[RFC,5/5] selftests/bpf: Add iter_task_vma_buildid test
Commit Message
Testing iterator access to build id in vma->vm_file object
by storing each binary with buildid into map and checking
it against buildid retrieved in user space.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
.../selftests/bpf/prog_tests/bpf_iter.c | 88 +++++++++++++++++++
.../bpf/progs/bpf_iter_task_vma_buildid.c | 49 +++++++++++
2 files changed, 137 insertions(+)
create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_task_vma_buildid.c
Comments
On Wed, Feb 1, 2023 at 5:58 AM Jiri Olsa <jolsa@kernel.org> wrote:
>
> Testing iterator access to build id in vma->vm_file object
> by storing each binary with buildid into map and checking
> it against buildid retrieved in user space.
>
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
> .../selftests/bpf/prog_tests/bpf_iter.c | 88 +++++++++++++++++++
> .../bpf/progs/bpf_iter_task_vma_buildid.c | 49 +++++++++++
> 2 files changed, 137 insertions(+)
> create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_task_vma_buildid.c
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
> index 3af6450763e9..fd3217b68c2e 100644
> --- a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
> +++ b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
> @@ -33,6 +33,7 @@
> #include "bpf_iter_bpf_link.skel.h"
> #include "bpf_iter_ksym.skel.h"
> #include "bpf_iter_sockmap.skel.h"
> +#include "bpf_iter_task_vma_buildid.skel.h"
>
> static int duration;
>
> @@ -1536,6 +1537,91 @@ static void test_task_vma_dead_task(void)
> bpf_iter_task_vma__destroy(skel);
> }
>
> +#define D_PATH_BUF_SIZE 1024
> +#define BUILD_ID_SIZE_MAX 20
> +
> +struct build_id {
> + u32 sz;
> + char data[BUILD_ID_SIZE_MAX];
> +};
> +
> +#define BUILDID_STR_SIZE (BPF_BUILD_ID_SIZE*2 + 1)
> +
> +static void test_task_vma_buildid(void)
> +{
> + int err, iter_fd = -1, proc_maps_fd = -1;
> + struct bpf_iter_task_vma_buildid *skel;
> + char key[D_PATH_BUF_SIZE], *prev_key;
> + char bpf_build_id[BUILDID_STR_SIZE];
> + int len, files_fd, i, cnt = 0;
> + struct build_id val;
> + char *build_id;
> + char c;
> +
> + skel = bpf_iter_task_vma_buildid__open();
> + if (!ASSERT_OK_PTR(skel, "bpf_iter_task_vma_buildid__open"))
> + return;
> +
> + err = bpf_iter_task_vma_buildid__load(skel);
> + if (!ASSERT_OK(err, "bpf_iter_task_vma_buildid__load"))
> + goto out;
minor: you can do __open_and_load() in one step
> +
> + skel->links.proc_maps = bpf_program__attach_iter(
> + skel->progs.proc_maps, NULL);
> +
> + if (!ASSERT_OK_PTR(skel->links.proc_maps, "bpf_program__attach_iter")) {
> + skel->links.proc_maps = NULL;
> + goto out;
> + }
> +
> + iter_fd = bpf_iter_create(bpf_link__fd(skel->links.proc_maps));
> + if (!ASSERT_GE(iter_fd, 0, "create_iter"))
> + goto out;
> +
> + /* trigger the iterator, there's no output, just map */
> + len = read(iter_fd, &c, 1);
> + ASSERT_EQ(len, 0, "len_check");
> +
> + files_fd = bpf_map__fd(skel->maps.files);
> +
> + prev_key = NULL;
> +
> + while (true) {
> + err = bpf_map_get_next_key(files_fd, prev_key, &key);
> + if (err) {
> + if (errno == ENOENT)
> + err = 0;
> + break;
> + }
> + if (bpf_map_lookup_elem(files_fd, key, &val))
> + break;
> + if (!ASSERT_LE(val.sz, BUILD_ID_SIZE_MAX, "buildid_size"))
> + break;
> +
> + memset(bpf_build_id, 0x0, sizeof(bpf_build_id));
> + for (i = 0; i < val.sz; i++) {
> + sprintf(bpf_build_id + i*2, "%02x",
> + (unsigned char) val.data[i]);
> + }
> +
> + if (!ASSERT_OK(read_buildid(key, &build_id), "read_buildid"))
> + break;
> +
> + printf("BUILDID %s %s %s\n", bpf_build_id, build_id, key);
debugging leftover or intentional?
> + ASSERT_OK(strncmp(bpf_build_id, build_id, strlen(bpf_build_id)), "buildid_cmp");
> +
> + free(build_id);
> + prev_key = key;
> + cnt++;
> + }
> +
> + printf("checked %d files\n", cnt);
ditto
> +out:
> + close(proc_maps_fd);
> + close(iter_fd);
> + bpf_iter_task_vma_buildid__destroy(skel);
> +}
> +
> void test_bpf_sockmap_map_iter_fd(void)
> {
> struct bpf_iter_sockmap *skel;
> @@ -1659,6 +1745,8 @@ void test_bpf_iter(void)
> test_task_vma();
> if (test__start_subtest("task_vma_dead_task"))
> test_task_vma_dead_task();
> + if (test__start_subtest("task_vma_buildid"))
> + test_task_vma_buildid();
> if (test__start_subtest("task_btf"))
> test_task_btf();
> if (test__start_subtest("tcp4"))
> diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_task_vma_buildid.c b/tools/testing/selftests/bpf/progs/bpf_iter_task_vma_buildid.c
> new file mode 100644
> index 000000000000..25e2179ae5f4
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/bpf_iter_task_vma_buildid.c
> @@ -0,0 +1,49 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include "bpf_iter.h"
> +#include <bpf/bpf_helpers.h>
> +#include <string.h>
> +
> +char _license[] SEC("license") = "GPL";
> +
> +#define VM_EXEC 0x00000004
> +#define D_PATH_BUF_SIZE 1024
> +
> +struct {
> + __uint(type, BPF_MAP_TYPE_HASH);
> + __uint(max_entries, 10000);
> + __type(key, char[D_PATH_BUF_SIZE]);
> + __type(value, struct build_id);
> +} files SEC(".maps");
> +
> +static char tmp_key[D_PATH_BUF_SIZE];
> +static struct build_id tmp_data;
> +
> +SEC("iter/task_vma") int proc_maps(struct bpf_iter__task_vma *ctx)
nit: let's keep SEC() on separate line from function itself
> +{
> + struct vm_area_struct *vma = ctx->vma;
> + struct seq_file *seq = ctx->meta->seq;
> + struct task_struct *task = ctx->task;
> + unsigned long file_key;
> + struct file *file;
> +
> + if (task == (void *)0 || vma == (void *)0)
> + return 0;
> +
> + if (!(vma->vm_flags & VM_EXEC))
> + return 0;
> +
> + file = vma->vm_file;
> + if (!file)
> + return 0;
> +
> + memset(tmp_key, 0x0, D_PATH_BUF_SIZE);
__builtin_memset() to not rely on compiler optimization?
> + bpf_d_path(&file->f_path, (char *) &tmp_key, D_PATH_BUF_SIZE);
> +
> + if (bpf_map_lookup_elem(&files, &tmp_key))
> + return 0;
> +
> + memcpy(&tmp_data, file->f_bid, sizeof(*file->f_bid));
same about __builtin_memcpy()
> + bpf_map_update_elem(&files, &tmp_key, &tmp_data, 0);
> + return 0;
> +}
> --
> 2.39.1
>
On Wed, Feb 08, 2023 at 04:01:42PM -0800, Andrii Nakryiko wrote:
SNIP
> > +static void test_task_vma_buildid(void)
> > +{
> > + int err, iter_fd = -1, proc_maps_fd = -1;
> > + struct bpf_iter_task_vma_buildid *skel;
> > + char key[D_PATH_BUF_SIZE], *prev_key;
> > + char bpf_build_id[BUILDID_STR_SIZE];
> > + int len, files_fd, i, cnt = 0;
> > + struct build_id val;
> > + char *build_id;
> > + char c;
> > +
> > + skel = bpf_iter_task_vma_buildid__open();
> > + if (!ASSERT_OK_PTR(skel, "bpf_iter_task_vma_buildid__open"))
> > + return;
> > +
> > + err = bpf_iter_task_vma_buildid__load(skel);
> > + if (!ASSERT_OK(err, "bpf_iter_task_vma_buildid__load"))
> > + goto out;
>
> minor: you can do __open_and_load() in one step
right, I copied that from another test, but removed all the
setup in between, so we can actually call just __open_and_load
SNIP
> > + memset(bpf_build_id, 0x0, sizeof(bpf_build_id));
> > + for (i = 0; i < val.sz; i++) {
> > + sprintf(bpf_build_id + i*2, "%02x",
> > + (unsigned char) val.data[i]);
> > + }
> > +
> > + if (!ASSERT_OK(read_buildid(key, &build_id), "read_buildid"))
> > + break;
> > +
> > + printf("BUILDID %s %s %s\n", bpf_build_id, build_id, key);
>
> debugging leftover or intentional?
>
> > + ASSERT_OK(strncmp(bpf_build_id, build_id, strlen(bpf_build_id)), "buildid_cmp");
> > +
> > + free(build_id);
> > + prev_key = key;
> > + cnt++;
> > + }
> > +
> > + printf("checked %d files\n", cnt);
>
> ditto
both intentional, first one can go out I guess, but the
number of checked files seemed interesting to me ;-)
SNIP
> > diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_task_vma_buildid.c b/tools/testing/selftests/bpf/progs/bpf_iter_task_vma_buildid.c
> > new file mode 100644
> > index 000000000000..25e2179ae5f4
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/progs/bpf_iter_task_vma_buildid.c
> > @@ -0,0 +1,49 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +
> > +#include "bpf_iter.h"
> > +#include <bpf/bpf_helpers.h>
> > +#include <string.h>
> > +
> > +char _license[] SEC("license") = "GPL";
> > +
> > +#define VM_EXEC 0x00000004
> > +#define D_PATH_BUF_SIZE 1024
> > +
> > +struct {
> > + __uint(type, BPF_MAP_TYPE_HASH);
> > + __uint(max_entries, 10000);
> > + __type(key, char[D_PATH_BUF_SIZE]);
> > + __type(value, struct build_id);
> > +} files SEC(".maps");
> > +
> > +static char tmp_key[D_PATH_BUF_SIZE];
> > +static struct build_id tmp_data;
> > +
> > +SEC("iter/task_vma") int proc_maps(struct bpf_iter__task_vma *ctx)
>
> nit: let's keep SEC() on separate line from function itself
ok
>
> > +{
> > + struct vm_area_struct *vma = ctx->vma;
> > + struct seq_file *seq = ctx->meta->seq;
> > + struct task_struct *task = ctx->task;
> > + unsigned long file_key;
> > + struct file *file;
> > +
> > + if (task == (void *)0 || vma == (void *)0)
> > + return 0;
> > +
> > + if (!(vma->vm_flags & VM_EXEC))
> > + return 0;
> > +
> > + file = vma->vm_file;
> > + if (!file)
> > + return 0;
> > +
> > + memset(tmp_key, 0x0, D_PATH_BUF_SIZE);
>
> __builtin_memset() to not rely on compiler optimization?
>
> > + bpf_d_path(&file->f_path, (char *) &tmp_key, D_PATH_BUF_SIZE);
> > +
> > + if (bpf_map_lookup_elem(&files, &tmp_key))
> > + return 0;
> > +
> > + memcpy(&tmp_data, file->f_bid, sizeof(*file->f_bid));
>
> same about __builtin_memcpy()
ah ok, did not know that, will check.. curious what could
go wrong by using not '__builtin_...' version?
thanks,
jirka
On Thu, Feb 9, 2023 at 6:04 AM Jiri Olsa <olsajiri@gmail.com> wrote:
>
> On Wed, Feb 08, 2023 at 04:01:42PM -0800, Andrii Nakryiko wrote:
>
> SNIP
>
> > > +static void test_task_vma_buildid(void)
> > > +{
> > > + int err, iter_fd = -1, proc_maps_fd = -1;
> > > + struct bpf_iter_task_vma_buildid *skel;
> > > + char key[D_PATH_BUF_SIZE], *prev_key;
> > > + char bpf_build_id[BUILDID_STR_SIZE];
> > > + int len, files_fd, i, cnt = 0;
> > > + struct build_id val;
> > > + char *build_id;
> > > + char c;
> > > +
> > > + skel = bpf_iter_task_vma_buildid__open();
> > > + if (!ASSERT_OK_PTR(skel, "bpf_iter_task_vma_buildid__open"))
> > > + return;
> > > +
> > > + err = bpf_iter_task_vma_buildid__load(skel);
> > > + if (!ASSERT_OK(err, "bpf_iter_task_vma_buildid__load"))
> > > + goto out;
> >
> > minor: you can do __open_and_load() in one step
>
> right, I copied that from another test, but removed all the
> setup in between, so we can actually call just __open_and_load
>
> SNIP
>
> > > + memset(bpf_build_id, 0x0, sizeof(bpf_build_id));
> > > + for (i = 0; i < val.sz; i++) {
> > > + sprintf(bpf_build_id + i*2, "%02x",
> > > + (unsigned char) val.data[i]);
> > > + }
> > > +
> > > + if (!ASSERT_OK(read_buildid(key, &build_id), "read_buildid"))
> > > + break;
> > > +
> > > + printf("BUILDID %s %s %s\n", bpf_build_id, build_id, key);
> >
> > debugging leftover or intentional?
> >
> > > + ASSERT_OK(strncmp(bpf_build_id, build_id, strlen(bpf_build_id)), "buildid_cmp");
> > > +
> > > + free(build_id);
> > > + prev_key = key;
> > > + cnt++;
> > > + }
> > > +
> > > + printf("checked %d files\n", cnt);
> >
> > ditto
>
> both intentional, first one can go out I guess, but the
> number of checked files seemed interesting to me ;-)
>
> SNIP
>
> > > diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_task_vma_buildid.c b/tools/testing/selftests/bpf/progs/bpf_iter_task_vma_buildid.c
> > > new file mode 100644
> > > index 000000000000..25e2179ae5f4
> > > --- /dev/null
> > > +++ b/tools/testing/selftests/bpf/progs/bpf_iter_task_vma_buildid.c
> > > @@ -0,0 +1,49 @@
> > > +// SPDX-License-Identifier: GPL-2.0
> > > +
> > > +#include "bpf_iter.h"
> > > +#include <bpf/bpf_helpers.h>
> > > +#include <string.h>
> > > +
> > > +char _license[] SEC("license") = "GPL";
> > > +
> > > +#define VM_EXEC 0x00000004
> > > +#define D_PATH_BUF_SIZE 1024
> > > +
> > > +struct {
> > > + __uint(type, BPF_MAP_TYPE_HASH);
> > > + __uint(max_entries, 10000);
> > > + __type(key, char[D_PATH_BUF_SIZE]);
> > > + __type(value, struct build_id);
> > > +} files SEC(".maps");
> > > +
> > > +static char tmp_key[D_PATH_BUF_SIZE];
> > > +static struct build_id tmp_data;
> > > +
> > > +SEC("iter/task_vma") int proc_maps(struct bpf_iter__task_vma *ctx)
> >
> > nit: let's keep SEC() on separate line from function itself
>
> ok
>
> >
> > > +{
> > > + struct vm_area_struct *vma = ctx->vma;
> > > + struct seq_file *seq = ctx->meta->seq;
> > > + struct task_struct *task = ctx->task;
> > > + unsigned long file_key;
> > > + struct file *file;
> > > +
> > > + if (task == (void *)0 || vma == (void *)0)
> > > + return 0;
> > > +
> > > + if (!(vma->vm_flags & VM_EXEC))
> > > + return 0;
> > > +
> > > + file = vma->vm_file;
> > > + if (!file)
> > > + return 0;
> > > +
> > > + memset(tmp_key, 0x0, D_PATH_BUF_SIZE);
> >
> > __builtin_memset() to not rely on compiler optimization?
> >
> > > + bpf_d_path(&file->f_path, (char *) &tmp_key, D_PATH_BUF_SIZE);
> > > +
> > > + if (bpf_map_lookup_elem(&files, &tmp_key))
> > > + return 0;
> > > +
> > > + memcpy(&tmp_data, file->f_bid, sizeof(*file->f_bid));
> >
> > same about __builtin_memcpy()
>
> ah ok, did not know that, will check.. curious what could
> go wrong by using not '__builtin_...' version?
if compiler doesn't optimize it into __builtin_memcpy() (which results
in just explicit assembly code to copy/set data word-by-word), then
BPF program will do actual call to memset(), which with C rules would
be inferred as extern symbol, which would fail BPF object loading with
error along the lines of "couldn't resolve memset extern".
>
> thanks,
> jirka
@@ -33,6 +33,7 @@
#include "bpf_iter_bpf_link.skel.h"
#include "bpf_iter_ksym.skel.h"
#include "bpf_iter_sockmap.skel.h"
+#include "bpf_iter_task_vma_buildid.skel.h"
static int duration;
@@ -1536,6 +1537,91 @@ static void test_task_vma_dead_task(void)
bpf_iter_task_vma__destroy(skel);
}
+#define D_PATH_BUF_SIZE 1024
+#define BUILD_ID_SIZE_MAX 20
+
+struct build_id {
+ u32 sz;
+ char data[BUILD_ID_SIZE_MAX];
+};
+
+#define BUILDID_STR_SIZE (BPF_BUILD_ID_SIZE*2 + 1)
+
+static void test_task_vma_buildid(void)
+{
+ int err, iter_fd = -1, proc_maps_fd = -1;
+ struct bpf_iter_task_vma_buildid *skel;
+ char key[D_PATH_BUF_SIZE], *prev_key;
+ char bpf_build_id[BUILDID_STR_SIZE];
+ int len, files_fd, i, cnt = 0;
+ struct build_id val;
+ char *build_id;
+ char c;
+
+ skel = bpf_iter_task_vma_buildid__open();
+ if (!ASSERT_OK_PTR(skel, "bpf_iter_task_vma_buildid__open"))
+ return;
+
+ err = bpf_iter_task_vma_buildid__load(skel);
+ if (!ASSERT_OK(err, "bpf_iter_task_vma_buildid__load"))
+ goto out;
+
+ skel->links.proc_maps = bpf_program__attach_iter(
+ skel->progs.proc_maps, NULL);
+
+ if (!ASSERT_OK_PTR(skel->links.proc_maps, "bpf_program__attach_iter")) {
+ skel->links.proc_maps = NULL;
+ goto out;
+ }
+
+ iter_fd = bpf_iter_create(bpf_link__fd(skel->links.proc_maps));
+ if (!ASSERT_GE(iter_fd, 0, "create_iter"))
+ goto out;
+
+ /* trigger the iterator, there's no output, just map */
+ len = read(iter_fd, &c, 1);
+ ASSERT_EQ(len, 0, "len_check");
+
+ files_fd = bpf_map__fd(skel->maps.files);
+
+ prev_key = NULL;
+
+ while (true) {
+ err = bpf_map_get_next_key(files_fd, prev_key, &key);
+ if (err) {
+ if (errno == ENOENT)
+ err = 0;
+ break;
+ }
+ if (bpf_map_lookup_elem(files_fd, key, &val))
+ break;
+ if (!ASSERT_LE(val.sz, BUILD_ID_SIZE_MAX, "buildid_size"))
+ break;
+
+ memset(bpf_build_id, 0x0, sizeof(bpf_build_id));
+ for (i = 0; i < val.sz; i++) {
+ sprintf(bpf_build_id + i*2, "%02x",
+ (unsigned char) val.data[i]);
+ }
+
+ if (!ASSERT_OK(read_buildid(key, &build_id), "read_buildid"))
+ break;
+
+ printf("BUILDID %s %s %s\n", bpf_build_id, build_id, key);
+ ASSERT_OK(strncmp(bpf_build_id, build_id, strlen(bpf_build_id)), "buildid_cmp");
+
+ free(build_id);
+ prev_key = key;
+ cnt++;
+ }
+
+ printf("checked %d files\n", cnt);
+out:
+ close(proc_maps_fd);
+ close(iter_fd);
+ bpf_iter_task_vma_buildid__destroy(skel);
+}
+
void test_bpf_sockmap_map_iter_fd(void)
{
struct bpf_iter_sockmap *skel;
@@ -1659,6 +1745,8 @@ void test_bpf_iter(void)
test_task_vma();
if (test__start_subtest("task_vma_dead_task"))
test_task_vma_dead_task();
+ if (test__start_subtest("task_vma_buildid"))
+ test_task_vma_buildid();
if (test__start_subtest("task_btf"))
test_task_btf();
if (test__start_subtest("tcp4"))
new file mode 100644
@@ -0,0 +1,49 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "bpf_iter.h"
+#include <bpf/bpf_helpers.h>
+#include <string.h>
+
+char _license[] SEC("license") = "GPL";
+
+#define VM_EXEC 0x00000004
+#define D_PATH_BUF_SIZE 1024
+
+struct {
+ __uint(type, BPF_MAP_TYPE_HASH);
+ __uint(max_entries, 10000);
+ __type(key, char[D_PATH_BUF_SIZE]);
+ __type(value, struct build_id);
+} files SEC(".maps");
+
+static char tmp_key[D_PATH_BUF_SIZE];
+static struct build_id tmp_data;
+
+SEC("iter/task_vma") int proc_maps(struct bpf_iter__task_vma *ctx)
+{
+ struct vm_area_struct *vma = ctx->vma;
+ struct seq_file *seq = ctx->meta->seq;
+ struct task_struct *task = ctx->task;
+ unsigned long file_key;
+ struct file *file;
+
+ if (task == (void *)0 || vma == (void *)0)
+ return 0;
+
+ if (!(vma->vm_flags & VM_EXEC))
+ return 0;
+
+ file = vma->vm_file;
+ if (!file)
+ return 0;
+
+ memset(tmp_key, 0x0, D_PATH_BUF_SIZE);
+ bpf_d_path(&file->f_path, (char *) &tmp_key, D_PATH_BUF_SIZE);
+
+ if (bpf_map_lookup_elem(&files, &tmp_key))
+ return 0;
+
+ memcpy(&tmp_data, file->f_bid, sizeof(*file->f_bid));
+ bpf_map_update_elem(&files, &tmp_key, &tmp_data, 0);
+ return 0;
+}