--dc+cDN39EJAMEtIO Content-Type: multipart/mixed; boundary="n8g4imXOkfNTN/H1" Content-Disposition: inline --n8g4imXOkfNTN/H1 Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Disposition: inline Content-Transfer-Encoding: quoted-printable My friend and fellow FreeBSD enthusiast Derek Marcotte recently pointed out= that FreeBSD has no easy way to set the logarithmic rounds for bcrypt pass= word hashes. Doing so is trivial in OpenBSD, and considering the capabilit= ies of current GPU attacks, I want this functionality. This issue was raised over eight years ago in kern/75934 by Steven Alexande= r Jr., who included a patch to add this feature. Unfortunately, this seems= to have been completely overlooked, and there were no public responses to = this PR. I commissioned Derek to come up with a solution by either updating Steven's= patch or by devising a new method. To paraphrase Derek's comments: -----BEGIN PARAPHRASIS----- I did some research into what other *BSDs are doing. OpenBSD and NetBSD us= e the algorithm name, a comma, and then the number of rounds: http://www.openbsd.org/cgi-bin/man.cgi?query=3Dlogin.conf&sektion=3D5 localcipher=3Dblowfish,6 http://netbsd.gw.com/cgi-bin/man-cgi?passwd.conf+5+NetBSD-current localcipher=3Dblowfish,6 To me, this isn't a good way to do it because we'd need special rules to pa= rse this extra field out of the previously unstructured data. This parsing= would be algorithm dependant. Everyone knows about modular crypt, so why not feed the modular crypt salt = string as the parameter directly? Instead of messing with different names,= give the power to the system admin to control this directly, so when crypt= is updated, pam_unix can take advantage. Each implementation of crypt alg= orithms already includes parsing of the salt magic. I found that patching pam_unix was the least invasive way to handle configu= rable hashes for login. I've added a passwd_modular parameter that will su= persede passwd_format when defined. passwd_modular will feed directly into= crypt, so any options that are passed to crypt via the salt are immediatel= y available for use in the master.passwd file. For example: :passwd_modular=3D$2a$11$:\ Now you can also set the rounds for sha512: :passwd_modular=3D$6$rounds=3D1000000$:\ To disable passwd_modular and revert to passwd_format: :passwd_modular=3Ddisabled:\ This also lets admins shoot themselves in the foot by supplying invalid or = bad salts. For example: :passwd_modular=3D$1$constantsalt:\ I had considered setting a second variable like ":passwd_param=3D8:\", but = then you really have to mess with crypt to make it work. I think it would = be a much more invasive change, and unnecessary, providing the documentatio= n for login.conf is brought up to date. FreeBSD 8.* doesn't have access to the SHA family of hashes. If this is me= rged back into 8, it will give much stronger password security when using $= 2a$08$ (or higher) than is currently available. bcrypt is preferable to sha512 because of its resilience to current GPU att= acks. This is expected to change. Hopefully, my patch will lay some groun= dwork to incorporate scrypt. -----END PARAPHRASIS----- I've attached a copy of Derek's patches for the FreeBSD 9-STABLE versions o= f pam_unix and the login.conf man page. These may have to be adjusted for = HEAD. I really like Derek's solution. It's working perfectly for bcrypt on my ow= n network, and I'm planning to distribute it to the hundreds of FreeBSD ser= vers that I am responsible for maintaining. In my opinion, committing Dere= k's patches will allow kern/75934 to be closed. --=20 A.J. Kehoe IV (Nanoman) | /"\ ASCII Ribbon Campaign Nanoman's Company | \ / - No HTML/RTF in E-mail E-mail: [email protected] | X - No proprietary attachments WWW: http://www.nanoman.ca/ | / \ - Respect for open standards --n8g4imXOkfNTN/H1 Content-Type: text/x-diff; charset=iso-8859-1 Content-Disposition: attachment; filename="pam_unix.c.patch" Content-Transfer-Encoding: quoted-printable --- /usr/src/lib/libpam/modules/pam_unix/pam_unix.c.orig 2013-07-07 10:20:4= 6.000000000 -0400 +++ /usr/src/lib/libpam/modules/pam_unix/pam_unix.c 2013-07-07 12:53:28.000= 000000 -0400 @@ -68,8 +68,9 @@ #include <security/pam_mod_misc.h> =20 #define PASSWORD_HASH "md5" +#define NOMODULAR "disabled" #define DEFAULT_WARN (2L * 7L * 86400L) /* Two weeks */ -#define SALTSIZE 32 +#define SALTSIZE 64 =20 #define LOCKED_PREFIX "*LOCKED*" #define LOCKED_PREFIX_LEN (sizeof(LOCKED_PREFIX) - 1) @@ -77,6 +78,7 @@ static void makesalt(char []); =20 static char password_hash[] =3D PASSWORD_HASH; +static char password_nomodular[] =3D NOMODULAR; =20 #define PAM_OPT_LOCAL_PASS "local_pass" #define PAM_OPT_NIS_PASS "nis_pass" @@ -272,7 +274,7 @@ char salt[SALTSIZE + 1]; login_cap_t *lc; struct passwd *pwd, *old_pwd; - const char *user, *old_pass, *new_pass; + const char *user, *old_pass, *new_pass, *modular_salt; char *encrypted; time_t passwordtime; int pfd, tfd, retval; @@ -378,16 +380,23 @@ return (PAM_BUF_ERR); =20 lc =3D login_getclass(pwd->pw_class); - if (login_setcryptfmt(lc, password_hash, NULL) =3D=3D NULL) - openpam_log(PAM_LOG_ERROR, - "can't set password cipher, relying on default"); - =09 + + memset(salt, 0, sizeof(salt)); + modular_salt =3D login_getcapstr(lc, "passwd_modular", password_nomodula= r, NULL); + if (strcmp(modular_salt, password_nomodular) =3D=3D 0) { + if (login_setcryptfmt(lc, password_hash, NULL) =3D=3D NULL) + openpam_log(PAM_LOG_ERROR, + "can't set password cipher, relying on default"); + } else { + strncpy(salt, modular_salt, sizeof(salt) - 1); + } + /* set password expiry date */ pwd->pw_change =3D 0; passwordtime =3D login_getcaptime(lc, "passwordtime", 0, 0); if (passwordtime > 0) pwd->pw_change =3D time(NULL) + passwordtime; - =09 + login_close(lc); makesalt(salt); pwd->pw_passwd =3D crypt(new_pass, salt); @@ -464,13 +473,25 @@ makesalt(char salt[SALTSIZE]) { int i; + int remainder; + + /* If a salt magic has already been set, skip to the free area */ + for (i =3D 0; i < SALTSIZE; i++) { + if (salt[i] =3D=3D '\0') { + break; + } + } =20 /* These are not really random numbers, they are just * numbers that change to thwart construction of a * dictionary. This is exposed to the public. */ - for (i =3D 0; i < SALTSIZE; i +=3D 4) - to64(&salt[i], arc4random(), 4); + while (i < SALTSIZE) { + remainder =3D SALTSIZE - i; + to64(&salt[i], arc4random(), (remainder < 4 ? remainder : 4) ); + i +=3D 4; + } + salt[SALTSIZE] =3D '\0'; } =20 --n8g4imXOkfNTN/H1 Content-Type: text/x-diff; charset=iso-8859-1 Content-Disposition: attachment; filename="login.conf.5.patch" Content-Transfer-Encoding: quoted-printable --- /usr/src/lib/libutil/login.conf.5.orig 2013-07-04 10:16:42.000000000 -0= 400 +++ /usr/src/lib/libutil/login.conf.5 2013-07-04 10:31:59.000000000 -0400 @@ -275,6 +275,14 @@ NIS clients using a .No non- Ns Fx NIS server should probably use "des". +.It "passwd_modular string $02$08$ The encryption format that new or" +changed passwords will use, based on the=20 +.Xr crypt 3=20 +magic constants. Overrides passwd_format when set. Valid values include "= disabled" to fall back to passwd_format, $02$08$ would be blf with work fac= tor 8, or $6$rounds=3D5000$ would be sha512 with 5000 rounds, will accept a= ny of the magic salt values from +.Xr crypt 3 +Be aware that setting this to an invalid crypt magic will likely fall back= to des. Appending text to after the salt magic, (e.g. $02$08$dontdothis) w= ill weaken the salt. Please refer to +.Xr crypt 3 +for proper syntax and useage. .It "passwd_prompt string The password prompt presented by .Xr login 1 .It "times.allow list List of time periods during which --n8g4imXOkfNTN/H1-- --dc+cDN39EJAMEtIO Content-Type: application/x-pkcs7-signature Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIIPUAYJKoZIhvcNAQcCoIIPQTCCDz0CAQExCzAJBgUrDgMCGgUAMAsGCSqGSIb3DQEHAaCC DLwwggV3MIIDX6ADAgECAgMM9zQwDQYJKoZIhvcNAQEFBQAweTEQMA4GA1UEChMHUm9vdCBD QTEeMBwGA1UECxMVaHR0cDovL3d3dy5jYWNlcnQub3JnMSIwIAYDVQQDExlDQSBDZXJ0IFNp Z25pbmcgQXV0aG9yaXR5MSEwHwYJKoZIhvcNAQkBFhJzdXBwb3J0QGNhY2VydC5vcmcwHhcN MTMwMzExMjMyMzI2WhcNMTMwOTA3MjMyMzI2WjA9MRgwFgYDVQQDEw9DQWNlcnQgV29UIFVz ZXIxITAfBgkqhkiG9w0BCQEWEm5hbm9tYW5AbmFub21hbi5jYTCCASIwDQYJKoZIhvcNAQEB BQADggEPADCCAQoCggEBAK9WRGqRDUDjWwNIfZTBp4FL5bI0kY3ZqvM6tEO+Sqp5YxATre8F a+BYbeNp/8MKfuPrRgE2jRzlePAx7kpvZUhRTGAZpncmHC7Z3FDl8Ugid4193ReCfPypb9Gs 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