1153939 Commits

Author SHA1 Message Date
Grant Seltzer
139df64d26 libbpf: Fix malformed documentation formatting
This fixes the doxygen format documentation above the
user_ring_buffer__* APIs. There has to be a newline
before the @brief, otherwise doxygen won't render them
for libbpf.readthedocs.org.

Signed-off-by: Grant Seltzer <grantseltzer@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230126024749.522278-1-grantseltzer@gmail.com
2023-01-27 23:02:03 +01:00
Stanislav Fomichev
a5f3a3f7c1 selftests/bpf: Properly enable hwtstamp in xdp_hw_metadata
The existing timestamping_enable() is a no-op because it applies
to the socket-related path that we are not verifying here
anymore. (but still leaving the code around hoping we can
have xdp->skb path verified here as well)

  poll: 1 (0)
  xsk_ring_cons__peek: 1
  0xf64788: rx_desc[0]->addr=100000000008000 addr=8100 comp_addr=8000
  rx_hash: 3697961069
  rx_timestamp:  1674657672142214773 (sec:1674657672.1422)
  XDP RX-time:   1674657709561774876 (sec:1674657709.5618) delta sec:37.4196
  AF_XDP time:   1674657709561871034 (sec:1674657709.5619) delta
sec:0.0001 (96.158 usec)
  0xf64788: complete idx=8 addr=8000

Also, maybe something to archive here, see [0] for Jesper's note
about NIC vs host clock delta.

0: https://lore.kernel.org/bpf/f3a116dc-1b14-3432-ad20-a36179ef0608@redhat.com/

v2:
- Restore original value (Martin)

Fixes: 297a3f124155 ("selftests/bpf: Simple program to dump XDP RX metadata")
Reported-by: Jesper Dangaard Brouer <jbrouer@redhat.com>
Tested-by: Jesper Dangaard Brouer <jbrouer@redhat.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20230126225030.510629-1-sdf@google.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
2023-01-26 22:10:31 -08:00
Martin KaFai Lau
0164776a2c Merge branch 'Enable bpf_setsockopt() on ktls enabled sockets.'
Kui-Feng Lee says:

====================

This patchset implements a change to bpf_setsockopt() which allows
ktls enabled sockets to be used with the SOL_TCP level. This is
necessary as when ktls is enabled, it changes the function pointer of
setsockopt of the socket, which bpf_setsockopt() checks in order to
make sure that the socket is a TCP socket. Checking sk_protocol
instead of the function pointer will ensure that bpf_setsockopt() with
the SOL_TCP level still works on sockets with ktls enabled.

The major differences form v2 are:
 - Add a read() call to make sure that the FIN has arrived.
 - Remove the dependency on other test's header.

The major differences from v1 are:
 - Test with a IPv6 connect as well.
 - Use ASSERT_OK()

v2: https://lore.kernel.org/bpf/20230124181220.2871611-1-kuifeng@meta.com/
v1: https://lore.kernel.org/bpf/20230121025716.3039933-1-kuifeng@meta.com/
====================

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
2023-01-25 15:10:36 -08:00
Kui-Feng Lee
d1246f9360 selftests/bpf: Calls bpf_setsockopt() on a ktls enabled socket.
Ensures that whenever bpf_setsockopt() is called with the SOL_TCP
option on a ktls enabled socket, the call will be accepted by the
system. The provided test makes sure of this by performing an
examination when the server side socket is in the CLOSE_WAIT state. At
this stage, ktls is still enabled on the server socket and can be used
to test if bpf_setsockopt() works correctly with linux.

Signed-off-by: Kui-Feng Lee <kuifeng@meta.com>
Link: https://lore.kernel.org/r/20230125201608.908230-3-kuifeng@meta.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
2023-01-25 15:10:34 -08:00
Kui-Feng Lee
2ab42c7b87 bpf: Check the protocol of a sock to agree the calls to bpf_setsockopt().
Resolve an issue when calling sol_tcp_sockopt() on a socket with ktls
enabled. Prior to this patch, sol_tcp_sockopt() would only allow calls
if the function pointer of setsockopt of the socket was set to
tcp_setsockopt(). However, any socket with ktls enabled would have its
function pointer set to tls_setsockopt(). To resolve this issue, the
patch adds a check of the protocol of the linux socket and allows
bpf_setsockopt() to be called if ktls is initialized on the linux
socket. This ensures that calls to sol_tcp_sockopt() will succeed on
sockets with ktls enabled.

Signed-off-by: Kui-Feng Lee <kuifeng@meta.com>
Link: https://lore.kernel.org/r/20230125201608.908230-2-kuifeng@meta.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
2023-01-25 14:49:11 -08:00
Alexei Starovoitov
a5f6b9d577 Merge branch 'Enable struct_ops programs to be sleepable'
David Vernet says:

====================

This is part 4 of https://lore.kernel.org/bpf/20230123232228.646563-1-void@manifault.com/

Part 3: https://lore.kernel.org/all/20230125050359.339273-1-void@manifault.com/
Part 2: https://lore.kernel.org/all/20230124160802.1122124-1-void@manifault.com/

Changelog:
----------
v3 -> v4:
- Fix accidental typo in name of dummy_st_ops introduced in v2, moving
  it back to dummy_st_ops from dummy_st_ops_success. Should fix s390x
  testruns.

v2 -> v3:
- Don't call a KF_SLEEPABLE kfunc from the dummy_st_ops testsuite, and
  remove the newly added bpf_kfunc_call_test_sleepable() test kfunc
  (Martin).
- Include vmlinux.h from progs/dummy_st_ops_success.c (previously
  progs/dummy_st_ops.c) rather than manually defining
  struct bpf_dummy_ops_state and struct bpf_dummy_ops.
  (Martin).
- Fix a typo added to prog_tests/dummy_st_ops.c in a previous version:
  s/trace_dummy_st_ops_success__open/trace_dummy_st_ops__open.

v1 -> v2:
- Add support for specifying sleepable struct_ops programs with
  struct_ops.s in libbpf (Alexei).
- Move failure test case into new dummy_st_ops_fail.c prog file.
- Update test_dummy_sleepable() to use struct_ops.s instead of manually
  setting prog flags. Also remove open_load_skel() helper which is no
  longer needed.
- Fix verifier tests to expect new sleepable prog failure message.
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-01-25 10:25:58 -08:00
David Vernet
7dd880592a bpf/selftests: Verify struct_ops prog sleepable behavior
In a set of prior changes, we added the ability for struct_ops programs
to be sleepable. This patch enhances the dummy_st_ops selftest suite to
validate this behavior by adding a new sleepable struct_ops entry to
dummy_st_ops.

Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230125164735.785732-5-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-01-25 10:25:57 -08:00
David Vernet
51a52a29eb bpf: Pass const struct bpf_prog * to .check_member
The .check_member field of struct bpf_struct_ops is currently passed the
member's btf_type via const struct btf_type *t, and a const struct
btf_member *member. This allows the struct_ops implementation to check
whether e.g. an ops is supported, but it would be useful to also enforce
that the struct_ops prog being loaded for that member has other
qualities, like being sleepable (or not). This patch therefore updates
the .check_member() callback to also take a const struct bpf_prog *prog
argument.

Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230125164735.785732-4-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-01-25 10:25:57 -08:00
David Vernet
913b2255c3 libbpf: Support sleepable struct_ops.s section
In a prior change, the verifier was updated to support sleepable
BPF_PROG_TYPE_STRUCT_OPS programs. A caller could set the program as
sleepable with bpf_program__set_flags(), but it would be more ergonomic
and more in-line with other sleepable program types if we supported
suffixing a struct_ops section name with .s to indicate that it's
sleepable.

Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230125164735.785732-3-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-01-25 10:25:57 -08:00
David Vernet
1e12d3ef47 bpf: Allow BPF_PROG_TYPE_STRUCT_OPS programs to be sleepable
BPF struct_ops programs currently cannot be marked as sleepable. This
need not be the case -- struct_ops programs can be sleepable, and e.g.
invoke kfuncs that export the KF_SLEEPABLE flag. So as to allow future
struct_ops programs to invoke such kfuncs, this patch updates the
verifier to allow struct_ops programs to be sleepable. A follow-on patch
will add support to libbpf for specifying struct_ops.s as a sleepable
struct_ops program, and then another patch will add testcases to the
dummy_st_ops selftest suite which test sleepable struct_ops behavior.

Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230125164735.785732-2-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-01-25 10:25:57 -08:00
Daniel T. Lee
2514a31241 selftests/bpf: Fix vmtest static compilation error
As stated in README.rst, in order to resolve errors with linker errors,
'LDLIBS=-static' should be used. Most problems will be solved by this
option, but in the case of urandom_read, this won't fix the problem. So
the Makefile is currently implemented to strip the 'static' option when
compiling the urandom_read. However, stripping this static option isn't
configured properly on $(LDLIBS) correctly, which is now causing errors
on static compilation.

    # LDLIBS=-static ./vmtest.sh
    ld.lld: error: attempted static link of dynamic object liburandom_read.so
    clang: error: linker command failed with exit code 1 (use -v to see invocation)
    make: *** [Makefile:190: /linux/tools/testing/selftests/bpf/urandom_read] Error 1
    make: *** Waiting for unfinished jobs....

This commit fixes this problem by configuring the strip with $(LDLIBS).

Fixes: 68084a136420 ("selftests/bpf: Fix building bpf selftests statically")
Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230125100440.21734-1-danieltimlee@gmail.com
2023-01-25 18:31:32 +01:00
Ian Rogers
13e07691a1 tools/resolve_btfids: Alter how HOSTCC is forced
HOSTCC is always wanted when building. Setting CC to HOSTCC happens
after tools/scripts/Makefile.include is included, meaning flags are
set assuming say CC is gcc, but then it can be later set to HOSTCC
which may be clang. tools/scripts/Makefile.include is needed for host
set up and common macros in objtool's Makefile. Rather than override
CC to HOSTCC, just pass CC as HOSTCC to Makefile.build, the libsubcmd
builds and the linkage step. This means the Makefiles don't see things
like CC changing and tool flag determination, and similar, work
properly.

Also, clear the passed subdir as otherwise an outer build may break by
inadvertently passing an inappropriate value.

Signed-off-by: Ian Rogers <irogers@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/bpf/20230124064324.672022-2-irogers@google.com
2023-01-25 18:28:14 +01:00
Ian Rogers
af03299d85 tools/resolve_btfids: Install subcmd headers
Previously tools/lib/subcmd was added to the include path, switch to
installing the headers and then including from that directory. This
avoids dependencies on headers internal to tools/lib/subcmd. Add the
missing subcmd directory to the affected #include.

Signed-off-by: Ian Rogers <irogers@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/bpf/20230124064324.672022-1-irogers@google.com
2023-01-25 18:28:08 +01:00
Alexei Starovoitov
0cea651d6f Merge branch 'Enable cpumasks to be used as kptrs'
David Vernet says:

====================

This is part 3 of https://lore.kernel.org/all/20230119235833.2948341-1-void@manifault.com/

Part 2: https://lore.kernel.org/bpf/20230120192523.3650503-1-void@manifault.com/

This series is based off of commit b613d335a743 ("bpf: Allow trusted
args to walk struct when checking BTF IDs").

Changelog:
----------
v2 -> v3:
- Rebase onto master (commit described above). Only conflict that
  required resolution was updating the task_kfunc selftest suite error
  message location.
- Put copyright onto one line in kernel/bpf/cpumask.c.
- Remove now-unneeded pid-checking logic from
  progs/nested_trust_success.c.
- Fix a couple of small grammatical typos in documentation.

v1 -> v2:
- Put back 'static' keyword in bpf_find_btf_id()
  (kernel test robot <lkp@intel.com>)
- Surround cpumask kfuncs in __diag() blocks to avoid no-prototype build
  warnings (kernel test robot <lkp@intel.com>)
- Enable ___init suffixes to a type definition to signal that a type is
  a nocast alias of another type. That is, that when passed to a kfunc
  that expects one of the two types, the verifier will reject the other
  even if they're equivalent according to the C standard (Kumar and
  Alexei)
- Reject NULL for all trusted args, not just PTR_TO_MEM (Kumar)
- Reject both NULL and PTR_MAYBE_NULL for all trusted args (Kumar and
  Alexei )
- Improve examples given in cpumask documentation (Alexei)
- Use __success macro for nested_trust test (Alexei)
- Fix comment typo in struct bpf_cpumask comment header.
- Fix another example in the bpf_cpumask doc examples.
- Add documentation for ___init suffix change mentioned above.
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-01-25 07:57:50 -08:00
David Vernet
027bdec893 bpf/docs: Document the nocast aliasing behavior of ___init
When comparing BTF IDs for pointers being passed to kfunc arguments, the
verifier will allow pointer types that are equivalent according to the C
standard. For example, for:

struct bpf_cpumask {
	cpumask_t cpumask;
	refcount_t usage;
};

The verifier will allow a struct bpf_cpumask * to be passed to a kfunc
that takes a const struct cpumask * (cpumask_t is a typedef of struct
cpumask). The exception to this rule is if a type is suffixed with
___init, such as:

struct nf_conn___init {
	struct nf_conn ct;
};

The verifier will _not_ allow a struct nf_conn___init * to be passed to
a kfunc that expects a struct nf_conn *. This patch documents this
behavior in the kfuncs documentation page.

Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230125143816.721952-8-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-01-25 07:57:50 -08:00
David Vernet
d94cbde218 bpf/docs: Document how nested trusted fields may be defined
A prior change defined a new BTF_TYPE_SAFE_NESTED macro in the verifier
which allows developers to specify when a pointee field in a struct type
should inherit its parent pointer's trusted status. This patch updates
the kfuncs documentation to specify this macro and how it can be used.

Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230125143816.721952-7-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-01-25 07:57:50 -08:00
David Vernet
bdbda39584 bpf/docs: Document cpumask kfuncs in a new file
Now that we've added a series of new cpumask kfuncs, we should document
them so users can easily use them. This patch adds a new cpumasks.rst
file to document them.

Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230125143816.721952-6-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-01-25 07:57:50 -08:00
David Vernet
7b6abcfa15 selftests/bpf: Add selftest suite for cpumask kfuncs
A recent patch added a new set of kfuncs for allocating, freeing,
manipulating, and querying cpumasks. This patch adds a new 'cpumask'
selftest suite which verifies their behavior.

Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230125143816.721952-5-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-01-25 07:57:50 -08:00
David Vernet
a6541f4d28 selftests/bpf: Add nested trust selftests suite
Now that defining trusted fields in a struct is supported, we should add
selftests to verify the behavior. This patch adds a few such testcases.

Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230125143816.721952-4-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-01-25 07:57:50 -08:00
David Vernet
516f4d3397 bpf: Enable cpumasks to be queried and used as kptrs
Certain programs may wish to be able to query cpumasks. For example, if
a program that is tracing percpu operations wishes to track which tasks
end up running on which CPUs, it could be useful to associate that with
the tasks' cpumasks. Similarly, programs tracking NUMA allocations, CPU
scheduling domains, etc, could potentially benefit from being able to
see which CPUs a task could be migrated to.

This patch enables these types of use cases by introducing a series of
bpf_cpumask_* kfuncs. Amongst these kfuncs, there are two separate
"classes" of operations:

1. kfuncs which allow the caller to allocate and mutate their own
   cpumask kptrs in the form of a struct bpf_cpumask * object. Such
   kfuncs include e.g. bpf_cpumask_create() to allocate the cpumask, and
   bpf_cpumask_or() to mutate it. "Regular" cpumasks such as p->cpus_ptr
   may not be passed to these kfuncs, and the verifier will ensure this
   is the case by comparing BTF IDs.

2. Read-only operations which operate on const struct cpumask *
   arguments. For example, bpf_cpumask_test_cpu(), which tests whether a
   CPU is set in the cpumask. Any trusted struct cpumask * or struct
   bpf_cpumask * may be passed to these kfuncs. The verifier allows
   struct bpf_cpumask * even though the kfunc is defined with struct
   cpumask * because the first element of a struct bpf_cpumask is a
   cpumask_t, so it is safe to cast.

A follow-on patch will add selftests which validate these kfuncs, and
another will document them.

Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230125143816.721952-3-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-01-25 07:57:49 -08:00
David Vernet
caf713c338 bpf: Disallow NULLable pointers for trusted kfuncs
KF_TRUSTED_ARGS kfuncs currently have a subtle and insidious bug in
validating pointers to scalars. Say that you have a kfunc like the
following, which takes an array as the first argument:

bool bpf_cpumask_empty(const struct cpumask *cpumask)
{
	return cpumask_empty(cpumask);
}

...
BTF_ID_FLAGS(func, bpf_cpumask_empty, KF_TRUSTED_ARGS)
...

If a BPF program were to invoke the kfunc with a NULL argument, it would
crash the kernel. The reason is that struct cpumask is defined as a
bitmap, which is itself defined as an array, and is accessed as a memory
address by bitmap operations. So when the verifier analyzes the
register, it interprets it as a pointer to a scalar struct, which is an
array of size 8. check_mem_reg() then sees that the register is NULL and
returns 0, and the kfunc crashes when it passes it down to the cpumask
wrappers.

To fix this, this patch adds a check for KF_ARG_PTR_TO_MEM which
verifies that the register doesn't contain a possibly-NULL pointer if
the kfunc is KF_TRUSTED_ARGS.

Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230125143816.721952-2-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-01-25 07:57:49 -08:00
David Vernet
b613d335a7 bpf: Allow trusted args to walk struct when checking BTF IDs
When validating BTF types for KF_TRUSTED_ARGS kfuncs, the verifier
currently enforces that the top-level type must match when calling
the kfunc. In other words, the verifier does not allow the BPF program
to pass a bitwise equivalent struct, despite it being allowed according
to the C standard.

For example, if you have the following type:

struct  nf_conn___init {
	struct nf_conn ct;
};

The C standard stipulates that it would be safe to pass a struct
nf_conn___init to a kfunc expecting a struct nf_conn. The verifier
currently disallows this, however, as semantically kfuncs may want to
enforce that structs that have equivalent types according to the C
standard, but have different BTF IDs, are not able to be passed to
kfuncs expecting one or the other. For example, struct nf_conn___init
may not be queried / looked up, as it is allocated but may not yet be
fully initialized.

On the other hand, being able to pass types that are equivalent
according to the C standard will be useful for other types of kfunc /
kptrs enabled by BPF.  For example, in a follow-on patch, a series of
kfuncs will be added which allow programs to do bitwise queries on
cpumasks that are either allocated by the program (in which case they'll
be a 'struct bpf_cpumask' type that wraps a cpumask_t as its first
element), or a cpumask that was allocated by the main kernel (in which
case it will just be a straight cpumask_t, as in task->cpus_ptr).

Having the two types of cpumasks allows us to distinguish between the
two for when a cpumask is read-only vs. mutatable. A struct bpf_cpumask
can be mutated by e.g. bpf_cpumask_clear(), whereas a regular cpumask_t
cannot be. On the other hand, a struct bpf_cpumask can of course be
queried in the exact same manner as a cpumask_t, with e.g.
bpf_cpumask_test_cpu().

If we were to enforce that top level types match, then a user that's
passing a struct bpf_cpumask to a read-only cpumask_t argument would
have to cast with something like bpf_cast_to_kern_ctx() (which itself
would need to be updated to expect the alias, and currently it only
accommodates a single alias per prog type). Additionally, not specifying
KF_TRUSTED_ARGS is not an option, as some kfuncs take one argument as a
struct bpf_cpumask *, and another as a struct cpumask *
(i.e. cpumask_t).

In order to enable this, this patch relaxes the constraint that a
KF_TRUSTED_ARGS kfunc must have strict type matching, and instead only
enforces strict type matching if a type is observed to be a "no-cast
alias" (i.e., that the type names are equivalent, but one is suffixed
with ___init).

Additionally, in order to try and be conservative and match existing
behavior / expectations, this patch also enforces strict type checking
for acquire kfuncs. We were already enforcing it for release kfuncs, so
this should also improve the consistency of the semantics for kfuncs.

Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230120192523.3650503-3-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-01-24 20:15:13 -08:00
David Vernet
57539b1c0a bpf: Enable annotating trusted nested pointers
In kfuncs, a "trusted" pointer is a pointer that the kfunc can assume is
safe, and which the verifier will allow to be passed to a
KF_TRUSTED_ARGS kfunc. Currently, a KF_TRUSTED_ARGS kfunc disallows any
pointer to be passed at a nonzero offset, but sometimes this is in fact
safe if the "nested" pointer's lifetime is inherited from its parent.
For example, the const cpumask_t *cpus_ptr field in a struct task_struct
will remain valid until the task itself is destroyed, and thus would
also be safe to pass to a KF_TRUSTED_ARGS kfunc.

While it would be conceptually simple to enable this by using BTF tags,
gcc unfortunately does not yet support this. In the interim, this patch
enables support for this by using a type-naming convention. A new
BTF_TYPE_SAFE_NESTED macro is defined in verifier.c which allows a
developer to specify the nested fields of a type which are considered
trusted if its parent is also trusted. The verifier is also updated to
account for this. A patch with selftests will be added in a follow-on
change, along with documentation for this feature.

Signed-off-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20230120192523.3650503-2-void@manifault.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-01-24 20:15:01 -08:00
Dave Thaler
0eb9d19e22 bpf, docs: Fix modulo zero, division by zero, overflow, and underflow
Fix modulo zero, division by zero, overflow, and underflow. Also clarify how
a negative immediate value is used in unsigned division.

Signed-off-by: Dave Thaler <dthaler@microsoft.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230124001218.827-1-dthaler1968@googlemail.com
2023-01-24 16:46:40 +01:00
Daniel Borkmann
ea403bb7b3 Merge branch 'libbpf-extend-arguments-tracing'
Andrii Nakryiko says:

====================
This patch set fixes and extends libbpf's bpf_tracing.h support for tracing
arguments of kprobes/uprobes, and syscall as a special case.

Depending on the architecture, anywhere between 3 and 8 arguments can be
passed to a function in registers (so relevant to kprobes and uprobes), but
before this patch set libbpf's macros in bpf_tracing.h only supported up to
5 arguments, which is limiting in practice. This patch set extends
bpf_tracing.h to support up to 8 arguments, if architecture allows. This
includes explicit PT_REGS_PARMx() macro family, as well as BPF_KPROBE() macro.

Now, with tracing syscall arguments situation is sometimes quite different.
For a lot of architectures syscall argument passing through registers differs
from function call sequence at least a little. For i386 it differs *a lot*.
This patch set addresses this issue across all currently supported
architectures and hopefully fixes existing issues. syscall(2) manpage defines
that either 6 or 7 arguments can be supported, depending on architecture, so
libbpf defines 6 or 7 registers per architecture to be used to fetch syscall
arguments.

Also, BPF_UPROBE and BPF_URETPROBE are introduced as part of this patch set.
They are aliases for BPF_KPROBE and BPF_KRETPROBE (as mechanics of argument
fetching of kernel functions and user-space functions are identical), but it
allows BPF users to have less confusing BPF-side code when working with
uprobes.

For both sets of changes selftests are extended to test these new register
definitions to architecture-defined limits. Unfortunately I don't have ability
to test it on all architectures, and BPF CI only tests 3 architecture (x86-64,
arm64, and s390x), so it would be greatly appreciated if people with access to
architectures other than above 3 helped review and test changes.
====================

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2023-01-23 20:53:18 +01:00
Andrii Nakryiko
a4d325ae46 libbpf: Clean up now not needed __PT_PARM{1-6}_SYSCALL_REG defaults
Each architecture supports at least 6 syscall argument registers, so now
that specs for each architecture is defined in bpf_tracing.h, remove
unnecessary macro overrides, which previously were required to keep
existing BPF_KSYSCALL() uses compiling and working.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230120200914.3008030-26-andrii@kernel.org
2023-01-23 20:53:01 +01:00
Andrii Nakryiko
92dc5cdfc1 selftests/bpf: Add 6-argument syscall tracing test
Turns out splice() is one of the syscalls that's using current maximum
number of arguments (six). This is perfect for testing, so extend
bpf_syscall_macro selftest to also trace splice() syscall, using
BPF_KSYSCALL() macro. This makes sure all the syscall argument register
definitions are correct.

Suggested-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Alan Maguire <alan.maguire@oracle.com> # arm64
Tested-by: Ilya Leoshkevich <iii@linux.ibm.com> # s390x
Link: https://lore.kernel.org/bpf/20230120200914.3008030-25-andrii@kernel.org
2023-01-23 20:53:01 +01:00
Andrii Nakryiko
12a299f0b5 libbpf: Define loongarch syscall regs spec in bpf_tracing.h
Define explicit table of registers used for syscall argument passing.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230120200914.3008030-24-andrii@kernel.org
2023-01-23 20:53:01 +01:00
Andrii Nakryiko
2cf802737f libbpf: Define arc syscall regs spec in bpf_tracing.h
Define explicit table of registers used for syscall argument passing.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230120200914.3008030-23-andrii@kernel.org
2023-01-23 20:53:01 +01:00
Andrii Nakryiko
a0426216a3 libbpf: Define riscv syscall regs spec in bpf_tracing.h
Define explicit table of registers used for syscall argument passing.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Pu Lehui <pulehui@huawei.com> # RISC-V
Link: https://lore.kernel.org/bpf/20230120200914.3008030-22-andrii@kernel.org
2023-01-23 20:53:01 +01:00
Andrii Nakryiko
377c15b1a2 libbpf: Define sparc syscall regs spec in bpf_tracing.h
Define explicit table of registers used for syscall argument passing.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230120200914.3008030-21-andrii@kernel.org
2023-01-23 20:53:01 +01:00
Andrii Nakryiko
c1cc01a2d1 libbpf: Define powerpc syscall regs spec in bpf_tracing.h
Define explicit table of registers used for syscall argument passing.
Note that 7th arg is supported on 32-bit powerpc architecture, by not on
powerpc64.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230120200914.3008030-20-andrii@kernel.org
2023-01-23 20:53:01 +01:00
Andrii Nakryiko
cfd0bbe915 libbpf: Define mips syscall regs spec in bpf_tracing.h
Define explicit table of registers used for syscall argument passing.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230120200914.3008030-19-andrii@kernel.org
2023-01-23 20:53:01 +01:00
Andrii Nakryiko
3488ea0584 libbpf: Define arm64 syscall regs spec in bpf_tracing.h
Define explicit table of registers used for syscall argument passing.
We need PT_REGS_PARM1_[CORE_]SYSCALL macros overrides, similarly to
s390x, due to orig_x0 not being present in UAPI's pt_regs, so we need to
utilize BPF CO-RE and custom pt_regs___arm64 definition.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Alan Maguire <alan.maguire@oracle.com> # arm64
Link: https://lore.kernel.org/bpf/20230120200914.3008030-18-andrii@kernel.org
2023-01-23 20:53:01 +01:00
Andrii Nakryiko
3a95c42d65 libbpf: Define arm syscall regs spec in bpf_tracing.h
Define explicit table of registers used for syscall argument passing.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230120200914.3008030-17-andrii@kernel.org
2023-01-23 20:53:01 +01:00
Andrii Nakryiko
e82b96a3a9 libbpf: Define s390x syscall regs spec in bpf_tracing.h
Define explicit table of registers used for syscall argument passing.
Note that we need custom overrides for PT_REGS_PARM1_[CORE_]SYSCALL
macros due to the need to use BPF CO-RE and custom local pt_regs
definitions to fetch orig_gpr2, storing 1st argument.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Ilya Leoshkevich <iii@linux.ibm.com> # s390x
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Link: https://lore.kernel.org/bpf/20230120200914.3008030-16-andrii@kernel.org
2023-01-23 20:53:00 +01:00
Andrii Nakryiko
ff00f9cbd2 libbpf: Define i386 syscall regs spec in bpf_tracing.h
Define explicit table of registers used for syscall argument passing.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230120200914.3008030-15-andrii@kernel.org
2023-01-23 20:53:00 +01:00
Andrii Nakryiko
d21fbceedd libbpf: Define x86-64 syscall regs spec in bpf_tracing.h
Define explicit table of registers used for syscall argument passing.
Remove now unnecessary overrides of PT_REGS_PARM5_[CORE_]SYSCALL macros.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230120200914.3008030-14-andrii@kernel.org
2023-01-23 20:53:00 +01:00
Andrii Nakryiko
8ccabeef91 libbpf: Improve syscall tracing support in bpf_tracing.h
Set up generic support in bpf_tracing.h for up to 7 syscall arguments
tracing with BPF_KSYSCALL, which seems to be the limit according to
syscall(2) manpage. Also change the way that syscall convention is
specified to be more explicit. Subsequent patches will adjust and define
proper per-architecture syscall conventions.

__PT_PARM1_SYSCALL_REG through __PT_PARM6_SYSCALL_REG is added
temporarily to keep everything working before each architecture has
syscall reg tables defined. They will be removed afterwards.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Alan Maguire <alan.maguire@oracle.com> # arm64
Link: https://lore.kernel.org/bpf/20230120200914.3008030-13-andrii@kernel.org
2023-01-23 20:53:00 +01:00
Andrii Nakryiko
bc72742beb selftests/bpf: Validate arch-specific argument registers limits
Update uprobe_autoattach selftest to validate architecture-specific
argument passing through registers. Use new BPF_UPROBE and
BPF_URETPROBE, and construct both BPF-side and user-space side in such
a way that for different architectures we are fetching and checking
different number of arguments, matching architecture-specific limit of
how many registers are available for argument passing.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Alan Maguire <alan.maguire@oracle.com> # arm64
Tested-by: Ilya Leoshkevich <iii@linux.ibm.com> # s390x
Link: https://lore.kernel.org/bpf/20230120200914.3008030-12-andrii@kernel.org
2023-01-23 20:53:00 +01:00
Andrii Nakryiko
ac4afd6e6f libbpf: Add BPF_UPROBE and BPF_URETPROBE macro aliases
Add BPF_UPROBE and BPF_URETPROBE macros, aliased to BPF_KPROBE and
BPF_KRETPROBE, respectively. This makes uprobe-based BPF program code
much less confusing, especially to people new to tracing, at no cost in
terms of maintainability. We'll use this macro in selftests in
subsequent patch.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230120200914.3008030-11-andrii@kernel.org
2023-01-23 20:53:00 +01:00
Andrii Nakryiko
55ff00d539 libbpf: Complete LoongArch (loongarch) spec in bpf_tracing.h
Add PARM6 through PARM8 definitions. Add kernel docs link describing ABI
for LoongArch.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230120200914.3008030-10-andrii@kernel.org
2023-01-23 20:53:00 +01:00
Andrii Nakryiko
0ac0865679 libbpf: Fix and complete ARC spec in bpf_tracing.h
Add PARM6 through PARM8 definitions. Also fix frame pointer (FP)
register definition. Also leave a link to where to find ABI spec.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230120200914.3008030-9-andrii@kernel.org
2023-01-23 20:53:00 +01:00
Andrii Nakryiko
b13ed8ca7f libbpf: Complete riscv arch spec in bpf_tracing.h
Add PARM6 through PARM8 definitions for RISC V (riscv) arch. Leave the
link for ABI doc for future reference.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Pu Lehui <pulehui@huawei.com> # RISC-V
Link: https://lore.kernel.org/bpf/20230120200914.3008030-8-andrii@kernel.org
2023-01-23 20:53:00 +01:00
Andrii Nakryiko
7f60f5d85e libbpf: Complete sparc spec in bpf_tracing.h
Add PARM6 definition for sparc architecture. Leave a link to calling
convention documentation.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230120200914.3008030-7-andrii@kernel.org
2023-01-23 20:53:00 +01:00
Andrii Nakryiko
2eb2be30b8 libbpf: Complete powerpc spec in bpf_tracing.h
Add definitions of PARM6 through PARM8 for powerpc architecture. Add
also a link to a functiona call sequence documentation for future reference.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230120200914.3008030-6-andrii@kernel.org
2023-01-23 20:52:59 +01:00
Andrii Nakryiko
1222445a5b libbpf: Complete mips spec in bpf_tracing.h
Add registers for PARM6 through PARM8. Add a link to an ABI. We don't
distinguish between O32, N32, and N64, so document that we assume N64
right now.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230120200914.3008030-5-andrii@kernel.org
2023-01-23 20:52:59 +01:00
Andrii Nakryiko
1dac40ac87 libbpf: Fix arm and arm64 specs in bpf_tracing.h
Remove invalid support for PARM5 on 32-bit arm, as per ABI. Add three
more argument registers for arm64. Also leave links to ABI specs for
future reference.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Alan Maguire <alan.maguire@oracle.com> # arm64
Link: https://lore.kernel.org/bpf/20230120200914.3008030-4-andrii@kernel.org
2023-01-23 20:52:59 +01:00
Andrii Nakryiko
013290329a libbpf: Add 6th argument support for x86-64 in bpf_tracing.h
Add r9 as register containing 6th argument on x86-64 architecture, as
per its ABI. Add also a link to a page describing ABI for easier future
reference.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230120200914.3008030-3-andrii@kernel.org
2023-01-23 20:52:59 +01:00
Andrii Nakryiko
3c59623d82 libbpf: Add support for fetching up to 8 arguments in kprobes
Add BPF_KPROBE() and PT_REGS_PARMx() support for up to 8 arguments, if
target architecture supports this. Currently all architectures are
limited to only 5 register-placed arguments, which is limiting even on
x86-64.

This patch adds generic macro machinery to support up to 8 arguments
both when explicitly fetching it from pt_regs through PT_REGS_PARMx()
macros, as well as more ergonomic access in BPF_KPROBE().

Also, for i386 architecture we now don't have to define fake PARM4 and
PARM5 definitions, they will be generically substituted, just like for
PARM6 through PARM8.

Subsequent patches will fill out architecture-specific definitions,
where appropriate.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Alan Maguire <alan.maguire@oracle.com> # arm64
Tested-by: Ilya Leoshkevich <iii@linux.ibm.com> # s390x
Link: https://lore.kernel.org/bpf/20230120200914.3008030-2-andrii@kernel.org
2023-01-23 20:52:59 +01:00