Debian patch to add a new 'nullok_secure' option to pam_unix, which accepts users with null passwords only when the applicant is connected from a tty listed in /etc/securetty. Authors: Sam Hartman , Steve Langasek Upstream-Status: Pending Signed-off-by: Ming Liu =================================================================== diff -urpN a/modules/pam_unix/Makefile.am b/modules/pam_unix/Makefile.am --- a/modules/pam_unix/Makefile.am 2013-07-05 09:51:31.014483164 +0800 +++ b/modules/pam_unix/Makefile.am 2013-07-05 10:26:12.884484000 +0800 @@ -30,7 +30,8 @@ if HAVE_VERSIONING pam_unix_la_LDFLAGS += -Wl,--version-script=$(srcdir)/../modules.map endif pam_unix_la_LIBADD = $(top_builddir)/libpam/libpam.la \ - @LIBCRYPT@ @LIBSELINUX@ $(NIS_LIBS) + @LIBCRYPT@ @LIBSELINUX@ $(NIS_LIBS) \ + ../pam_securetty/tty_secure.lo securelib_LTLIBRARIES = pam_unix.la diff -urpN a/modules/pam_unix/pam_unix.8 b/modules/pam_unix/pam_unix.8 --- a/modules/pam_unix/pam_unix.8 2013-07-05 09:52:16.825108201 +0800 +++ b/modules/pam_unix/pam_unix.8 2013-07-05 10:28:34.724483774 +0800 @@ -220,7 +220,14 @@ A little more extreme than debug\&. .RS 4 The default action of this module is to not permit the user access to a service if their official password is blank\&. The \fBnullok\fR -argument overrides this default\&. +argument overrides this default and allows any user with a blank password to access the service\&. +.RE +.PP +\fBnullok_secure\fR +.RS 4 +The default action of this module is to not permit the user access to a service if their official password is blank\&. The +\fBnullok_secure\fR +argument overrides this default and allows any user with a blank password to access the service as long as the value of PAM_TTY is set to one of the values found in /etc/securetty\&. .RE .PP \fBtry_first_pass\fR diff -urpN a/modules/pam_unix/pam_unix.8.xml b/modules/pam_unix/pam_unix.8.xml --- a/modules/pam_unix/pam_unix.8.xml 2013-07-05 09:52:38.775108523 +0800 +++ b/modules/pam_unix/pam_unix.8.xml 2013-07-05 10:30:23.084483630 +0800 @@ -135,7 +135,24 @@ The default action of this module is to not permit the user access to a service if their official password is blank. - The argument overrides this default. + The argument overrides this default + and allows any user with a blank password to access the + service. + + + + + + + + + + The default action of this module is to not permit the + user access to a service if their official password is blank. + The argument overrides this + default and allows any user with a blank password to access + the service as long as the value of PAM_TTY is set to one of + the values found in /etc/securetty. diff -urpN a/modules/pam_unix/README b/modules/pam_unix/README --- a/modules/pam_unix/README 2013-07-05 09:51:52.205107846 +0800 +++ b/modules/pam_unix/README 2013-07-05 10:27:10.774484537 +0800 @@ -57,7 +57,16 @@ nullok The default action of this module is to not permit the user access to a service if their official password is blank. The nullok argument overrides - this default. + this default and allows any user with a blank password to access the + service. + +nullok_secure + + The default action of this module is to not permit the user access to a + service if their official password is blank. The nullok_secure argument + overrides this default and allows any user with a blank password to access + the service as long as the value of PAM_TTY is set to one of the values + found in /etc/securetty. try_first_pass diff -urpN a/modules/pam_unix/support.c b/modules/pam_unix/support.c --- a/modules/pam_unix/support.c 2013-07-05 09:50:49.134482523 +0800 +++ b/modules/pam_unix/support.c 2013-07-05 09:56:26.924484267 +0800 @@ -84,14 +84,22 @@ int _set_ctrl(pam_handle_t *pamh, int fl /* now parse the arguments to this module */ for (; argc-- > 0; ++argv) { - int j; + int j, sl; D(("pam_unix arg: %s", *argv)); for (j = 0; j < UNIX_CTRLS_; ++j) { - if (unix_args[j].token - && !strncmp(*argv, unix_args[j].token, strlen(unix_args[j].token))) { - break; + if (unix_args[j].token) { + sl = strlen(unix_args[j].token); + if (unix_args[j].token[sl-1] == '=') { + /* exclude argument from comparison */ + if (!strncmp(*argv, unix_args[j].token, sl)) + break; + } else { + /* compare full strings */ + if (!strcmp(*argv, unix_args[j].token)) + break; + } } } @@ -461,6 +469,7 @@ static int _unix_run_helper_binary(pam_h child = fork(); if (child == 0) { int i=0; + int nullok = off(UNIX__NONULL, ctrl); struct rlimit rlim; static char *envp[] = { NULL }; char *args[] = { NULL, NULL, NULL, NULL }; @@ -488,7 +497,18 @@ static int _unix_run_helper_binary(pam_h /* exec binary helper */ args[0] = strdup(CHKPWD_HELPER); args[1] = x_strdup(user); - if (off(UNIX__NONULL, ctrl)) { /* this means we've succeeded */ + + if (on(UNIX_NULLOK_SECURE, ctrl)) { + const void *uttyname; + retval = pam_get_item(pamh, PAM_TTY, &uttyname); + if (retval != PAM_SUCCESS || uttyname == NULL + || _pammodutil_tty_secure(pamh, (const char *)uttyname) != PAM_SUCCESS) + { + nullok = 0; + } + } + + if (nullok) { args[2]=strdup("nullok"); } else { args[2]=strdup("nonull"); @@ -567,6 +587,17 @@ _unix_blankpasswd (pam_handle_t *pamh, u if (on(UNIX__NONULL, ctrl)) return 0; /* will fail but don't let on yet */ + if (on(UNIX_NULLOK_SECURE, ctrl)) { + int retval2; + const void *uttyname; + retval2 = pam_get_item(pamh, PAM_TTY, &uttyname); + if (retval2 != PAM_SUCCESS || uttyname == NULL) + return 0; + + if (_pammodutil_tty_secure(pamh, (const char *)uttyname) != PAM_SUCCESS) + return 0; + } + /* UNIX passwords area */ retval = get_pwd_hash(pamh, name, &pwd, &salt); @@ -653,7 +684,8 @@ int _unix_verify_password(pam_handle_t * } } } else { - retval = verify_pwd_hash(p, salt, off(UNIX__NONULL, ctrl)); + retval = verify_pwd_hash(p, salt, + _unix_blankpasswd(pamh, ctrl, name)); } if (retval == PAM_SUCCESS) { diff -urpN a/modules/pam_unix/support.h b/modules/pam_unix/support.h --- a/modules/pam_unix/support.h 2013-07-05 09:51:10.385107934 +0800 +++ b/modules/pam_unix/support.h 2013-07-05 10:23:54.815107842 +0800 @@ -90,8 +90,9 @@ typedef struct { password hash algorithms */ #define UNIX_BLOWFISH_PASS 26 /* new password hashes will use blowfish */ #define UNIX_MIN_PASS_LEN 27 /* min length for password */ +#define UNIX_NULLOK_SECURE 28 /* NULL passwords allowed only on secure ttys */ /* -------------- */ -#define UNIX_CTRLS_ 28 /* number of ctrl arguments defined */ +#define UNIX_CTRLS_ 29 /* number of ctrl arguments defined */ #define UNIX_DES_CRYPT(ctrl) (off(UNIX_MD5_PASS,ctrl)&&off(UNIX_BIGCRYPT,ctrl)&&off(UNIX_SHA256_PASS,ctrl)&&off(UNIX_SHA512_PASS,ctrl)&&off(UNIX_BLOWFISH_PASS,ctrl)) @@ -109,7 +110,7 @@ static const UNIX_Ctrls unix_args[UNIX_C /* UNIX_NOT_SET_PASS */ {"not_set_pass", _ALL_ON_, 0100}, /* UNIX__PRELIM */ {NULL, _ALL_ON_^(0600), 0200}, /* UNIX__UPDATE */ {NULL, _ALL_ON_^(0600), 0400}, -/* UNIX__NONULL */ {NULL, _ALL_ON_, 01000}, +/* UNIX__NONULL */ {NULL, _ALL_ON_^(0x10000000), 0x200}, /* UNIX__QUIET */ {NULL, _ALL_ON_, 02000}, /* UNIX_USE_AUTHTOK */ {"use_authtok", _ALL_ON_, 04000}, /* UNIX_SHADOW */ {"shadow", _ALL_ON_, 010000}, @@ -127,7 +128,8 @@ static const UNIX_Ctrls unix_args[UNIX_C /* UNIX_SHA512_PASS */ {"sha512", _ALL_ON_^(0260420000), 040000000}, /* UNIX_ALGO_ROUNDS */ {"rounds=", _ALL_ON_, 0100000000}, /* UNIX_BLOWFISH_PASS */ {"blowfish", _ALL_ON_^(0260420000), 0200000000}, -/* UNIX_MIN_PASS_LEN */ {"minlen=", _ALL_ON_, 0400000000}, +/* UNIX_MIN_PASS_LEN */ {"minlen=", _ALL_ON_, 0400000000}, +/* UNIX_NULLOK_SECURE */ {"nullok_secure", _ALL_ON_^(0x200), 0x10000000}, }; #define UNIX_DEFAULTS (unix_args[UNIX__NONULL].flag) @@ -163,6 +165,9 @@ extern int _unix_read_password(pam_handl ,const char *data_name ,const void **pass); +extern int _pammodutil_tty_secure(const pam_handle_t *pamh, + const char *uttyname); + extern int _unix_run_verify_binary(pam_handle_t *pamh, unsigned int ctrl, const char *user, int *daysleft); #endif /* _PAM_UNIX_SUPPORT_H */