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Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
 Andrii Nakryiko
|
7cccee42bf |
selftests/bpf: Test FD-based cgroup attachment
Add selftests to exercise FD-based cgroup BPF program attachments and their intermixing with legacy cgroup BPF attachments. Auto-detachment and program replacement (both unconditional and cmpxchng-like) are tested as well. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200330030001.2312810-5-andriin@fb.com |
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Andrii Nakryiko
|
cc4f864bb1 |
libbpf: Add support for bpf_link-based cgroup attachment
Add bpf_program__attach_cgroup(), which uses BPF_LINK_CREATE subcommand to
create an FD-based kernel bpf_link. Also add low-level bpf_link_create() API.
If expected_attach_type is not specified explicitly with
bpf_program__set_expected_attach_type(), libbpf will try to determine proper
attach type from BPF program's section definition.
Also add support for bpf_link's underlying BPF program replacement:
- unconditional through high-level bpf_link__update_program() API;
- cmpxchg-like with specifying expected current BPF program through
low-level bpf_link_update() API.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200330030001.2312810-4-andriin@fb.com
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Andrii Nakryiko
|
0c991ebc8c |
bpf: Implement bpf_prog replacement for an active bpf_cgroup_link
Add new operation (LINK_UPDATE), which allows to replace active bpf_prog from under given bpf_link. Currently this is only supported for bpf_cgroup_link, but will be extended to other kinds of bpf_links in follow-up patches. For bpf_cgroup_link, implemented functionality matches existing semantics for direct bpf_prog attachment (including BPF_F_REPLACE flag). User can either unconditionally set new bpf_prog regardless of which bpf_prog is currently active under given bpf_link, or, optionally, can specify expected active bpf_prog. If active bpf_prog doesn't match expected one, no changes are performed, old bpf_link stays intact and attached, operation returns a failure. cgroup_bpf_replace() operation is resolving race between auto-detachment and bpf_prog update in the same fashion as it's done for bpf_link detachment, except in this case update has no way of succeeding because of target cgroup marked as dying. So in this case error is returned. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200330030001.2312810-3-andriin@fb.com |
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Andrii Nakryiko
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af6eea5743 |
bpf: Implement bpf_link-based cgroup BPF program attachment
Implement new sub-command to attach cgroup BPF programs and return FD-based bpf_link back on success. bpf_link, once attached to cgroup, cannot be replaced, except by owner having its FD. Cgroup bpf_link supports only BPF_F_ALLOW_MULTI semantics. Both link-based and prog-based BPF_F_ALLOW_MULTI attachments can be freely intermixed. To prevent bpf_cgroup_link from keeping cgroup alive past the point when no BPF program can be executed, implement auto-detachment of link. When cgroup_bpf_release() is called, all attached bpf_links are forced to release cgroup refcounts, but they leave bpf_link otherwise active and allocated, as well as still owning underlying bpf_prog. This is because user-space might still have FDs open and active, so bpf_link as a user-referenced object can't be freed yet. Once last active FD is closed, bpf_link will be freed and underlying bpf_prog refcount will be dropped. But cgroup refcount won't be touched, because cgroup is released already. The inherent race between bpf_cgroup_link release (from closing last FD) and cgroup_bpf_release() is resolved by both operations taking cgroup_mutex. So the only additional check required is when bpf_cgroup_link attempts to detach itself from cgroup. At that time we need to check whether there is still cgroup associated with that link. And if not, exit with success, because bpf_cgroup_link was already successfully detached. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Roman Gushchin <guro@fb.com> Link: https://lore.kernel.org/bpf/20200330030001.2312810-2-andriin@fb.com |
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 Alexei Starovoitov
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e5ffcc9191 |
Merge branch 'subreg-bounds'
John Fastabend says:
====================
This series adds ALU32 signed and unsigned min/max bounds.
The origins of this work is to fix do_refine_retval_range() which before
this series clamps the return value bounds to [0, max]. However, this
is not correct because its possible these functions may return negative
errors so the correct bound is [*MIN, max]. Where *MIN is the signed
and unsigned min values U64_MIN and S64_MIN. And 'max' here is the max
positive value returned by this routine.
Patch 1 changes the do_refine_retval_range() to return the correct bounds
but this breaks existing programs that were depending on the old incorrect
bound. To repair these old programs we add ALU32 bounds to properly track
the return values from these helpers. The ALU32 bounds are needed because
clang realizes these helepers return 'int' type and will use jmp32 ops
with the return value. With current state of things this does little to
help 64bit bounds and with patch 1 applied will cause many programs to
fail verifier pass. See patch 5 for trace details on how this happens.
Patch 2 does the ALU32 addition it adds the new bounds and populates them
through the verifier. Design note, initially a var32 was added but as
pointed out by Alexei and Edward it is not strictly needed so it was
removed here. This worked out nicely.
Patch 3 notes that the refine return value can now also bound the 32-bit
subregister allowing better bouinds tracking in these cases.
Patches 4 adds a C test case to test_progs which will cause the verifier
to fail if new 32bit and do_refine_retval_range() is incorrect.
Patches 5 and 6 fix test cases that broke after refining the return
values from helpers. I attempted to be explicit about each failure and
why we need the change. See patches for details.
Patch 7 adds some bounds check tests to ensure bounds checking when
mixing alu32, alu64 and jmp32 ops together.
Thanks to Alexei, Edward, and Daniel for initial feedback it helped clean
this up a lot.
v2:
- rebased to bpf-next
- fixed tnum equals optimization for combining 32->64bits
- updated patch to fix verifier test correctly
- updated refine_retval_range to set both s32_*_value and s*_value we
need both to get better bounds tracking
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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 John Fastabend
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41f70fe064 |
bpf: Test_verifier, add alu32 bounds tracking tests
Its possible to have divergent ALU32 and ALU64 bounds when using JMP32 instructins and ALU64 arithmatic operations. Sometimes the clang will even generate this code. Because the case is a bit tricky lets add a specific test for it. Here is pseudocode asm version to illustrate the idea, 1 r0 = 0xffffffff00000001; 2 if w0 > 1 goto %l[fail]; 3 r0 += 1 5 if w0 > 2 goto %l[fail] 6 exit The intent here is the verifier will fail the load if the 32bit bounds are not tracked correctly through ALU64 op. Similarly we can check the 64bit bounds are correctly zero extended after ALU32 ops. 1 r0 = 0xffffffff00000001; 2 w0 += 1 2 if r0 > 3 goto %l[fail]; 6 exit The above will fail if we do not correctly zero extend 64bit bounds after 32bit op. Signed-off-by: John Fastabend <john.fastabend@gmail.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/158560430155.10843.514209255758200922.stgit@john-Precision-5820-Tower |
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John Fastabend
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32f13a5add |
bpf: Test_verifier, #65 error message updates for trunc of boundary-cross
After changes to add update_reg_bounds after ALU ops and 32-bit bounds
tracking truncation of boundary crossing range will fail earlier and with
a different error message. Now the test error trace is the following
11: (17) r1 -= 2147483584
12: R0_w=map_value(id=0,off=0,ks=8,vs=8,imm=0)
R1_w=invP(id=0,smin_value=-2147483584,smax_value=63)
R10=fp0 fp-8_w=mmmmmmmm
12: (17) r1 -= 2147483584
13: R0_w=map_value(id=0,off=0,ks=8,vs=8,imm=0)
R1_w=invP(id=0,
umin_value=18446744069414584448,umax_value=18446744071562068095,
var_off=(0xffffffff00000000; 0xffffffff))
R10=fp0 fp-8_w=mmmmmmmm
13: (77) r1 >>= 8
14: R0_w=map_value(id=0,off=0,ks=8,vs=8,imm=0)
R1_w=invP(id=0,
umin_value=72057594021150720,umax_value=72057594029539328,
var_off=(0xffffffff000000; 0xffffff),
s32_min_value=-16777216,s32_max_value=-1,
u32_min_value=-16777216)
R10=fp0 fp-8_w=mmmmmmmm
14: (0f) r0 += r1
value 72057594021150720 makes map_value pointer be out of bounds
Because we have 'umin_value == umax_value' instead of previously
where 'umin_value != umax_value' we can now fail earlier noting
that pointer addition is out of bounds.
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/158560428103.10843.6316594510312781186.stgit@john-Precision-5820-Tower
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John Fastabend
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9ac26e9973 |
bpf: Test_verifier, bpf_get_stack return value add <0
With current ALU32 subreg handling and retval refine fix from last
patches we see an expected failure in test_verifier. With verbose
verifier state being printed at each step for clarity we have the
following relavent lines [I omit register states that are not
necessarily useful to see failure cause],
#101/p bpf_get_stack return R0 within range FAIL
Failed to load prog 'Success'!
[..]
14: (85) call bpf_get_stack#67
R0_w=map_value(id=0,off=0,ks=8,vs=48,imm=0)
R3_w=inv48
15:
R0=inv(id=0,smax_value=48,var32_off=(0x0; 0xffffffff))
15: (b7) r1 = 0
16:
R0=inv(id=0,smax_value=48,var32_off=(0x0; 0xffffffff))
R1_w=inv0
16: (bf) r8 = r0
17:
R0=inv(id=0,smax_value=48,var32_off=(0x0; 0xffffffff))
R1_w=inv0
R8_w=inv(id=0,smax_value=48,var32_off=(0x0; 0xffffffff))
17: (67) r8 <<= 32
18:
R0=inv(id=0,smax_value=48,var32_off=(0x0; 0xffffffff))
R1_w=inv0
R8_w=inv(id=0,smax_value=9223372032559808512,
umax_value=18446744069414584320,
var_off=(0x0; 0xffffffff00000000),
s32_min_value=0,
s32_max_value=0,
u32_max_value=0,
var32_off=(0x0; 0x0))
18: (c7) r8 s>>= 32
19
R0=inv(id=0,smax_value=48,var32_off=(0x0; 0xffffffff))
R1_w=inv0
R8_w=inv(id=0,smin_value=-2147483648,
smax_value=2147483647,
var32_off=(0x0; 0xffffffff))
19: (cd) if r1 s< r8 goto pc+16
R0=inv(id=0,smax_value=48,var32_off=(0x0; 0xffffffff))
R1_w=inv0
R8_w=inv(id=0,smin_value=-2147483648,
smax_value=0,
var32_off=(0x0; 0xffffffff))
20:
R0=inv(id=0,smax_value=48,var32_off=(0x0; 0xffffffff))
R1_w=inv0
R8_w=inv(id=0,smin_value=-2147483648,
smax_value=0,
R9=inv48
20: (1f) r9 -= r8
21: (bf) r2 = r7
22:
R2_w=map_value(id=0,off=0,ks=8,vs=48,imm=0)
22: (0f) r2 += r8
value -2147483648 makes map_value pointer be out of bounds
After call bpf_get_stack() on line 14 and some moves we have at line 16
an r8 bound with max_value 48 but an unknown min value. This is to be
expected bpf_get_stack call can only return a max of the input size but
is free to return any negative error in the 32-bit register space. The
C helper is returning an int so will use lower 32-bits.
Lines 17 and 18 clear the top 32 bits with a left/right shift but use
ARSH so we still have worst case min bound before line 19 of -2147483648.
At this point the signed check 'r1 s< r8' meant to protect the addition
on line 22 where dst reg is a map_value pointer may very well return
true with a large negative number. Then the final line 22 will detect
this as an invalid operation and fail the program. What we want to do
is proceed only if r8 is positive non-error. So change 'r1 s< r8' to
'r1 s> r8' so that we jump if r8 is negative.
Next we will throw an error because we access past the end of the map
value. The map value size is 48 and sizeof(struct test_val) is 48 so
we walk off the end of the map value on the second call to
get bpf_get_stack(). Fix this by changing sizeof(struct test_val) to
24 by using 'sizeof(struct test_val) / 2'. After this everything passes
as expected.
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/158560426019.10843.3285429543232025187.stgit@john-Precision-5820-Tower
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John Fastabend
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d2db08c7a1 |
bpf: Test_progs, add test to catch retval refine error handling
Before this series the verifier would clamp return bounds of bpf_get_stack() to [0, X] and this led the verifier to believe that a JMP_JSLT 0 would be false and so would prune that path. The result is anything hidden behind that JSLT would be unverified. Add a test to catch this case by hiding an goto pc-1 behind the check which will cause an infinite loop if not rejected. Signed-off-by: John Fastabend <john.fastabend@gmail.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/158560423908.10843.11783152347709008373.stgit@john-Precision-5820-Tower |
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John Fastabend
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fa123ac022 |
bpf: Verifier, refine 32bit bound in do_refine_retval_range
Further refine return values range in do_refine_retval_range by noting
these are int return types (We will assume here that int is a 32-bit type).
Two reasons to pull this out of original patch. First it makes the original
fix impossible to backport. And second I've not seen this as being problematic
in practice unlike the other case.
Fixes:
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John Fastabend
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3f50f132d8 |
bpf: Verifier, do explicit ALU32 bounds tracking
It is not possible for the current verifier to track ALU32 and JMP ops
correctly. This can result in the verifier aborting with errors even though
the program should be verifiable. BPF codes that hit this can work around
it by changin int variables to 64-bit types, marking variables volatile,
etc. But this is all very ugly so it would be better to avoid these tricks.
But, the main reason to address this now is do_refine_retval_range() was
assuming return values could not be negative. Once we fixed this code that
was previously working will no longer work. See do_refine_retval_range()
patch for details. And we don't want to suddenly cause programs that used
to work to fail.
The simplest example code snippet that illustrates the problem is likely
this,
53: w8 = w0 // r8 <- [0, S32_MAX],
// w8 <- [-S32_MIN, X]
54: w8 <s 0 // r8 <- [0, U32_MAX]
// w8 <- [0, X]
The expected 64-bit and 32-bit bounds after each line are shown on the
right. The current issue is without the w* bounds we are forced to use
the worst case bound of [0, U32_MAX]. To resolve this type of case,
jmp32 creating divergent 32-bit bounds from 64-bit bounds, we add explicit
32-bit register bounds s32_{min|max}_value and u32_{min|max}_value. Then
from branch_taken logic creating new bounds we can track 32-bit bounds
explicitly.
The next case we observed is ALU ops after the jmp32,
53: w8 = w0 // r8 <- [0, S32_MAX],
// w8 <- [-S32_MIN, X]
54: w8 <s 0 // r8 <- [0, U32_MAX]
// w8 <- [0, X]
55: w8 += 1 // r8 <- [0, U32_MAX+1]
// w8 <- [0, X+1]
In order to keep the bounds accurate at this point we also need to track
ALU32 ops. To do this we add explicit ALU32 logic for each of the ALU
ops, mov, add, sub, etc.
Finally there is a question of how and when to merge bounds. The cases
enumerate here,
1. MOV ALU32 - zext 32-bit -> 64-bit
2. MOV ALU64 - copy 64-bit -> 32-bit
3. op ALU32 - zext 32-bit -> 64-bit
4. op ALU64 - n/a
5. jmp ALU32 - 64-bit: var32_off | upper_32_bits(var64_off)
6. jmp ALU64 - 32-bit: (>> (<< var64_off))
Details for each case,
For "MOV ALU32" BPF arch zero extends so we simply copy the bounds
from 32-bit into 64-bit ensuring we truncate var_off and 64-bit
bounds correctly. See zext_32_to_64.
For "MOV ALU64" copy all bounds including 32-bit into new register. If
the src register had 32-bit bounds the dst register will as well.
For "op ALU32" zero extend 32-bit into 64-bit the same as move,
see zext_32_to_64.
For "op ALU64" calculate both 32-bit and 64-bit bounds no merging
is done here. Except we have a special case. When RSH or ARSH is
done we can't simply ignore shifting bits from 64-bit reg into the
32-bit subreg. So currently just push bounds from 64-bit into 32-bit.
This will be correct in the sense that they will represent a valid
state of the register. However we could lose some accuracy if an
ARSH is following a jmp32 operation. We can handle this special
case in a follow up series.
For "jmp ALU32" mark 64-bit reg unknown and recalculate 64-bit bounds
from tnum by setting var_off to ((<<(>>var_off)) | var32_off). We
special case if 64-bit bounds has zero'd upper 32bits at which point
we can simply copy 32-bit bounds into 64-bit register. This catches
a common compiler trick where upper 32-bits are zeroed and then
32-bit ops are used followed by a 64-bit compare or 64-bit op on
a pointer. See __reg_combine_64_into_32().
For "jmp ALU64" cast the bounds of the 64bit to their 32-bit
counterpart. For example s32_min_value = (s32)reg->smin_value. For
tnum use only the lower 32bits via, (>>(<<var_off)). See
__reg_combine_64_into_32().
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/158560419880.10843.11448220440809118343.stgit@john-Precision-5820-Tower
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John Fastabend
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100605035e |
bpf: Verifier, do_refine_retval_range may clamp umin to 0 incorrectly
do_refine_retval_range() is called to refine return values from specified
helpers, probe_read_str and get_stack at the moment, the reasoning is
because both have a max value as part of their input arguments and
because the helper ensure the return value will not be larger than this
we can set smax values of the return register, r0.
However, the return value is a signed integer so setting umax is incorrect
It leads to further confusion when the do_refine_retval_range() then calls,
__reg_deduce_bounds() which will see a umax value as meaning the value is
unsigned and then assuming it is unsigned set the smin = umin which in this
case results in 'smin = 0' and an 'smax = X' where X is the input argument
from the helper call.
Here are the comments from _reg_deduce_bounds() on why this would be safe
to do.
/* Learn sign from unsigned bounds. Signed bounds cross the sign
* boundary, so we must be careful.
*/
if ((s64)reg->umax_value >= 0) {
/* Positive. We can't learn anything from the smin, but smax
* is positive, hence safe.
*/
reg->smin_value = reg->umin_value;
reg->smax_value = reg->umax_value = min_t(u64, reg->smax_value,
reg->umax_value);
But now we incorrectly have a return value with type int with the
signed bounds (0,X). Suppose the return value is negative, which is
possible the we have the verifier and reality out of sync. Among other
things this may result in any error handling code being falsely detected
as dead-code and removed. For instance the example below shows using
bpf_probe_read_str() causes the error path to be identified as dead
code and removed.
>From the 'llvm-object -S' dump,
r2 = 100
call 45
if r0 s< 0 goto +4
r4 = *(u32 *)(r7 + 0)
But from dump xlate
(b7) r2 = 100
(85) call bpf_probe_read_compat_str#-96768
(61) r4 = *(u32 *)(r7 +0) <-- dropped if goto
Due to verifier state after call being
R0=inv(id=0,umax_value=100,var_off=(0x0; 0x7f))
To fix omit setting the umax value because its not safe. The only
actual bounds we know is the smax. This results in the correct bounds
(SMIN, X) where X is the max length from the helper. After this the
new verifier state looks like the following after call 45.
R0=inv(id=0,smax_value=100)
Then xlated version no longer removed dead code giving the expected
result,
(b7) r2 = 100
(85) call bpf_probe_read_compat_str#-96768
(c5) if r0 s< 0x0 goto pc+4
(61) r4 = *(u32 *)(r7 +0)
Note, bpf_probe_read_* calls are root only so we wont hit this case
with non-root bpf users.
v3: comment had some documentation about meta set to null case which
is not relevant here and confusing to include in the comment.
v2 note: In original version we set msize_smax_value from check_func_arg()
and propagated this into smax of retval. The logic was smax is the bound
on the retval we set and because the type in the helper is ARG_CONST_SIZE
we know that the reg is a positive tnum_const() so umax=smax. Alexei
pointed out though this is a bit odd to read because the register in
check_func_arg() has a C type of u32 and the umax bound would be the
normally relavent bound here. Pulling in extra knowledge about future
checks makes reading the code a bit tricky. Further having a signed
meta data that can only ever be positive is also a bit odd. So dropped
the msize_smax_value metadata and made it a u64 msize_max_value to
indicate its unsigned. And additionally save bound from umax value in
check_arg_funcs which is the same as smax due to as noted above tnumx_cont
and negative check but reads better. By my analysis nothing functionally
changes in v2 but it does get easier to read so that is win.
Fixes:
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 KP Singh
|
4edf16b72c |
bpf, lsm: Make BPF_LSM depend on BPF_EVENTS
LSM and tracing programs share their helpers with bpf_tracing_func_proto
which is only defined (in bpf_trace.c) when BPF_EVENTS is enabled.
Instead of adding __weak symbol, make BPF_LSM depend on BPF_EVENTS so
that both tracing and LSM programs can actually share helpers.
Fixes:
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Alexei Starovoitov
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c58b1558a7 |
Merge branch 'bpf_sk_assign'
Joe Stringer says:
====================
Introduce a new helper that allows assigning a previously-found socket
to the skb as the packet is received towards the stack, to cause the
stack to guide the packet towards that socket subject to local routing
configuration. The intention is to support TProxy use cases more
directly from eBPF programs attached at TC ingress, to simplify and
streamline Linux stack configuration in scale environments with Cilium.
Normally in ip{,6}_rcv_core(), the skb will be orphaned, dropping any
existing socket reference associated with the skb. Existing tproxy
implementations in netfilter get around this restriction by running the
tproxy logic after ip_rcv_core() in the PREROUTING table. However, this
is not an option for TC-based logic (including eBPF programs attached at
TC ingress).
This series introduces the BPF helper bpf_sk_assign() to associate the
socket with the skb on the ingress path as the packet is passed up the
stack. The initial patch in the series simply takes a reference on the
socket to ensure safety, but later patches relax this for listen
sockets.
To ensure delivery to the relevant socket, we still consult the routing
table, for full examples of how to configure see the tests in patch #5;
the simplest form of the route would look like this:
$ ip route add local default dev lo
This series is laid out as follows:
* Patch 1 extends the eBPF API to add sk_assign() and defines a new
socket free function to allow the later paths to understand when the
socket associated with the skb should be kept through receive.
* Patches 2-3 optimize the receive path to avoid taking a reference on
listener sockets during receive.
* Patches 4-5 extends the selftests with examples of the new
functionality and validation of correct behaviour.
Changes since v4:
* Fix build with CONFIG_INET disabled
* Rebase
Changes since v3:
* Use sock_gen_put() directly instead of sock_edemux() from sock_pfree()
* Commit message wording fixups
* Add acks from Martin, Lorenz
* Rebase
Changes since v2:
* Add selftests for UDP socket redirection
* Drop the early demux optimization patch (defer for more testing)
* Fix check for orphaning after TC act return
* Tidy up the tests to clean up properly and be less noisy.
Changes since v1:
* Replace the metadata_dst approach with using the skb->destructor to
determine whether the socket has been prefetched. This is much
simpler.
* Avoid taking a reference on listener sockets during receive
* Restrict assigning sockets across namespaces
* Restrict assigning SO_REUSEPORT sockets
* Fix cookie usage for socket dst check
* Rebase the tests against test_progs infrastructure
* Tidy up commit messages
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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 Joe Stringer
|
8a02a17036 |
selftests: bpf: Extend sk_assign tests for UDP
Add support for testing UDP sk_assign to the existing tests. Signed-off-by: Joe Stringer <joe@wand.net.nz> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Lorenz Bauer <lmb@cloudflare.com> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20200329225342.16317-6-joe@wand.net.nz |
||
 Lorenz BauerandJoe Stringer
|
2d7824ffd2 |
selftests: bpf: Add test for sk_assign
Attach a tc direct-action classifier to lo in a fresh network namespace, and rewrite all connection attempts to localhost:4321 to localhost:1234 (for port tests) and connections to unreachable IPv4/IPv6 IPs to the local socket (for address tests). Includes implementations for both TCP and UDP. Keep in mind that both client to server and server to client traffic passes the classifier. Signed-off-by: Lorenz Bauer <lmb@cloudflare.com> Signed-off-by: Joe Stringer <joe@wand.net.nz> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20200329225342.16317-5-joe@wand.net.nz Co-authored-by: Joe Stringer <joe@wand.net.nz> |
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|
Joe Stringer
|
7ae215d23c |
bpf: Don't refcount LISTEN sockets in sk_assign()
Avoid taking a reference on listen sockets by checking the socket type in the sk_assign and in the corresponding skb_steal_sock() code in the the transport layer, and by ensuring that the prefetch free (sock_pfree) function uses the same logic to check whether the socket is refcounted. Suggested-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Joe Stringer <joe@wand.net.nz> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20200329225342.16317-4-joe@wand.net.nz |
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|
Joe Stringer
|
71489e21d7 |
net: Track socket refcounts in skb_steal_sock()
Refactor the UDP/TCP handlers slightly to allow skb_steal_sock() to make the determination of whether the socket is reference counted in the case where it is prefetched by earlier logic such as early_demux. Signed-off-by: Joe Stringer <joe@wand.net.nz> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20200329225342.16317-3-joe@wand.net.nz |
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|
Joe Stringer
|
cf7fbe660f |
bpf: Add socket assign support
Add support for TPROXY via a new bpf helper, bpf_sk_assign(). This helper requires the BPF program to discover the socket via a call to bpf_sk*_lookup_*(), then pass this socket to the new helper. The helper takes its own reference to the socket in addition to any existing reference that may or may not currently be obtained for the duration of BPF processing. For the destination socket to receive the traffic, the traffic must be routed towards that socket via local route. The simplest example route is below, but in practice you may want to route traffic more narrowly (eg by CIDR): $ ip route add local default dev lo This patch avoids trying to introduce an extra bit into the skb->sk, as that would require more invasive changes to all code interacting with the socket to ensure that the bit is handled correctly, such as all error-handling cases along the path from the helper in BPF through to the orphan path in the input. Instead, we opt to use the destructor variable to switch on the prefetch of the socket. Signed-off-by: Joe Stringer <joe@wand.net.nz> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20200329225342.16317-2-joe@wand.net.nz |
||
 Daniel Borkmann
|
b49e42a2df |
bpf, doc: Add John as official reviewer to BPF subsystem
We've added John Fastabend to our weekly BPF patch review rotation over last months now where he provided excellent and timely feedback on BPF patches. Therefore, add him to the BPF core reviewer team to the MAINTAINERS file to reflect that. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: John Fastabend <john.fastabend@gmail.com> Link: https://lore.kernel.org/bpf/0e9a74933b3f21f4c5b5a3bc7f8e900b39805639.1585556231.git.daniel@iogearbox.net |
||
|
KP Singh
|
f50b49a0bf |
bpf: btf: Fix arg verification in btf_ctx_access()
The bounds checking for the arguments accessed in the BPF program breaks when the expected_attach_type is not BPF_TRACE_FEXIT, BPF_LSM_MAC or BPF_MODIFY_RETURN resulting in no check being done for the default case (the programs which do not receive the return value of the attached function in its arguments) when the index of the argument being accessed is equal to the number of arguments (nr_args). This was a result of a misplaced "else if" block introduced by the Commit |
||
 Jann Horn
|
0fc31b10cf |
bpf: Simplify reg_set_min_max_inv handling
reg_set_min_max_inv() contains exactly the same logic as reg_set_min_max(), just flipped around. While this makes sense in a cBPF verifier (where ALU operations are not symmetric), it does not make sense for eBPF. Replace reg_set_min_max_inv() with a helper that flips the opcode around, then lets reg_set_min_max() do the complicated work. Signed-off-by: Jann Horn <jannh@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200330160324.15259-4-daniel@iogearbox.net |
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|
Jann Horn
|
604dca5e3a |
bpf: Fix tnum constraints for 32-bit comparisons
The BPF verifier tried to track values based on 32-bit comparisons by (ab)using the tnum state via |
||
|
Daniel Borkmann
|
f2d67fec0b |
bpf: Undo incorrect __reg_bound_offset32 handling
Anatoly has been fuzzing with kBdysch harness and reported a hang in
one of the outcomes:
0: (b7) r0 = 808464432
1: (7f) r0 >>= r0
2: (14) w0 -= 808464432
3: (07) r0 += 808464432
4: (b7) r1 = 808464432
5: (de) if w1 s<= w0 goto pc+0
R0_w=invP(id=0,umin_value=808464432,umax_value=5103431727,var_off=(0x30303020;0x10000001f)) R1_w=invP808464432 R10=fp0
6: (07) r0 += -2144337872
7: (14) w0 -= -1607454672
8: (25) if r0 > 0x30303030 goto pc+0
R0_w=invP(id=0,umin_value=271581184,umax_value=271581311,var_off=(0x10300000;0x7f)) R1_w=invP808464432 R10=fp0
9: (76) if w0 s>= 0x303030 goto pc+2
12: (95) exit
from 8 to 9: safe
from 5 to 6: R0_w=invP(id=0,umin_value=808464432,umax_value=5103431727,var_off=(0x30303020;0x10000001f)) R1_w=invP808464432 R10=fp0
6: (07) r0 += -2144337872
7: (14) w0 -= -1607454672
8: (25) if r0 > 0x30303030 goto pc+0
R0_w=invP(id=0,umin_value=271581184,umax_value=271581311,var_off=(0x10300000;0x7f)) R1_w=invP808464432 R10=fp0
9: safe
from 8 to 9: safe
verification time 589 usec
stack depth 0
processed 17 insns (limit 1000000) [...]
The underlying program was xlated as follows:
# bpftool p d x i 9
0: (b7) r0 = 808464432
1: (7f) r0 >>= r0
2: (14) w0 -= 808464432
3: (07) r0 += 808464432
4: (b7) r1 = 808464432
5: (de) if w1 s<= w0 goto pc+0
6: (07) r0 += -2144337872
7: (14) w0 -= -1607454672
8: (25) if r0 > 0x30303030 goto pc+0
9: (76) if w0 s>= 0x303030 goto pc+2
10: (05) goto pc-1
11: (05) goto pc-1
12: (95) exit
The verifier rewrote original instructions it recognized as dead code with
'goto pc-1', but reality differs from verifier simulation in that we're
actually able to trigger a hang due to hitting the 'goto pc-1' instructions.
Taking different examples to make the issue more obvious: in this example
we're probing bounds on a completely unknown scalar variable in r1:
[...]
5: R0_w=inv1 R1_w=inv(id=0) R10=fp0
5: (18) r2 = 0x4000000000
7: R0_w=inv1 R1_w=inv(id=0) R2_w=inv274877906944 R10=fp0
7: (18) r3 = 0x2000000000
9: R0_w=inv1 R1_w=inv(id=0) R2_w=inv274877906944 R3_w=inv137438953472 R10=fp0
9: (18) r4 = 0x400
11: R0_w=inv1 R1_w=inv(id=0) R2_w=inv274877906944 R3_w=inv137438953472 R4_w=inv1024 R10=fp0
11: (18) r5 = 0x200
13: R0_w=inv1 R1_w=inv(id=0) R2_w=inv274877906944 R3_w=inv137438953472 R4_w=inv1024 R5_w=inv512 R10=fp0
13: (2d) if r1 > r2 goto pc+4
R0_w=inv1 R1_w=inv(id=0,umax_value=274877906944,var_off=(0x0; 0x7fffffffff)) R2_w=inv274877906944 R3_w=inv137438953472 R4_w=inv1024 R5_w=inv512 R10=fp0
14: R0_w=inv1 R1_w=inv(id=0,umax_value=274877906944,var_off=(0x0; 0x7fffffffff)) R2_w=inv274877906944 R3_w=inv137438953472 R4_w=inv1024 R5_w=inv512 R10=fp0
14: (ad) if r1 < r3 goto pc+3
R0_w=inv1 R1_w=inv(id=0,umin_value=137438953472,umax_value=274877906944,var_off=(0x0; 0x7fffffffff)) R2_w=inv274877906944 R3_w=inv137438953472 R4_w=inv1024 R5_w=inv512 R10=fp0
15: R0=inv1 R1=inv(id=0,umin_value=137438953472,umax_value=274877906944,var_off=(0x0; 0x7fffffffff)) R2=inv274877906944 R3=inv137438953472 R4=inv1024 R5=inv512 R10=fp0
15: (2e) if w1 > w4 goto pc+2
R0=inv1 R1=inv(id=0,umin_value=137438953472,umax_value=274877906944,var_off=(0x0; 0x7f00000000)) R2=inv274877906944 R3=inv137438953472 R4=inv1024 R5=inv512 R10=fp0
16: R0=inv1 R1=inv(id=0,umin_value=137438953472,umax_value=274877906944,var_off=(0x0; 0x7f00000000)) R2=inv274877906944 R3=inv137438953472 R4=inv1024 R5=inv512 R10=fp0
16: (ae) if w1 < w5 goto pc+1
R0=inv1 R1=inv(id=0,umin_value=137438953472,umax_value=274877906944,var_off=(0x0; 0x7f00000000)) R2=inv274877906944 R3=inv137438953472 R4=inv1024 R5=inv512 R10=fp0
[...]
We're first probing lower/upper bounds via jmp64, later we do a similar
check via jmp32 and examine the resulting var_off there. After fall-through
in insn 14, we get the following bounded r1 with 0x7fffffffff unknown marked
bits in the variable section.
Thus, after knowing r1 <= 0x4000000000 and r1 >= 0x2000000000:
max: 0b100000000000000000000000000000000000000 / 0x4000000000
var: 0b111111111111111111111111111111111111111 / 0x7fffffffff
min: 0b010000000000000000000000000000000000000 / 0x2000000000
Now, in insn 15 and 16, we perform a similar probe with lower/upper bounds
in jmp32.
Thus, after knowing r1 <= 0x4000000000 and r1 >= 0x2000000000 and
w1 <= 0x400 and w1 >= 0x200:
max: 0b100000000000000000000000000000000000000 / 0x4000000000
var: 0b111111100000000000000000000000000000000 / 0x7f00000000
min: 0b010000000000000000000000000000000000000 / 0x2000000000
The lower/upper bounds haven't changed since they have high bits set in
u64 space and the jmp32 tests can only refine bounds in the low bits.
However, for the var part the expectation would have been 0x7f000007ff
or something less precise up to 0x7fffffffff. A outcome of 0x7f00000000
is not correct since it would contradict the earlier probed bounds
where we know that the result should have been in [0x200,0x400] in u32
space. Therefore, tests with such info will lead to wrong verifier
assumptions later on like falsely predicting conditional jumps to be
always taken, etc.
The issue here is that __reg_bound_offset32()'s implementation from
commit
|
||
|
Daniel Borkmann
|
641cd7b06c |
Merge branch 'bpf-lsm'
KP Singh says: ==================== ** Motivation Google does analysis of rich runtime security data to detect and thwart threats in real-time. Currently, this is done in custom kernel modules but we would like to replace this with something that's upstream and useful to others. The current kernel infrastructure for providing telemetry (Audit, Perf etc.) is disjoint from access enforcement (i.e. LSMs). Augmenting the information provided by audit requires kernel changes to audit, its policy language and user-space components. Furthermore, building a MAC policy based on the newly added telemetry data requires changes to various LSMs and their respective policy languages. This patchset allows BPF programs to be attached to LSM hooks This facilitates a unified and dynamic (not requiring re-compilation of the kernel) audit and MAC policy. ** Why an LSM? Linux Security Modules target security behaviours rather than the kernel's API. For example, it's easy to miss out a newly added system call for executing processes (eg. execve, execveat etc.) but the LSM framework ensures that all process executions trigger the relevant hooks irrespective of how the process was executed. Allowing users to implement LSM hooks at runtime also benefits the LSM eco-system by enabling a quick feedback loop from the security community about the kind of behaviours that the LSM Framework should be targeting. ** How does it work? The patchset introduces a new eBPF (https://docs.cilium.io/en/v1.6/bpf/) program type BPF_PROG_TYPE_LSM which can only be attached to LSM hooks. Loading and attachment of BPF programs requires CAP_SYS_ADMIN. The new LSM registers nop functions (bpf_lsm_<hook_name>) as LSM hook callbacks. Their purpose is to provide a definite point where BPF programs can be attached as BPF_TRAMP_MODIFY_RETURN trampoline programs for hooks that return an int, and BPF_TRAMP_FEXIT trampoline programs for void LSM hooks. Audit logs can be written using a format chosen by the eBPF program to the perf events buffer or to global eBPF variables or maps and can be further processed in user-space. ** BTF Based Design The current design uses BTF: * https://facebookmicrosites.github.io/bpf/blog/2018/11/14/btf-enhancement.html * https://lwn.net/Articles/803258 which allows verifiable read-only structure accesses by field names rather than fixed offsets. This allows accessing the hook parameters using a dynamically created context which provides a certain degree of ABI stability: // Only declare the structure and fields intended to be used // in the program struct vm_area_struct { unsigned long vm_start; } __attribute__((preserve_access_index)); // Declare the eBPF program mprotect_audit which attaches to // to the file_mprotect LSM hook and accepts three arguments. SEC("lsm/file_mprotect") int BPF_PROG(mprotect_audit, struct vm_area_struct *vma, unsigned long reqprot, unsigned long prot, int ret) { unsigned long vm_start = vma->vm_start; return 0; } By relocating field offsets, BTF makes a large portion of kernel data structures readily accessible across kernel versions without requiring a large corpus of BPF helper functions and requiring recompilation with every kernel version. The BTF type information is also used by the BPF verifier to validate memory accesses within the BPF program and also prevents arbitrary writes to the kernel memory. The limitations of BTF compatibility are described in BPF Co-Re (http://vger.kernel.org/bpfconf2019_talks/bpf-core.pdf, i.e. field renames, #defines and changes to the signature of LSM hooks). This design imposes that the MAC policy (eBPF programs) be updated when the inspected kernel structures change outside of BTF compatibility guarantees. In practice, this is only required when a structure field used by a current policy is removed (or renamed) or when the used LSM hooks change. We expect the maintenance cost of these changes to be acceptable as compared to the design presented in the RFC. (https://lore.kernel.org/bpf/20190910115527.5235-1-kpsingh@chromium.org/). ** Usage Examples A simple example and some documentation is included in the patchset. In order to better illustrate the capabilities of the framework some more advanced prototype (not-ready for review) code has also been published separately: * Logging execution events (including environment variables and arguments) https://github.com/sinkap/linux-krsi/blob/patch/v1/examples/samples/bpf/lsm_audit_env.c * Detecting deletion of running executables: https://github.com/sinkap/linux-krsi/blob/patch/v1/examples/samples/bpf/lsm_detect_exec_unlink.c * Detection of writes to /proc/<pid>/mem: https://github.com/sinkap/linux-krsi/blob/patch/v1/examples/samples/bpf/lsm_audit_env.c We have updated Google's internal telemetry infrastructure and have started deploying this LSM on our Linux Workstations. This gives us more confidence in the real-world applications of such a system. ** Changelog: - v8 -> v9: https://lore.kernel.org/bpf/20200327192854.31150-1-kpsingh@chromium.org/ * Fixed a selftest crash when CONFIG_LSM doesn't have "bpf". * Added James' Ack. * Rebase. - v7 -> v8: https://lore.kernel.org/bpf/20200326142823.26277-1-kpsingh@chromium.org/ * Removed CAP_MAC_ADMIN check from bpf_lsm_verify_prog. LSMs can add it in their own bpf_prog hook. This can be revisited as a separate patch. * Added Andrii and James' Ack/Review tags. * Fixed an indentation issue and missing newlines in selftest error a cases. * Updated a comment as suggested by Alexei. * Updated the documentation to use the newer libbpf API and some other fixes. * Rebase - v6 -> v7: https://lore.kernel.org/bpf/20200325152629.6904-1-kpsingh@chromium.org/ * Removed __weak from the LSM attachment nops per Kees' suggestion. Will send a separate patch (if needed) to update the noinline definition in include/linux/compiler_attributes.h. * waitpid to wait specifically for the forked child in selftests. * Comment format fixes in security/... as suggested by Casey. * Added Acks from Kees and Andrii and Casey's Reviewed-by: tags to the respective patches. * Rebase - v5 -> v6: https://lore.kernel.org/bpf/20200323164415.12943-1-kpsingh@chromium.org/ * Updated LSM_HOOK macro to define a default value and cleaned up the BPF LSM hook declarations. * Added Yonghong's Acks and Kees' Reviewed-by tags. * Simplification of the selftest code. * Rebase and fixes suggested by Andrii and Yonghong and some other minor fixes noticed in internal review. - v4 -> v5: https://lore.kernel.org/bpf/20200220175250.10795-1-kpsingh@chromium.org/ * Removed static keys and special casing of BPF calls from the LSM framework. * Initialized the BPF callbacks (nops) as proper LSM hooks. * Updated to using the newly introduced BPF_TRAMP_MODIFY_RETURN trampolines in https://lkml.org/lkml/2020/3/4/877 * Addressed Andrii's feedback and rebased. - v3 -> v4: * Moved away from allocating a separate security_hook_heads and adding a new special case for arch_prepare_bpf_trampoline to using BPF fexit trampolines called from the right place in the LSM hook and toggled by static keys based on the discussion in: https://lore.kernel.org/bpf/CAG48ez25mW+_oCxgCtbiGMX07g_ph79UOJa07h=o_6B6+Q-u5g@mail.gmail.com/ * Since the code does not deal with security_hook_heads anymore, it goes from "being a BPF LSM" to "BPF program attachment to LSM hooks". * Added a new test case which ensures that the BPF programs' return value is reflected by the LSM hook. - v2 -> v3 does not change the overall design and has some minor fixes: * LSM_ORDER_LAST is introduced to represent the behaviour of the BPF LSM * Fixed the inadvertent clobbering of the LSM Hook error codes * Added GPL license requirement to the commit log * The lsm_hook_idx is now the more conventional 0-based index * Some changes were split into a separate patch ("Load btf_vmlinux only once per object") https://lore.kernel.org/bpf/20200117212825.11755-1-kpsingh@chromium.org/ * Addressed Andrii's feedback on the BTF implementation * Documentation update for using generated vmlinux.h to simplify programs * Rebase - Changes since v1: https://lore.kernel.org/bpf/20191220154208.15895-1-kpsingh@chromium.org * Eliminate the requirement to maintain LSM hooks separately in security/bpf/hooks.h Use BPF trampolines to dynamically allocate security hooks * Drop the use of securityfs as bpftool provides the required introspection capabilities. Update the tests to use the bpf_skeleton and global variables * Use O_CLOEXEC anonymous fds to represent BPF attachment in line with the other BPF programs with the possibility to use bpf program pinning in the future to provide "permanent attachment". * Drop the logic based on prog names for handling re-attachment. * Drop bpf_lsm_event_output from this series and send it as a separate patch. ==================== Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> |
||
|
KP Singh
|
4dece7f3b9 |
bpf: lsm: Add Documentation
Document how eBPF programs (BPF_PROG_TYPE_LSM) can be loaded and attached (BPF_LSM_MAC) to the LSM hooks. Signed-off-by: KP Singh <kpsingh@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Brendan Jackman <jackmanb@google.com> Reviewed-by: Florent Revest <revest@google.com> Reviewed-by: Thomas Garnier <thgarnie@google.com> Reviewed-by: James Morris <jamorris@linux.microsoft.com> Link: https://lore.kernel.org/bpf/20200329004356.27286-9-kpsingh@chromium.org |
||
|
KP Singh
|
03e54f100d |
bpf: lsm: Add selftests for BPF_PROG_TYPE_LSM
* Load/attach a BPF program that hooks to file_mprotect (int) and bprm_committed_creds (void). * Perform an action that triggers the hook. * Verify if the audit event was received using the shared global variables for the process executed. * Verify if the mprotect returns a -EPERM. Signed-off-by: KP Singh <kpsingh@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Brendan Jackman <jackmanb@google.com> Reviewed-by: Florent Revest <revest@google.com> Reviewed-by: Thomas Garnier <thgarnie@google.com> Reviewed-by: James Morris <jamorris@linux.microsoft.com> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200329004356.27286-8-kpsingh@chromium.org |
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|
KP Singh
|
1e092a0318 |
tools/libbpf: Add support for BPF_PROG_TYPE_LSM
Since BPF_PROG_TYPE_LSM uses the same attaching mechanism as BPF_PROG_TYPE_TRACING, the common logic is refactored into a static function bpf_program__attach_btf_id. A new API call bpf_program__attach_lsm is still added to avoid userspace conflicts if this ever changes in the future. Signed-off-by: KP Singh <kpsingh@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Brendan Jackman <jackmanb@google.com> Reviewed-by: Florent Revest <revest@google.com> Reviewed-by: James Morris <jamorris@linux.microsoft.com> Acked-by: Yonghong Song <yhs@fb.com> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200329004356.27286-7-kpsingh@chromium.org |
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|
KP Singh
|
520b7aa00d |
bpf: lsm: Initialize the BPF LSM hooks
* The hooks are initialized using the definitions in include/linux/lsm_hook_defs.h. * The LSM can be enabled / disabled with CONFIG_BPF_LSM. Signed-off-by: KP Singh <kpsingh@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Brendan Jackman <jackmanb@google.com> Reviewed-by: Florent Revest <revest@google.com> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: James Morris <jamorris@linux.microsoft.com> Link: https://lore.kernel.org/bpf/20200329004356.27286-6-kpsingh@chromium.org |
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|
KP Singh
|
9e4e01dfd3 |
bpf: lsm: Implement attach, detach and execution
JITed BPF programs are dynamically attached to the LSM hooks using BPF trampolines. The trampoline prologue generates code to handle conversion of the signature of the hook to the appropriate BPF context. The allocated trampoline programs are attached to the nop functions initialized as LSM hooks. BPF_PROG_TYPE_LSM programs must have a GPL compatible license and and need CAP_SYS_ADMIN (required for loading eBPF programs). Upon attachment: * A BPF fexit trampoline is used for LSM hooks with a void return type. * A BPF fmod_ret trampoline is used for LSM hooks which return an int. The attached programs can override the return value of the bpf LSM hook to indicate a MAC Policy decision. Signed-off-by: KP Singh <kpsingh@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Brendan Jackman <jackmanb@google.com> Reviewed-by: Florent Revest <revest@google.com> Acked-by: Andrii Nakryiko <andriin@fb.com> Acked-by: James Morris <jamorris@linux.microsoft.com> Link: https://lore.kernel.org/bpf/20200329004356.27286-5-kpsingh@chromium.org |
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KP Singh
|
9d3fdea789 |
bpf: lsm: Provide attachment points for BPF LSM programs
When CONFIG_BPF_LSM is enabled, nop functions, bpf_lsm_<hook_name>, are generated for each LSM hook. These functions are initialized as LSM hooks in a subsequent patch. Signed-off-by: KP Singh <kpsingh@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Brendan Jackman <jackmanb@google.com> Reviewed-by: Florent Revest <revest@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Acked-by: Yonghong Song <yhs@fb.com> Acked-by: James Morris <jamorris@linux.microsoft.com> Link: https://lore.kernel.org/bpf/20200329004356.27286-4-kpsingh@chromium.org |
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KP Singh
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98e828a065 |
security: Refactor declaration of LSM hooks
The information about the different types of LSM hooks is scattered in two locations i.e. union security_list_options and struct security_hook_heads. Rather than duplicating this information even further for BPF_PROG_TYPE_LSM, define all the hooks with the LSM_HOOK macro in lsm_hook_defs.h which is then used to generate all the data structures required by the LSM framework. The LSM hooks are defined as: LSM_HOOK(<return_type>, <default_value>, <hook_name>, args...) with <default_value> acccessible in security.c as: LSM_RET_DEFAULT(<hook_name>) Signed-off-by: KP Singh <kpsingh@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Brendan Jackman <jackmanb@google.com> Reviewed-by: Florent Revest <revest@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Casey Schaufler <casey@schaufler-ca.com> Acked-by: James Morris <jamorris@linux.microsoft.com> Link: https://lore.kernel.org/bpf/20200329004356.27286-3-kpsingh@chromium.org |
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KP Singh
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fc611f47f2 |
bpf: Introduce BPF_PROG_TYPE_LSM
Introduce types and configs for bpf programs that can be attached to LSM hooks. The programs can be enabled by the config option CONFIG_BPF_LSM. Signed-off-by: KP Singh <kpsingh@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Brendan Jackman <jackmanb@google.com> Reviewed-by: Florent Revest <revest@google.com> Reviewed-by: Thomas Garnier <thgarnie@google.com> Acked-by: Yonghong Song <yhs@fb.com> Acked-by: Andrii Nakryiko <andriin@fb.com> Acked-by: James Morris <jamorris@linux.microsoft.com> Link: https://lore.kernel.org/bpf/20200329004356.27286-2-kpsingh@chromium.org |
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 Toke Høiland-Jørgensen
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e5fb60ee4c |
selftests: Add test for overriding global data value before load
This adds a test to exercise the new bpf_map__set_initial_value() function. The test simply overrides the global data section with all zeroes, and checks that the new value makes it into the kernel map on load. Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200329132253.232541-2-toke@redhat.com |
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Toke Høiland-Jørgensen
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e2842be53d |
libbpf: Add setter for initial value for internal maps
For internal maps (most notably the maps backing global variables), libbpf uses an internal mmaped area to store the data after opening the object. This data is subsequently copied into the kernel map when the object is loaded. This adds a function to set a new value for that data, which can be used to before it is loaded into the kernel. This is especially relevant for RODATA maps, since those are frozen on load. Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200329132253.232541-1-toke@redhat.com |
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Daniel Borkmann
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5a95cbb80e |
bpf, net: Fix build issue when net ns not configured
Fix a redefinition of 'net_gen_cookie' error that was overlooked
when net ns is not configured.
Fixes:
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Alexei Starovoitov
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ae661deca7 |
Merge branch 'ifla_xdp_expected_fd'
Toke Høiland-Jørgensen says: ==================== This series adds support for atomically replacing the XDP program loaded on an interface. This is achieved by means of a new netlink attribute that can specify the expected previous program to replace on the interface. If set, the kernel will compare this "expected fd" attribute with the program currently loaded on the interface, and reject the operation if it does not match. With this primitive, userspace applications can avoid stepping on each other's toes when simultaneously updating the loaded XDP program. Changelog: v4: - Switch back to passing FD instead of ID (Andrii) - Rename flag to XDP_FLAGS_REPLACE (for consistency with other similar uses) v3: - Pass existing ID instead of FD (Jakub) - Use opts struct for new libbpf function (Andrii) v2: - Fix checkpatch nits and add .strict_start_type to netlink policy (Jakub) ==================== Signed-off-by: Alexei Starovoitov <ast@kernel.org> |
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Toke Høiland-Jørgensen
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87854a0b57 |
selftests/bpf: Add tests for attaching XDP programs
This adds tests for the various replacement operations using IFLA_XDP_EXPECTED_FD. Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/158515700967.92963.15098921624731968356.stgit@toke.dk |
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Toke Høiland-Jørgensen
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bd5ca3ef93 |
libbpf: Add function to set link XDP fd while specifying old program
This adds a new function to set the XDP fd while specifying the FD of the program to replace, using the newly added IFLA_XDP_EXPECTED_FD netlink parameter. The new function uses the opts struct mechanism to be extendable in the future. Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/158515700857.92963.7052131201257841700.stgit@toke.dk |
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Toke Høiland-Jørgensen
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50a3e678b5 |
tools: Add EXPECTED_FD-related definitions in if_link.h
This adds the IFLA_XDP_EXPECTED_FD netlink attribute definition and the XDP_FLAGS_REPLACE flag to if_link.h in tools/include. Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/158515700747.92963.8615391897417388586.stgit@toke.dk |
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Toke Høiland-Jørgensen
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92234c8f15 |
xdp: Support specifying expected existing program when attaching XDP
While it is currently possible for userspace to specify that an existing XDP program should not be replaced when attaching to an interface, there is no mechanism to safely replace a specific XDP program with another. This patch adds a new netlink attribute, IFLA_XDP_EXPECTED_FD, which can be set along with IFLA_XDP_FD. If set, the kernel will check that the program currently loaded on the interface matches the expected one, and fail the operation if it does not. This corresponds to a 'cmpxchg' memory operation. Setting the new attribute with a negative value means that no program is expected to be attached, which corresponds to setting the UPDATE_IF_NOEXIST flag. A new companion flag, XDP_FLAGS_REPLACE, is also added to explicitly request checking of the EXPECTED_FD attribute. This is needed for userspace to discover whether the kernel supports the new attribute. Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Reviewed-by: Jakub Kicinski <kuba@kernel.org> Link: https://lore.kernel.org/bpf/158515700640.92963.3551295145441017022.stgit@toke.dk |
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 Jean-Philippe Menil
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e9ff9d5254 |
bpf: Fix build warning regarding missing prototypes
Fix build warnings when building net/bpf/test_run.o with W=1 due
to missing prototype for bpf_fentry_test{1..6}.
Instead of declaring prototypes, turn off warnings with
__diag_{push,ignore,pop} as pointed out by Alexei.
Signed-off-by: Jean-Philippe Menil <jpmenil@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200327204713.28050-1-jpmenil@gmail.com
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 Fletcher Dunn
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291cfe365b |
libbpf, xsk: Init all ring members in xsk_umem__create and xsk_socket__create
Fix a sharp edge in xsk_umem__create and xsk_socket__create. Almost all of the members of the ring buffer structs are initialized, but the "cached_xxx" variables are not all initialized. The caller is required to zero them. This is needlessly dangerous. The results if you don't do it can be very bad. For example, they can cause xsk_prod_nb_free and xsk_cons_nb_avail to return values greater than the size of the queue. xsk_ring_cons__peek can return an index that does not refer to an item that has been queued. I have confirmed that without this change, my program misbehaves unless I memset the ring buffers to zero before calling the function. Afterwards, my program works without (or with) the memset. Signed-off-by: Fletcher Dunn <fletcherd@valvesoftware.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Magnus Karlsson <magnus.karlsson@intel.com> Link: https://lore.kernel.org/bpf/85f12913cde94b19bfcb598344701c38@valvesoftware.com |
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Alexei Starovoitov
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2cf69d3fa5 |
Merge branch 'cgroup-helpers'
Daniel Borkmann says: ==================== This adds various straight-forward helper improvements and additions to BPF cgroup based connect(), sendmsg(), recvmsg() and bind-related hooks which would allow to implement more fine-grained policies and improve current load balancer limitations we're seeing. For details please see individual patches. I've tested them on Kubernetes & Cilium and also added selftests for the small verifier extension. Thanks! ==================== Signed-off-by: Alexei Starovoitov <ast@kernel.org> |
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Daniel Borkmann
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23599ada0e |
bpf: Add selftest cases for ctx_or_null argument type
Add various tests to make sure the verifier keeps catching them: # ./test_verifier [...] #230/p pass ctx or null check, 1: ctx OK #231/p pass ctx or null check, 2: null OK #232/p pass ctx or null check, 3: 1 OK #233/p pass ctx or null check, 4: ctx - const OK #234/p pass ctx or null check, 5: null (connect) OK #235/p pass ctx or null check, 6: null (bind) OK #236/p pass ctx or null check, 7: ctx (bind) OK #237/p pass ctx or null check, 8: null (bind) OK [...] Summary: 1595 PASSED, 0 SKIPPED, 0 FAILED Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/c74758d07b1b678036465ef7f068a49e9efd3548.1585323121.git.daniel@iogearbox.net |
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Daniel Borkmann
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834ebca845 |
bpf: Enable retrival of pid/tgid/comm from bpf cgroup hooks
We already have the bpf_get_current_uid_gid() helper enabled, and given we now have perf event RB output available for connect(), sendmsg(), recvmsg() and bind-related hooks, add a trivial change to enable bpf_get_current_pid_tgid() and bpf_get_current_comm() as well. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/18744744ed93c06343be8b41edcfd858706f39d7.1585323121.git.daniel@iogearbox.net |
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Daniel Borkmann
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0f09abd105 |
bpf: Enable bpf cgroup hooks to retrieve cgroup v2 and ancestor id
Enable the bpf_get_current_cgroup_id() helper for connect(), sendmsg(),
recvmsg() and bind-related hooks in order to retrieve the cgroup v2
context which can then be used as part of the key for BPF map lookups,
for example. Given these hooks operate in process context 'current' is
always valid and pointing to the app that is performing mentioned
syscalls if it's subject to a v2 cgroup. Also with same motivation of
commit
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Daniel Borkmann
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5a52ae4e32 |
bpf: Allow to retrieve cgroup v1 classid from v2 hooks
Today, Kubernetes is still operating on cgroups v1, however, it is possible to retrieve the task's classid based on 'current' out of connect(), sendmsg(), recvmsg() and bind-related hooks for orchestrators which attach to the root cgroup v2 hook in a mixed env like in case of Cilium, for example, in order to then correlate certain pod traffic and use it as part of the key for BPF map lookups. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/555e1c69db7376c0947007b4951c260e1074efc3.1585323121.git.daniel@iogearbox.net |
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Daniel Borkmann
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f318903c0b |
bpf: Add netns cookie and enable it for bpf cgroup hooks
In Cilium we're mainly using BPF cgroup hooks today in order to implement
kube-proxy free Kubernetes service translation for ClusterIP, NodePort (*),
ExternalIP, and LoadBalancer as well as HostPort mapping [0] for all traffic
between Cilium managed nodes. While this works in its current shape and avoids
packet-level NAT for inter Cilium managed node traffic, there is one major
limitation we're facing today, that is, lack of netns awareness.
In Kubernetes, the concept of Pods (which hold one or multiple containers)
has been built around network namespaces, so while we can use the global scope
of attaching to root BPF cgroup hooks also to our advantage (e.g. for exposing
NodePort ports on loopback addresses), we also have the need to differentiate
between initial network namespaces and non-initial one. For example, ExternalIP
services mandate that non-local service IPs are not to be translated from the
host (initial) network namespace as one example. Right now, we have an ugly
work-around in place where non-local service IPs for ExternalIP services are
not xlated from connect() and friends BPF hooks but instead via less efficient
packet-level NAT on the veth tc ingress hook for Pod traffic.
On top of determining whether we're in initial or non-initial network namespace
we also have a need for a socket-cookie like mechanism for network namespaces
scope. Socket cookies have the nice property that they can be combined as part
of the key structure e.g. for BPF LRU maps without having to worry that the
cookie could be recycled. We are planning to use this for our sessionAffinity
implementation for services. Therefore, add a new bpf_get_netns_cookie() helper
which would resolve both use cases at once: bpf_get_netns_cookie(NULL) would
provide the cookie for the initial network namespace while passing the context
instead of NULL would provide the cookie from the application's network namespace.
We're using a hole, so no size increase; the assignment happens only once.
Therefore this allows for a comparison on initial namespace as well as regular
cookie usage as we have today with socket cookies. We could later on enable
this helper for other program types as well as we would see need.
(*) Both externalTrafficPolicy={Local|Cluster} types
[0] https://github.com/cilium/cilium/blob/master/bpf/bpf_sock.c
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/c47d2346982693a9cf9da0e12690453aded4c788.1585323121.git.daniel@iogearbox.net
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Daniel Borkmann
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fcf752ea8c |
bpf: Enable perf event rb output for bpf cgroup progs
Currently, connect(), sendmsg(), recvmsg() and bind-related hooks
are all lacking perf event rb output in order to push notifications
or monitoring events up to user space. Back in commit
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