pkg/sca/sca.go: Implement getLdSoConfDLibPaths

This commit implements the machinery necessary for SCA to consider
files under /etc/ld.so.conf.d/.

The idea is that, if there is a configuration for ld.so.conf.d being
installed by the package on hand, then the libraries shipped by the
package should be listed as "provides" if they're installed inside the
paths listed in the ld.so.conf.d configuration file.

Signed-off-by: Sergio Durigan Junior <[email protected]>

Author: sergiodj

pkg/sca/sca.go

@@ -15,10 +15,12 @@
 package sca
 
 import (
+	"bufio"
 	"bytes"
 	"context"
 	"debug/buildinfo"
 	"debug/elf"
+	"errors"
 	"fmt"
 	"io"
 	"io/fs"
@@ -72,9 +74,10 @@ type SCAHandle interface {
 	BaseDependencies() config.Dependencies
 }
 
-// DependencyGenerator takes an SCAHandle and config.Dependencies pointer and returns
-// findings based on analysis.
-type DependencyGenerator func(context.Context, SCAHandle, *config.Dependencies) error
+// DependencyGenerator takes an SCAHandle, config.Dependencies pointer
+// and a list of paths to be appended to libDirs and returns findings
+// based on analysis.
+type DependencyGenerator func(context.Context, SCAHandle, *config.Dependencies, []string) error
 
 func isInDir(path string, dirs []string) bool {
 	mydir := filepath.Dir(path)
@@ -86,7 +89,83 @@ func isInDir(path string, dirs []string) bool {
 	return false
 }
 
-func generateCmdProviders(ctx context.Context, hdl SCAHandle, generated *config.Dependencies) error {
+// getLdSoConfDLibPaths will iterate over the files being installed by
+// the package and all its subpackages, and for each configuration
+// file found under /etc/ld.so.conf.d/ it will parse the file and add
+// its contents to a string vector.  This vector will ultimately
+// contain all extra paths that will be considered by ld when doing
+// symbol resolution.
+func getLdSoConfDLibPaths(ctx context.Context, hdl SCAHandle) ([]string, error) {
+	var extraLibPaths []string
+	targetPackageNames := hdl.RelativeNames()
+
+	log := clog.FromContext(ctx)
+
+	log.Info("scanning for ld.so.conf.d files...")
+
+	for _, pkgName := range targetPackageNames {
+		fsys, err := hdl.FilesystemForRelative(pkgName)
+		if err != nil {
+			return nil, err
+		}
+
+		if err := fs.WalkDir(fsys, "etc/ld.so.conf.d", func(path string, d fs.DirEntry, err error) error {
+			if err != nil {
+				if errors.Is(err, fs.ErrNotExist) {
+					return fs.SkipAll
+				}
+				return err
+			}
+
+			// We're only interested in files whose suffix is ".conf"
+			if !strings.HasSuffix(path, ".conf") {
+				return nil
+			}
+
+			fi, err := d.Info()
+			if err != nil {
+				return err
+			}
+
+			if !fi.Mode().IsRegular() {
+				return nil
+			}
+
+			log.Infof("  found ld.so.conf.d file %s", path)
+
+			fd, err := fsys.Open(path)
+			if err != nil {
+				return err
+			}
+			defer fd.Close()
+
+			scanner := bufio.NewScanner(fd)
+			for scanner.Scan() {
+				line := scanner.Text()
+				if line == "" || line[0] != '/' {
+					continue
+				}
+				// Strip the initial slash since
+				// libDirs paths need to be relative.
+				line = line[1:]
+				log.Infof("    found extra lib path %s", line)
+				extraLibPaths = append(extraLibPaths, line)
+			}
+
+			if err := scanner.Err(); err != nil {
+				return err
+			}
+
+			return nil
+		}); err != nil {
+			return nil, err
+		}
+	}
+
+	return extraLibPaths, nil
+}
+
+func generateCmdProviders(ctx context.Context, hdl SCAHandle, generated *config.Dependencies, extraLibDirs []string) error {
 	log := clog.FromContext(ctx)
 
 	log.Info("scanning for commands...")
@@ -149,7 +228,7 @@ func findInterpreter(bin *elf.File) (string, error) {
 
 // dereferenceCrossPackageSymlink attempts to dereference a symlink across multiple package
 // directories.
-func dereferenceCrossPackageSymlink(hdl SCAHandle, path string) (string, string, error) {
+func dereferenceCrossPackageSymlink(hdl SCAHandle, path string, extraLibDirs []string) (string, string, error) {
 	targetPackageNames := hdl.RelativeNames()
 
 	pkgFS, err := hdl.Filesystem()
@@ -164,13 +243,15 @@ func dereferenceCrossPackageSymlink(hdl SCAHandle, path string) (string, string,
 
 	realPath = filepath.Base(realPath)
 
+	expandedLibDirs := append(libDirs, extraLibDirs...)
+
 	for _, pkgName := range targetPackageNames {
 		baseFS, err := hdl.FilesystemForRelative(pkgName)
 		if err != nil {
 			return "", "", err
 		}
 
-		for _, libDir := range libDirs {
+		for _, libDir := range expandedLibDirs {
 			testPath := filepath.Join(libDir, realPath)
 
 			if _, err := baseFS.Stat(testPath); err == nil {
@@ -182,13 +263,13 @@ func dereferenceCrossPackageSymlink(hdl SCAHandle, path string) (string, string,
 	return "", "", nil
 }
 
-func processSymlinkSo(ctx context.Context, hdl SCAHandle, path string, generated *config.Dependencies) error {
+func processSymlinkSo(ctx context.Context, hdl SCAHandle, path string, generated *config.Dependencies, extraLibDirs []string) error {
 	log := clog.FromContext(ctx)
 	if !strings.Contains(path, ".so") {
 		return nil
 	}
 
-	targetPkg, realPath, err := dereferenceCrossPackageSymlink(hdl, path)
+	targetPkg, realPath, err := dereferenceCrossPackageSymlink(hdl, path, extraLibDirs)
 	if err != nil {
 		return nil
 	}
@@ -233,7 +314,7 @@ func processSymlinkSo(ctx context.Context, hdl SCAHandle, path string, generated
 	return nil
 }
 
-func generateSharedObjectNameDeps(ctx context.Context, hdl SCAHandle, generated *config.Dependencies) error {
+func generateSharedObjectNameDeps(ctx context.Context, hdl SCAHandle, generated *config.Dependencies, extraLibDirs []string) error {
 	log := clog.FromContext(ctx)
 	log.Infof("scanning for shared object dependencies...")
 
@@ -242,6 +323,8 @@ func generateSharedObjectNameDeps(ctx context.Context, hdl SCAHandle, generated
 		return err
 	}
 
+	expandedLibDirs := append(libDirs, extraLibDirs...)
+
 	if err := fs.WalkDir(fsys, ".", func(path string, d fs.DirEntry, err error) error {
 		if err != nil {
 			return err
@@ -258,7 +341,7 @@ func generateSharedObjectNameDeps(ctx context.Context, hdl SCAHandle, generated
 		isLink := mode.Type()&fs.ModeSymlink == fs.ModeSymlink
 
 		if isLink {
-			if err := processSymlinkSo(ctx, hdl, path, generated); err != nil {
+			if err := processSymlinkSo(ctx, hdl, path, generated, extraLibDirs); err != nil {
 				return err
 			}
 		}
@@ -349,7 +432,7 @@ func generateSharedObjectNameDeps(ctx context.Context, hdl SCAHandle, generated
 			for _, soname := range sonames {
 				libver := sonameLibver(soname)
 
-				if isInDir(path, libDirs) {
+				if isInDir(path, expandedLibDirs) {
 					generated.Provides = append(generated.Provides, fmt.Sprintf("so:%s=%s", soname, libver))
 				} else {
 					generated.Vendored = append(generated.Vendored, fmt.Sprintf("so:%s=%s", soname, libver))
@@ -395,7 +478,7 @@ var generateRuntimePkgConfigDeps = true
 
 // generatePkgConfigDeps generates a list of provided pkg-config package names and versions,
 // as well as dependency relationships.
-func generatePkgConfigDeps(ctx context.Context, hdl SCAHandle, generated *config.Dependencies) error {
+func generatePkgConfigDeps(ctx context.Context, hdl SCAHandle, generated *config.Dependencies, extraLibDirs []string) error {
 	log := clog.FromContext(ctx)
 	log.Infof("scanning for pkg-config data...")
 
@@ -485,7 +568,7 @@ func generatePkgConfigDeps(ctx context.Context, hdl SCAHandle, generated *config
 
 // generatePythonDeps generates a python-3.X-base dependency for packages which ship
 // Python modules.
-func generatePythonDeps(ctx context.Context, hdl SCAHandle, generated *config.Dependencies) error {
+func generatePythonDeps(ctx context.Context, hdl SCAHandle, generated *config.Dependencies, extraLibDirs []string) error {
 	log := clog.FromContext(ctx)
 	log.Infof("scanning for python modules...")
 
@@ -549,7 +632,7 @@ func generatePythonDeps(ctx context.Context, hdl SCAHandle, generated *config.De
 
 // generateRubyDeps generates a ruby-X.Y dependency for packages which ship
 // Ruby gems.
-func generateRubyDeps(ctx context.Context, hdl SCAHandle, generated *config.Dependencies) error {
+func generateRubyDeps(ctx context.Context, hdl SCAHandle, generated *config.Dependencies, extraLibDirs []string) error {
 	log := clog.FromContext(ctx)
 	log.Infof("scanning for ruby gems...")
 
@@ -596,7 +679,7 @@ func generateRubyDeps(ctx context.Context, hdl SCAHandle, generated *config.Depe
 }
 
 // For a documentation package add a dependency on man-db and / or texinfo as appropriate
-func generateDocDeps(ctx context.Context, hdl SCAHandle, generated *config.Dependencies) error {
+func generateDocDeps(ctx context.Context, hdl SCAHandle, generated *config.Dependencies, extraLibDirs []string) error {
 	log := clog.FromContext(ctx)
 	log.Infof("scanning for -doc package...")
 	if !strings.HasSuffix(hdl.PackageName(), "-doc") {
@@ -720,7 +803,7 @@ func getShbang(fp io.Reader) (string, error) {
 	return bin, nil
 }
 
-func generateShbangDeps(ctx context.Context, hdl SCAHandle, generated *config.Dependencies) error {
+func generateShbangDeps(ctx context.Context, hdl SCAHandle, generated *config.Dependencies, extraLibDirs []string) error {
 	log := clog.FromContext(ctx)
 	log.Infof("scanning for shbang deps...")
 
@@ -774,6 +857,11 @@ func generateShbangDeps(ctx context.Context, hdl SCAHandle, generated *config.De
 // Analyze runs the SCA analyzers on a given SCA handle, modifying the generated dependencies
 // set as needed.
 func Analyze(ctx context.Context, hdl SCAHandle, generated *config.Dependencies) error {
+	extraLibDirs, err := getLdSoConfDLibPaths(ctx, hdl)
+	if err != nil {
+		return err
+	}
+
 	generators := []DependencyGenerator{
 		generateSharedObjectNameDeps,
 		generateCmdProviders,
@@ -785,7 +873,7 @@ func Analyze(ctx context.Context, hdl SCAHandle, generated *config.Dependencies)
 	}
 
 	for _, gen := range generators {
-		if err := gen(ctx, hdl, generated); err != nil {
+		if err := gen(ctx, hdl, generated, extraLibDirs); err != nil {
 			return err
 		}
 	}