swverify — Verify Software
Posix:
swverify [-d|-r] [-F] [-f file] [-t targetfile] \\
[-x option=value] [-X options_file] [-W option] \\
[software_selections] [@targets]
swverify # Verify standard input
swverify selection [@ target] # Verify Installed Software
swverify -d [@ target]
swverify -d @- # dash means standard input
swverify [–scm|–order-files] -d @. # . means current directory
swverify [–scm|–order-files] -d @:package_directory
Implementation Extension:
swverify [-Wd] -Wemit-digest-file [portable_archive_file]
swverify [-Wd] -Wemit-signed-file [portable_archive_file]
swverify [-Wd] [-Wsha1] -Wemit-digest-file [portable_archive_file]
swverify [-Wd] -Wget-sig-if=sigfilename [portable_archive_file]
The swverify utility checks the accuracy of software in distributions and installed_software. If no options are given, a serial distribution on stdin is verified.
Currently, swverify does not read the defaults files. "/" is the default target for installed software. Stdin is the default target for distributions. The built-in value of "installed_software_catalog" is "var/lib/swbis/catalog".
-d
Specify to operate on a distribution rather than installed software.
-r
Specify that target is an alternate root target. (Not currently used)
software_selections
See other man pages.
targets
See other man pages. Currently, only one (1) target can be specified.
-x option=value
Specify the extended option overriding the defaults file value. This option not yet implemented.
-X FILE
Specify the extended options filename, FILE, overriding the default filename. This option not yet implemented.
Other POSIX options not implemented.
Not yet implemented.
-W option[,option,...]
Specify the implementation extension option. Syntax: -W option[=option_argument[,option...] Options may be separated by a comma.
−−checksig | -W checksig
This is the default action and is the same as the POSIX syntax "-d @target". If target file is not a directory then verify archive md5 and sha1 and gpg signature directly from the file. If target file is a directory, attempt to verify the signature using GNU tar and gpg and if successful execute the distributor extension script checksig. If checksig does not exist then exit with failure. FILE may be "." (current directory) or "-" (standard input). A serial archive file may be compressed with gzip, bzip2, or Unix compress.
–order-catalog
Use the order of files in catalog/dfiles/files to recreate the signed data when verifying the directory (unpacked tarball) form of the package.
–cvs
Read and process information in the ./catalog (before it is authenticated) to correct the file sytem meta-data in an attempt to verify the GPG signature. It only affects verification on the directory (unpacked tarball), not tarball verification. It is required when verifying an exported or working SCM (Source Code Management, such as CVS) directory if the SCM does not preserve and restore file system meta-data. This option also emliminates the dependency on the order of files in file system directories.
–scm
Currently, same as the –cvs option.
–no-checkdigest
When verifying the directory form, do not run the checkdigest script even if the GPG signed data contains the checkdigest script.
–signed-file [FILE]
Write the GPG signed portion of the package to stdout without verifying it. Read archive file FILE or standard input and write the signed file (i.e. gpg's signed stuff) to stdout. This is the catalog section of the Posix package. This option is supported for the tarball file and unpacked tarball directory. Use of the –scm option may be required for the unpacked tarball directory form.
–digest-file [FILE]
Write the payload portion of the package to stdout without verifying its digest matches the digest in the signed data. This is the storage section of the Posix package. This option is not supported for the unpacked tarball form.
-W emit-signed-file | -W C
Same as –signed-data. Also the same as -WC
-W emit-digest-file [FILE]
Same as –digest-data. Also the same as -WS
-W show-auth-files | -W d
Writes the relevent security file to stderr. Applies to emit-digest-file and emit-signed-file modes.
-W sig-number=N
Operates on the Nth signature, 0 is last, 1 is the first.
-W get-sig-if=outputfile
Verifies the archive digests by comparing to the digests in the catalog and if they match write the sigfile to outputfile and the signed data to stdout.
Not yet implemented.
This script was named 'checksig'. As of 2006-03-28, the name of this script should be 'checkdigest'. The name 'checksig' should be considered deprecated for new packages.
A software distributor may choose to provide a checkdigest script. The checkdigest script is part of the distribution object. It is used to verify the directory form of a distribution (as distinguished from installed_software). The verified attributes are the same as those verified from the archive file form with the addition of the distribution file list. In addition the script may chose to verify the adjunct_md5sum and file.md5 digests and symbolic links. Due to the constraints of reproducing the archive message digests from the directory, which include tar utility dependence and file owner/group specification, this script may not be useful to all distributors.
The script may require the SW_CONTROL_TAG environment variable be set to "checkdigest" or "checkfile" and if not exit with failure. swverify will set this variable to "checkfile" if the –scm or –cvs option is used, and otherwise to "checkdigest". The script may take different action based on the value. Currently, the checkdigest script used by the swbis source package will omit the archive digests checks if set to SW_CONTROL_TAG="checkfile" since reproducing the archive digest is not possible when the package is exported from CVS due to file system meta-data non-preservation. In this case the file list is checked and the md5 and sha1 digests are verified for each regular file.
The design separates the payload and catalog, therefore, verification requires verifying the storage section md5 and sha1 message digests and then verifying the signature of the catalog. Naturally, it is required that the signed data include the storage section message digests and that they match the storage sections. The storage section digests are stored as separate attribute files in the dfiles catalog directory.
The checksig (i.e. swverify -d @-) mode verifies a tarballs embedded signature. This mode checks all the security files in the package and is the preferred way to authenticate a package. The emit-signed-file, emit-digest-file modes are useful for testing, sanity checks and custom applications. The get-sig-if is the function used when verifying a tarball.
The design of the authentication attributes supports manual verification of the archive file (e.g. tarball) form of the distribution, that is verification take place on the uncompressed archive using 'gpg', GNU 'tar' and the swbis utility 'swverify' (or the library utility 'arf2arf').
The authentication requires the following steps:
1) Obtain the signature from the package.
2) Recreate the signed data and present this byte stream and
the signature to GNU privacy guard (gpg) for authentication.
3) Obtain the message digest (md5, sha1,) contained in the
control file in the authenticated archive byte stream.
4) Recreate the digest byte stream and present to the appropriate
hash generation program to generate the message digest.
5) Compare the digest message generated in step 4 to the
authenicated digest obtained in step 3.
1) Obtain the signature from the package.
#!/bin/sh
tar zxf - -O \\*/catalog/dfiles/signature < swbis-0.460.tar.gz
2) Recreate the signed data
#!/bin/sh
swverify -WC < swbis-0.460.tar.gz | gpg –verify /dev/tty -
# Cut and paste the signature file obtained in step 1
3) Obtain the message digest
#!/bin/sh
swverify -WC < swbis-0.460.tar.gz | \\
tar xf - -O \\*/catalog/dfiles/md5sum
4) Create the digested byte stream
#!/bin/sh
swverify -WS < swbis-0.460.tar.gz | md5sum
Verifying the unpacked tarball package form.
The design of the authentication attributes supports manual verification of the directory (unpacked) form of the distribution, that is verification takes place on the leading package directory and its contents. It should be noted that it is left to the user to verify that the archive installed no files outside of this directory as this would likely indicate a trojan'ed package.
If authenticating on a GNU/Linux system using GNU tar it is possible to validate the archive message digests and signature if the following are true:
1) The package file is a tar archive.
2) The installed version of GNU tar produces archives with
bit-for-bit sameness relative to the swpackage(8) utility
that generated the signature and message digests. For packages
made with swbis versions >= 0.474 and with format option "ustar"
you will need GNU tar 1.14 or 1.15.*
3) The package has a single leading package directory, like a source
package.
4) The package catalog contains the 'checkdigest' script.
5) The package catalog contains the distribution file list.
6) The ownership names are present and have the same uid's and gid's.
7) The package was unpacked with a version of tar that
preserves all file times. Use for example "tar xpf".
In this example, the package has a single path name prefix called, namedir and the file owner/group are root. These restrictions are suited to source packages. Verify the signature:
#!/bin/sh
tar cf - -b1 –owner=root –group=root \\
–exclude=namedir/catalog/dfiles/signature \\
namedir/catalog | gpg –verify namedir/catalog/dfiles/signature -
If this fails try using GNU tar option –posix. If this fails then, try experimenting with the owner, group, and numeric-id options. If you are unable to verify a tar byte stream using gpg(1) that contains the storage section message digests, then the package cannot be authenticated.
Assuming you successfully verified the catalog as shown above, now generate the message digest and compare it to the md5sum file attribute from the same byte stream that gpg(1) claims is authenticate.
#!/bin/sh
grep -v namedir/catalog namedir/catalog/dfiles/files | \\
tar cf - -b1 –owner=root –group=root \\
–files-from=- –no-recursion | md5sum
tar cf - -b1 –owner=root –group=root \\
–exclude=namedir/catalog/dfiles/signature \\
namedir/catalog | tar xf - -O namedir/catalog/dfiles/md5sum
Likewise for the sha1 digest.
If the package has symbolic links, Verify the adjunct_md5sum:
#!/bin/sh
grep -v namedir/catalog namedir/catalog/dfiles/files | \\
( while read file; do if [ ! -h $file ]; then echo $file; fi done; )|\\
tar cf - -b1 –owner=root –group=root \\
–files-from=- –no-recursion | md5sum
cat namedir/catalog/dfiles/adjunct_md5sum
The symbolic link files must be verified manually by comparing to the INFO file information.
Below is output from successful authentication. The authentication requires checking the archive md5 message digest (and sha1 if present). All present message digests must succeed and if this is true then the signed file is written and gpg proceeds to check the signature.
If the sig_header file is present then the requirement that its data be identical to the ustar header of every signature file is enforced. If any one of these checks fails, authentication fails.
#!/bin/sh
swverify –checksig mypackage-00.1.tar.gz
# - or -
swverify -d @- < mypackage-00.1.tar.gz
gpg: /home/userx/.gnupg/options:82: deprecated option "honor-http-proxy"
gpg: please use "keyserver-options honor-http-proxy" instead
gpg: WARNING: using insecure memory!
gpg: please see http://www.gnupg.org/faq.html for more information
swbis: Archive digest: md5 OK (Good)
swbis: Archive digest: sha1 OK (Good)
gpg: Signature made Sun Mar 16 20:28:23 2003 EST using DSA key ID 82B0DBE4
gpg: Good signature from "Test User (pass=Iforgot) localhost>"
Primary key fingerprint: 77BB A98E B3A2 ED4C 217E 8A25 2BF4 28AB 82D0 DDE4
Authenticating using 'swverify' is subject to the same constraints as verifying manually using GNU tools because swverify implements this using GNU tools.
'swverify' when verifying the directory form of a distribution attempts to authenticate the exported catalog signature. If it is successful it executes the 'checkdigest' script found in the 'catalog/dfiles' directory of the exported catalog. If the 'checkdigest' script does not exist, authentication fails. 'swverify' will only attempt to run the 'checkdigest' script if it is found in the dfiles directory of an authenticated catalog.
'swverify' currently has no provision to verify the archive section (i.e. the file storage structure) of a directory (unpacked) form of a POSIX distribution. It is the role of the checkdigest script to do this.
For example, if filemypackage-00.1 is a directory unpacked with a tar reading utility that preserved file times then try,
#!/bin/sh
swverify –checksig mypackage-00.1
or change directory into mypackage-00.1 and use the POSIX syntax:
swverify -d @.
swverify -d @`pwd`/mypackage-00.1
Below is example output of a package with a 'checksig' script.
swverify: Attempting to verify using –posix tar option.
gpg: /home/userx/.gnupg/options:82: deprecated option "honor-http-proxy"
gpg: please use "keyserver-options honor-http-proxy" instead
gpg: WARNING: using insecure memory!
gpg: please see http://www.gnupg.org/faq.html for more information
gpg: Signature made Sun Mar 16 21:00:54 2003 EST using DSA key ID 82B0DBE4
gpg: BAD signature from "Test User (pass=Iforgot) localhost>"
swverify: First attempt failed.
swverify: Attempting to verify without using –posix tar option.
gpg: /home/jhl/.gnupg/options:82: deprecated option "honor-http-proxy"
gpg: please use "keyserver-options honor-http-proxy" instead
gpg: WARNING: using insecure memory!
gpg: please see http://www.gnupg.org/faq.html for more information
gpg: Signature made Sun Mar 16 21:00:54 2003 EST using DSA key ID 82B0DBE4
gpg: Good signature from "Test User (pass=Iforgot) localhost>"
gpg: WARNING: This key is not certified with a trusted signature!
gpg: There is no indication that the signature belongs to the owner.
Primary key fingerprint: 77BB A98E B3A2 ED4C 217E 8A25 2BF4 28AB 82D0 DDE4
swverify: GPG signature verified.
swverify: Got it!
swverify: The vendor extension script checksig can now be executed.
checksig: Checking files OK (Good)
checksig: Checking Archive md5 OK (Good)
checksig: Checking Archive sha1 OK (Good)
gpg: /home/userx/.gnupg/options:82: deprecated option "honor-http-proxy"
gpg: please use "keyserver-options honor-http-proxy" instead
gpg: WARNING: using insecure memory!
gpg: please see http://www.gnupg.org/faq.html for more information
gpg: Signature made Sun Mar 16 21:00:54 2003 EST using DSA key ID 82B0DBE4
gpg: Good signature from "Test User (pass=Iforgot) localhost>"
gpg: WARNING: This key is not certified with a trusted signature!
gpg: There is no indication that the signature belongs to the owner.
Primary key fingerprint: 77BB A98E B3A2 ED4C 217E 8A25 2BF4 28AB 82D0 DDE4
checksig: Signature proper OK (Good)
checksig: /usr/bin/gpg exit status : 0
(This capability is only partially implemented.) Verifying Installed Software involves comparing the package meta-data to the live file system. The validity of a successful comparison depends on the validity of the installed software catalog. swverify makes no attempt to check the validity of the entire catalog, however, it can use the distribution GPG signature, which is stored in the catalog, to authenticate the meta-data of the selected package.
Below is an example. Note, the package is selected on the basis of its product or bundle tag.
$ swverify -r your_product_tag @ /
swverify: verifying installed software at:
swverify: //var/lib/swbis/catalog/swbis/your_product_tag/0.000/0
gpg: WARNING: –honor-http-proxy is a deprecated option.
gpg: please use "–keyserver-options honor-http-proxy" instead
gpg: Signature made Fri Feb 20 00:21:00 2004 EST using DSA key ID 82B0DBE4
gpg: Good signature from "Test User (pass=Iforgot) localhost>"
Fingerprint: 77BB B98D A3A2 ED4C 217E 9A25 8BF4 05AB 82B0 DBE4
swverify: Warning: file checks not implemented
swverify: signature verification return status=0
Here are some examples that verify the archive digests.
#!/bin/sh
cat your-tarball | swverify -Wd -WS | md5sum
Your should see a pair of identical digests. Use the -Wsha1 option to check the sha1 digest in a similar manner.
** IMPORTANT ** This does not mean that the data is authenticate in the sense of being attributable to a person, merely that the md5sum attribute and the payload byte stream match.
To inspect the digested data, try:
#!/bin/sh
cat your-tarball | swverify -WS | tar tvf -
Here is an example which allows inspection of the signed file.
cat your-tarball | swverify -WC | tar tvf -
This is the mode that is used internally when verifying a tarball. Below is an example of using this mode manually.
#!/bin/sh
cat your-tarball | swverify -Wget-sig-if=/dev/tty | \\
gpg –verify /dev/tty -
Now try to copy and paste the sigfile and gpg should attempt to verify the signature.
Note: This verifies the md5 or sha1 digests before writing the signed data to stdout. If the sha1 or md5 match fails then an empty file is written to stdout.
Examples of verifying distributions and installed software.
* Verify a tar archive
swverify -d < foo-1.1.tar.gz
or
swverify -d @`pwd`/foo-1.1.tar.gz
or
swverify -d @:foo-1.1.tar.gz
or
cat foo-1.1.tar.gz | swverify -d @-
Note: –checksig and '-d' perform the same operations.
* Verify a unpacked distribution
swverify -d @`pwd`/foo-1.1
or
cd foo-1.1; swverify -d @.
or
swverify -d @:foo-1.1
Note: –checksig and '-d' perform the same operations.
* Verify an exported SCM Directory
# This is the same as directory verification except the '–cvs' option is needed.
* Verify installed software
swverify foo.foo @/tmp/test
or
swverify foo.foo # at default target
Exit status of the checksig script or gpg utility for –checksig directory operation. 0 if successful on all targets, 1 if failed on all targets, 2 if failed on some targets.
/var/lib/swbis/catalog # Location of installed catalog
/usr/lib/swbis/swdefaults
/usr/lib/swbis/swbisdefaults
$HOME/.swbis/swdefaults
$HOME/.swbis/swbisdefaults
IEEE Std 1387.2-1995 (ISO/IEC 15068-2:1999), Open Group CAE C701.
info swbis
sw(5), swbis(1), swign(1), swpackage(8), gpg(1), libexec/swbis/arf2arf
swverify: The verification utility of the swbis project. Author: Jim Lowe Email: jhlowe at acm.org Version: 1.13 Last Updated: 2010-02-04 Copying: GNU Free Documentation License
The signature file's archive header (or data) is not part of the signed data therefore it may be subject to undetectable tampering, however, swverify does perform sanity checks on the pathname, permissions and filetype if
the sig_header file (See sw(5) manual page.) is not present [due to being signed by a old swpackage version], and if sig_header is present, swverify requires that it match the sig file header. The ability to verify the unpacked directory form of the package depends on many factors not immediately obvious, among them are the tar header uname and gname, and whether they are preserved by the reading utility, and whether these names are in the system database files /etc/passwd and /etc/group, and if so, whether they assign the same uid/gid as the package.
Verification of the directory form of a distribution (i.e. the installed tarball path name prefix) such as running 'swverify -d @.' after running 'swign @.' will fail if the order of directory entries is not compatible with traditional Unix file system directory entry ordering, which is the order of file creation. This ordering is almost always apparent on Ext2 file system for small directories (but not always for big directories). Ext3, reiserFS, and DarwinOS et.al file systems do not have this ordering, use of the '–order-catalog' option is therefore required. Use of the '–cvs' or '–order-catalog' options is theoretically problematic because it causes the use and interpretation of data in the verification of that same data therefore opening possible attack vectors.