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substitute-binary: Defer narinfo authentication and authorization checks.

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* guix/scripts/substitute-binary.scm (narinfo-signature->canonical-sexp):
  Catch 'gcry-error' around 'string->canonical-sexp' call, and re-raise
  as a SRFI-35 &message and &nar-signature-error.
  (narinfo-maker): Handle when SIGNATURE is #f or an invalid canonical
  sexp.
  (&nar-signature-error, &nar-invalid-hash-error): New variables.
  (assert-valid-signature): Use them.  Expect 'signature' to be a
  canonical sexp.
  (read-narinfo): Remove authentication and authorization checks.
  (%signature-line-rx): New variable.
  (assert-valid-narinfo, valid-narinfo?): New procedures.
  (guix-substitute-binary): Wrap body in 'with-error-handling'.
  [valid?]: New procedure.
  <--query>: Show only store items of narinfos that match
  'valid-narinfo?'.
  <--substitute>: Call 'assert-valid-narinfo'.
* tests/substitute-binary.scm (test-error*): Use 'test-equal'.
  (%keypair): Remove.
  (%public-key, %private-key): Load from signing-key.{pub,sec}.
  (signature-body): Add #:public-key parameter.
  (call-with-narinfo): New procedure.
  (with-narinfo): New macro.
  ("corrupt signature data", "unauthorized public key", "invalid
  signature"): Make the first argument to 'assert-valid-signature' a
  canonical sexp.
  ("invalid hash", "valid read-narinfo", "valid write-narinfo"):
  Remove.
  ("query narinfo with invalid hash", "query narinfo signed with
  authorized key", "query narinfo signed with unauthorized key",
  "substitute, invalid hash", "substitute, unauthorized key"): New
  tests.
This commit is contained in:
Ludovic Courtès 2014-03-30 22:29:35 +02:00
parent 00230df107
commit cdea30e061
2 changed files with 303 additions and 186 deletions
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125
guix/scripts/substitute-binary.scm
View File

@ -247,8 +247,19 @@ failure."
((not (= 1 maybe-number))
(leave (_ "unsupported signature version: ~a~%")
maybe-number))
(else (string->canonical-sexp
(utf8->string (base64-decode sig)))))))
(else
(let ((signature (utf8->string (base64-decode sig))))
(catch 'gcry-error
(lambda ()
(string->canonical-sexp signature))
(lambda (err . _)
(raise (condition
(&message
(message "signature is not a valid \
s-expression"))
(&nar-signature-error
(file #f)
(signature signature) (port #f)))))))))))
(x
(leave (_ "invalid format of the signature field: ~a~%") x))))
@ -273,33 +284,24 @@ must contain the original contents of a narinfo file."
((or #f "") #f)
(_ deriver))
system
(narinfo-signature->canonical-sexp signature)
(false-if-exception
(and=> signature narinfo-signature->canonical-sexp))
str)))
(define &nar-signature-error (@@ (guix nar) &nar-signature-error))
(define &nar-invalid-hash-error (@@ (guix nar) &nar-invalid-hash-error))
;;; XXX: The following function is nearly an exact copy of the one from
;;; 'guix/nar.scm'. Factorize as soon as we know how to make the latter
;;; public (see <https://lists.gnu.org/archive/html/guix-devel/2014-03/msg00097.html>).
;;; Keep this one private to avoid confusion.
(define* (assert-valid-signature signature hash port
#:optional (acl (current-acl)))
"Bail out if SIGNATURE, a string (as produced by 'canonical-sexp->string'),
doesn't match HASH, a bytevector containing the expected hash for FILE."
(let* ((&nar-signature-error (@@ (guix nar) &nar-signature-error))
(&nar-invalid-hash-error (@@ (guix nar) &nar-invalid-hash-error))
;; XXX: This is just to keep the errors happy; get a sensible
;; filename.
"Bail out if SIGNATURE, a canonical sexp, doesn't match HASH, a bytevector
containing the expected hash for FILE."
(let* (;; XXX: This is just to keep the errors happy; get a sensible
;; file name.
(file #f)
(signature (catch 'gcry-error
(lambda ()
(string->canonical-sexp signature))
(lambda (err . _)
(raise (condition
(&message
(message "signature is not a valid \
s-expression"))
(&nar-signature-error
(file file)
(signature signature) (port port)))))))
(subject (signature-subject signature))
(data (signature-signed-data signature)))
(if (and data subject)
@ -324,25 +326,42 @@ s-expression"))
(&nar-signature-error
(signature signature) (file file) (port port)))))))
(define* (read-narinfo port #:optional url (acl (current-acl)))
(define* (read-narinfo port #:optional url)
"Read a narinfo from PORT. If URL is true, it must be a string used to
build full URIs from relative URIs found while reading PORT."
(let* ((str (utf8->string (get-bytevector-all port)))
(rx (make-regexp "(.+)^[[:blank:]]*Signature:[[:blank:]].+$"))
(res (or (regexp-exec rx str)
(leave (_ "cannot find the Signature line: ~a~%")
str)))
(hash (sha256 (string->utf8 (match:substring res 1))))
(narinfo (alist->record (fields->alist (open-input-string str))
build full URIs from relative URIs found while reading PORT.
No authentication and authorization checks are performed here!"
(let ((str (utf8->string (get-bytevector-all port))))
(alist->record (call-with-input-string str fields->alist)
(narinfo-maker str url)
'("StorePath" "URL" "Compression"
"FileHash" "FileSize" "NarHash" "NarSize"
"References" "Deriver" "System"
"Signature")))
(signature (canonical-sexp->string (narinfo-signature narinfo))))
"Signature"))))
(define %signature-line-rx
;; Regexp matching a signature line in a narinfo.
(make-regexp "(.+)^[[:blank:]]*Signature:[[:blank:]].+$"))
(define* (assert-valid-narinfo narinfo #:optional (acl (current-acl)))
"Raise an exception if NARINFO lacks a signature, has an invalid signature,
or is signed by an unauthorized key."
(let* ((contents (narinfo-contents narinfo))
(res (regexp-exec %signature-line-rx contents)))
(if (not res)
(if %allow-unauthenticated-substitutes?
narinfo
(leave (_ "narinfo lacks a signature: ~s~%")
contents))
(let ((hash (sha256 (string->utf8 (match:substring res 1))))
(signature (narinfo-signature narinfo)))
(unless %allow-unauthenticated-substitutes?
(assert-valid-signature signature hash port acl))
narinfo))
(assert-valid-signature signature hash #f acl))
narinfo))))
(define (valid-narinfo? narinfo)
"Return #t if NARINFO's signature is not valid."
(false-if-exception (begin (assert-valid-narinfo narinfo) #t)))
(define (write-narinfo narinfo port)
"Write NARINFO to PORT."
@ -353,7 +372,8 @@ build full URIs from relative URIs found while reading PORT."
(call-with-output-string (cut write-narinfo narinfo <>)))
(define (string->narinfo str cache-uri)
"Return the narinfo represented by STR."
"Return the narinfo represented by STR. Assume CACHE-URI as the base URI of
the cache STR originates form."
(call-with-input-string str (cut read-narinfo <> cache-uri)))
(define (fetch-narinfo cache path)
@ -391,9 +411,9 @@ check what it has."
(string-append %narinfo-cache-directory "/"
(store-path-hash-part path)))
(define (cache-entry narinfo)
(define (cache-entry cache-uri narinfo)
`(narinfo (version 1)
(cache-uri ,(narinfo-uri-base narinfo))
(cache-uri ,cache-uri)
(date ,(time-second now))
(value ,(and=> narinfo narinfo->string))))
@ -432,7 +452,7 @@ check what it has."
(when cache
(with-atomic-file-output cache-file
(lambda (out)
(write (cache-entry narinfo) out))))
(write (cache-entry (cache-url cache) narinfo) out))))
narinfo))))
(define (remove-expired-cached-narinfos)
@ -570,6 +590,21 @@ Internal tool to substitute a pre-built binary to a local build.\n"))
(lambda (n proc lst)
(par-map proc lst))))
(define (check-acl-initialized)
"Warn if the ACL is uninitialized."
(define (singleton? acl)
;; True if ACL contains just the user's public key.
(and (file-exists? %public-key-file)
(let ((key (call-with-input-file %public-key-file
(compose string->canonical-sexp
get-string-all))))
(equal? (acl->public-keys acl) (list key)))))
(let ((acl (current-acl)))
(when (or (null? acl) (singleton? acl))
(warning (_ "ACL for archive imports seems to be uninitialized, \
substitutes may be unavailable\n")))))
(define (guix-substitute-binary . args)
"Implement the build daemon's substituter protocol."
(mkdir-p %narinfo-cache-directory)
@ -598,9 +633,13 @@ substituter disabled~%")
(force-output (current-output-port))
(with-networking
(with-error-handling ; for signature errors
(match args
(("--query")
(let ((cache (delay (open-cache %cache-url))))
(define (valid? obj)
(and (narinfo? obj) (valid-narinfo? obj)))
(let loop ((command (read-line)))
(or (eof-object? command)
(begin
@ -614,9 +653,8 @@ substituter disabled~%")
paths)
'())))
(for-each (lambda (narinfo)
(when narinfo
(format #t "~a~%" (narinfo-path narinfo))))
(filter narinfo? substitutable))
(format #t "~a~%" (narinfo-path narinfo)))
(filter valid? substitutable))
(newline)))
(("info" paths ..1)
;; Reply info about PATHS if it's in CACHE.
@ -641,7 +679,7 @@ substituter disabled~%")
(format #t "~a\n~a\n"
(or (narinfo-file-size narinfo) 0)
(or (narinfo-size narinfo) 0)))
(filter narinfo? substitutable))
(filter valid? substitutable))
(newline)))
(wtf
(error "unknown `--query' command" wtf)))
@ -651,6 +689,9 @@ substituter disabled~%")
(let* ((cache (delay (open-cache %cache-url)))
(narinfo (lookup-narinfo cache store-path))
(uri (narinfo-uri narinfo)))
;; Make sure it is signed and everything.
(assert-valid-narinfo narinfo)
;; Tell the daemon what the expected hash of the Nar itself is.
(format #t "~a~%" (narinfo-hash narinfo))
@ -687,7 +728,7 @@ substituter disabled~%")
(("--help")
(show-help))
(opts
(leave (_ "~a: unrecognized options~%") opts)))))
(leave (_ "~a: unrecognized options~%") opts))))))
;;; Local Variables:

182
tests/substitute-binary.scm
View File

@ -24,7 +24,13 @@
#:use-module (guix nar)
#:use-module (guix pk-crypto)
#:use-module (guix pki)
#:use-module (guix config)
#:use-module ((guix store) #:select (%store-prefix))
#:use-module ((guix build utils) #:select (delete-file-recursively))
#:use-module (rnrs bytevectors)
#:use-module (rnrs io ports)
#:use-module (web uri)
#:use-module (srfi srfi-26)
#:use-module (srfi srfi-34)
#:use-module ((srfi srfi-64) #:hide (test-error)))
@ -36,52 +42,37 @@
;;; XXX: Replace with 'test-error' from SRFI-64 as soon as it allow us to
;;; catch specific exceptions.
(define-syntax-rule (test-error* name exp)
(test-assert name
(test-equal name
1
(catch 'quit
(lambda ()
exp
#f)
(const #t))))
(define %keypair
;; (display (canonical-sexp->string
;; (generate-key "(genkey (rsa (nbits 4:1024)))")))
(string->canonical-sexp
"(key-data
(public-key
(rsa
(n #00D74A00F16DD109A8E773291856A4EF9EE2C2D975E0BC207EA24245C9CFE39E32D8BA5442A2720A57E3A9D9E55E596A8B19CB2EF844E5E859362593914BD626433C887FB798AE87E1DA95D372DFC81E220B8802B04CEC818D9B6B4E2108817755AEBAC23D2FD2B0AB82A52FD785194F3C2D7B9327212588DB74D464EEE5DC9F5B#)
(e #010001#)
)
)
(private-key
(rsa
(n #00D74A00F16DD109A8E773291856A4EF9EE2C2D975E0BC207EA24245C9CFE39E32D8BA5442A2720A57E3A9D9E55E596A8B19CB2EF844E5E859362593914BD626433C887FB798AE87E1DA95D372DFC81E220B8802B04CEC818D9B6B4E2108817755AEBAC23D2FD2B0AB82A52FD785194F3C2D7B9327212588DB74D464EEE5DC9F5B#)
(e #010001#)
(d #40E6D963EF143E9241BC10DE7A785C988C89EB1EC33253A5796AFB38FCC804D015500EC8CBCA0F5E318EE9D660DC19E7774E2E89BFD38379297EA87EFBDAC24BA32EE5339215382B2C89F5A817FD9131CA8E8A0A70D58E26E847AD0C447053671A6B2D7746087DE058A02B17701752B8A36EB414435921615AE7CAA8AC48E451#)
(p #00EA88C0C19FE83C09285EF49FF88A1159357FD870031C20F15EF5103FBEB10925299BCA197F7143D6792A1BA7044EDA572EC94FA6B00889F9857216CF5B984403#)
(q #00EAFE541EE9E0531255A85CADBEF64D5F679766D7209F521ADD131CF4B7DA9DF5414901342A146EE84FAA1E35EE0D0F6CE3F5F25989C0D1E9FA5B678D78C113C9#)
(u #59C80FA2C48181F6855691C9D443619BA46C7648056E081697C370D8096E8EF165122D5E55F8FD6A2DCC404FA8BDCDC1FD20B4D76A433F25E8FD6901EC2DBDAD#)
)
)
)"))
(lambda (key value)
value))))
(define %public-key
(find-sexp-token %keypair 'public-key))
;; This key is known to be in the ACL by default.
(call-with-input-file (string-append %config-directory "/signing-key.pub")
(compose string->canonical-sexp get-string-all)))
(define %private-key
(find-sexp-token %keypair 'private-key))
(call-with-input-file (string-append %config-directory "/signing-key.sec")
(compose string->canonical-sexp get-string-all)))
(define (signature-body str)
(define* (signature-body str #:key (public-key %public-key))
"Return the signature of STR as the base64-encoded body of a narinfo's
'Signature' field."
(base64-encode
(string->utf8
(canonical-sexp->string
(signature-sexp (bytevector->hash-data (sha256 (string->utf8 str))
#:key-type 'rsa)
%private-key
%public-key)))))
public-key)))))
(define %signature-body
;; Body of the signature of the word "secret".
(signature-body "secret"))
(define %wrong-public-key
@ -93,6 +84,8 @@
)"))
(define %wrong-signature
;; 'Signature' field where the public key doesn't match the private key used
;; to make the signature.
(let* ((body (string->canonical-sexp
(utf8->string
(base64-decode %signature-body))))
@ -106,14 +99,18 @@
(string-append "1;irrelevant;" body*)))
(define* (signature str #:optional (body %signature-body))
"Return the 'Signature' field value with STR as the version part and BODY as
the actual base64-encoded signature part."
(string-append str ";irrelevant;" body))
(define %signature
;; Signature computed over the word "secret".
(signature "1" %signature-body))
(define %acl
(public-keys->acl (list %public-key)))
(test-begin "substitute-binary")
(test-error* "not a number"
@ -127,7 +124,7 @@
(define-syntax-rule (test-error-condition name pred exp)
(test-assert name
(guard (condition ((pred condition) (pk 'true condition #t))
(guard (condition ((pred condition) #t)
(else #f))
exp
#f)))
@ -135,63 +132,142 @@
;;; XXX: Do we need a better predicate hierarchy for these tests?
(test-error-condition "corrupt signature data"
nar-signature-error?
(assert-valid-signature "invalid sexp" "irrelevant"
(assert-valid-signature (string->canonical-sexp "(foo bar baz)") "irrelevant"
(open-input-string "irrelevant")
%acl))
(test-error-condition "unauthorized public key"
nar-signature-error?
(assert-valid-signature (canonical-sexp->string
(narinfo-signature->canonical-sexp %signature))
(assert-valid-signature (narinfo-signature->canonical-sexp %signature)
"irrelevant"
(open-input-string "irrelevant")
(public-keys->acl '())))
(test-error-condition "invalid signature"
nar-signature-error?
(assert-valid-signature (canonical-sexp->string
(narinfo-signature->canonical-sexp
%wrong-signature))
(assert-valid-signature (narinfo-signature->canonical-sexp
%wrong-signature)
(sha256 (string->utf8 "secret"))
(open-input-string "irrelevant")
(public-keys->acl (list %wrong-public-key))))
(define %narinfo
"StorePath: /nix/store/foo
(string-append "StorePath: " (%store-prefix)
"/aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa-foo
URL: nar/foo
Compression: bzip2
NarHash: sha256:7
NarSize: 42
References: bar baz
Deriver: foo.drv
System: mips64el-linux\n")
Deriver: " (%store-prefix) "/foo.drv
System: mips64el-linux\n"))
(define (narinfo sig)
"Return a narinfo with SIG as its 'Signature' field."
(format #f "~aSignature: ~a~%" %narinfo sig))
(define %signed-narinfo
;; Narinfo with a valid signature.
(narinfo (signature "1" (signature-body %narinfo))))
(test-error-condition "invalid hash"
(define (call-with-narinfo narinfo thunk)
"Call THUNK in a context where $GUIX_BINARY_SUBSTITUTE_URL is populated with
a file for NARINFO."
(let ((narinfo-directory (and=> (string->uri (getenv
"GUIX_BINARY_SUBSTITUTE_URL"))
uri-path))
(cache-directory (string-append (getenv "XDG_CACHE_HOME")
"/guix/substitute-binary/")))
(dynamic-wind
(lambda ()
(when (file-exists? cache-directory)
(delete-file-recursively cache-directory))
(call-with-output-file (string-append narinfo-directory
"/nix-cache-info")
(lambda (port)
(format port "StoreDir: ~a\nWantMassQuery: 0\n"
(%store-prefix))))
(call-with-output-file (string-append narinfo-directory "/"
"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
".narinfo")
(cut display narinfo <>))
(set! (@@ (guix scripts substitute-binary)
%allow-unauthenticated-substitutes?)
#f))
thunk
(lambda ()
(delete-file-recursively cache-directory)))))
(define-syntax-rule (with-narinfo narinfo body ...)
(call-with-narinfo narinfo (lambda () body ...)))
(test-equal "query narinfo with invalid hash"
;; The hash of '%signature' is computed over the word "secret", not
;; '%narinfo'.
nar-invalid-hash-error?
(read-narinfo (open-input-string (narinfo %signature))
"https://example.com" %acl))
""
(test-assert "valid read-narinfo"
(read-narinfo (open-input-string %signed-narinfo)
"https://example.com" %acl))
(with-narinfo (narinfo %signature)
(string-trim-both
(with-output-to-string
(lambda ()
(with-input-from-string (string-append "have " (%store-prefix)
"/aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa-foo")
(lambda ()
(guix-substitute-binary "--query"))))))))
(test-equal "valid write-narinfo"
%signed-narinfo
(call-with-output-string
(lambda (port)
(write-narinfo (read-narinfo (open-input-string %signed-narinfo)
"https://example.com" %acl)
port))))
(test-equal "query narinfo signed with authorized key"
(string-append (%store-prefix) "/aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa-foo")
(with-narinfo %signed-narinfo
(string-trim-both
(with-output-to-string
(lambda ()
(with-input-from-string (string-append "have " (%store-prefix)
"/aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa-foo")
(lambda ()
(guix-substitute-binary "--query"))))))))
(test-equal "query narinfo signed with unauthorized key"
"" ; not substitutable
(with-narinfo (narinfo (signature "1"
(signature-body %narinfo
#:public-key %wrong-public-key)))
(string-trim-both
(with-output-to-string
(lambda ()
(with-input-from-string (string-append "have " (%store-prefix)
"/aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa-foo")
(lambda ()
(guix-substitute-binary "--query"))))))))
(test-error* "substitute, invalid hash"
;; The hash of '%signature' is computed over the word "secret", not
;; '%narinfo'.
(with-narinfo (narinfo %signature)
(guix-substitute-binary "--substitute"
(string-append (%store-prefix)
"/aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa-foo")
"foo")))
(test-error* "substitute, unauthorized key"
(with-narinfo (narinfo (signature "1"
(signature-body %narinfo
#:public-key %wrong-public-key)))
(guix-substitute-binary "--substitute"
(string-append (%store-prefix)
"/aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa-foo")
"foo")))
(test-end "substitute-binary")
(exit (= (test-runner-fail-count (test-runner-current)) 0))
;;; Local Variables:
;;; eval: (put 'with-narinfo 'scheme-indent-function 1)
;;; eval: (put 'test-error* 'scheme-indent-function 1)
;;; End: