security-and-privacy/gnupg
security-and-privacy/gnupg
1
0
Fork 0
mirror of git://git.gnupg.org/gnupg.git synced 2025-01-21 14:47:03 +01:00
Code Activity

Stricter test of allowed signature packet compositions.

Browse Source 
There is still one problem to solve.
This commit is contained in:
Werner Koch 2006-03-06 21:28:25 +00:00
parent a200f76dcf
commit 3e08d87168
7 changed files with 304 additions and 128 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
NEWS
View File

@ -51,6 +51,10 @@ Noteworthy changes in version 1.4.3
are HTTP and finger, plus anything that cURL supplies, if built
with cURL support.
* Files containing several signed messages are not anymore allowed
because there is no clean way to report the status of such files
back to the caller.
Noteworthy changes in version 1.4.2 (2005-07-26)
------------------------------------------------

10
checks/ChangeLog
View File

@ -1,3 +1,13 @@
2006-03-06 Werner Koch <wk@g10code.com>
* defs.inc: Print error messages also to stderr. Allow for
verbose environment variable.
(linefeed): New.
(suspend_error, resume_error): New.
* verify.test: More tests.
* multisig.test: Better error printing.
(sig_1ls1ls_valid, sig_ls_valid): Moved to the non-valid group.
2006-02-14 Werner Koch <wk@gnupg.org>
* verify.test: New.

34
checks/defs.inc
View File

@ -31,22 +31,52 @@ LANGUAGE=
LC_ALL=
LC_MESSAGES=
# Internal use.
defs_stop_on_error=no
defs_error_seen=no
#--------------------------------
#------ utility functions -------
#--------------------------------
fatal () {
echo "$pgmname: fatal:" $* >&2
[ -n "${BASH_VERSION+set}" ] && echo "$pgmname: fatal:" $* >&5
exit 1;
}
error () {
echo "$pgmname:" $* >&2
exit 1
defs_error_seen=yes
[ -n "${BASH_VERSION+set}" ] && echo "$pgmname:" $* >&5
if [ x$defs_stop_on_error != xyes ]; then
exit 1
fi
}
# Call this at the start of a test and resume_error at the end to keep
# on running all subtests without immediately exiting on error.
suspend_error () {
defs_stop_on_error=yes
}
resume_error () {
if [ x$defs_error_seen = xyes ]; then
exit 1
fi
defs_stop_on_error=no
defs_error_seen=no
}
info () {
echo "$pgmname:" $* >&2
if [ -n "${verbose+set}" ]; then
[ -n "${BASH_VERSION+set}" ] && echo "$pgmname:" $* >&5
fi
}
linefeed () {
echo >&2
}
@ -126,6 +156,8 @@ fi
GPG="../g10/gpg --no-permission-warning --homedir . "
[ -n "${BASH_VERSION+set}" ] && exec 5>/dev/stderr
exec 2> ${pgmname}.log
:

40
checks/multisig.test
View File

@ -2,12 +2,14 @@
# Check that gpg verifies only signatures where there is no ambiguity
# in the order of packets. Needs the Demo Keys Lima and Mike.
# Note: We do son't support multiple signaturess anymore thus thsi test is
# not really needed becuase verify could do the same. We keep it anyway.
. $srcdir/defs.inc || exit 3
# (variable intialization was created using:
# for i in files; do echo "`echo $i | sed 's,[.-],_,g'`='"; \
# gpg --no-version --enarmor <$i | grep -v ^Comment:; echo "'" ; done
# )
suspend_error
sig_1ls1ls_valid='
-----BEGIN PGP ARMORED FILE-----
@ -119,13 +121,11 @@ cnksIEkgY2FuJ3QgZG8gdGhhdAo=
-----END PGP ARMORED FILE-----
'
save_IFS="${IFS}"
IFS=""
for i in "$sig_1ls1ls_valid" "$sig_ls_valid" "$sig_sl_valid"; do
echo "$i" | ./gpg_dearmor >x
IFS="${save_IFS}"
$GPG --verify x 2>/dev/null || error "valid is invalid"
IFS=""
for i in sig_sl_valid ; do
eval "(IFS=; echo \"\$$i\")" | ./gpg_dearmor >x
$GPG --verify x 2>/dev/null || error "valid is invalid ($i)"
linefeed
done
#for i in "$sig_11lss_valid_but_is_not" "$sig_11lss11lss_valid_but_is_not" \
# "$sig_ssl_valid_but_is_not"; do
@ -133,13 +133,13 @@ done
# $GPG --verify <x 2>/dev/null || error "valid is invalid"
#done
# without the +e ksh seems to terminate the for loop
set +e
for i in "$sig_1lsls_invalid" "$sig_lsls_invalid" \
"$sig_lss_invalid" "$sig_slsl_invalid" ; do
echo "$i" | ./gpg_dearmor >x
IFS="${save_IFS}"
$GPG --verify <x 2>/dev/null && error "invalid is valid"
IFS=""
for i in sig_1ls1ls_valid sig_ls_valid \
sig_1lsls_invalid sig_lsls_invalid \
sig_lss_invalid sig_slsl_invalid ; do
eval "(IFS=; echo \"\$$i\")" | ./gpg_dearmor >x
$GPG --verify <x 2>/dev/null && error "invalid is valid ($i)"
linefeed
done
IFS="${save_IFS}"
resume_error

120
checks/verify.test
View File

@ -2,10 +2,126 @@
. $srcdir/defs.inc || exit 3
#info check that verify fails for bad input data
suspend_error
#
# Two simple tests to check that verify fails for bad input data
#
info "checking bogus signature 1"
../tools/mk-tdata --char 0x2d 64 >x
$GPG --verify x data-500 && error "no error code from verify"
info "checking bogus signature 2"
../tools/mk-tdata --char 0xca 64 >x
$GPG --verify x data-500 && error "no error code from verify"
exit 0
linefeed
# A variable to collect the test names
tests=""
# A plain signed message created using
# echo abc | gpg --homedir . --passphrase-fd 0 -u Alpha -z0 -sa msg
tests="$tests msg_ols_asc"
msg_ols_asc='-----BEGIN PGP MESSAGE-----
kA0DAAIRLXJ8x2hpdzQBrQEHYgNtc2dEDFJaSSB0aGluayB0aGF0IGFsbCByaWdo
dC10aGlua2luZyBwZW9wbGUgaW4gdGhpcyBjb3VudHJ5IGFyZSBzaWNrIGFuZAp0
aXJlZCBvZiBiZWluZyB0b2xkIHRoYXQgb3JkaW5hcnkgZGVjZW50IHBlb3BsZSBh
cmUgZmVkIHVwIGluIHRoaXMKY291bnRyeSB3aXRoIGJlaW5nIHNpY2sgYW5kIHRp
cmVkLiAgSSdtIGNlcnRhaW5seSBub3QuICBCdXQgSSdtCnNpY2sgYW5kIHRpcmVk
IG9mIGJlaW5nIHRvbGQgdGhhdCBJIGFtLgotIE1vbnR5IFB5dGhvbgqIPwMFAEQM
UlotcnzHaGl3NBECR4IAoJlEGTY+bHjD2HYuCixLQCmk01pbAKCIjkzLOAmkZNm0
D8luT78c/1x45Q==
=a29i
-----END PGP MESSAGE-----'
# A plain signed message created using
# echo abc | gpg --homedir . --passphrase-fd 0 -u Alpha -sa msg
tests="$tests msg_cols_asc"
msg_cols_asc='-----BEGIN PGP MESSAGE-----
owGbwMvMwCSoW1RzPCOz3IRxLSN7EnNucboLT6Cgp0JJRmZeNpBMLFFIzMlRKMpM
zyjRBQtm5qUrFKTmF+SkKmTmgdQVKyTnl+aVFFUqJBalKhRnJmcrJOalcJVkFqWm
KOSnKSSlgrSU5OekQMzLL0rJzEsEKk9JTU7NK4EZBtKcBtRRWgAzlwtmbnlmSQbU
GJjxCmDj9RQUPNVzFZJTi0oSM/NyKhXy8kuAYk6lJSBxLlTF2NziqZCYq8elq+Cb
n1dSqRBQWZKRn8fVYc/MygAKBljYCDIFiTDMT+9seu836Q+bevyHTJ0dzPNuvCjn
ZpgrwX38z58rJsfYDhwOSS4SkN/d6vUAAA==
=s6sY
-----END PGP MESSAGE-----'
# A PGP 2 style message.
tests="$tests msg_sl_asc"
msg_sl_asc='-----BEGIN PGP MESSAGE-----
iD8DBQBEDFJaLXJ8x2hpdzQRAkeCAKCZRBk2Pmx4w9h2LgosS0AppNNaWwCgiI5M
yzgJpGTZtA/Jbk+/HP9ceOWtAQdiA21zZ0QMUlpJIHRoaW5rIHRoYXQgYWxsIHJp
Z2h0LXRoaW5raW5nIHBlb3BsZSBpbiB0aGlzIGNvdW50cnkgYXJlIHNpY2sgYW5k
CnRpcmVkIG9mIGJlaW5nIHRvbGQgdGhhdCBvcmRpbmFyeSBkZWNlbnQgcGVvcGxl
IGFyZSBmZWQgdXAgaW4gdGhpcwpjb3VudHJ5IHdpdGggYmVpbmcgc2ljayBhbmQg
dGlyZWQuICBJJ20gY2VydGFpbmx5IG5vdC4gIEJ1dCBJJ20Kc2ljayBhbmQgdGly
ZWQgb2YgYmVpbmcgdG9sZCB0aGF0IEkgYW0uCi0gTW9udHkgUHl0aG9uCg==
=0ukK
-----END PGP MESSAGE-----'
# An OpenPGP message lacking the onepass packet. We used to accept
# such messages but now consider them invalid.
tests="$tests bad_ls_asc"
bad_ls_asc='-----BEGIN PGP MESSAGE-----
rQEHYgNtc2dEDFJaSSB0aGluayB0aGF0IGFsbCByaWdodC10aGlua2luZyBwZW9w
bGUgaW4gdGhpcyBjb3VudHJ5IGFyZSBzaWNrIGFuZAp0aXJlZCBvZiBiZWluZyB0
b2xkIHRoYXQgb3JkaW5hcnkgZGVjZW50IHBlb3BsZSBhcmUgZmVkIHVwIGluIHRo
aXMKY291bnRyeSB3aXRoIGJlaW5nIHNpY2sgYW5kIHRpcmVkLiAgSSdtIGNlcnRh
aW5seSBub3QuICBCdXQgSSdtCnNpY2sgYW5kIHRpcmVkIG9mIGJlaW5nIHRvbGQg
dGhhdCBJIGFtLgotIE1vbnR5IFB5dGhvbgqIPwMFAEQMUlotcnzHaGl3NBECR4IA
oJlEGTY+bHjD2HYuCixLQCmk01pbAKCIjkzLOAmkZNm0D8luT78c/1x45Q==
=Mpiu
-----END PGP MESSAGE-----'
# A signed message prefixed with an unsigned literal packet.
# (fols = faked-literal-data, one-pass, literal-data, signature)
# This should throw an error because running gpg to extract the
# signed data will return both literal data packets
tests="$tests bad_fols_asc"
bad_fols_asc='-----BEGIN PGP MESSAGE-----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=UNM4
-----END PGP MESSAGE-----'
#
# Now run the tests.
#
for i in $tests ; do
info "checking: $i"
case "$i" in
msg_*_asc)
eval "(IFS=; echo \"\$$i\")" >x
$GPG --verify x || error "verify of $i failed"
;;
bad_*_asc)
eval "(IFS=; echo \"\$$i\")" >x
$GPG --verify x && error "verify of $i succeeded but should not"
;;
*)
error "No handler for test case $i"
;;
esac
linefeed
done
resume_error

5
g10/ChangeLog
View File

@ -1,7 +1,8 @@
2006-03-06 Werner Koch <wk@g10code.com>
* mainproc.c (check_sig_and_print): Check for multiple plaintexts
before a signature. Reported by Tavis Ormandy.
* mainproc.c (check_sig_and_print): Made the composition test more
tight. This is due to another bug report by Tavis Ormandy.
(add_onepass_sig): Simplified.
2006-03-05 Werner Koch <wk@g10code.com>

219
g10/mainproc.c
View File

@ -114,27 +114,14 @@ release_list( CTX c )
static int
add_onepass_sig( CTX c, PACKET *pkt )
{
KBNODE node;
KBNODE node;
if( c->list ) { /* add another packet */
/* We can only append another onepass packet if the list
* does contain only onepass packets */
for( node=c->list; node && node->pkt->pkttype == PKT_ONEPASS_SIG;
node = node->next )
;
if( node ) {
/* this is not the case, so we flush the current thing and
* allow this packet to start a new verification thing */
release_list( c );
c->list = new_kbnode( pkt );
}
else
add_kbnode( c->list, new_kbnode( pkt ));
}
else /* insert the first one */
c->list = node = new_kbnode( pkt );
if ( c->list ) /* add another packet */
add_kbnode( c->list, new_kbnode( pkt ));
else /* insert the first one */
c->list = node = new_kbnode( pkt );
return 1;
return 1;
}
@ -1416,93 +1403,118 @@ pka_uri_from_sig (PKT_signature *sig)
static int
check_sig_and_print( CTX c, KBNODE node )
{
PKT_signature *sig = node->pkt->pkt.signature;
const char *astr;
int rc, is_expkey=0, is_revkey=0;
PKT_signature *sig = node->pkt->pkt.signature;
const char *astr;
int rc, is_expkey=0, is_revkey=0;
if( opt.skip_verify ) {
log_info(_("signature verification suppressed\n"));
return 0;
}
/* It is not in all cases possible to check multiple signatures:
* PGP 2 (which is also allowed by OpenPGP), does use the packet
* sequence: sig+data, OpenPGP does use onepas+data=sig and GnuPG
* sometimes uses (because I did'nt read the specs right) data+sig.
* Because it is possible to create multiple signatures with
* different packet sequence (e.g. data+sig and sig+data) it might
* not be possible to get it right: let's say we have:
* data+sig, sig+data,sig+data and we have not yet encountered the last
* data, we could also see this a one data with 2 signatures and then
* data+sig.
* To protect against this we check that all signatures follow
* without any intermediate packets. Note, that we won't get this
* error when we use onepass packets or cleartext signatures because
* we reset the list every time
*
* FIXME: Now that we have these marker packets, we should create a
* real grammar and check against this.
*/
if (opt.skip_verify)
{
KBNODE n;
int n_sig = 0;
int n_plaintext = 0;
int sig_seen, onepass_seen;
for (n=c->list; n; n=n->next )
{
if ( n->pkt->pkttype == PKT_SIGNATURE )
n_sig++;
else if (n->pkt->pkttype == PKT_GPG_CONTROL
&& (n->pkt->pkt.gpg_control->control
== CTRLPKT_PLAINTEXT_MARK) )
n_plaintext++;
}
for (sig_seen=onepass_seen=0,n=c->list; n; n=n->next )
{
if (n->pkt->pkttype == PKT_ONEPASS_SIG)
{
onepass_seen++;
}
else if (n->pkt->pkttype == PKT_GPG_CONTROL
&& (n->pkt->pkt.gpg_control->control
== CTRLPKT_CLEARSIGN_START) )
{
onepass_seen++; /* Handle the same way as a onepass. */
}
else if ( (sig_seen && n->pkt->pkttype != PKT_SIGNATURE) )
{
log_error(_("can't handle these multiple signatures\n"));
return 0;
}
else if ( n->pkt->pkttype == PKT_SIGNATURE )
{
sig_seen = 1;
}
else if (n_sig > 1 && !sig_seen && !onepass_seen
&& n->pkt->pkttype == PKT_GPG_CONTROL
&& (n->pkt->pkt.gpg_control->control
== CTRLPKT_PLAINTEXT_MARK) )
{
/* Plaintext before signatures but no onepass
signature packets. */
log_error(_("can't handle these multiple signatures\n"));
return 0;
}
else if (n_plaintext > 1 && !sig_seen && !onepass_seen
&& n->pkt->pkttype == PKT_GPG_CONTROL
&& (n->pkt->pkt.gpg_control->control
== CTRLPKT_PLAINTEXT_MARK) )
{
/* More than one plaintext before a signature but no
onepass packets. */
log_error(_("can't handle this ambiguous signed data\n"));
return 0;
}
}
log_info(_("signature verification suppressed\n"));
return 0;
}
/* Check that the message composition is valid.
Per RFC-2440bis (-15) allowed:
S{1,n} -- detached signature.
S{1,n} P -- old style PGP2 signature
O{1,n} P S{1,n} -- standard OpenPGP signature.
C P S{1,n} -- cleartext signature.
O = One-Pass Signature packet.
S = Signature packet.
P = OpenPGP Message packet (Encrypted | Compressed | Literal)
(Note that the current rfc2440bis draft also allows
for a signed message but that does not work as it
introduces ambiguities.)
We keep track of these packages using the marker packet
CTRLPKT_PLAINTEXT_MARK.
C = Marker packet for cleartext signatures.
We reject all other messages.
Actually we are calling this too often, i.e. for verification of
each message but better have some duplicate work than to silently
introduce a bug here.
*/
{
KBNODE n;
int n_onepass, n_sig;
log_debug ("checking signature packet composition\n");
dump_kbnode (c->list);
n = c->list;
assert (n);
if ( n->pkt->pkttype == PKT_SIGNATURE )
{
/* This is either "S{1,n}" case (detached signature) or
"S{1,n} P" (old style PGP2 signature). */
for (n = n->next; n; n = n->next)
if (n->pkt->pkttype != PKT_SIGNATURE)
break;
if (!n)
; /* Okay, this is a detached signature. */
else if (n->pkt->pkttype == PKT_GPG_CONTROL
&& (n->pkt->pkt.gpg_control->control
== CTRLPKT_PLAINTEXT_MARK) )
{
if (n->next)
goto ambiguous; /* We only allow one P packet. */
}
else
goto ambiguous;
}
else if (n->pkt->pkttype == PKT_ONEPASS_SIG)
{
/* This is the "O{1,n} P S{1,n}" case (standard signature). */
for (n_onepass=1, n = n->next;
n && n->pkt->pkttype == PKT_ONEPASS_SIG; n = n->next)
n_onepass++;
if (!n || !(n->pkt->pkttype == PKT_GPG_CONTROL
&& (n->pkt->pkt.gpg_control->control
== CTRLPKT_PLAINTEXT_MARK)))
goto ambiguous;
for (n_sig=0, n = n->next;
n && n->pkt->pkttype == PKT_SIGNATURE; n = n->next)
n_sig++;
if (n || !n_sig)
goto ambiguous;
if (n_onepass != n_sig)
{
log_info ("number of one-pass packets does not match "
"number of signature packets\n");
goto ambiguous;
}
}
else if (n->pkt->pkttype == PKT_GPG_CONTROL
&& n->pkt->pkt.gpg_control->control == CTRLPKT_CLEARSIGN_START )
{
/* This is the "C P S{1,n}" case (clear text signature). */
n = n->next;
if (!n || !(n->pkt->pkttype == PKT_GPG_CONTROL
&& (n->pkt->pkt.gpg_control->control
== CTRLPKT_PLAINTEXT_MARK)))
goto ambiguous;
for (n_sig=0, n = n->next;
n && n->pkt->pkttype == PKT_SIGNATURE; n = n->next)
n_sig++;
if (n || !n_sig)
goto ambiguous;
}
else
{
ambiguous:
log_error(_("can't handle this ambiguous signature data\n"));
return 0;
}
}
/* (Indendation below not yet changed to GNU style.) */
astr = pubkey_algo_to_string( sig->pubkey_algo );
if(keystrlen()>8)
{
@ -1926,7 +1938,8 @@ proc_tree( CTX c, KBNODE node )
/* prepare to create all requested message digests */
c->mfx.md = md_open(0, 0);
/* fixme: why looking for the signature packet and not 1passpacket*/
/* fixme: why looking for the signature packet and not the
one-pass packet? */
for( n1 = node; (n1 = find_next_kbnode(n1, PKT_SIGNATURE )); ) {
md_enable( c->mfx.md, n1->pkt->pkt.signature->digest_algo);
}