #16
  0000003c:  f2dfffe7  movk x7, #0xffff, lsl #32
  00000040:  f2ffffe7  movk x7, #0xffff, lsl #48
  00000044:  d29dddc7  mov x7, #0xeeee // #61166
  00000048:  f2bdddc7  movk x7, #0xeeee, lsl #16
  0000004c:  f2ddddc7  movk x7, #0xeeee, lsl #32
  00000050:  f2fdddc7  movk x7, #0xeeee, lsl #48
  [...]

Also, add a couple of test cases to make sure JITs pass
this test. Tested on Cavium ThunderX ARMv8. The added
test cases all pass after the fix.

Fixes: 8eee539ddea0 ("arm64: bpf: fix out-of-bounds read in bpf2a64_offset()")
Reported-by: David S. Miller 
Signed-off-by: Daniel Borkmann 
Acked-by: Alexei Starovoitov 
Cc: Xi Wang 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

bpf: add mod default A and X test cases

2015-11-05T05:05:50+00:00

When running "mod X" operation, if X is 0 the filter has to be halt.
Add new test cases to cover A = A mod X if X is 0, and A = A mod 1.

CC: Xi Wang 
CC: Zi Shen Lim 
Signed-off-by: Yang Shi 
Acked-by: Daniel Borkmann 
Acked-by: Alexei Starovoitov 
Acked-by: Zi Shen Lim 
Acked-by: Xi Wang 
Signed-off-by: David S. Miller

test_bpf: add tests checking that JIT/interpreter sets A and X to 0.

2015-08-07T05:02:32+00:00

It is mandatory for the JIT or interpreter to reset the A and X
registers to 0 before running the filter. Check that it is the case on
various ALU and JMP instructions.

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

test_bpf: add more tests for LD_ABS and LD_IND.

2015-08-07T05:02:32+00:00

This exerces the LD_ABS and LD_IND instructions for various sizes and
alignments. This also checks that X when used as an offset to a
BPF_IND instruction first in a filter is correctly set to 0.

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

test_bpf: add module parameters to filter the tests to run.

2015-08-07T05:02:32+00:00

When developping on the interpreter or a particular JIT, it can be
interesting to restrict the tests list to a specific test or a
particular range of tests.

This patch adds the following module parameters to the test_bpf module:

* test_name=: only the specified named test will be run.

* test_id=: only the test with the specified id will be run
  (see the output of test_bpf without parameters to get the test id).

* test_range=,: only the tests within IDs in the
  specified id range are run (see the output of test_bpf without
  parameters to get the test ids).

Any invalid range, test id or test name will result in -EINVAL being
returned and no tests being run.

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

test_bpf: test LD_ABS and LD_IND instructions on fragmented skbs.

2015-08-07T05:02:32+00:00

These new tests exercise various load sizes and offsets crossing the
head/fragment boundary.

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

test_bpf: allow tests to specify an skb fragment.

2015-08-07T05:02:31+00:00

This introduce a new test->aux flag (FLAG_SKB_FRAG) to tell the
populate_skb() function to add a fragment to the test skb containing
the data specified in test->frag_data).

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

test_bpf: avoid oopsing the kernel when generate_test_data() fails.

2015-08-07T05:02:31+00:00

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

test_bpf: assign type to native eBPF test cases

2015-07-30T18:13:20+00:00

As JITs start to perform optimizations whether to clear A and X on eBPF
programs in the prologue, we should actually assign a program type to the
native eBPF test cases. It doesn't really matter which program type, as
these instructions don't go through the verifier, but it needs to be a
type != BPF_PROG_TYPE_UNSPEC. This reflects eBPF programs loaded via bpf(2)
system call (!= type unspec) vs. classic BPF to eBPF migrations (== type
unspec).

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