elf: special case current version for Ubuntu/Debian

Signed-off-by: Michael Schubert <[email protected]>

bpf_test.go

@@ -41,8 +41,6 @@ func TestModuleLoadBCC(t *testing.T) {
 }
 
 func TestModuleLoadELF(t *testing.T) {
-	// Does not work yet reliable across distributions
-	return
 	b := elf.NewModule("./tests/dummy.o")
 	if b == nil {
 		t.Fatal("prog is nil")

elf/elf.go

@@ -25,7 +25,9 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"os"
+	"regexp"
 	"strconv"
 	"strings"
 	"syscall"
@@ -257,17 +259,8 @@ func utsnameStr(in []int8) string {
 	return string(out)
 }
 
-func currentVersion() (int, error) {
-	var buf syscall.Utsname
-	if err := syscall.Uname(&buf); err != nil {
-		return -1, err
-	}
-
-	releaseStr := strings.Trim(utsnameStr(buf.Release[:]), "\x00")
-
-	kernelVersionStr := strings.Split(releaseStr, "-")[0]
-
-	kernelVersionParts := strings.Split(kernelVersionStr, ".")
+func kernelVersionFromString(versionString string) (int, error) {
+	kernelVersionParts := strings.Split(versionString, ".")
 	if len(kernelVersionParts) != 3 {
 		return -1, errors.New("not enough version information")
 	}
@@ -292,6 +285,63 @@ func currentVersion() (int, error) {
 	return out, nil
 }
 
+func currentVersionUname() (int, error) {
+	var buf syscall.Utsname
+	if err := syscall.Uname(&buf); err != nil {
+		return -1, err
+	}
+	releaseStr := strings.Trim(utsnameStr(buf.Release[:]), "\x00")
+	kernelVersionStr := strings.Split(releaseStr, "-")[0]
+	return kernelVersionFromString(kernelVersionStr)
+}
+
+func currentVersionUbuntu() (int, error) {
+	procVersion, err := ioutil.ReadFile("/proc/version_signature")
+	if err != nil {
+		return -1, err
+	}
+	var u1, u2, releaseStr string
+	_, err = fmt.Sscanf(string(procVersion), "%s %s %s", &u1, &u2, &releaseStr)
+	if err != nil {
+		return -1, err
+	}
+	kernelVersionStr := strings.Split(releaseStr, "-")[0]
+	return kernelVersionFromString(kernelVersionStr)
+}
+
+var debianVersionRegex = regexp.MustCompile(`.* SMP Debian (\d+\.\d+.\d+-\d+) .*`)
+
+func currentVersionDebian() (int, error) {
+	procVersion, err := ioutil.ReadFile("/proc/version")
+	if err != nil {
+		return -1, err
+	}
+	match := debianVersionRegex.FindStringSubmatch(string(procVersion))
+	if len(match) != 2 {
+		return -1, fmt.Errorf("failed to get kernel version from /proc/version: %s", procVersion)
+	}
+	kernelVersionStr := strings.Split(match[1], "-")[0]
+	return kernelVersionFromString(kernelVersionStr)
+}
+
+func currentVersion() (int, error) {
+	onUbuntu, err := pathExists("/proc/version_signature")
+	if err != nil {
+		return -1, err
+	}
+	if onUbuntu {
+		return currentVersionUbuntu()
+	}
+	onDebian, err := pathExists("/etc/debian_version")
+	if err != nil {
+		return -1, err
+	}
+	if onDebian {
+		return currentVersionDebian()
+	}
+	return currentVersionUname()
+}
+
 func elfReadMaps(file *elf.File) (map[string]*Map, error) {
 	maps := make(map[string]*Map)
 	for sectionIdx, section := range file.Sections {

elf/utils.go

@@ -0,0 +1,14 @@
+package elf
+
+import "os"
+
+func pathExists(path string) (bool, error) {
+	_, err := os.Stat(path)
+	if err == nil {
+		return true, nil
+	}
+	if os.IsNotExist(err) {
+		return false, nil
+	}
+	return true, err
+}