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-rw-r--r--tools/lib/bpf/libbpf.c131
-rw-r--r--tools/lib/bpf/libbpf.h5
-rw-r--r--tools/lib/bpf/libbpf.map5
-rw-r--r--tools/testing/selftests/bpf/prog_tests/link_pinning.c105
-rw-r--r--tools/testing/selftests/bpf/progs/test_link_pinning.c25
5 files changed, 244 insertions, 27 deletions
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 996162801f7a..f8c4042e5855 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -6931,6 +6931,8 @@ int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr,
struct bpf_link {
int (*detach)(struct bpf_link *link);
int (*destroy)(struct bpf_link *link);
+ char *pin_path; /* NULL, if not pinned */
+ int fd; /* hook FD, -1 if not applicable */
bool disconnected;
};
@@ -6960,26 +6962,109 @@ int bpf_link__destroy(struct bpf_link *link)
err = link->detach(link);
if (link->destroy)
link->destroy(link);
+ if (link->pin_path)
+ free(link->pin_path);
free(link);
return err;
}
-struct bpf_link_fd {
- struct bpf_link link; /* has to be at the top of struct */
- int fd; /* hook FD */
-};
+int bpf_link__fd(const struct bpf_link *link)
+{
+ return link->fd;
+}
+
+const char *bpf_link__pin_path(const struct bpf_link *link)
+{
+ return link->pin_path;
+}
+
+static int bpf_link__detach_fd(struct bpf_link *link)
+{
+ return close(link->fd);
+}
+
+struct bpf_link *bpf_link__open(const char *path)
+{
+ struct bpf_link *link;
+ int fd;
+
+ fd = bpf_obj_get(path);
+ if (fd < 0) {
+ fd = -errno;
+ pr_warn("failed to open link at %s: %d\n", path, fd);
+ return ERR_PTR(fd);
+ }
+
+ link = calloc(1, sizeof(*link));
+ if (!link) {
+ close(fd);
+ return ERR_PTR(-ENOMEM);
+ }
+ link->detach = &bpf_link__detach_fd;
+ link->fd = fd;
+
+ link->pin_path = strdup(path);
+ if (!link->pin_path) {
+ bpf_link__destroy(link);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ return link;
+}
+
+int bpf_link__pin(struct bpf_link *link, const char *path)
+{
+ int err;
+
+ if (link->pin_path)
+ return -EBUSY;
+ err = make_parent_dir(path);
+ if (err)
+ return err;
+ err = check_path(path);
+ if (err)
+ return err;
+
+ link->pin_path = strdup(path);
+ if (!link->pin_path)
+ return -ENOMEM;
+
+ if (bpf_obj_pin(link->fd, link->pin_path)) {
+ err = -errno;
+ zfree(&link->pin_path);
+ return err;
+ }
+
+ pr_debug("link fd=%d: pinned at %s\n", link->fd, link->pin_path);
+ return 0;
+}
+
+int bpf_link__unpin(struct bpf_link *link)
+{
+ int err;
+
+ if (!link->pin_path)
+ return -EINVAL;
+
+ err = unlink(link->pin_path);
+ if (err != 0)
+ return -errno;
+
+ pr_debug("link fd=%d: unpinned from %s\n", link->fd, link->pin_path);
+ zfree(&link->pin_path);
+ return 0;
+}
static int bpf_link__detach_perf_event(struct bpf_link *link)
{
- struct bpf_link_fd *l = (void *)link;
int err;
- err = ioctl(l->fd, PERF_EVENT_IOC_DISABLE, 0);
+ err = ioctl(link->fd, PERF_EVENT_IOC_DISABLE, 0);
if (err)
err = -errno;
- close(l->fd);
+ close(link->fd);
return err;
}
@@ -6987,7 +7072,7 @@ struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog,
int pfd)
{
char errmsg[STRERR_BUFSIZE];
- struct bpf_link_fd *link;
+ struct bpf_link *link;
int prog_fd, err;
if (pfd < 0) {
@@ -7005,7 +7090,7 @@ struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog,
link = calloc(1, sizeof(*link));
if (!link)
return ERR_PTR(-ENOMEM);
- link->link.detach = &bpf_link__detach_perf_event;
+ link->detach = &bpf_link__detach_perf_event;
link->fd = pfd;
if (ioctl(pfd, PERF_EVENT_IOC_SET_BPF, prog_fd) < 0) {
@@ -7024,7 +7109,7 @@ struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog,
libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
return ERR_PTR(err);
}
- return (struct bpf_link *)link;
+ return link;
}
/*
@@ -7312,18 +7397,11 @@ out:
return link;
}
-static int bpf_link__detach_fd(struct bpf_link *link)
-{
- struct bpf_link_fd *l = (void *)link;
-
- return close(l->fd);
-}
-
struct bpf_link *bpf_program__attach_raw_tracepoint(struct bpf_program *prog,
const char *tp_name)
{
char errmsg[STRERR_BUFSIZE];
- struct bpf_link_fd *link;
+ struct bpf_link *link;
int prog_fd, pfd;
prog_fd = bpf_program__fd(prog);
@@ -7336,7 +7414,7 @@ struct bpf_link *bpf_program__attach_raw_tracepoint(struct bpf_program *prog,
link = calloc(1, sizeof(*link));
if (!link)
return ERR_PTR(-ENOMEM);
- link->link.detach = &bpf_link__detach_fd;
+ link->detach = &bpf_link__detach_fd;
pfd = bpf_raw_tracepoint_open(tp_name, prog_fd);
if (pfd < 0) {
@@ -7348,7 +7426,7 @@ struct bpf_link *bpf_program__attach_raw_tracepoint(struct bpf_program *prog,
return ERR_PTR(pfd);
}
link->fd = pfd;
- return (struct bpf_link *)link;
+ return link;
}
static struct bpf_link *attach_raw_tp(const struct bpf_sec_def *sec,
@@ -7362,7 +7440,7 @@ static struct bpf_link *attach_raw_tp(const struct bpf_sec_def *sec,
struct bpf_link *bpf_program__attach_trace(struct bpf_program *prog)
{
char errmsg[STRERR_BUFSIZE];
- struct bpf_link_fd *link;
+ struct bpf_link *link;
int prog_fd, pfd;
prog_fd = bpf_program__fd(prog);
@@ -7375,7 +7453,7 @@ struct bpf_link *bpf_program__attach_trace(struct bpf_program *prog)
link = calloc(1, sizeof(*link));
if (!link)
return ERR_PTR(-ENOMEM);
- link->link.detach = &bpf_link__detach_fd;
+ link->detach = &bpf_link__detach_fd;
pfd = bpf_raw_tracepoint_open(NULL, prog_fd);
if (pfd < 0) {
@@ -7409,10 +7487,9 @@ struct bpf_link *bpf_program__attach(struct bpf_program *prog)
static int bpf_link__detach_struct_ops(struct bpf_link *link)
{
- struct bpf_link_fd *l = (void *)link;
__u32 zero = 0;
- if (bpf_map_delete_elem(l->fd, &zero))
+ if (bpf_map_delete_elem(link->fd, &zero))
return -errno;
return 0;
@@ -7421,7 +7498,7 @@ static int bpf_link__detach_struct_ops(struct bpf_link *link)
struct bpf_link *bpf_map__attach_struct_ops(struct bpf_map *map)
{
struct bpf_struct_ops *st_ops;
- struct bpf_link_fd *link;
+ struct bpf_link *link;
__u32 i, zero = 0;
int err;
@@ -7453,10 +7530,10 @@ struct bpf_link *bpf_map__attach_struct_ops(struct bpf_map *map)
return ERR_PTR(err);
}
- link->link.detach = bpf_link__detach_struct_ops;
+ link->detach = bpf_link__detach_struct_ops;
link->fd = map->fd;
- return (struct bpf_link *)link;
+ return link;
}
enum bpf_perf_event_ret
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 02fc58a21a7f..d38d7a629417 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -219,6 +219,11 @@ LIBBPF_API void bpf_program__unload(struct bpf_program *prog);
struct bpf_link;
+LIBBPF_API struct bpf_link *bpf_link__open(const char *path);
+LIBBPF_API int bpf_link__fd(const struct bpf_link *link);
+LIBBPF_API const char *bpf_link__pin_path(const struct bpf_link *link);
+LIBBPF_API int bpf_link__pin(struct bpf_link *link, const char *path);
+LIBBPF_API int bpf_link__unpin(struct bpf_link *link);
LIBBPF_API void bpf_link__disconnect(struct bpf_link *link);
LIBBPF_API int bpf_link__destroy(struct bpf_link *link);
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 7b014c8cdece..5129283c0284 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -238,5 +238,10 @@ LIBBPF_0.0.7 {
LIBBPF_0.0.8 {
global:
+ bpf_link__fd;
+ bpf_link__open;
+ bpf_link__pin;
+ bpf_link__pin_path;
+ bpf_link__unpin;
bpf_program__set_attach_target;
} LIBBPF_0.0.7;
diff --git a/tools/testing/selftests/bpf/prog_tests/link_pinning.c b/tools/testing/selftests/bpf/prog_tests/link_pinning.c
new file mode 100644
index 000000000000..a743288cf384
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/link_pinning.c
@@ -0,0 +1,105 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Facebook */
+
+#include <test_progs.h>
+#include <sys/stat.h>
+
+#include "test_link_pinning.skel.h"
+
+static int duration = 0;
+
+void test_link_pinning_subtest(struct bpf_program *prog,
+ struct test_link_pinning__bss *bss)
+{
+ const char *link_pin_path = "/sys/fs/bpf/pinned_link_test";
+ struct stat statbuf = {};
+ struct bpf_link *link;
+ int err, i;
+
+ link = bpf_program__attach(prog);
+ if (CHECK(IS_ERR(link), "link_attach", "err: %ld\n", PTR_ERR(link)))
+ goto cleanup;
+
+ bss->in = 1;
+ usleep(1);
+ CHECK(bss->out != 1, "res_check1", "exp %d, got %d\n", 1, bss->out);
+
+ /* pin link */
+ err = bpf_link__pin(link, link_pin_path);
+ if (CHECK(err, "link_pin", "err: %d\n", err))
+ goto cleanup;
+
+ CHECK(strcmp(link_pin_path, bpf_link__pin_path(link)), "pin_path1",
+ "exp %s, got %s\n", link_pin_path, bpf_link__pin_path(link));
+
+ /* check that link was pinned */
+ err = stat(link_pin_path, &statbuf);
+ if (CHECK(err, "stat_link", "err %d errno %d\n", err, errno))
+ goto cleanup;
+
+ bss->in = 2;
+ usleep(1);
+ CHECK(bss->out != 2, "res_check2", "exp %d, got %d\n", 2, bss->out);
+
+ /* destroy link, pinned link should keep program attached */
+ bpf_link__destroy(link);
+ link = NULL;
+
+ bss->in = 3;
+ usleep(1);
+ CHECK(bss->out != 3, "res_check3", "exp %d, got %d\n", 3, bss->out);
+
+ /* re-open link from BPFFS */
+ link = bpf_link__open(link_pin_path);
+ if (CHECK(IS_ERR(link), "link_open", "err: %ld\n", PTR_ERR(link)))
+ goto cleanup;
+
+ CHECK(strcmp(link_pin_path, bpf_link__pin_path(link)), "pin_path2",
+ "exp %s, got %s\n", link_pin_path, bpf_link__pin_path(link));
+
+ /* unpin link from BPFFS, program still attached */
+ err = bpf_link__unpin(link);
+ if (CHECK(err, "link_unpin", "err: %d\n", err))
+ goto cleanup;
+
+ /* still active, as we have FD open now */
+ bss->in = 4;
+ usleep(1);
+ CHECK(bss->out != 4, "res_check4", "exp %d, got %d\n", 4, bss->out);
+
+ bpf_link__destroy(link);
+ link = NULL;
+
+ /* Validate it's finally detached.
+ * Actual detachment might get delayed a bit, so there is no reliable
+ * way to validate it immediately here, let's count up for long enough
+ * and see if eventually output stops being updated
+ */
+ for (i = 5; i < 10000; i++) {
+ bss->in = i;
+ usleep(1);
+ if (bss->out == i - 1)
+ break;
+ }
+ CHECK(i == 10000, "link_attached", "got to iteration #%d\n", i);
+
+cleanup:
+ if (!IS_ERR(link))
+ bpf_link__destroy(link);
+}
+
+void test_link_pinning(void)
+{
+ struct test_link_pinning* skel;
+
+ skel = test_link_pinning__open_and_load();
+ if (CHECK(!skel, "skel_open", "failed to open skeleton\n"))
+ return;
+
+ if (test__start_subtest("pin_raw_tp"))
+ test_link_pinning_subtest(skel->progs.raw_tp_prog, skel->bss);
+ if (test__start_subtest("pin_tp_btf"))
+ test_link_pinning_subtest(skel->progs.tp_btf_prog, skel->bss);
+
+ test_link_pinning__destroy(skel);
+}
diff --git a/tools/testing/selftests/bpf/progs/test_link_pinning.c b/tools/testing/selftests/bpf/progs/test_link_pinning.c
new file mode 100644
index 000000000000..bbf2a5264dc0
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_link_pinning.c
@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Facebook */
+
+#include <stdbool.h>
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+int in = 0;
+int out = 0;
+
+SEC("raw_tp/sys_enter")
+int raw_tp_prog(const void *ctx)
+{
+ out = in;
+ return 0;
+}
+
+SEC("tp_btf/sys_enter")
+int tp_btf_prog(const void *ctx)
+{
+ out = in;
+ return 0;
+}
+
+char _license[] SEC("license") = "GPL";
generated by cgit v1.2.3 (git 2.0.4) at 2026-09-18 19:54:24 +0000