programs with function calls are often passing various
pointers via stack. When all calls are inlined llvm
flattens stack accesses and optimizes away extra branches.
When functions are not inlined it becomes the job of
the verifier to recognize zero initialized stack to avoid
exploring paths that program will not take.
The following program would fail otherwise:

ptr = &buffer_on_stack;
*ptr = 0;
...
func_call(.., ptr, ...) {
  if (..)
    *ptr = bpf_map_lookup();
}
...
if (*ptr != 0) {
  // Access (*ptr)->field is valid.
  // Without stack_zero tracking such (*ptr)->field access
  // will be rejected
}

since stack slots are no longer uniform invalid | spill | misc
add liveness marking to all slots, but do it in 8 byte chunks.
So if nothing was read or written in [fp-16, fp-9] range
it will be marked as LIVE_NONE.
If any byte in that range was read, it will be marked LIVE_READ
and stacksafe() check will perform byte-by-byte verification.
If all bytes in the range were written the slot will be
marked as LIVE_WRITTEN.
This significantly speeds up state equality comparison
and reduces total number of states processed.

                    before   after
bpf_lb-DLB_L3.o       2051    2003
bpf_lb-DLB_L4.o       3287    3164
bpf_lb-DUNKNOWN.o     1080    1080
bpf_lxc-DDROP_ALL.o   24980   12361
bpf_lxc-DUNKNOWN.o    34308   16605
bpf_netdev.o          15404   10962
bpf_overlay.o         7191    6679
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

Allow arbitrary function calls from bpf function to another bpf function.

To recognize such set of bpf functions the verifier does:
1. runs control flow analysis to detect function boundaries
2. proceeds with verification of all functions starting from main(root) function
It recognizes that the stack of the caller can be accessed by the callee
(if the caller passed a pointer to its stack to the callee) and the callee
can store map_value and other pointers into the stack of the caller.
3. keeps track of the stack_depth of each function to make sure that total
stack depth is still less than 512 bytes
4. disallows pointers to the callee stack to be stored into the caller stack,
since they will be invalid as soon as the callee returns
5. to reuse all of the existing state_pruning logic each function call
is considered to be independent call from the verifier point of view.
The verifier pretends to inline all function calls it sees are being called.
It stores the callsite instruction index as part of the state to make sure
that two calls to the same callee from two different places in the caller
will be different from state pruning point of view
6. more safety checks are added to liveness analysis

Implementation details:
. struct bpf_verifier_state is now consists of all stack frames that
  led to this function
. struct bpf_func_state represent one stack frame. It consists of
  registers in the given frame and its stack
. propagate_liveness() logic had a premature optimization where
  mark_reg_read() and mark_stack_slot_read() were manually inlined
  with loop iterating over parents for each register or stack slot.
  Undo this optimization to reuse more complex mark_*_read() logic
. skip_callee() logic is not necessary from safety point of view,
  but without it mark_*_read() markings become too conservative,
  since after returning from the funciton call a read of r6-r9
  will incorrectly propagate the read marks into callee causing
  inefficient pruning later
. mark_*_read() logic is now aware of control flow which makes it
  more complex. In the future the plan is to rewrite liveness
  to be hierarchical. So that liveness can be done within
  basic block only and control flow will be responsible for
  propagation of liveness information along cfg and between calls.
. tail_calls and ld_abs insns are not allowed in the programs with
  bpf-to-bpf calls
. returning stack pointers to the caller or storing them into stack
  frame of the caller is not allowed

Testing:
. no difference in cilium processed_insn numbers
. large number of tests follows in next patches
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

Allow arbitrary function calls from bpf function to another bpf function.

Since the beginning of bpf all bpf programs were represented as a single function
and program authors were forced to use always_inline for all functions
in their C code. That was causing llvm to unnecessary inflate the code size
and forcing developers to move code to header files with little code reuse.

With a bit of additional complexity teach verifier to recognize
arbitrary function calls from one bpf function to another as long as
all of functions are presented to the verifier as a single bpf program.
New program layout:
r6 = r1    // some code
..
r1 = ..    // arg1
r2 = ..    // arg2
call pc+1  // function call pc-relative
exit
.. = r1    // access arg1
.. = r2    // access arg2
..
call pc+20 // second level of function call
...

It allows for better optimized code and finally allows to introduce
the core bpf libraries that can be reused in different projects,
since programs are no longer limited by single elf file.
With function calls bpf can be compiled into multiple .o files.

This patch is the first step. It detects programs that contain
multiple functions and checks that calls between them are valid.
It splits the sequence of bpf instructions (one program) into a set
of bpf functions that call each other. Calls to only known
functions are allowed. In the future the verifier may allow
calls to unresolved functions and will do dynamic linking.
This logic supports statically linked bpf functions only.

Such function boundary detection could have been done as part of
control flow graph building in check_cfg(), but it's cleaner to
separate function boundary detection vs control flow checks within
a subprogram (function) into logically indepedent steps.
Follow up patches may split check_cfg() further, but not check_subprogs().

Only allow bpf-to-bpf calls for root only and for non-hw-offloaded programs.
These restrictions can be relaxed in the future.
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

Error injection is sloppy and very ad-hoc.  BPF could fill this niche
perfectly with it's kprobe functionality.  We could make sure errors are
only triggered in specific call chains that we care about with very
specific situations.  Accomplish this with the bpf_override_funciton
helper.  This will modify the probe'd callers return value to the
specified value and set the PC to an override function that simply
returns, bypassing the originally probed function.  This gives us a nice
clean way to implement systematic error injection for all of our code
paths.
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NIngo Molnar <mingo@kernel.org>
Signed-off-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>

don't pass large struct bpf_reg_state by value.
Instead pass it by pointer.
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

verifier knows how to trim paths that are known not to be
taken at run-time when register containing run-time constant
is compared with another constant.
It was done only for JEQ comparison.
Extend it to include JNE as well.
More cases can be added in the future.

                     before  after
bpf_lb-DLB_L3.o       2270    2051
bpf_lb-DLB_L4.o       3682    3287
bpf_lb-DUNKNOWN.o     1110    1080
bpf_lxc-DDROP_ALL.o   27876   24980
bpf_lxc-DUNKNOWN.o    38780   34308
bpf_netdev.o          16937   15404
bpf_overlay.o         7929    7191
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

registers with pointers filled from stack were missing live_written marks
which caused liveness propagation to unnecessary mark more registers as
live_read and miss state pruning opportunities later on.

                     before  after
bpf_lb-DLB_L3.o       2285   2270
bpf_lb-DLB_L4.o       3723   3682
bpf_lb-DUNKNOWN.o     1110   1110
bpf_lxc-DDROP_ALL.o   27954  27876
bpf_lxc-DUNKNOWN.o    38954  38780
bpf_netdev.o          16943  16937
bpf_overlay.o         7929   7929
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

when verifier hits an internal bug don't mark register R10==FP as uninit,
since it's read only register and it's not technically correct to let
verifier run further, since it may assume that R10 has valid auxiliary state.

While developing subsequent patches this issue was discovered,
though the code eventually changed that aux reg state doesn't have
pointers any more it is still safer to avoid clearing readonly register.
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

let verifier print register and stack liveness information
into verifier log
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

fix incorrect stack state prints in print_verifier_state()

Fixes: 638f5b90 ("bpf: reduce verifier memory consumption")
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

when the verifier detects that register contains a runtime constant
and it's compared with another constant it will prune exploration
of the branch that is guaranteed not to be taken at runtime.
This is all correct, but malicious program may be constructed
in such a way that it always has a constant comparison and
the other branch is never taken under any conditions.
In this case such path through the program will not be explored
by the verifier. It won't be taken at run-time either, but since
all instructions are JITed the malicious program may cause JITs
to complain about using reserved fields, etc.
To fix the issue we have to track the instructions explored by
the verifier and sanitize instructions that are dead at run time
with NOPs. We cannot reject such dead code, since llvm generates
it for valid C code, since it doesn't do as much data flow
analysis as the verifier does.

Fixes: 17a52670 ("bpf: verifier (add verifier core)")
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

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: NGianluca Borello <g.borello@gmail.com>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

For helpers, the argument type ARG_CONST_SIZE_OR_ZERO permits the
access size to be 0 when accessing the previous argument (arg).
Right now, it requires the arg needs to be NULL when size passed
is 0 or could be 0. It also requires a non-NULL arg when the size
is proved to be non-0.

This patch changes verifier ARG_CONST_SIZE_OR_ZERO behavior
such that for size-0 or possible size-0, it is not required
the arg equal to NULL.

There are a couple of reasons for this semantics change, and
all of them intends to simplify user bpf programs which
may improve user experience and/or increase chances of
verifier acceptance. Together with the next patch which
changes bpf_probe_read arg2 type from ARG_CONST_SIZE to
ARG_CONST_SIZE_OR_ZERO, the following two examples, which
fail the verifier currently, are able to get verifier acceptance.

Example 1:
   unsigned long len = pend - pstart;
   len = len > MAX_PAYLOAD_LEN ? MAX_PAYLOAD_LEN : len;
   len &= MAX_PAYLOAD_LEN;
   bpf_probe_read(data->payload, len, pstart);

It does not have test for "len > 0" and it failed the verifier.
Users may not be aware that they have to add this test.
Converting the bpf_probe_read helper to have
ARG_CONST_SIZE_OR_ZERO helps the above code get
verifier acceptance.

Example 2:
  Here is one example where llvm "messed up" the code and
  the verifier fails.

......
   unsigned long len = pend - pstart;
   if (len > 0 && len <= MAX_PAYLOAD_LEN)
     bpf_probe_read(data->payload, len, pstart);
......

The compiler generates the following code and verifier fails:
......
39: (79) r2 = *(u64 *)(r10 -16)
40: (1f) r2 -= r8
41: (bf) r1 = r2
42: (07) r1 += -1
43: (25) if r1 > 0xffe goto pc+3
  R0=inv(id=0) R1=inv(id=0,umax_value=4094,var_off=(0x0; 0xfff))
  R2=inv(id=0) R6=map_value(id=0,off=0,ks=4,vs=4095,imm=0) R7=inv(id=0)
  R8=inv(id=0) R9=inv0 R10=fp0
44: (bf) r1 = r6
45: (bf) r3 = r8
46: (85) call bpf_probe_read#45
R2 min value is negative, either use unsigned or 'var &= const'
......

The compiler optimization is correct. If r1 = 0,
r1 - 1 = 0xffffffffffffffff > 0xffe.  If r1 != 0, r1 - 1 will not wrap.
r1 > 0xffe at insn #43 can actually capture
both "r1 > 0" and "len <= MAX_PAYLOAD_LEN".
This however causes an issue in verifier as the value range of arg2
"r2" does not properly get refined and lead to verification failure.

Relaxing bpf_prog_read arg2 from ARG_CONST_SIZE to ARG_CONST_SIZE_OR_ZERO
allows the following simplied code:
   unsigned long len = pend - pstart;
   if (len <= MAX_PAYLOAD_LEN)
     bpf_probe_read(data->payload, len, pstart);

The llvm compiler will generate less complex code and the
verifier is able to verify that the program is okay.
Signed-off-by: NYonghong Song <yhs@fb.com>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

NACK'd by x86 maintainer.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Error injection is sloppy and very ad-hoc.  BPF could fill this niche
perfectly with it's kprobe functionality.  We could make sure errors are
only triggered in specific call chains that we care about with very
specific situations.  Accomplish this with the bpf_override_funciton
helper.  This will modify the probe'd callers return value to the
specified value and set the PC to an override function that simply
returns, bypassing the originally probed function.  This gives us a nice
clean way to implement systematic error injection for all of our code
paths.
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NJosef Bacik <jbacik@fb.com>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Cgroup v2 lacks the device controller, provided by cgroup v1.
This patch adds a new eBPF program type, which in combination
of previously added ability to attach multiple eBPF programs
to a cgroup, will provide a similar functionality, but with some
additional flexibility.

This patch introduces a BPF_PROG_TYPE_CGROUP_DEVICE program type.
A program takes major and minor device numbers, device type
(block/character) and access type (mknod/read/write) as parameters
and returns an integer which defines if the operation should be
allowed or terminated with -EPERM.
Signed-off-by: NRoman Gushchin <guro@fb.com>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NTejun Heo <tj@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Thanks to the ability to load a program for a specific device,
running verifier twice is no longer needed.
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: NQuentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The fact that we don't know which device the program is going
to be used on is quite limiting in current eBPF infrastructure.
We have to reverse or limit the changes which kernel makes to
the loaded bytecode if we want it to be offloaded to a networking
device.  We also have to invent new APIs for debugging and
troubleshooting support.

Make it possible to load programs for a specific netdev.  This
helps us to bring the debug information closer to the core
eBPF infrastructure (e.g. we will be able to reuse the verifer
log in device JIT).  It allows device JITs to perform translation
on the original bytecode.

__bpf_prog_get() when called to get a reference for an attachment
point will now refuse to give it if program has a device assigned.
Following patches will add a version of that function which passes
the expected netdev in. @type argument in __bpf_prog_get() is
renamed to attach_type to make it clearer that it's only set on
attachment.

All calls to ndo_bpf are protected by rtnl, only verifier callbacks
are not.  We need a wait queue to make sure netdev doesn't get
destroyed while verifier is still running and calling its driver.
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: NSimon Horman <simon.horman@netronome.com>
Reviewed-by: NQuentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

do_check() can fail early without allocating env->cur_state under
memory pressure.  Syzkaller found the stack below on the linux-next
tree because of this.

  kasan: CONFIG_KASAN_INLINE enabled
  kasan: GPF could be caused by NULL-ptr deref or user memory access
  general protection fault: 0000 [#1] SMP KASAN
  Dumping ftrace buffer:
     (ftrace buffer empty)
  Modules linked in:
  CPU: 1 PID: 27062 Comm: syz-executor5 Not tainted 4.14.0-rc7+ #106
  Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
  task: ffff8801c2c74700 task.stack: ffff8801c3e28000
  RIP: 0010:free_verifier_state kernel/bpf/verifier.c:347 [inline]
  RIP: 0010:bpf_check+0xcf4/0x19c0 kernel/bpf/verifier.c:4533
  RSP: 0018:ffff8801c3e2f5c8 EFLAGS: 00010202
  RAX: dffffc0000000000 RBX: 00000000fffffff4 RCX: 0000000000000000
  RDX: 0000000000000070 RSI: ffffffff817d5aa9 RDI: 0000000000000380
  RBP: ffff8801c3e2f668 R08: 0000000000000000 R09: 1ffff100387c5d9f
  R10: 00000000218c4e80 R11: ffffffff85b34380 R12: ffff8801c4dc6a28
  R13: 0000000000000000 R14: ffff8801c4dc6a00 R15: ffff8801c4dc6a20
  FS:  00007f311079b700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 00000000004d4a24 CR3: 00000001cbcd0000 CR4: 00000000001406e0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  Call Trace:
   bpf_prog_load+0xcbb/0x18e0 kernel/bpf/syscall.c:1166
   SYSC_bpf kernel/bpf/syscall.c:1690 [inline]
   SyS_bpf+0xae9/0x4620 kernel/bpf/syscall.c:1652
   entry_SYSCALL_64_fastpath+0x1f/0xbe
  RIP: 0033:0x452869
  RSP: 002b:00007f311079abe8 EFLAGS: 00000212 ORIG_RAX: 0000000000000141
  RAX: ffffffffffffffda RBX: 0000000000758020 RCX: 0000000000452869
  RDX: 0000000000000030 RSI: 0000000020168000 RDI: 0000000000000005
  RBP: 00007f311079aa20 R08: 0000000000000000 R09: 0000000000000000
  R10: 0000000000000000 R11: 0000000000000212 R12: 00000000004b7550
  R13: 00007f311079ab58 R14: 00000000004b7560 R15: 0000000000000000
  Code: df 48 c1 ea 03 80 3c 02 00 0f 85 e6 0b 00 00 4d 8b 6e 20 48 b8 00 00 00 00 00 fc ff df 49 8d bd 80 03 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 b6 0b 00 00 49 8b bd 80 03 00 00 e8 d6 0c 26
  RIP: free_verifier_state kernel/bpf/verifier.c:347 [inline] RSP: ffff8801c3e2f5c8
  RIP: bpf_check+0xcf4/0x19c0 kernel/bpf/verifier.c:4533 RSP: ffff8801c3e2f5c8
  ---[ end trace c8d37f339dc64004 ]---

Fixes: 638f5b90 ("bpf: reduce verifier memory consumption")
Fixes: 1969db47 ("bpf: fix verifier memory leaks")
Signed-off-by: NCraig Gallek <kraig@google.com>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The bpf_verifer_ops array is generated dynamically and may be
empty depending on configuration, which then causes an out
of bounds access:

kernel/bpf/verifier.c: In function 'bpf_check':
kernel/bpf/verifier.c:4320:29: error: array subscript is above array bounds [-Werror=array-bounds]

This adds a check to the start of the function as a workaround.
I would assume that the function is never called in that configuration,
so the warning is probably harmless.

Fixes: 00176a34 ("bpf: remove the verifier ops from program structure")
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

I ran into this link error with the latest net-next plus linux-next
trees when networking is disabled:

kernel/bpf/verifier.o:(.rodata+0x2958): undefined reference to `tc_cls_act_analyzer_ops'
kernel/bpf/verifier.o:(.rodata+0x2970): undefined reference to `xdp_analyzer_ops'

It seems that the code was written to deal with varying contents of
the arrray, but the actual #ifdef was missing. Both tc_cls_act_analyzer_ops
and xdp_analyzer_ops are defined in the core networking code, so adding
a check for CONFIG_NET seems appropriate here, and I've verified this with
many randconfig builds

Fixes: 4f9218aa ("bpf: move knowledge about post-translation offsets out of verifier")
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Follow-up to 0fd4759c ("bpf: fix pattern matches for direct
packet access") to cover also the remaining data_meta/data matches
in the verifier. The matches are also refactored a bit to simplify
handling of all the cases.
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Two minor cleanups after Dave's recent merge in f8ddadc4
("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 390ee7e2
("bpf: enforce return code for cgroup-bpf programs").
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

fix verifier memory leaks

Fixes: 638f5b90 ("bpf: reduce verifier memory consumption")
Signed-off-by: NAlexei Starovoitov <ast@fb.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

the verifier got progressively smarter over time and size of its internal
state grew as well. Time to reduce the memory consumption.

Before:
sizeof(struct bpf_verifier_state) = 6520
After:
sizeof(struct bpf_verifier_state) = 896

It's done by observing that majority of BPF programs use little to
no stack whereas verifier kept all of 512 stack slots ready always.
Instead dynamically reallocate struct verifier state when stack
access is detected.
Runtime difference before vs after is within a noise.
The number of processed instructions stays the same.
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Alexander had a test program with direct packet access, where
the access test was in the form of data + X > data_end. In an
unrelated change to the program LLVM decided to swap the branches
and emitted code for the test in form of data + X <= data_end.
We hadn't seen these being generated previously, thus verifier
would reject the program. Therefore, fix up the verifier to
detect all test cases, so we don't run into such issues in the
future.

Fixes: b4e432f1 ("bpf: enable BPF_J{LT, LE, SLT, SLE} opcodes in verifier")
Reported-by: NAlexander Alemayhu <alexander@alemayhu.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

During review I noticed that the current logic for direct packet
access marking in check_cond_jmp_op() has an off by one for the
upper right range border when marking in find_good_pkt_pointers()
with BPF_JLT and BPF_JLE. It's not really harmful given access
up to pkt_end is always safe, but we should nevertheless correct
the range marking before it becomes ABI. If pkt_data' denotes a
pkt_data derived pointer (pkt_data + X), then for pkt_data' < pkt_end
in the true branch as well as for pkt_end <= pkt_data' in the false
branch we mark the range with X although it should really be X - 1
in these cases. For example, X could be pkt_end - pkt_data, then
when testing for pkt_data' < pkt_end the verifier simulation cannot
deduce that a byte load of pkt_data' - 1 would succeed in this
branch.

Fixes: b4e432f1 ("bpf: enable BPF_J{LT, LE, SLT, SLE} opcodes in verifier")
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Use the fact that verifier ops are now separate from program
ops to define a separate set of callbacks for verification of
already translated programs.

Since we expect the analyzer ops to be defined only for
a small subset of all program types initialize their array
by hand (don't use linux/bpf_types.h).
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Since the verifier ops don't have to be associated with
the program for its entire lifetime we can move it to
verifier's struct bpf_verifier_env.
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

struct bpf_verifier_ops contains both verifier ops and operations
used later during program's lifetime (test_run).  Split the runtime
ops into a different structure.

BPF_PROG_TYPE() will now append ## _prog_ops or ## _verifier_ops
to the names.
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Commit f1174f77 ("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: f1174f77 ("bpf/verifier: rework value tracking")
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NEdward Cree <ecree@solarflare.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch connects cpumap to the xdp_do_redirect_map infrastructure.

Still no SKB allocation are done yet.  The XDP frames are transferred
to the other CPU, but they are simply refcnt decremented on the remote
CPU.  This served as a good benchmark for measuring the overhead of
remote refcnt decrement.  If driver page recycle cache is not
efficient then this, exposes a bottleneck in the page allocator.

A shout-out to MST's ptr_ring, which is the secret behind is being so
efficient to transfer memory pointers between CPUs, without constantly
bouncing cache-lines between CPUs.

V3: Handle !CONFIG_BPF_SYSCALL pointed out by kbuild test robot.

V4: Make Generic-XDP aware of cpumap type, but don't allow redirect yet,
 as implementation require a separate upstream discussion.

V5:
 - Fix a maybe-uninitialized pointed out by kbuild test robot.
 - Restrict bpf-prog side access to cpumap, open when use-cases appear
 - Implement cpu_map_enqueue() as a more simple void pointer enqueue

V6:
 - Allow cpumap type for usage in helper bpf_redirect_map,
   general bpf-prog side restriction moved to earlier patch.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The 'cpumap' is primarily used as a backend map for XDP BPF helper
call bpf_redirect_map() and XDP_REDIRECT action, like 'devmap'.

This patch implement the main part of the map.  It is not connected to
the XDP redirect system yet, and no SKB allocation are done yet.

The main concern in this patch is to ensure the datapath can run
without any locking.  This adds complexity to the setup and tear-down
procedure, which assumptions are extra carefully documented in the
code comments.

V2:
 - make sure array isn't larger than NR_CPUS
 - make sure CPUs added is a valid possible CPU

V3: fix nitpicks from Jakub Kicinski <kubakici@wp.pl>

V5:
 - Restrict map allocation to root / CAP_SYS_ADMIN
 - WARN_ON_ONCE if queue is not empty on tear-down
 - Return -EPERM on memlock limit instead of -ENOMEM
 - Error code in __cpu_map_entry_alloc() also handle ptr_ring_cleanup()
 - Moved cpu_map_enqueue() to next patch

V6: all notice by Daniel Borkmann
 - Fix err return code in cpu_map_alloc() introduced in V5
 - Move cpu_possible() check after max_entries boundary check
 - Forbid usage initially in check_map_func_compatibility()

V7:
 - Fix alloc error path spotted by Daniel Borkmann
 - Did stress test adding+removing CPUs from the map concurrently
 - Fixed refcnt issue on cpu_map_entry, kthread started too soon
 - Make sure packets are flushed during tear-down, involved use of
   rcu_barrier() and kthread_run only exit after queue is empty
 - Fix alloc error path in __cpu_map_entry_alloc() for ptr_ring

V8:
 - Nitpicking comments and gramma by Edward Cree
 - Fix missing semi-colon introduced in V7 due to rebasing
 - Move struct bpf_cpu_map_entry members cpu+map_id to tracepoint patch
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Use a simplified is_valid_access() callback when verifier
is used for program analysis by non-host JITs.  This allows
us to teach the verifier about packet start and packet end
offsets for direct packet access.

We can extend the callback as needed but for most packet
processing needs there isn't much more the offloads may
require.
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: NSimon Horman <simon.horman@netronome.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Verifier log buffer can be quite large (up to 16MB currently).
As Eric Dumazet points out if we allow multiple verification
requests to proceed simultaneously, malicious user may use the
verifier as a way of allocating large amounts of unswappable
memory to OOM the host.

Switch to a strategy of allocating a smaller buffer (1024B)
and writing it out into the user buffer after every print.

While at it remove the old BUG_ON().

This is in preparation of the global verifier lock removal.
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: NSimon Horman <simon.horman@netronome.com>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Separate the instruction printing into a standalone source file.
This way sneaky code from tools/ can compile it in directly.
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: NSimon Horman <simon.horman@netronome.com>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The biggest piece of global state protected by the verifier lock
is the verifier_log.  Move that log to struct bpf_verifier_env.
struct bpf_verifier_env has to be passed now to all invocations
of verbose().
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: NSimon Horman <simon.horman@netronome.com>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Put the loose log_* variables into a structure.  This will make
it simpler to remove the global verifier state in following patches.
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: NSimon Horman <simon.horman@netronome.com>
Acked-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

while processing Rx = Ry instruction the verifier does
regs[insn->dst_reg] = regs[insn->src_reg]
which often clears write mark (when Ry doesn't have it)
that was just set by check_reg_arg(Rx) prior to the assignment.
That causes mark_reg_read() to keep marking Rx in this block as
REG_LIVE_READ (since the logic incorrectly misses that it's
screened by the write) and in many of its parents (until lucky
write into the same Rx or beginning of the program).
That causes is_state_visited() logic to miss many pruning opportunities.

Furthermore mark_reg_read() logic propagates the read mark
for BPF_REG_FP as well (though it's readonly) which causes
harmless but unnecssary work during is_state_visited().
Note that do_propagate_liveness() skips FP correctly,
so do the same in mark_reg_read() as well.
It saves 0.2 seconds for the test below

program               before  after
bpf_lb-DLB_L3.o       2604    2304
bpf_lb-DLB_L4.o       11159   3723
bpf_lb-DUNKNOWN.o     1116    1110
bpf_lxc-DDROP_ALL.o   34566   28004
bpf_lxc-DUNKNOWN.o    53267   39026
bpf_netdev.o          17843   16943
bpf_overlay.o         8672    7929
time                  ~11 sec  ~4 sec

Fixes: dc503a8a ("bpf/verifier: track liveness for pruning")
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NEdward Cree <ecree@solarflare.com>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Hardware pmu counters are limited resources. When there are more
pmu based perf events opened than available counters, kernel will
multiplex these events so each event gets certain percentage
(but not 100%) of the pmu time. In case that multiplexing happens,
the number of samples or counter value will not reflect the
case compared to no multiplexing. This makes comparison between
different runs difficult.

Typically, the number of samples or counter value should be
normalized before comparing to other experiments. The typical
normalization is done like:
  normalized_num_samples = num_samples * time_enabled / time_running
  normalized_counter_value = counter_value * time_enabled / time_running
where time_enabled is the time enabled for event and time_running is
the time running for event since last normalization.

This patch adds helper bpf_perf_event_read_value for kprobed based perf
event array map, to read perf counter and enabled/running time.
The enabled/running time is accumulated since the perf event open.
To achieve scaling factor between two bpf invocations, users
can can use cpu_id as the key (which is typical for perf array usage model)
to remember the previous value and do the calculation inside the
bpf program.
Signed-off-by: NYonghong Song <yhs@fb.com>
Acked-by: NAlexei Starovoitov <ast@fb.com>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>