Allow customizing the base path and don't mount the BPF fs if it is a…

…lready mounted (#741)

Makefile

@@ -174,6 +174,11 @@ test:
 	@echo "### Testing code"
 	go test -race -mod vendor -a ./... -coverpkg=./... -coverprofile $(TEST_OUTPUT)/cover.all.txt
 
+.PHONY: test-privileged
+test-privileged:
+	@echo "### Testing code with privileged tests enabled"
+	PRIVILEGED_TESTS=true go test -race -mod vendor -a ./... -coverpkg=./... -coverprofile $(TEST_OUTPUT)/cover.all.txt
+
 .PHONY: cov-exclude-generated
 cov-exclude-generated:
 	grep -vE $(EXCLUDE_COVERAGE_FILES) $(TEST_OUTPUT)/cover.all.txt > $(TEST_OUTPUT)/cover.txt

NOTICE

@@ -15,6 +15,10 @@ The Initial Developer of some parts of the product, which are copied from, deriv
 inspired by ebpf-go (https://github.com/cilium/ebpf).
 Copyright Authors of Cilium.
 
+The Initial Developer of some parts of the product, which are copied from, derived from, or
+inspired by ebpf-go (https://github.com/cilium/cilium).
+Copyright Authors of Cilium.
+
 The Initial Developer of some parts of the product, which are copied from, derived from, or
 inspired by NetObserv eBPF Agent (https://github.com/netobserv/netobserv-ebpf-agent).
 Copyright Red Hat/IBM.
@@ -305,4 +309,209 @@ FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-SOFTWARE.
+SOFTWARE.
+
+
+License notice for cilium
+--------------------------
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+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
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+      "You" (or "Your") shall mean an individual or Legal Entity
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+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
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+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
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+      designated in writing by the copyright owner as "Not a Contribution."
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+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
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+      Work and such Derivative Works in Source or Object form.
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+   3. Grant of Patent License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
+      use, offer to sell, sell, import, and otherwise transfer the Work,
+      where such license applies only to those patent claims licensable
+      by such Contributor that are necessarily infringed by their
+      Contribution(s) alone or by combination of their Contribution(s)
+      with the Work to which such Contribution(s) was submitted. If You
+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
+      modifications, and in Source or Object form, provided that You
+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
+          attribution notices from the Source form of the Work,
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+          the Derivative Works; and
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+      (d) If the Work includes a "NOTICE" text file as part of its
+          distribution, then any Derivative Works that You distribute must
+          include a readable copy of the attribution notices contained
+          within such NOTICE file, excluding those notices that do not
+          pertain to any part of the Derivative Works, in at least one
+          of the following places: within a NOTICE text file distributed
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+          documentation, if provided along with the Derivative Works; or,
+          within a display generated by the Derivative Works, if and
+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "{}"
+      replaced with your own identifying information. (Don't include
+      the brackets!)  The text should be enclosed in the appropriate
+      comment syntax for the file format. We also recommend that a
+      file or class name and description of purpose be included on the
+      same "printed page" as the copyright notice for easier
+      identification within third-party archives.
+
+   Copyright {yyyy} Authors of Cilium
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.

pkg/beyla/config.go

@@ -3,6 +3,7 @@ package beyla
 import (
 	"fmt"
 	"io"
+	"os"
 	"time"
 
 	"github.com/caarlos0/env/v9"
@@ -36,6 +37,7 @@ var DefaultConfig = Config{
 		BatchLength:  100,
 		BatchTimeout: time.Second,
 		BpfBaseDir:   "/var/run/beyla",
+		BpfPath:      fmt.Sprintf("beyla-%d", os.Getpid()),
 	},
 	Grafana: otel.GrafanaConfig{
 		OTLP: otel.GrafanaOTLP{

pkg/beyla/config_test.go

@@ -93,6 +93,7 @@ network:
 			BatchLength:  100,
 			BatchTimeout: time.Second,
 			BpfBaseDir:   "/var/run/beyla",
+			BpfPath:      DefaultConfig.EBPF.BpfPath,
 		},
 		Grafana: otel.GrafanaConfig{
 			OTLP: otel.GrafanaOTLP{

pkg/internal/discover/attacher.go

@@ -2,9 +2,7 @@ package discover
 
 import (
 	"context"
-	"fmt"
 	"log/slog"
-	"os"
 	"path"
 
 	"github.com/cilium/ebpf/link"
@@ -193,7 +191,7 @@ func monitorPIDs(tracer *ebpf.ProcessTracer, ie *Instrumentable) {
 // it will be:
 //   - current beyla PID
 func BuildPinPath(cfg *beyla.Config) string {
-	return path.Join(cfg.EBPF.BpfBaseDir, fmt.Sprintf("beyla-%d", os.Getpid()))
+	return path.Join(cfg.EBPF.BpfBaseDir, cfg.EBPF.BpfPath)
 }
 
 func (ta *TraceAttacher) notifyProcessDeletion(ie *Instrumentable) {

pkg/internal/discover/attacher_linux.go

@@ -24,7 +24,7 @@ func (ta *TraceAttacher) mountBpfPinPath() error {
 		}
 	}
 
-	return bpfMount(ta.pinPath)
+	return ta.bpfMount(ta.pinPath)
 }
 
 func (ta *TraceAttacher) unmountBpfPinPath() {
@@ -40,8 +40,20 @@ func (ta *TraceAttacher) unmountBpfPinPath() {
 	}
 }
 
-func bpfMount(pinPath string) error {
-	return unix.Mount(pinPath, pinPath, "bpf", 0, "")
+func (ta *TraceAttacher) bpfMount(pinPath string) error {
+	mounted, bpffsInstance, err := IsMountFS(FilesystemTypeBPFFS, pinPath)
+	if err != nil {
+		return err
+	}
+	if !mounted {
+		return unix.Mount(pinPath, pinPath, "bpf", 0, "")
+	}
+	if !bpffsInstance {
+		return fmt.Errorf("mount in the custom directory %s has a different filesystem than BPFFS", pinPath)
+	}
+	ta.log.Info(fmt.Sprintf("Detected mounted BPF filesystem at %v", pinPath))
+
+	return nil
 }
 
 func (ta *TraceAttacher) init() error {

pkg/internal/discover/attacher_linux_privileged_test.go

@@ -0,0 +1,55 @@
+//go:build linux
+
+package discover
+
+import (
+	"log/slog"
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestMountBpfPinPath(t *testing.T) {
+	if os.Getenv(privilegedEnv) == "" {
+		t.Skipf("Set %s to run this test", privilegedEnv)
+	}
+	tmpDir := "path"
+	ta := &TraceAttacher{
+		log:     slog.With("component", "discover.TraceAttacher"),
+		pinPath: tmpDir,
+	}
+
+	// Nothing there to start the test
+	mounted, matched, err := IsMountFS(FilesystemTypeBPFFS, tmpDir)
+	assert.NoError(t, err)
+	assert.False(t, mounted)
+	assert.False(t, matched)
+
+	err = ta.mountBpfPinPath()
+	assert.NoError(t, err)
+
+	// Check that it is mounted
+	mounted, matched, err = IsMountFS(FilesystemTypeBPFFS, tmpDir)
+	assert.NoError(t, err)
+	assert.True(t, mounted)
+	assert.True(t, matched)
+
+	// Ensure mounting the same path twice does not fail
+	err = ta.mountBpfPinPath()
+	assert.NoError(t, err)
+
+	// Check that it is mounted
+	mounted, matched, err = IsMountFS(FilesystemTypeBPFFS, tmpDir)
+	assert.NoError(t, err)
+	assert.True(t, mounted)
+	assert.True(t, matched)
+
+	ta.unmountBpfPinPath()
+
+	// Check that it is cleaned up
+	mounted, matched, err = IsMountFS(FilesystemTypeBPFFS, tmpDir)
+	assert.NoError(t, err)
+	assert.False(t, mounted)
+	assert.False(t, matched)
+}