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syzkaller was able to generate the following XDP program ...
(18) r0 = 0x0
(61) r5 = *(u32 *)(r1 +12)
(04) (u32) r0 += (u32) 0
(95) exit
... and trigger a NULL pointer dereference in ___bpf_prog_run()
via bpf_prog_test_run_xdp() where this was attempted to run.
Reason is that recent xdp_rxq_info addition to XDP programs
updated all drivers, but not bpf_prog_test_run_xdp(), where
xdp_buff is set up. Thus when context rewriter does the deref
on the netdev it's NULL at runtime. Fix it by using xdp_rxq
from loopback dev. __netif_get_rx_queue() helper can also be
reused in various other locations later on.
Fixes: 02dd3291b2f0 ("bpf: finally expose xdp_rxq_info to XDP bpf-programs")
Reported-by: syzbot+1eb094057b338eb1fc00@syzkaller.appspotmail.com
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Update selftests to relfect recent changes and add various new
test cases.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Commit 111e6b45315c ("selftests/bpf: make test_verifier run most programs")
enables tools/testing/selftests/bpf/test_verifier unit cases to run
via bpf_prog_test_run command. With the latest code base,
test_verifier had one test case failure:
...
#473/p check deducing bounds from const, 2 FAIL retval 1 != 0
0: (b7) r0 = 1
1: (75) if r0 s>= 0x1 goto pc+1
R0=inv1 R1=ctx(id=0,off=0,imm=0) R10=fp0,call_-1
2: (95) exit
from 1 to 3: R0=inv1 R1=ctx(id=0,off=0,imm=0) R10=fp0,call_-1
3: (d5) if r0 s<= 0x1 goto pc+1
R0=inv1 R1=ctx(id=0,off=0,imm=0) R10=fp0,call_-1
4: (95) exit
from 3 to 5: R0=inv1 R1=ctx(id=0,off=0,imm=0) R10=fp0,call_-1
5: (1f) r1 -= r0
6: (95) exit
processed 7 insns (limit 131072), stack depth 0
...
The test case does not set return value in the test
structure and hence the return value from the prog run
is assumed to be 0. However, the actual return value is 1.
As a result, the test failed. The fix is to correctly set
the return value in the test structure.
Fixes: 111e6b45315c ("selftests/bpf: make test_verifier run most programs")
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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Alexei Starovoitov says:
====================
pull-request: bpf-next 2018-01-19
The following pull-request contains BPF updates for your *net-next* tree.
The main changes are:
1) bpf array map HW offload, from Jakub.
2) support for bpf_get_next_key() for LPM map, from Yonghong.
3) test_verifier now runs loaded programs, from Alexei.
4) xdp cpumap monitoring, from Jesper.
5) variety of tests, cleanups and small x64 JIT optimization, from Daniel.
6) user space can now retrieve HW JITed program, from Jiong.
Note there is a minor conflict between Russell's arm32 JIT fixes
and removal of bpf_jit_enable variable by Daniel which should
be resolved by keeping Russell's comment and removing that variable.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
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The BPF verifier conflict was some minor contextual issue.
The TUN conflict was less trivial. Cong Wang fixed a memory leak of
tfile->tx_array in 'net'. This is an skb_array. But meanwhile in
net-next tun changed tfile->tx_arry into tfile->tx_ring which is a
ptr_ring.
Signed-off-by: David S. Miller <davem@davemloft.net>
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Add couple of missing test cases for eBPF div/mod by zero to the
new test_verifier prog runtime feature. Also one for an empty prog
and only exit.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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to improve test coverage make test_verifier run all successfully loaded
programs on 64-byte zero initialized data.
For clsbpf and xdp it means empty 64-byte packet.
For lwt and socket_filters it's 64-byte packet where skb->data
points after L2.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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syzkaller generated a BPF proglet and triggered a warning with
the following:
0: (b7) r0 = 0
1: (d5) if r0 s<= 0x0 goto pc+0
R0=inv0 R1=ctx(id=0,off=0,imm=0) R10=fp0
2: (1f) r0 -= r1
R0=inv0 R1=ctx(id=0,off=0,imm=0) R10=fp0
verifier internal error: known but bad sbounds
What happens is that in the first insn, r0's min/max value
are both 0 due to the immediate assignment, later in the jsle
test the bounds are updated for the min value in the false
path, meaning, they yield smin_val = 1, smax_val = 0, and when
ctx pointer is subtracted from r0, verifier bails out with the
internal error and throwing a WARN since smin_val != smax_val
for the known constant.
For min_val > max_val scenario it means that reg_set_min_max()
and reg_set_min_max_inv() (which both refine existing bounds)
demonstrated that such branch cannot be taken at runtime.
In above scenario for the case where it will be taken, the
existing [0, 0] bounds are kept intact. Meaning, the rejection
is not due to a verifier internal error, and therefore the
WARN() is not necessary either.
We could just reject such cases in adjust_{ptr,scalar}_min_max_vals()
when either known scalars have smin_val != smax_val or
umin_val != umax_val or any scalar reg with bounds
smin_val > smax_val or umin_val > umax_val. However, there
may be a small risk of breakage of buggy programs, so handle
this more gracefully and in adjust_{ptr,scalar}_min_max_vals()
just taint the dst reg as unknown scalar when we see ops with
such kind of src reg.
Reported-by: syzbot+6d362cadd45dc0a12ba4@syzkaller.appspotmail.com
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Overlapping changes all over.
The mini-qdisc bits were a little bit tricky, however.
Signed-off-by: David S. Miller <davem@davemloft.net>
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Alexei found that verifier does not reject stores into context
via BPF_ST instead of BPF_STX. And while looking at it, we
also should not allow XADD variant of BPF_STX.
The context rewriter is only assuming either BPF_LDX_MEM- or
BPF_STX_MEM-type operations, thus reject anything other than
that so that assumptions in the rewriter properly hold. Add
test cases as well for BPF selftests.
Fixes: d691f9e8d440 ("bpf: allow programs to write to certain skb fields")
Reported-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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The following snippet was throwing an 'unknown opcode cc' warning
in BPF interpreter:
0: (18) r0 = 0x0
2: (7b) *(u64 *)(r10 -16) = r0
3: (cc) (u32) r0 s>>= (u32) r0
4: (95) exit
Although a number of JITs do support BPF_ALU | BPF_ARSH | BPF_{K,X}
generation, not all of them do and interpreter does neither. We can
leave existing ones and implement it later in bpf-next for the
remaining ones, but reject this properly in verifier for the time
being.
Fixes: 17a5267067f3 ("bpf: verifier (add verifier core)")
Reported-by: syzbot+93c4904c5c70348a6890@syzkaller.appspotmail.com
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Daniel Borkmann says:
====================
pull-request: bpf-next 2017-12-28
The following pull-request contains BPF updates for your *net-next* tree.
The main changes are:
1) Fix incorrect state pruning related to recognition of zero initialized
stack slots, where stacksafe exploration would mistakenly return a
positive pruning verdict too early ignoring other slots, from Gianluca.
2) Various BPF to BPF calls related follow-up fixes. Fix an off-by-one
in maximum call depth check, and rework maximum stack depth tracking
logic to fix a bypass of the total stack size check reported by Jann.
Also fix a bug in arm64 JIT where prog->jited_len was uninitialized.
Addition of various test cases to BPF selftests, from Alexei.
3) Addition of a BPF selftest to test_verifier that is related to BPF to
BPF calls which demonstrates a late caller stack size increase and
thus out of bounds access. Fixed above in 2). Test case from Jann.
4) Addition of correlating BPF helper calls, BPF to BPF calls as well
as BPF maps to bpftool xlated dump in order to allow for better
BPF program introspection and debugging, from Daniel.
5) Fixing several bugs in BPF to BPF calls kallsyms handling in order
to get it actually to work for subprogs, from Daniel.
6) Extending sparc64 JIT support for BPF to BPF calls and fix a couple
of build errors for libbpf on sparc64, from David.
7) Allow narrower context access for BPF dev cgroup typed programs in
order to adapt to LLVM code generation. Also adjust memlock rlimit
in the test_dev_cgroup BPF selftest, from Yonghong.
8) Add netdevsim Kconfig entry to BPF selftests since test_offload.py
relies on netdevsim device being available, from Jakub.
9) Reduce scope of xdp_do_generic_redirect_map() to being static,
from Xiongwei.
10) Minor cleanups and spelling fixes in BPF verifier, from Colin.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
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fix off by one error in max call depth check
and add a test
Fixes: f4d7e40a5b71 ("bpf: introduce function calls (verification)")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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to test inner logic of stack depth tracking
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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This checks that it is not possible to bypass the total stack size check in
update_stack_depth() by calling a function that uses a large amount of
stack memory *before* using a large amount of stack memory in the caller.
Currently, the first added testcase causes a rejection as expected, but
the second testcase is (AFAICS incorrectly) accepted:
[...]
#483/p calls: stack overflow using two frames (post-call access) FAIL
Unexpected success to load!
0: (85) call pc+2
caller:
R10=fp0,call_-1
callee:
frame1: R1=ctx(id=0,off=0,imm=0) R10=fp0,call_0
3: (72) *(u8 *)(r10 -300) = 0
4: (b7) r0 = 0
5: (95) exit
returning from callee:
frame1: R0_w=inv0 R1=ctx(id=0,off=0,imm=0) R10=fp0,call_0
to caller at 1:
R0_w=inv0 R10=fp0,call_-1
from 5 to 1: R0=inv0 R10=fp0,call_-1
1: (72) *(u8 *)(r10 -300) = 0
2: (95) exit
processed 6 insns, stack depth 300+300
[...]
Summary: 704 PASSED, 1 FAILED
AFAICS the JIT-generated code for the second testcase shows that this
really causes the stack pointer to be decremented by 300+300:
first function:
00000000 55 push rbp
00000001 4889E5 mov rbp,rsp
00000004 4881EC58010000 sub rsp,0x158
0000000B 4883ED28 sub rbp,byte +0x28
[...]
00000025 E89AB3AFE5 call 0xffffffffe5afb3c4
0000002A C685D4FEFFFF00 mov byte [rbp-0x12c],0x0
[...]
00000041 4883C528 add rbp,byte +0x28
00000045 C9 leave
00000046 C3 ret
second function:
00000000 55 push rbp
00000001 4889E5 mov rbp,rsp
00000004 4881EC58010000 sub rsp,0x158
0000000B 4883ED28 sub rbp,byte +0x28
[...]
00000025 C685D4FEFFFF00 mov byte [rbp-0x12c],0x0
[...]
0000003E 4883C528 add rbp,byte +0x28
00000042 C9 leave
00000043 C3 ret
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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Commit cc2b14d51053 ("bpf: teach verifier to recognize zero initialized
stack") introduced a very relaxed check when comparing stacks of different
states, effectively returning a positive result in many cases where it
shouldn't.
This can create problems in cases such as this following C pseudocode:
long var;
long *x = bpf_map_lookup(...);
if (!x)
return;
if (*x != 0xbeef)
var = 0;
else
var = 1;
/* This is the key part, calling a helper causes an explored state
* to be saved with the information that "var" is on the stack as
* STACK_ZERO, since the helper is first met by the verifier after
* the "var = 0" assignment. This state will however be wrongly used
* also for the "var = 1" case, so the verifier assumes "var" is always
* 0 and will replace the NULL assignment with nops, because the
* search pruning prevents it from exploring the faulty branch.
*/
bpf_ktime_get_ns();
if (var)
*(long *)0 = 0xbeef;
Fix the issue by making sure that the stack is fully explored before
returning a positive comparison result.
Also attach a couple tests that highlight the bad behavior. In the first
test, without this fix instructions 16 and 17 are replaced with nops
instead of being rejected by the verifier.
The second test, instead, allows a program to make a potentially illegal
read from the stack.
Fixes: cc2b14d51053 ("bpf: teach verifier to recognize zero initialized stack")
Signed-off-by: Gianluca Borello <g.borello@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Lots of overlapping changes. Also on the net-next side
the XDP state management is handled more in the generic
layers so undo the 'net' nfp fix which isn't applicable
in net-next.
Include a necessary change by Jakub Kicinski, with log message:
====================
cls_bpf no longer takes care of offload tracking. Make sure
netdevsim performs necessary checks. This fixes a warning
caused by TC trying to remove a filter it has not added.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
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Do not allow root to convert valid pointers into unknown scalars.
In particular disallow:
ptr &= reg
ptr <<= reg
ptr += ptr
and explicitly allow:
ptr -= ptr
since pkt_end - pkt == length
1.
This minimizes amount of address leaks root can do.
In the future may need to further tighten the leaks with kptr_restrict.
2.
If program has such pointer math it's likely a user mistake and
when verifier complains about it right away instead of many instructions
later on invalid memory access it's easier for users to fix their progs.
3.
when register holding a pointer cannot change to scalar it allows JITs to
optimize better. Like 32-bit archs could use single register for pointers
instead of a pair required to hold 64-bit scalars.
4.
reduces architecture dependent behavior. Since code:
r1 = r10;
r1 &= 0xff;
if (r1 ...)
will behave differently arm64 vs x64 and offloaded vs native.
A significant chunk of ptr mangling was allowed by
commit f1174f77b50c ("bpf/verifier: rework value tracking")
yet some of it was allowed even earlier.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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These tests should cover the following cases:
- MOV with both zero-extended and sign-extended immediates
- implicit truncation of register contents via ALU32/MOV32
- implicit 32-bit truncation of ALU32 output
- oversized register source operand for ALU32 shift
- right-shift of a number that could be positive or negative
- map access where adding the operation size to the offset causes signed
32-bit overflow
- direct stack access at a ~4GiB offset
Also remove the F_LOAD_WITH_STRICT_ALIGNMENT flag from a bunch of tests
that should fail independent of what flags userspace passes.
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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Add some additional checks for few more corner cases.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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adjust two tests, since verifier got smarter
and add new one to test stack_zero logic
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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Add extensive set of tests for bpf_call verification logic:
calls: basic sanity
calls: using r0 returned by callee
calls: callee is using r1
calls: callee using args1
calls: callee using wrong args2
calls: callee using two args
calls: callee changing pkt pointers
calls: two calls with args
calls: two calls with bad jump
calls: recursive call. test1
calls: recursive call. test2
calls: unreachable code
calls: invalid call
calls: jumping across function bodies. test1
calls: jumping across function bodies. test2
calls: call without exit
calls: call into middle of ld_imm64
calls: call into middle of other call
calls: two calls with bad fallthrough
calls: two calls with stack read
calls: two calls with stack write
calls: spill into caller stack frame
calls: two calls with stack write and void return
calls: ambiguous return value
calls: two calls that return map_value
calls: two calls that return map_value with bool condition
calls: two calls that return map_value with incorrect bool check
calls: two calls that receive map_value via arg=ptr_stack_of_caller. test1
calls: two calls that receive map_value via arg=ptr_stack_of_caller. test2
calls: two jumps that receive map_value via arg=ptr_stack_of_jumper. test3
calls: two calls that receive map_value_ptr_or_null via arg. test1
calls: two calls that receive map_value_ptr_or_null via arg. test2
calls: pkt_ptr spill into caller stack
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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Add a test that i) uses LD_ABS, ii) zeroing R6 before call, iii) calls
a helper that triggers reload of cached skb data, iv) uses LD_ABS again.
It's added for test_bpf in order to do runtime testing after JITing as
well as test_verifier to test that the sequence is allowed.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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With the current ARG_PTR_TO_MEM/ARG_PTR_TO_UNINIT_MEM semantics, an helper
argument can be NULL when the next argument type is ARG_CONST_SIZE_OR_ZERO
and the verifier can prove the value of this next argument is 0. However,
most helpers are just interested in handling <!NULL, 0>, so forcing them to
deal with <NULL, 0> makes the implementation of those helpers more
complicated for no apparent benefits, requiring them to explicitly handle
those corner cases with checks that bpf programs could start relying upon,
preventing the possibility of removing them later.
Solve this by making ARG_PTR_TO_MEM/ARG_PTR_TO_UNINIT_MEM never accept NULL
even when ARG_CONST_SIZE_OR_ZERO is set, and introduce a new argument type
ARG_PTR_TO_MEM_OR_NULL to explicitly deal with the NULL case.
Currently, the only helper that needs this is bpf_csum_diff_proto(), so
change arg1 and arg3 to this new type as well.
Also add a new battery of tests that explicitly test the
!ARG_PTR_TO_MEM_OR_NULL combination: all the current ones testing the
various <NULL, 0> variations are focused on bpf_csum_diff, so cover also
other helpers.
Signed-off-by: Gianluca Borello <g.borello@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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There are four tests in test_verifier using bpf_probe_write_user
helper. These four tests will emit the following kernel messages
[ 12.974753] test_verifier[220] is installing a program with bpf_probe_write_user
helper that may corrupt user memory!
[ 12.979285] test_verifier[220] is installing a program with bpf_probe_write_user
helper that may corrupt user memory!
......
This may confuse certain users. This patch replaces bpf_probe_write_user
with bpf_trace_printk. The test_verifier already uses bpf_trace_printk
earlier in the test and a trace_printk warning message has been printed.
So this patch does not emit any more kernel messages.
Fixes: b6ff63911232 ("bpf: fix and add test cases for ARG_CONST_SIZE_OR_ZERO semantics change")
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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Fix a few test cases to allow non-NULL map/packet/stack pointer
with size = 0. Change a few tests using bpf_probe_read to use
bpf_probe_write_user so ARG_CONST_SIZE arg can still be properly
tested. One existing test case already covers size = 0 with non-NULL
packet pointer, so add additional tests so all cases of
size = 0 and 0 <= size <= legal_upper_bound with non-NULL
map/packet/stack pointer are covered.
Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Lets also add test cases to cover all possible data_meta access tests
for good/bad access cases so we keep tracking them.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Two minor cleanups after Dave's recent merge in f8ddadc4db6c
("Merge git://git.kernel.org...") of net into net-next in
order to get the code in line with what was done originally
in the net tree: i) use max() instead of max_t() since both
ranges are u16, ii) don't split the direct access test cases
in the middle with bpf_exit test cases from 390ee7e29fc
("bpf: enforce return code for cgroup-bpf programs").
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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There were quite a few overlapping sets of changes here.
Daniel's bug fix for off-by-ones in the new BPF branch instructions,
along with the added allowances for "data_end > ptr + x" forms
collided with the metadata additions.
Along with those three changes came veritifer test cases, which in
their final form I tried to group together properly. If I had just
trimmed GIT's conflict tags as-is, this would have split up the
meta tests unnecessarily.
In the socketmap code, a set of preemption disabling changes
overlapped with the rename of bpf_compute_data_end() to
bpf_compute_data_pointers().
Changes were made to the mv88e6060.c driver set addr method
which got removed in net-next.
The hyperv transport socket layer had a locking change in 'net'
which overlapped with a change of socket state macro usage
in 'net-next'.
Signed-off-by: David S. Miller <davem@davemloft.net>
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Lets add test cases to cover really all possible direct packet
access tests for good/bad access cases so we keep tracking them.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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The skb->mark field is a union with reserved_tailroom which is used
in the TCP code paths from stream memory allocation. Allowing SK_SKB
programs to set this field creates a conflict with future code
optimizations, such as "gifting" the skb to the egress path instead
of creating a new skb and doing a memcpy.
Because we do not have a released version of SK_SKB yet lets just
remove it for now. A more appropriate scratch pad to use at the
socket layer is dev_scratch, but lets add that in future kernels
when needed.
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Commit f1174f77b50c ("bpf/verifier: rework value tracking")
removed the crafty selection of which pointer types are
allowed to be modified. This is OK for most pointer types
since adjust_ptr_min_max_vals() will catch operations on
immutable pointers. One exception is PTR_TO_CTX which is
now allowed to be offseted freely.
The intent of aforementioned commit was to allow context
access via modified registers. The offset passed to
->is_valid_access() verifier callback has been adjusted
by the value of the variable offset.
What is missing, however, is taking the variable offset
into account when the context register is used. Or in terms
of the code adding the offset to the value passed to the
->convert_ctx_access() callback. This leads to the following
eBPF user code:
r1 += 68
r0 = *(u32 *)(r1 + 8)
exit
being translated to this in kernel space:
0: (07) r1 += 68
1: (61) r0 = *(u32 *)(r1 +180)
2: (95) exit
Offset 8 is corresponding to 180 in the kernel, but offset
76 is valid too. Verifier will "accept" access to offset
68+8=76 but then "convert" access to offset 8 as 180.
Effective access to offset 248 is beyond the kernel context.
(This is a __sk_buff example on a debug-heavy kernel -
packet mark is 8 -> 180, 76 would be data.)
Dereferencing the modified context pointer is not as easy
as dereferencing other types, because we have to translate
the access to reading a field in kernel structures which is
usually at a different offset and often of a different size.
To allow modifying the pointer we would have to make sure
that given eBPF instruction will always access the same
field or the fields accessed are "compatible" in terms of
offset and size...
Disallow dereferencing modified context pointers and add
to selftests the test case described here.
Fixes: f1174f77b50c ("bpf/verifier: rework value tracking")
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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with addition of tnum logic the verifier got smart enough and
we can enforce return codes at program load time.
For now do so for cgroup-bpf program types.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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This patch extends the libbpf to provide API support to
allow specifying BPF object name.
In tools/lib/bpf/libbpf, the C symbol of the function
and the map is used. Regarding section name, all maps are
under the same section named "maps". Hence, section name
is not a good choice for map's name. To be consistent with
map, bpf_prog also follows and uses its function symbol as
the prog's name.
This patch adds logic to collect function's symbols in libbpf.
There is existing codes to collect the map's symbols and no change
is needed.
The bpf_load_program_name() and bpf_map_create_name() are
added to take the name argument. For the other bpf_map_create_xxx()
variants, a name argument is directly added to them.
In samples/bpf, bpf_load.c in particular, the symbol is also
used as the map's name and the map symbols has already been
collected in the existing code. For bpf_prog, bpf_load.c does
not collect the function symbol name. We can consider to collect
them later if there is a need to continue supporting the bpf_load.c.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Add various test_verifier selftests, and a simple xdp/tc functional
test that is being attached to veths. Also let new versions of clang
use the recently added -mcpu=probe support [1] for the BPF target,
so that it can probe the underlying kernel for BPF insn set extensions.
We could also just set this options always, where older versions just
ignore it and give a note to the user that the -mcpu value is not
supported, but given emitting the note cannot be turned off from clang
side lets not confuse users running selftests with it, thus fallback
to the default generic one when we see that clang doesn't support it.
Also allow CPU option to be overridden in the Makefile from command
line.
[1] https://github.com/llvm-mirror/llvm/commit/d7276a40d87b89aed89978dec6457a5b8b3a0db5
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Neither ___bpf_prog_run nor the JITs accept it.
Also adds a new test case.
Fixes: 17a5267067f3 ("bpf: verifier (add verifier core)")
Signed-off-by: Edward Cree <ecree@solarflare.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Tests packet read/writes and additional skb fields.
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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The test makes a read through a map value pointer, then considers pruning
a branch where the register holds an adjusted map value pointer. It
should not prune, but currently it does.
Signed-off-by: Alexei Starovoitov <ast@fb.com>
[ecree@solarflare.com: added test-name and patch description]
Signed-off-by: Edward Cree <ecree@solarflare.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Writes in straight-line code should not prevent reads from propagating
along jumps. With current verifier code, the jump from 3 to 5 does not
add a read mark on 3:R0 (because 5:R0 has a write mark), meaning that
the jump from 1 to 3 gets pruned as safe even though R0 is NOT_INIT.
Verifier output:
0: (61) r2 = *(u32 *)(r1 +0)
1: (35) if r2 >= 0x0 goto pc+1
R1=ctx(id=0,off=0,imm=0) R2=inv(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R10=fp0
2: (b7) r0 = 0
3: (35) if r2 >= 0x0 goto pc+1
R0=inv0 R1=ctx(id=0,off=0,imm=0) R2=inv(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R10=fp0
4: (b7) r0 = 0
5: (95) exit
from 3 to 5: safe
from 1 to 3: safe
processed 8 insns, stack depth 0
Signed-off-by: Edward Cree <ecree@solarflare.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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This adds tests to access new __sk_buff members from sk skb program
type.
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Add test cases to the verifier selftest suite in order to verify that
i) direct packet access, and ii) dynamic map value access is working
with the changes related to the new instructions.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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The UDP offload conflict is dealt with by simply taking what is
in net-next where we have removed all of the UFO handling code
entirely.
The TCP conflict was a case of local variables in a function
being removed from both net and net-next.
In netvsc we had an assignment right next to where a missing
set of u64 stats sync object inits were added.
Signed-off-by: David S. Miller <davem@davemloft.net>
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Variable ctx accesses and stack accesses aren't allowed, because we can't
determine what type of value will be read.
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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A number of selftests fell foul of the changed MAX_PACKET_OFF handling.
For instance, "direct packet access: test2" was potentially reading four
bytes from pkt + 0xffff, which could take it past the verifier's limit,
causing the program to be rejected (checks against pkt_end didn't give
us any reg->range).
Increase the shifts by one so that R2 is now mask 0x7fff instead of
mask 0xffff.
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Some of the verifier's error messages have changed, and some constructs
that previously couldn't be verified are now accepted.
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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We really must check with #if __BYTE_ORDER == XYZ instead of
just presence of #ifdef __LITTLE_ENDIAN. I noticed that when
actually running this on big endian machine, the latter test
resolves to true for user space, same for #ifdef __BIG_ENDIAN.
E.g., looking at endian.h from libc, both are also defined
there, so we really must test this against __BYTE_ORDER instead
for proper insns selection. For the kernel, such checks are
fine though e.g. see 13da9e200fe4 ("Revert "endian: #define
__BYTE_ORDER"") and 415586c9e6d3 ("UAPI: fix endianness conditionals
in M32R's asm/stat.h") for some more context, but not for
user space. Lets also make sure to properly include endian.h.
After that, suite passes for me:
./test_verifier: ELF 64-bit MSB executable, [...]
Linux foo 4.13.0-rc3+ #4 SMP Fri Aug 4 06:59:30 EDT 2017 s390x s390x s390x GNU/Linux
Before fix: Summary: 505 PASSED, 11 FAILED
After fix: Summary: 516 PASSED, 0 FAILED
Fixes: 18f3d6be6be1 ("selftests/bpf: Add test cases to test narrower ctx field loads")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong <yhs@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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There is a bug in the verifier's handling of BPF_SUB: [a,b] - [c,d] yields
was [a-c, b-d] rather than the correct [a-d, b-c]. So here is a test
which, with the bogus handling, will produce ranges of [0,0] and thus
allowed accesses; whereas the correct handling will give a range of
[-255, 255] (and hence the right-shift will give a range of [0, 255]) and
the accesses will be rejected.
Signed-off-by: Edward Cree <ecree@solarflare.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Add a couple of more test cases to BPF selftests that are related
to mixed signed and unsigned checks.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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These failed due to a bug in verifier bounds handling.
Signed-off-by: Edward Cree <ecree@solarflare.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Fix the few existing test cases that used mixed signed/unsigned
bounds and switch them only to one flavor. Reason why we need this
is that proper boundaries cannot be derived from mixed tests.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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