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From b6545b83f94c5fb7aec1478b8d458a1393f479c8 Mon Sep 17 00:00:00 2001
From: "Maxin B. John" <maxin.john@intel.com>
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 <hartmans@debian.org>,
Steve Langasek <vorlon@debian.org>
Upstream-Status: Pending
Signed-off-by: Ming Liu <ming.liu@windriver.com>
Signed-off-by: Amarnath Valluri <amarnath.valluri@intel.com>
Signed-off-by: Maxin B. John <maxin.john@intel.com>
---
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 @@
<para>
The default action of this module is to not permit the
user access to a service if their official password is blank.
- The <option>nullok</option> argument overrides this default.
+ The <option>nullok</option> argument overrides this default
+ and allows any user with a blank password to access the
+ service.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term>
+ <option>nullok_secure</option>
+ </term>
+ <listitem>
+ <para>
+ The default action of this module is to not permit the
+ user access to a service if their official password is blank.
+ The <option>nullok_secure</option> 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.
</para>
</listitem>
</varlistentry>
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
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