From 7009aebcd4c978e0f9d7cbb1f45c482104ff3019 Mon Sep 17 00:00:00 2001 From: Dmitry Vyukov Date: Tue, 16 Apr 2024 10:04:45 +0200 Subject: pkg/vminfo: add package This moves significant part of logic from the target to host (#1541), eventually this will allow us to switch target code from Go to C++. Currnetly syz-fuzzer parses a number of system files (/proc/cpuinfo) in non-trivial ways and passes that info to the host. This is problematic to recreate in C++. So instead make the fuzzer part as simple as possible: now it merely reads the gives set of files and returns contents. The rest of the parsing happens on the host (the new vminfo package). Package vminfo extracts information about the target VM. The package itself runs on the host, which may be a different OS/arch. User of the package first requests set of files that needs to be fetched from the VM (Checker.RequiredFiles), then fetches these files, and calls Checker.MachineInfo to parse the files and extract information about the VM. The information includes information about kernel modules and OS-specific info (for Linux that includes things like parsed /proc/cpuinfo). This also requires changing RPC flow between fuzzer and manager. Currently, Check call is optional and happens only for first VMs. With this change Check is always done because we need to return contents of the requested files always. The plan is to switch the rest of the pkg/host package to this scheme later: instead of some complex custom logic, we need to express it as some simple operations on the target (checking file presence, etc), and the rest of the logic on the host. --- pkg/host/machine_info_linux.go | 157 ----------------------------------------- 1 file changed, 157 deletions(-) (limited to 'pkg/host/machine_info_linux.go') diff --git a/pkg/host/machine_info_linux.go b/pkg/host/machine_info_linux.go index 8bb5e8188..fceb3ab78 100644 --- a/pkg/host/machine_info_linux.go +++ b/pkg/host/machine_info_linux.go @@ -4,171 +4,14 @@ package host import ( - "bufio" - "bytes" - "fmt" - "os" "path/filepath" - "regexp" - "strconv" "strings" ) func init() { - machineInfoFuncs = []machineInfoFunc{ - {"CPU Info", readCPUInfo}, - {"KVM", readKVMInfo}, - } - machineModulesInfo = getModulesInfo machineGlobsInfo = getGlobsInfo } -func readCPUInfo(buffer *bytes.Buffer) error { - file, err := os.Open("/proc/cpuinfo") - if err != nil { - return err - } - defer file.Close() - - scanner := bufio.NewScanner(file) - scanCPUInfo(buffer, scanner) - return nil -} - -func scanCPUInfo(buffer *bytes.Buffer, scanner *bufio.Scanner) { - keyIndices := make(map[string]int) - type keyValues struct { - key string - values []string - } - var info []keyValues - - for scanner.Scan() { - splitted := strings.Split(scanner.Text(), ":") - if len(splitted) != 2 { - continue - } - key := strings.TrimSpace(splitted[0]) - val := strings.TrimSpace(splitted[1]) - - if idx, ok := keyIndices[key]; !ok { - idx = len(keyIndices) - keyIndices[key] = idx - info = append(info, keyValues{key, []string{val}}) - } else { - info[idx].values = append(info[idx].values, val) - } - } - - for _, kv := range info { - // It is guaranteed that len(vals) >= 1 - key := kv.key - vals := kv.values - if allEqual(vals) { - fmt.Fprintf(buffer, "%-20s: %s\n", key, vals[0]) - } else { - fmt.Fprintf(buffer, "%-20s: %s\n", key, strings.Join(vals, ", ")) - } - } -} - -func allEqual(slice []string) bool { - if len(slice) == 0 { - return true - } - for i := 1; i < len(slice); i++ { - if slice[i] != slice[0] { - return false - } - } - return true -} - -func readKVMInfo(buffer *bytes.Buffer) error { - files, err := os.ReadDir("/sys/module/") - if err != nil { - return err - } - - for _, file := range files { - name := file.Name() - if !strings.HasPrefix(name, "kvm") { - continue - } - - paramPath := filepath.Join("/sys", "module", name, "parameters") - params, err := os.ReadDir(paramPath) - if err != nil { - if os.IsNotExist(err) { - continue - } - return err - } - - if len(params) == 0 { - continue - } - - fmt.Fprintf(buffer, "/sys/module/%s:\n", name) - for _, key := range params { - keyName := key.Name() - data, err := os.ReadFile(filepath.Join(paramPath, keyName)) - if err != nil { - return err - } - fmt.Fprintf(buffer, "\t%s: ", keyName) - buffer.Write(data) - } - buffer.WriteByte('\n') - } - return nil -} - -func getModuleTextAddr(moduleName string) (uint64, error) { - addrPath := filepath.Join("/sys", "module", moduleName, "sections", ".text") - addrContent, err := os.ReadFile(addrPath) - if err != nil { - return 0, fmt.Errorf("could not read module .text address file: %w", err) - } - addrString := strings.TrimSpace(string(addrContent)) - addr, err := strconv.ParseUint(addrString, 0, 64) - if err != nil { - return 0, fmt.Errorf("address parsing error in %v: %w", moduleName, err) - } - return addr, nil -} - -func getModulesInfo() ([]KernelModule, error) { - var modules []KernelModule - re := regexp.MustCompile(`(\w+) ([0-9]+) .*(0[x|X][a-fA-F0-9]+)[^\n]*`) - modulesText, _ := os.ReadFile("/proc/modules") - for _, m := range re.FindAllSubmatch(modulesText, -1) { - name := string(m[1]) - modAddr, err := strconv.ParseUint(string(m[3]), 0, 64) - if err != nil { - // /proc/modules is broken, bail out. - return nil, fmt.Errorf("address parsing error in /proc/modules: %w", err) - } - textAddr, err := getModuleTextAddr(name) - if err != nil { - // Module address unavailable, .text is probably 0. Skip this module. - continue - } - modSize, err := strconv.ParseUint(string(m[2]), 0, 64) - if err != nil { - // /proc/modules is broken, bail out. - return nil, fmt.Errorf("module size parsing error in /proc/modules: %w", err) - } - offset := modAddr - textAddr - modules = append(modules, KernelModule{ - Name: string(m[1]), - Addr: textAddr, - Size: modSize - offset, - }) - } - return modules, nil -} - func getGlobsInfo(globs map[string]bool) (map[string][]string, error) { var err error files := make(map[string][]string, len(globs)) -- cgit mrf-deployment