selftests/bpf: Attempt to build BPF programs with -Wsign-compare

GCC's -Wall includes -Wsign-compare while clang does not.
Since BPF programs are built with clang we need to add this flag explicitly
to catch problematic comparisons like:

int i = -1;
unsigned int j = 1;
if (i < j) // this is false.

long i = -1;
unsigned int j = 1;
if (i < j) // this is true.

C standard for reference:

- If either operand is unsigned long the other shall be converted to unsigned long.

- Otherwise, if one operand is a long int and the other unsigned int, then if a
long int can represent all the values of an unsigned int, the unsigned int
shall be converted to a long int; otherwise both operands shall be converted to
unsigned long int.

- Otherwise, if either operand is long, the other shall be converted to long.

- Otherwise, if either operand is unsigned, the other shall be converted to unsigned.

Unfortunately clang's -Wsign-compare is very noisy.
It complains about (s32)a == (u32)b which is safe and doen't have surprising behavior.

This patch fixes some of the issues. It needs a follow up to fix the rest.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/bpf/20231226191148.48536-2-alexei.starovoitov@gmail.com

selftests/bpf: add bpf_for_each(), bpf_for(), and bpf_repeat() macros

Add bpf_for_each(), bpf_for(), and bpf_repeat() macros that make writing
open-coded iterator-based loops much more convenient and natural. These
macros utilize cleanup attribute to ensure proper destruction of the
iterator and thanks to that manage to provide the ergonomics that is
very close to C language's for() construct. Typical loop would look like:

int i;
int arr[N];

bpf_for(i, 0, N) {
/* verifier will know that i >= 0 && i < N, so could be used to
* directly access array elements with no extra checks
*/
arr[i] = i;
}

bpf_repeat() is very similar, but it doesn't expose iteration number and
is meant as a simple "repeat action N times" loop:

bpf_repeat(N) { /* whatever, N times */ }

Note that `break` and `continue` statements inside the {} block work as
expected.

bpf_for_each() is a generalization over any kind of BPF open-coded
iterator allowing to use for-each-like approach instead of calling
low-level bpf_iter_<type>_{new,next,destroy}() APIs explicitly. E.g.:

struct cgroup *cg;

bpf_for_each(cgroup, cg, some, input, args) {
/* do something with each cg */
}

would call (not-yet-implemented) bpf_iter_cgroup_{new,next,destroy}()
functions to form a loop over cgroups, where `some, input, args` are
passed verbatim into constructor as

bpf_iter_cgroup_new(&it, some, input, args).

As a first demonstration, add pyperf variant based on the bpf_for() loop.

Also clean up a few tests that either included bpf_misc.h header
unnecessarily from the user-space, which is unsupported, or included it
before any common types are defined (and thus leading to unnecessary
compilation warnings, potentially).

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20230308184121.1165081-6-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

selftests/bpf: Fix test_lsm on s390x

Use syscall macros to access the setdomainname() arguments; currently
the code uses gprs[2] instead of orig_gpr2 for the first argument.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Link: https://lore.kernel.org/r/20230128000650.1516334-16-iii@linux.ibm.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

selftests/bpf: Fix attach point for non-x86 arches in test_progs/lsm

Use SYS_PREFIX macro from bpf_misc.h instead of hard-coded '__x64_'
prefix for sys_setdomainname attach point in lsm test.

Signed-off-by: Artem Savkov <asavkov@redhat.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220816055231.717006-1-asavkov@redhat.com

selftests/bpf: Add a test for map-in-map and per-cpu maps in sleepable progs

Add a basic test for map-in-map and per-cpu maps in sleepable programs.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: KP Singh <kpsingh@kernel.org>
Link: https://lore.kernel.org/bpf/20210210033634.62081-10-alexei.starovoitov@gmail.com

bpf: Remove bpf_lsm_file_mprotect from sleepable list.

Technically the bpf programs can sleep while attached to bpf_lsm_file_mprotect,
but such programs need to access user memory. So they're in might_fault()
category. Which means they cannot be called from file_mprotect lsm hook that
takes write lock on mm->mmap_lock.
Adjust the test accordingly.

Also add might_fault() to __bpf_prog_enter_sleepable() to catch such deadlocks early.

Fixes: 1e6c62a88215 ("bpf: Introduce sleepable BPF programs")
Fixes: e68a144547fc ("selftests/bpf: Add sleepable tests")
Reported-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200831201651.82447-1-alexei.starovoitov@gmail.com

selftests/bpf: Add sleepable tests

Modify few tests to sanity test sleepable bpf functionality.

Running 'bench trig-fentry-sleep' vs 'bench trig-fentry' and 'perf report':
sleepable with SRCU:
3.86% bench [k] __srcu_read_unlock
3.22% bench [k] __srcu_read_lock
0.92% bench [k] bpf_prog_740d4210cdcd99a3_bench_trigger_fentry_sleep
0.50% bench [k] bpf_trampoline_10297
0.26% bench [k] __bpf_prog_exit_sleepable
0.21% bench [k] __bpf_prog_enter_sleepable

sleepable with RCU_TRACE:
0.79% bench [k] bpf_prog_740d4210cdcd99a3_bench_trigger_fentry_sleep
0.72% bench [k] bpf_trampoline_10381
0.31% bench [k] __bpf_prog_exit_sleepable
0.29% bench [k] __bpf_prog_enter_sleepable

non-sleepable with RCU:
0.88% bench [k] bpf_prog_740d4210cdcd99a3_bench_trigger_fentry
0.84% bench [k] bpf_trampoline_10297
0.13% bench [k] __bpf_prog_enter
0.12% bench [k] __bpf_prog_exit

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: KP Singh <kpsingh@google.com>
Link: https://lore.kernel.org/bpf/20200827220114.69225-6-alexei.starovoitov@gmail.com

bpf, lsm: Fix the file_mprotect LSM test.

The test was previously using an mprotect on the heap memory allocated
using malloc and was expecting the allocation to be always using
sbrk(2). This is, however, not always true and in certain conditions
malloc may end up using anonymous mmaps for heap alloctions. This means
that the following condition that is used in the "lsm/file_mprotect"
program is not sufficent to detect all mprotect calls done on heap
memory:

is_heap = (vma->vm_start >= vma->vm_mm->start_brk &&
vma->vm_end <= vma->vm_mm->brk);

The test is updated to use an mprotect on memory allocated on the stack.
While this would result in the splitting of the vma, this happens only
after the security_file_mprotect hook. So, the condition used in the BPF
program holds true.

Fixes: 03e54f100d57 ("bpf: lsm: Add selftests for BPF_PROG_TYPE_LSM")
Reported-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: KP Singh <kpsingh@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200402200751.26372-1-kpsingh@chromium.org

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