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dmng.go
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dmng.go
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// Copyright (c) 2023 Unibg Seclab (https://seclab.unibg.it)
//
// Permission is hereby granted, free of charge, to any person obtaining a copy of
// this software and associated documentation files (the "Software"), to deal in
// the Software without restriction, including without limitation the rights to
// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
// the Software, and to permit persons to whom the Software is furnished to do so,
// subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 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.
package main
import (
"bytes"
"errors"
"fmt"
"io/ioutil"
"os"
"os/user"
"path"
"strings"
dmng "dmng/utils"
"github.com/akamensky/argparse"
)
// error check shorthand that panics
func checkErr(err error) {
if err != nil {
panic(err)
}
}
func init() {
user, err := user.Current()
checkErr(err)
PROFILES_FOLDER = "/home/" + user.Username + "/.dmng_profiles"
}
// security profiles folder
var PROFILES_FOLDER string
type Permission = dmng.Permission
type PolicyRow = dmng.PolicyRow
type SecurityProfile = dmng.SecurityProfile
type PolicyIdentifier = dmng.PolicyIdentifier
// parser debug flag
var DEBUG_PARSER bool = false
// active context
var CTX string
// active policy
var POL int
// command
var CMD string
// extended command
var EXTD_CMD string
// permission (mask)
var PERMISSION string
func main() {
/*
CMD LINE PARSER AND ARGUMENTS
*/
parser := argparse.NewParser("dmng", "A command line tool to manage the "+
"requirements associated with a binary (or script)")
// 1. extended arguments
debug := parser.Flag("", "debug",
&argparse.Options{
Help: "Print additional information to console",
})
serialize := parser.String("", "serialize",
&argparse.Options{
Required: false,
Help: "Serialize the policy to a given filename",
})
fixdepth := parser.String("", "fixdepth",
&argparse.Options{
Required: false,
Help: "Update the `max_depth` attribute of a given policy according" +
" to the content of `Deny`",
})
setctx := parser.String("", "setcontext",
&argparse.Options{
Required: false,
Help: "Set the active policy context of a command. A policy context is active" +
" until it's replaced by another one.",
})
getctx := parser.Flag("", "getcontext",
&argparse.Options{
Required: false,
Help: "Get the active policy context",
})
profile := parser.Flag("", "profile",
&argparse.Options{
Required: false,
Help: "Print to console the profile of a command",
})
// 2. abbreviated arguments
command := parser.String("c", "command",
&argparse.Options{
Required: false,
Help: "Set the command name",
})
add := parser.String("a", "add",
&argparse.Options{
Required: false,
Help: "Add a requirement (the absolute path) to the active policy",
})
remove := parser.String("r", "remove",
&argparse.Options{
Required: false,
Help: "Remove a requirement from the active policy. SQL-like requirement" +
" patterns supported",
})
update := parser.String("u", "update",
&argparse.Options{
Required: false,
Help: "Update the permission associated with a requirement in the active policy." +
" SQL-like requirement patterns supported",
})
permission := parser.String("p", "permission",
&argparse.Options{
Required: false,
Help: "Set the Unix-like permission mask. Valid symbols are `r`, `w`, `x`, `-`." +
" Order matters",
})
deny := parser.Flag("d", "deny",
&argparse.Options{
Help: "Flag to add/remove/update a requirement to/from the deny list. To be used" +
" in conjunction with `--add`, `--remove`, `--update` or `--wipe`",
})
inspect := parser.Flag("i", "inspect",
&argparse.Options{
Required: false,
Help: "Print to console the entries stored by the current policy",
})
trace := parser.Flag("t", "trace",
&argparse.Options{
Required: false,
Help: "Trace a program and automatically add requirements to the active policy",
})
simulate := parser.Float("s", "simulate",
&argparse.Options{
Required: false,
Help: "Set dynamic tracing. To be used in conjuction with `--trace`. " +
"Requires the simulation time in seconds (e.g., 1, 2, 3.5)",
})
build := parser.Flag("b", "build",
&argparse.Options{
Required: false,
Help: "Build the security profile for the active policy",
})
goal := parser.Int("g", "goal",
&argparse.Options{
Required: false,
Help: "Set the maximum number of entries in the security profile (default 30)." +
" To be used in conjunction with `--goal`",
})
wipe := parser.Flag("w", "wipe",
&argparse.Options{
Required: false,
Help: "Wipe the entries associated with the active policy. If no other option" +
" is provided, wipes the whole DB",
})
example := parser.Flag("e", "example",
&argparse.Options{
Required: false,
Help: "Print some usage examples",
})
/*
READ CMD LINE INPUT
*/
err := parser.Parse(os.Args)
if err != nil {
fmt.Println(parser.Usage(err))
fmt.Printf("[Error] invalid input\n")
failure()
}
/*
UTILITY
*/
if *example {
printUsageInfo()
success()
} else {
createDB()
if *debug {
enableDebugMode()
}
if *serialize != "" {
BuildProfiles(*goal, *serialize)
success()
}
if *fixdepth != "" {
FixPolicy(*fixdepth)
success()
}
if *permission != "" {
PERMISSION = strings.ToLower(*permission)
}
if *command != "" {
// support also space separated shell commands
sntzCmd := preprocessCommand(strings.Trim(*command, " "))
cmdKeywords := strings.Split(sntzCmd, " ")
CMD = cmdKeywords[0]
EXTD_CMD = CMD
if len(cmdKeywords) > 1 {
EXTD_CMD = strings.Join(cmdKeywords, " ")
}
fmt.Printf("[*] Command to trace: `%s`\n", EXTD_CMD)
if *setctx != "" {
CTX = *setctx
updateContext()
success()
}
if *getctx {
getContext()
success()
}
retrieveActiveContext()
retrieveActivePolicy()
if *trace {
if *simulate != 0.0 {
traceDynamic(*simulate)
} else {
traceStatic()
}
success()
} else if *wipe {
isDeny := *deny
removeActivePolicy(isDeny)
success()
} else if *build {
BuildSecurityProfile(*goal)
success()
} else if *inspect {
inspectCommand()
success()
} else if *profile {
printProfile()
success()
} else if *add != "" {
// check
if *remove != "" {
fmt.Println("[Error] Cannot use `--add` and `--remove` at the same time")
failure()
}
path := *add
isDeny := *deny
addPath(path, isDeny)
success()
} else if *remove != "" {
path := *remove
isDeny := *deny
removePath(path, isDeny)
success()
} else if *update != "" {
path := *update
updatePath(path)
success()
}
} else if *wipe {
wipeDB()
success()
} else if *getctx {
getAvailableContexts()
success()
}
}
// you shouldn't end up here
printUsageInfo()
failure()
}
/*
UTILITY FUNCTIONS
*/
func success() {
os.Exit(0)
}
func failure() {
os.Exit(1)
}
func getContext() {
c := dmng.GetActiveContext(CMD)
fmt.Printf("[*] CMD: %s, CTX: %s\n", CMD, c)
}
func getAvailableContexts() {
data := *dmng.GetAvailableContexts()
for k, v := range data {
fmt.Printf("[*] CMD %s: , available CTX: |", k)
for _, e := range v {
fmt.Printf(" %s |", e)
}
fmt.Println()
}
}
func printUsageInfo() {
user, err := user.Current()
checkErr(err)
infoPath := "/home/" + user.Username + "/.config/dmng/usage.txt"
info, err := ioutil.ReadFile(infoPath)
checkErr(err)
fmt.Println(string(info))
}
func createDB() {
// create the database if it doesn't exists
dmng.CreateDB()
}
func enableDebugMode() {
// propagate debug mode
dmng.DEBUG_COMMAND = true
dmng.DEBUG_DB = true
dmng.DEBUG_TRUNCATE = true
dmng.DEBUG_SERIALIZER = true
DEBUG_PARSER = true
}
func updateContext() {
// update the profiles-DB cache
dmng.UpdateCacheContext(CMD, CTX)
// set a new active policy in the profiles-DB
dmng.UpdatePolicyContext(CMD, CTX)
// get the active policy context
POL = dmng.GetActivePolicyContext(CMD, CTX)
fmt.Printf("[*] Set CTX: %s, CMD: %s, POL: %d\n", CTX, CMD, POL)
}
func retrieveActiveContext() {
// get the active context from the profiles-DB
CTX = dmng.GetActiveContext(CMD)
}
// Preprocesses multi-keywords commands sanitizing file paths
func preprocessCommand(cmd string) string {
// multi-string check
keywords := strings.Split(cmd, " ")
if len(keywords) == 1 {
return cmd
}
var sntzCmd strings.Builder
// copy program name
fmt.Fprintf(&sntzCmd, "%s ", keywords[0])
cwd, err := os.Getwd()
if err != nil {
fmt.Println("[E] Unable to get the current folder")
failure()
}
basicOps := map[string]bool{
">": true,
">>": true,
"<": true,
"<<": true,
"|": true,
}
// for each token in keywords
for _, tok := range keywords[1:] {
_, err := os.Stat(tok)
// check if tok is file
if _, ok := basicOps[tok]; !ok && err == nil {
// make the path global and sanitize it
if !strings.HasPrefix(tok, "/") {
tok = cwd + "/" + tok
}
tok = path.Clean(tok)
}
fmt.Fprintf(&sntzCmd, "%s ", tok)
// else resolve the file and sanitize it
}
return sntzCmd.String()[:len(sntzCmd.String())-1]
}
func retrieveActivePolicy() {
// get the active policy from the profiles-DB
POL = dmng.GetActivePolicyContext(CMD, CTX)
}
func traceDynamic(simulationTime float64) {
// add to the profiles-DB the chain-of-links to the executable
dmng.GetType(POL, CMD, false)
fmt.Printf("[*] Tracing command with `strace`:\t%s\n", CMD)
dmng.Strace(POL, EXTD_CMD, simulationTime)
}
// Retrieves all the requirements found for the given `command` and
// adds them to the profiles-DB
func traceStatic() {
// get the path and the type associated with the command
command_path, program_type := dmng.GetType(POL, CMD, true)
help_wrapper := "[*] Command wrapper found, try the `--simulate` option"
help_tracepath := "[*] No direct path to the ELF program, try the `--simulate` option"
// print info to console
fmt.Printf("[*] Command path:\t%s\n", command_path)
switch program_type {
case dmng.ELFProgram:
// get the transient libraries of an ELF file
dmng.ELFHandler(POL, CMD, command_path)
case dmng.BourneShellScript:
fmt.Println(help_wrapper)
case dmng.PosixShellScript:
fmt.Println(help_wrapper)
case -1:
// undetermined program type
fmt.Println(help_tracepath)
}
success()
}
func removeActivePolicy(isDeny bool) {
if isDeny {
dmng.WipeDenials(POL)
} else {
dmng.RemoveCommand(POL, CMD, CTX)
}
}
// Builds the security profiles for all the commands in the profiles-DB
// and writes the policy file. `goal` is the maximum number of
// permissioned targets in the permission Trie of each policy. `fname`
// is the filename to store the marshaled policy.
func BuildProfiles(goal int, fname string) {
// for each policy in the profiles-DB
pids := dmng.GetAllAvailablePolicies()
// profiles mapping 1:1 policies
var profiles []SecurityProfile
// build the security profile for each policy
for _, pid := range pids {
// set the vars POL, CMD and CTX
POL = pid.Pol
CMD = pid.Cmd
CTX = pid.Ctx
profiles = append(profiles, BuildSecurityProfile(goal))
fmt.Printf("[*] Policy for CMD: %s and CTX: %s created successfully\n", CMD, CTX)
}
// ensure the dmng_profiles folder is available
createProfilesFolder(fname)
// serialize the policies
dmng.SerializePolicy(pids, profiles, PROFILES_FOLDER, fname)
fmt.Printf("[*] Policy serialized to file %s\n", dmng.POLICY_DIR+"/"+fname)
}
// Updates the content of a serialized policy fixing possible errors in
// the `max_depth` attribute. `pname` is the policy name.
func FixPolicy(pname string) {
dmng.FixDepth(PROFILES_FOLDER, pname)
fmt.Printf("[*] Policy %s updated successfully\n", dmng.POLICY_DIR+"/"+pname)
}
// Builds the security profile of a command, possibly reducing the
// cardinality of requirements to less than or equal to `goal`. Returns
// the entries in the profile created
func BuildSecurityProfile(goal int) SecurityProfile {
if goal < 0 {
fmt.Println("[Error] Invalid number of permissions (goal) found")
failure()
}
if goal == 0 {
// set default value
goal = 50
}
var lof []PolicyRow
// retrieve requirements
lof = dmng.GetCommandRequirements(POL)
// build command Trie
commandTrie := dmng.CreateTrie(CMD, lof)
if DEBUG_PARSER {
fmt.Printf("[D] Initial number of permissioned nodes: %d\n",
commandTrie.CountPermissionedNodes())
}
// print Trie before pruning
var profile_buffer bytes.Buffer
if DEBUG_PARSER {
fmt.Println("[D] Print Trie:")
commandTrie.PrintTrie(&profile_buffer, 0)
fmt.Print(profile_buffer.String())
}
// prune Trie
successful_pruning := commandTrie.PruneTrie(goal)
// print Trie after pruning
if DEBUG_PARSER {
fmt.Println("[D] Print Trie:")
profile_buffer = bytes.Buffer{}
commandTrie.PrintTrie(&profile_buffer, 0)
fmt.Print(profile_buffer.String())
}
if !successful_pruning {
fmt.Printf("[W] Pruning goal not achieved "+
"(still %d nodes)!\n", commandTrie.CountPermissionedNodes())
}
if dmng.DEBUG_TRUNCATE {
// print new profile permissions
fmt.Printf("[*] New %s profile created successfully\n", CMD)
profile_buffer = bytes.Buffer{}
commandTrie.PrintTrieProfile(&profile_buffer)
fmt.Print(profile_buffer.String())
}
// wipe old security profile
dmng.WipeSecurityProfile(POL)
// retrieve the new security profile and save it into the profiles-DB
sp := SecurityProfile{}
commandTrie.GetSecurityProfile(&sp.Entries)
dmng.CreateSecurityProfile(POL, &sp.Entries)
return sp
}
// Creates the policy folder. Removes the old policy serialization
// (`fname`) if present
func createProfilesFolder(fname string) {
// check if the dmng_profiles directory already exists
if _, err := os.Stat(PROFILES_FOLDER); errors.Is(err, os.ErrNotExist) {
err := os.Mkdir(PROFILES_FOLDER, 0750)
if err != nil {
panic("Unable to create the `" + PROFILES_FOLDER +
"` directory, check your permissions")
}
} else {
err := os.Remove(dmng.POLICY_DIR + "/" + fname)
if err != nil && !errors.Is(err, os.ErrNotExist) {
panic(err)
}
}
// check folder permissions
err := os.Chmod(PROFILES_FOLDER, 0750)
checkErr(err)
}
func printProfile() {
rows := dmng.GetSecurityProfile(POL)
fmt.Printf("[*] Security profile CTX: %s, CMD: %s, POL: %d\n", CTX, CMD, POL)
for i, r := range rows {
fmt.Printf(" %d,\t%s,\t%s\n", i, r.Perm.ToString(), r.Req)
}
}
func inspectCommand() {
// apply mask filter if provided
if PERMISSION != "" {
if !dmng.IsValidMask(PERMISSION) {
fmt.Println("[Error] Invalid permission or permission mask found")
failure()
}
fmt.Printf("[*] Inspect command %s, mask %s\n", CMD, PERMISSION)
fmt.Printf("\n Permissions (CTX: %s, POL: %d):\n", CTX, POL)
dmng.PrintPermissionedRequirements(POL, PERMISSION)
} else {
mask := "___ => ANY"
fmt.Printf("[*] Inspect command %s, mask %s\n", CMD, mask)
fmt.Printf("\n Permissions (CTX: %s, POL: %d):\n", CTX, POL)
// print the requirements
dmng.PrintRequirements(POL)
}
// print the denials
fmt.Printf("\n Denials (CTX: %s, POL: %d):\n", CTX, POL)
dmng.PrintDenials(POL)
}
// Adds a path to the list of requirements of deny
func addPath(path string, isDeny bool) {
// check path
if !dmng.IsValidRequirement(path) {
fmt.Println("[Error] Invalid requirement (file or directory not found)")
failure()
}
if isDeny {
if PERMISSION != "" {
fmt.Println("[Error] Permission not needed with a deny.")
failure()
}
dmng.AddDenial(POL, path)
fmt.Println("[*] Denial for command " + CMD + " added")
} else {
if !dmng.IsValidPerm(PERMISSION) {
fmt.Println("[Error] Invalid permission found")
failure()
}
perm := int(dmng.InitPermission(PERMISSION).ToUnixInt())
dmng.AddRequirement(POL, path, perm, dmng.USER_INPUT)
fmt.Println("[*] Requirement of command " + CMD + " added")
}
}
// Removes a path from the list of requirements or deny
func removePath(path string, isDeny bool) {
if isDeny {
// check
if PERMISSION != "" {
fmt.Println("[Error] Permission not needed with a deny.")
failure()
}
dmng.RemoveDenial(POL, path)
fmt.Println("[*] Denial for command " + CMD + " removed")
} else {
if PERMISSION == "" {
fmt.Println("[Error] `--remove` without permission regex is unsupported, use `--wipe` instead")
failure()
} else {
// check permission regex is valid
if !dmng.IsValidPerm(PERMISSION) {
fmt.Println("[Error] Invalid permission or permission regex found")
failure()
}
perm := int(dmng.InitPermission(PERMISSION).ToUnixInt())
// NB we don't check path to be a valid SQL pattern
dmng.RemovePermissionedRequirements(POL, path, perm)
}
}
}
// Updates a path in the list of requirements
func updatePath(path string) {
// check
if PERMISSION != "" {
if !dmng.IsValidPerm(PERMISSION) {
fmt.Println("[Error] Invalid permission found")
failure()
}
perm := int(dmng.InitPermission(PERMISSION).ToUnixInt())
// NB, we don't check *update to be a valid SQL pattern
dmng.UpdateRequirementPermission(POL, path, perm)
} else {
fmt.Println("[Error] A permission is required if you want to perform an update")
failure()
}
}
func wipeDB() {
// wipe profiles-DB
dmng.WipeProfiles()
}