From b6545b83f94c5fb7aec1478b8d458a1393f479c8 Mon Sep 17 00:00:00 2001 From: "Maxin B. John" Date: Wed, 25 May 2016 14:12:25 +0300 Subject: [PATCH] pam_unix: support 'nullok_secure' option 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 Signed-off-by: Amarnath Valluri Signed-off-by: Maxin B. John --- modules/pam_unix/Makefile.am | 3 ++- modules/pam_unix/pam_unix.8.xml | 19 ++++++++++++++++++- modules/pam_unix/support.c | 40 +++++++++++++++++++++++++++++++++++----- modules/pam_unix/support.h | 8 ++++++-- 4 files changed, 61 insertions(+), 9 deletions(-) diff --git a/modules/pam_unix/Makefile.am b/modules/pam_unix/Makefile.am index 56df178..2bba460 100644 --- a/modules/pam_unix/Makefile.am +++ b/modules/pam_unix/Makefile.am @@ -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@ @TIRPC_LIBS@ @NSL_LIBS@ + @LIBCRYPT@ @LIBSELINUX@ @TIRPC_LIBS@ @NSL_LIBS@ \ + ../pam_securetty/tty_secure.lo securelib_LTLIBRARIES = pam_unix.la diff --git a/modules/pam_unix/pam_unix.8.xml b/modules/pam_unix/pam_unix.8.xml index 1b318f1..be0330e 100644 --- a/modules/pam_unix/pam_unix.8.xml +++ b/modules/pam_unix/pam_unix.8.xml @@ -159,7 +159,24 @@ 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 --git a/modules/pam_unix/support.c b/modules/pam_unix/support.c index fc8595e..29e3341 100644 --- a/modules/pam_unix/support.c +++ b/modules/pam_unix/support.c @@ -183,13 +183,22 @@ int _set_ctrl(pam_handle_t *pamh, int flags, int *remember, int *rounds, /* now parse the arguments to this module */ for (; argc-- > 0; ++argv) { + int 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; + } } } @@ -560,6 +569,7 @@ static int _unix_run_helper_binary(pam_handle_t *pamh, const char *passwd, if (child == 0) { static char *envp[] = { NULL }; const char *args[] = { NULL, NULL, NULL, NULL }; + int nullok = off(UNIX__NONULL, ctrl); /* XXX - should really tidy up PAM here too */ @@ -587,7 +597,16 @@ static int _unix_run_helper_binary(pam_handle_t *pamh, const char *passwd, /* exec binary helper */ args[0] = CHKPWD_HELPER; args[1] = 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]="nullok"; } else { args[2]="nonull"; @@ -672,6 +691,17 @@ _unix_blankpasswd (pam_handle_t *pamh, unsigned int ctrl, const char *name) 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); @@ -758,7 +788,7 @@ int _unix_verify_password(pam_handle_t * pamh, const char *name } } } 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 --git a/modules/pam_unix/support.h b/modules/pam_unix/support.h index b4c279c..8da4a8e 100644 --- a/modules/pam_unix/support.h +++ b/modules/pam_unix/support.h @@ -98,8 +98,9 @@ typedef struct { #define UNIX_QUIET 28 /* Don't print informational messages */ #define UNIX_NO_PASS_EXPIRY 29 /* Don't check for password expiration if not used for authentication */ #define UNIX_DES 30 /* DES, default */ +#define UNIX_NULLOK_SECURE 31 /* NULL passwords allowed only on secure ttys */ /* -------------- */ -#define UNIX_CTRLS_ 31 /* number of ctrl arguments defined */ +#define UNIX_CTRLS_ 32 /* 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)) @@ -117,7 +118,7 @@ static const UNIX_Ctrls unix_args[UNIX_CTRLS_] = /* UNIX_AUTHTOK_TYPE */ {"authtok_type=", _ALL_ON_, 0100, 0}, /* UNIX__PRELIM */ {NULL, _ALL_ON_^(0600), 0200, 0}, /* UNIX__UPDATE */ {NULL, _ALL_ON_^(0600), 0400, 0}, -/* UNIX__NONULL */ {NULL, _ALL_ON_, 01000, 0}, +/* UNIX__NONULL */ {NULL, _ALL_ON_^(02000000000), 01000, 0}, /* UNIX__QUIET */ {NULL, _ALL_ON_, 02000, 0}, /* UNIX_USE_AUTHTOK */ {"use_authtok", _ALL_ON_, 04000, 0}, /* UNIX_SHADOW */ {"shadow", _ALL_ON_, 010000, 0}, @@ -139,6 +140,7 @@ static const UNIX_Ctrls unix_args[UNIX_CTRLS_] = /* UNIX_QUIET */ {"quiet", _ALL_ON_, 01000000000, 0}, /* UNIX_NO_PASS_EXPIRY */ {"no_pass_expiry", _ALL_ON_, 02000000000, 0}, /* UNIX_DES */ {"des", _ALL_ON_^(0260420000), 0, 1}, +/* UNIX_NULLOK_SECURE */ {"nullok_secure", _ALL_ON_^(01000), 02000000000, 0}, }; #define UNIX_DEFAULTS (unix_args[UNIX__NONULL].flag) @@ -172,6 +174,8 @@ extern int _unix_read_password(pam_handle_t * pamh ,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 */ -- 2.4.0