#lang scheme/base (require scheme/port syntax/moddep scheme/gui/dynamic) (provide gui? sandbox-init-hook sandbox-reader sandbox-input sandbox-output sandbox-error-output sandbox-propagate-breaks sandbox-coverage-enabled sandbox-namespace-specs sandbox-override-collection-paths sandbox-security-guard sandbox-path-permissions sandbox-network-guard sandbox-make-inspector sandbox-make-logger sandbox-eval-limits kill-evaluator break-evaluator set-eval-limits put-input get-output get-error-output get-uncovered-expressions make-evaluator make-module-evaluator call-with-limits with-limits exn:fail:resource? exn:fail:resource-resource) (define gui? (gui-available?)) (define-syntax mz/mr ; use a value for mzscheme, or pull a mred binding (syntax-rules () [(mz/mr mzval mrsym) (if gui? (gui-dynamic-require 'mrsym) mzval)])) ;; Configuration ------------------------------------------------------------ (define sandbox-init-hook (make-parameter void)) (define sandbox-input (make-parameter #f)) (define sandbox-output (make-parameter #f)) (define sandbox-error-output (make-parameter (lambda () (dup-output-port (current-error-port))))) (define sandbox-eval-limits (make-parameter '(30 20))) ; 30sec, 20mb (define sandbox-propagate-breaks (make-parameter #t)) (define sandbox-coverage-enabled (make-parameter #f)) (define sandbox-namespace-specs (make-parameter `(,(mz/mr make-base-namespace make-gui-namespace) #| no modules here by default |#))) (define (default-sandbox-reader source) (let loop ([l '()]) (let ([expr (read-syntax source)]) (if (eof-object? expr) (reverse l) (loop (cons expr l)))))) (define sandbox-reader (make-parameter default-sandbox-reader)) (define sandbox-override-collection-paths (make-parameter '())) (define teaching-langs '(beginner beginner-abbr intermediate intermediate-lambda advanced)) ;; Security Guard ----------------------------------------------------------- (define sep (bytes-ref (path->bytes (simplify-path "/")) 0)) ; '\' on windows (define (simplify-path* path) (if (symbol? path) #f (simplify-path (cleanse-path (path->complete-path (cond [(bytes? path) (bytes->path path)] [(string? path) (string->path path)] [else path])))))) (define permission-order '(execute write delete read exists)) (define (perm<=? p1 p2) (memq p1 (memq p2 permission-order))) ;; gets a path (can be bytes/string), returns a regexp for that path that ;; matches also subdirs (if it's a directory) (define path->bregexp (let* ([sep-re (regexp-quote (bytes sep))] [last-sep (byte-regexp (bytes-append sep-re #"?$"))] [suffix-re (bytes-append #"(?:$|" sep-re #")")]) (lambda (path) (if (byte-regexp? path) path (let* ([path (path->bytes (simplify-path* path))] [path (regexp-quote (regexp-replace last-sep path #""))]) (byte-regexp (bytes-append #"^" path suffix-re))))))) (define sandbox-path-permissions (make-parameter '() (lambda (new) (map (lambda (perm) (cons (car perm) (map path->bregexp (cdr perm)))) new)))) (define sandbox-network-guard (make-parameter (lambda (what . xs) (error what "network access denied: ~e" xs)))) (define default-sandbox-guard (let ([orig-security (current-security-guard)]) (make-security-guard orig-security (lambda (what path modes) (when path (let ([needed (let loop ([order permission-order]) (cond [(null? order) (error 'default-sandbox-guard "unknown access modes: ~e" modes)] [(memq (car order) modes) (car order)] [else (loop (cdr order))]))] [bpath (parameterize ([current-security-guard orig-security]) (path->bytes (simplify-path* path)))]) (unless (ormap (lambda (perm) (and (perm<=? needed (car perm)) (regexp-match (cadr perm) bpath))) (sandbox-path-permissions)) (error what "file access denied ~a" (cons path modes)))))) (lambda args (apply (sandbox-network-guard) args))))) (define sandbox-security-guard (make-parameter default-sandbox-guard)) (define sandbox-make-inspector (make-parameter make-inspector)) (define sandbox-make-logger (make-parameter current-logger)) ;; computes permissions that are needed for require specs (`read' for all ;; files and "compiled" subdirs, `exists' for the base-dir) (define (module-specs->path-permissions mods) (define paths (module-specs->non-lib-paths mods)) (define bases (let loop ([paths paths] [bases '()]) (if (null? paths) (reverse bases) (let-values ([(base name dir?) (split-path (car paths))]) (let ([base (simplify-path* base)]) (loop (cdr paths) (if (member base bases) bases (cons base bases)))))))) (append (map (lambda (p) `(read ,(path->bytes p))) paths) (map (lambda (b) `(read ,(build-path b "compiled"))) bases) (map (lambda (b) `(exists ,b)) bases))) ;; takes a module-spec list and returns all module paths that are needed ;; ==> ignores (lib ...) modules (define (module-specs->non-lib-paths mods) (define (lib? x) (if (module-path-index? x) (let-values ([(m base) (module-path-index-split x)]) (lib? m)) (and (pair? x) (eq? 'lib (car x))))) ;; turns a module spec to a simple one (except for lib specs) (define (simple-modspec mod) (cond [(and (pair? mod) (eq? 'lib (car mod))) #f] [(module-path? mod) (simplify-path* (resolve-module-path mod #f))] [(not (and (pair? mod) (pair? (cdr mod)))) ;; don't know what this is, leave as is #f] [(eq? 'only (car mod)) (simple-modspec (cadr mod))] [(eq? 'rename (car mod)) (simple-modspec (cadr mod))] [(and (eq? 'prefix (car mod)) (pair? (cddr mod))) (simple-modspec (caddr mod))] [else #f])) (let loop ([todo (filter values (map simple-modspec mods))] [r '()]) (cond [(null? todo) r] [(member (car todo) r) (loop (cdr todo) r)] [else (let ([path (car todo)]) (loop (filter values (map (lambda (i) (simplify-path* (resolve-module-path-index i path))) (filter (lambda (i) (and (module-path-index? i) (not (lib? i)))) (apply append (call-with-values (lambda () (module-compiled-imports (get-module-code (car todo)))) list))))) (cons path r)))]))) ;; Resources ---------------------------------------------------------------- (define-struct (exn:fail:resource exn:fail) (resource)) (define memory-accounting? (custodian-memory-accounting-available?)) (define (call-with-limits sec mb thunk) (let ([r #f] [c (make-custodian)] ;; used to copy parameter changes from the nested thread [p current-preserved-thread-cell-values]) (when (and mb memory-accounting?) (custodian-limit-memory c (* mb 1024 1024) c)) (parameterize ([current-custodian c]) ;; The nested-thread can die on a time-out or memory-limit, ;; and never throws an exception, so we never throw an error, ;; just assume the a death means the custodian was shut down ;; due to memory limit. Note: cannot copy the ;; parameterization in this case. (with-handlers ([exn:fail? (lambda (e) (unless r (set! r (cons #f 'memory))))]) (call-in-nested-thread (lambda () (define this (current-thread)) (define timer (and sec (thread (lambda () (sleep sec) ;; even in this case there are no parameters ;; to copy, since it is on a different thread (set! r (cons #f 'time)) (kill-thread this))))) (set! r (with-handlers ([void (lambda (e) (list (p) raise e))]) (call-with-values thunk (lambda vs (list* (p) values vs))))) (when timer (kill-thread timer))))) (custodian-shutdown-all c) (unless r (error 'call-with-limits "internal error")) ;; apply parameter changes first (when (car r) (p (car r))) (if (pair? (cdr r)) (apply (cadr r) (cddr r)) (raise (make-exn:fail:resource (format "with-limit: out of ~a" (cdr r)) (current-continuation-marks) (cdr r))))))) (define-syntax with-limits (syntax-rules () [(with-limits sec mb body ...) (call-with-limits sec mb (lambda () body ...))])) ;; Execution ---------------------------------------------------------------- (define (literal-identifier=? x y) (or (free-identifier=? x y) (eq? (syntax-e x) (syntax-e y)))) (define-namespace-anchor anchor) (define (make-evaluation-namespace) (let* ([specs (sandbox-namespace-specs)] [new-ns ((car specs))] [orig-ns (namespace-anchor->empty-namespace anchor)] [mods (cdr specs)]) (parameterize ([current-namespace orig-ns]) (for-each (lambda (mod) (dynamic-require mod #f)) mods)) (parameterize ([current-namespace new-ns]) (for-each (lambda (ms) (namespace-attach-module orig-ns ms)) mods)) new-ns)) (define (extract-required language requires) (let* ([requires (cond [(string? language) (cons language requires)] [(not (pair? language)) requires] [(memq (car language) '(lib file planet quote)) (cons language requires)] [(eq? (car language) 'begin) requires] [else (error 'extract-required "bad language spec: ~e" language)])]) requires)) (define (input->port inp) ;; returns #f when it can't create a port (cond [(input-port? inp) inp] [(string? inp) (open-input-string inp)] [(bytes? inp) (open-input-bytes inp)] [(path? inp) (open-input-file inp)] [else #f])) ;; Gets an input spec returns a list of syntaxes. The input can be a list of ;; sexprs/syntaxes, or a list with a single input port spec ;; (path/string/bytes) value. (define (input->code inps source n) (if (null? inps) '() (let ([p (input->port (car inps))]) (cond [(and p (null? (cdr inps))) (port-count-lines! p) (parameterize ([current-input-port p]) ((sandbox-reader) source))] [p (error 'input->code "ambiguous inputs: ~e" inps)] [else (let loop ([inps inps] [n n] [r '()]) (if (null? inps) (reverse r) (loop (cdr inps) (and n (add1 n)) ;; 1st at line#1, pos#1, 2nd at line#2, pos#2 etc ;; (starting from the `n' argument) (cons (datum->syntax #f (car inps) (list source n (and n 0) n (and n 1))) r))))])))) (define ((init-for-language language)) (cond [(or (not (pair? language)) (not (eq? 'special (car language)))) (void)] [(eq? (cadr language) 'r5rs) (read-case-sensitive #f) (read-square-bracket-as-paren #f) (read-curly-brace-as-paren #f) (read-accept-infix-dot #f)] [(memq (cadr language) teaching-langs) (read-case-sensitive #t) (read-decimal-as-inexact #f)])) ;; Returns a single (module ...) or (begin ...) expression (a `begin' list ;; will be evaluated one by one -- the language might not have a `begin'). ;; ;; FIXME: inserting `#%require's here is bad if the language has a ;; `#%module-begin' that processes top-level forms specially. ;; A more general solution would be to create anew module that exports ;; the given language plus all of the given extra requires. ;; ;; We use `#%requre' because, unlike the `require' of scheme/base, ;; it comes from `#%kernel', so it's always present through ;; transitive requires. (define (build-program language requires input-program) (let* ([body (append (if (and (pair? requires) (eq? 'begin (car requires))) (cdr requires) (map (lambda (r) (list #'#%require r)) requires)) (input->code input-program 'program 1))] [use-lang (lambda (lang) `(module program ,lang . ,body))]) (cond [(decode-language language) => (lambda (l) (use-lang l))] [(module-path? language) (use-lang language)] [(and (list? language) (eq? 'begin (car language))) (append language body)] [else (error 'make-evaluator "bad language spec: ~e" language)]))) (define (decode-language language) (cond [(and (list? language) (= 2 (length language)) (eq? (car language) 'special) (memq (cadr language) teaching-langs)) `(lib ,(format "htdp-~a.ss" (cadr language)) "lang")] [(equal? language '(special r5rs)) `(lib "lang.ss" "r5rs")] [else #f])) ;; Like a toplevel (eval `(begin ,@exprs)), but the language that is used may ;; not have a begin. (define (eval* exprs) (call-with-continuation-prompt (lambda () (if (null? exprs) (void) (let ([deftag (default-continuation-prompt-tag)]) (let loop ([expr (car exprs)] [exprs (cdr exprs)]) (if (null? exprs) (eval expr) (begin (call-with-continuation-prompt (lambda () (eval expr)) deftag (lambda (x) (abort-current-continuation deftag x))) (loop (car exprs) (cdr exprs)))))))))) (define (evaluate-program program limits uncovered!) (when uncovered! (eval `(,#'#%require scheme/private/sandbox-coverage))) ;; the actual evaluation happens under specified limits, if given (let ([run (if (and (pair? program) (eq? 'begin (car program))) (lambda () (eval* (cdr program))) (lambda () (eval program)))] [sec (and limits (car limits))] [mb (and limits (cadr limits))]) (if (or sec mb) (call-with-limits sec mb run) (run))) (let ([ns (syntax-case* program (module) literal-identifier=? [(module mod . body) (identifier? #'mod) (let ([mod #'mod]) (eval `(,#'require (quote ,mod))) (module->namespace `(quote ,(syntax-e mod))))] [_else #f])]) (when uncovered! (let ([get (let ([ns (current-namespace)]) (lambda () (eval '(get-uncovered-expressions) ns)))]) (uncovered! (list (get) get)))) (when ns (current-namespace ns)))) (define current-eventspace (mz/mr (make-parameter #f) current-eventspace)) (define make-eventspace (mz/mr void make-eventspace)) (define run-in-bg (mz/mr thread queue-callback)) (define null-input (open-input-bytes #"")) (define bg-run->thread (if gui? (lambda (ignored) ((mz/mr void eventspace-handler-thread) (current-eventspace))) values)) ;; special message values for the evaluator procedure, also inside the user ;; context they're used for function applications. (define-struct evaluator-message (msg args)) (define-syntax define-evaluator-messenger (syntax-rules () ;; with extra args [(define-evaluator-messenger (name arg ...) msg) (define (name evaluator arg ...) (evaluator (make-evaluator-message msg (list arg ...))))] [(define-evaluator-messenger (name . args) msg) (define (name evaluator . args) (evaluator (make-evaluator-message msg (list* args))))] ;; without [(define-evaluator-messenger name msg) (define name (let ([evmsg (make-evaluator-message msg '())]) (lambda (evaluator) (evaluator evmsg))))])) (define-evaluator-messenger kill-evaluator 'kill) (define-evaluator-messenger break-evaluator 'break) (define-evaluator-messenger (set-eval-limits . xs) 'limits) (define-evaluator-messenger (put-input . xs) 'input) (define-evaluator-messenger get-output 'output) (define-evaluator-messenger get-error-output 'error-output) (define-evaluator-messenger (get-uncovered-expressions . xs) 'uncovered) (define (make-evaluator* init-hook require-perms program-or-maker) (define cust (make-custodian)) (define coverage? (sandbox-coverage-enabled)) (define uncovered #f) (define input-ch (make-channel)) (define result-ch (make-channel)) (define input #f) (define output #f) (define error-output #f) (define limits (sandbox-eval-limits)) (define user-thread #t) ; set later to the thread (define orig-cust (current-custodian)) (define (user-kill) (when user-thread (let ([t user-thread]) (set! user-thread #f) (custodian-shutdown-all cust) (kill-thread t))) ; just in case (void)) (define (user-break) (when user-thread (break-thread user-thread))) (define (user-process) (with-handlers ([void (lambda (exn) (channel-put result-ch exn))]) ;; first set up the environment (init-hook) ((sandbox-init-hook)) ;; now read and evaluate the input program (evaluate-program (if (procedure? program-or-maker) (program-or-maker) program-or-maker) limits (and coverage? (lambda (es+get) (set! uncovered es+get)))) (channel-put result-ch 'ok)) ;; finally wait for interaction expressions (let loop ([n 1]) (let ([expr (channel-get input-ch)]) (when (eof-object? expr) (channel-put result-ch expr) (user-kill)) (with-handlers ([void (lambda (exn) (channel-put result-ch (cons 'exn exn)))]) (let* ([run (if (evaluator-message? expr) (lambda () (apply (evaluator-message-msg expr) (evaluator-message-args expr))) (lambda () (eval* (input->code (list expr) 'eval n))))] [sec (and limits (car limits))] [mb (and limits (cadr limits))] [run (if (or sec mb) (lambda () (with-limits sec mb (run))) run)]) (channel-put result-ch (cons 'vals (call-with-values run list))))) (loop (add1 n))))) (define (user-eval expr) (let ([r (if user-thread (begin (channel-put input-ch expr) (let loop () (with-handlers ([(lambda (e) (and (sandbox-propagate-breaks) (exn:break? e))) (lambda (e) (user-break) (loop))]) (channel-get result-ch)))) eof)]) (cond [(eof-object? r) (error 'evaluator "terminated")] [(eq? (car r) 'exn) (raise (cdr r))] [else (apply values (cdr r))]))) (define get-uncovered (case-lambda [() (get-uncovered #t)] [(prog?) (get-uncovered prog? 'program)] [(prog? src) (unless uncovered (error 'get-uncovered-expressions "no coverage information")) (let ([uncovered (if prog? (car uncovered) ((cadr uncovered)))]) (if src (filter (lambda (x) (equal? src (syntax-source x))) uncovered) uncovered))])) (define (output-getter p) (if (procedure? p) (user-eval (make-evaluator-message p '())) p)) (define input-putter (case-lambda [() (input-putter input)] [(arg) (cond [(not input) (error 'put-input "evaluator input is not 'pipe")] [(or (string? arg) (bytes? arg)) (display arg input) (flush-output input)] [(eof-object? arg) (close-output-port input)] [else (error 'put-input "bad argument: ~e" arg)])])) (define (evaluator expr) (if (evaluator-message? expr) (let ([msg (evaluator-message-msg expr)]) (case msg [(kill) (user-kill)] [(break) (user-break)] [(limits) (set! limits (evaluator-message-args expr))] [(input) (apply input-putter (evaluator-message-args expr))] [(output) (output-getter output)] [(error-output) (output-getter error-output)] [(uncovered) (apply get-uncovered (evaluator-message-args expr))] [else (error 'evaluator "internal error, bad message: ~e" msg)])) (user-eval expr))) (define linked-outputs? #f) (define (make-output what out set-out! allow-link?) (cond [(not out) (open-output-nowhere)] [(and (procedure? out) (procedure-arity-includes? out 0)) (out)] [(output-port? out) out] [(eq? out 'pipe) (let-values ([(i o) (make-pipe)]) (set-out! i) o)] [(memq out '(bytes string)) (let* ([bytes? (eq? 'bytes out)] ;; the following doesn't really matter: they're the same [out ((if bytes? open-output-bytes open-output-string))]) (set-out! (lambda () (parameterize ([current-custodian orig-cust]) (let ([buf (get-output-bytes out #t)]) (if bytes? buf (bytes->string/utf-8 buf #\?)))))) out)] [else (error 'make-evaluator "bad sandox-~a spec: ~e" what out)])) (parameterize* ; the order in these matters (;; create a sandbox context first [current-custodian cust] [current-thread-group (make-thread-group)] [current-namespace (make-evaluation-namespace)] ;; set up the IO context [current-input-port (let ([inp (sandbox-input)]) (cond [(not inp) null-input] [(input->port inp) => values] [(and (procedure? inp) (procedure-arity-includes? inp 0)) (inp)] [(eq? 'pipe inp) (let-values ([(i o) (make-pipe)]) (set! input o) i)] [else (error 'make-evaluator "bad sandbox-input: ~e" inp)]))] [current-output-port (make-output 'output (sandbox-output) (lambda (o) (set! output o)) #f)] [current-error-port (make-output 'error-output (sandbox-error-output) (lambda (o) (set! error-output o)) #t)] ;; paths [current-library-collection-paths (filter directory-exists? (append (sandbox-override-collection-paths) (current-library-collection-paths)))] [sandbox-path-permissions (append (map (lambda (p) `(read ,p)) (current-library-collection-paths)) (module-specs->path-permissions require-perms) (sandbox-path-permissions))] ;; general info [current-command-line-arguments '#()] ;; restrict the sandbox context from this point [current-security-guard (sandbox-security-guard)] [exit-handler (lambda x (error 'exit "user code cannot exit"))] [current-inspector ((sandbox-make-inspector))] [current-logger ((sandbox-make-logger))] ;; This breaks because we need to load some libraries that are trusted ;; [current-code-inspector (make-inspector)] ;; Note the above definition of `current-eventspace': in MzScheme, it ;; is an unused parameter. Also note that creating an eventspace ;; starts a thread that will eventually run the callback code (which ;; evaluates the program in `run-in-bg') -- so this parameterization ;; must be nested in the above (which is what paramaterize* does), or ;; it will not use the new namespace. [current-eventspace (make-eventspace)]) (set! user-thread (bg-run->thread (run-in-bg user-process))) (let ([r (channel-get result-ch)]) (if (eq? r 'ok) ;; initial program executed ok, so return an evaluator evaluator ;; program didn't execute (raise r))))) (define (make-evaluator language #:requires [requires null] #:allow-read [allow null] . input-program) ;; `input-program' is either a single argument specifying a file/string, or ;; multiple arguments for a sequence of expressions (let (;; make it possible to provide #f for no language and no requires [lang language] ;; make it possible to use simple paths to files to require [reqs (if (not (list? requires)) (error 'make-evaluator "bad requires: ~e" requires) (map (lambda (r) (if (or (pair? r) (symbol? r)) r `(file ,(path->string (simplify-path* r))))) requires))]) (make-evaluator* (init-for-language lang) (append (extract-required (or (decode-language lang) lang) reqs) allow) (lambda () (build-program lang reqs input-program))))) (define (make-module-evaluator input-program #:allow-read [allow null]) ;; this is for a complete module input program (let ([prog (input->code (list input-program) 'program #f)]) (unless (= 1 (length prog)) (error 'make-evaluator "expecting a single `module' program; ~a" (if (zero? (length prog)) "no program expressions given" "got more than a single expression"))) (syntax-case* (car prog) (module) literal-identifier=? [(module modname lang body ...) (make-evaluator* void allow (car prog))] [_else (error 'make-evaluator "expecting a `module' program; got ~e" (syntax->datum (car prog)))])))