autofs-5.1.0 - add config option to force use of program map stdvars
From: Ian Kent <ikent@redhat.com>
Enabling the extended environment (including $HOME, for example) for
program maps opens automount(8) to a privilege escalation.
Rather than just removing the entended environment a configuration
option is added to disable it by default so that those who wish to
use it can do so if they wish.
---
CHANGELOG | 1 +
include/defaults.h | 2 ++
lib/defaults.c | 12 ++++++++++++
man/autofs.5 | 5 +++++
man/autofs.conf.5.in | 9 +++++++++
modules/lookup_program.c | 14 +++++++++++++-
redhat/autofs.conf.default.in | 11 +++++++++++
samples/autofs.conf.default.in | 11 +++++++++++
8 files changed, 64 insertions(+), 1 deletion(-)
diff --git a/CHANGELOG b/CHANGELOG
index f491f74..02fe33c 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -43,6 +43,7 @@
- ensure negative cache isn't updated on remount.
- dont add wildcard to negative cache.
- add a prefix to program map stdvars.
+- add config option to force use of program map stdvars.
04/06/2014 autofs-5.1.0
=======================
diff --git a/include/defaults.h b/include/defaults.h
index 6ca20d0..4f32e12 100644
--- a/include/defaults.h
+++ b/include/defaults.h
@@ -30,6 +30,7 @@
#define DEFAULT_UMOUNT_WAIT "12"
#define DEFAULT_BROWSE_MODE "1"
#define DEFAULT_LOGGING "none"
+#define DEFAULT_FORCE_STD_PROG_MAP_ENV "0"
#define DEFAULT_LDAP_TIMEOUT "-1"
#define DEFAULT_LDAP_NETWORK_TIMEOUT "8"
@@ -151,6 +152,7 @@ unsigned int defaults_get_timeout(void);
unsigned int defaults_get_negative_timeout(void);
unsigned int defaults_get_browse_mode(void);
unsigned int defaults_get_logging(void);
+unsigned int defaults_force_std_prog_map_env(void);
const char *defaults_get_ldap_server(void);
unsigned int defaults_get_ldap_timeout(void);
unsigned int defaults_get_ldap_network_timeout(void);
diff --git a/lib/defaults.c b/lib/defaults.c
index 83f6ac7..5711e65 100644
--- a/lib/defaults.c
+++ b/lib/defaults.c
@@ -51,6 +51,7 @@
#define NAME_NEGATIVE_TIMEOUT "negative_timeout"
#define NAME_BROWSE_MODE "browse_mode"
#define NAME_LOGGING "logging"
+#define NAME_FORCE_STD_PROG_MAP_ENV "force_standard_program_map_env"
#define NAME_LDAP_URI "ldap_uri"
#define NAME_LDAP_TIMEOUT "ldap_timeout"
@@ -1590,6 +1591,17 @@ unsigned int defaults_get_logging(void)
return logging;
}
+unsigned int defaults_force_std_prog_map_env(void)
+{
+ int res;
+
+ res = conf_get_yesno(autofs_gbl_sec, NAME_FORCE_STD_PROG_MAP_ENV);
+ if (res < 0)
+ res = atoi(DEFAULT_FORCE_STD_PROG_MAP_ENV);
+
+ return res;
+}
+
unsigned int defaults_get_ldap_timeout(void)
{
int res;
diff --git a/man/autofs.5 b/man/autofs.5
index 6c53520..6143f1a 100644
--- a/man/autofs.5
+++ b/man/autofs.5
@@ -190,6 +190,11 @@ SHOST Short hostname (domain part removed if present)
.fi
.RE
.sp
+If a program map is used these standard environment variables will have
+a prefix of "AUTOFS_" to prevent interpreted languages like python from
+being able to load and execute arbitray code from a user home directory.
+.RE
+.sp
Additional entries can be defined with the -Dvariable=Value map-option to
.BR automount (8).
.SS Executable Maps
diff --git a/man/autofs.conf.5.in b/man/autofs.conf.5.in
index c959b52..382d873 100644
--- a/man/autofs.conf.5.in
+++ b/man/autofs.conf.5.in
@@ -71,6 +71,15 @@ options replace the global options (program default "yes", append options).
.B logging
.br
set default log level "none", "verbose" or "debug" (program default "none").
+.TP
+.B force_standard_program_map_env
+.br
+override the use of a prefix with standard environment variables when a
+program map is executed. Since program maps are run as the privileded
+user setting these standard environment variables opens automount(8) to
+potential user privilege escalation when the program map is written in a
+language that can load components from, for example, a user home directory
+(program default "no").
.SS LDAP Configuration
.P
Configuration settings available are:
diff --git a/modules/lookup_program.c b/modules/lookup_program.c
index 6fc861a..6cbab0f 100644
--- a/modules/lookup_program.c
+++ b/modules/lookup_program.c
@@ -129,6 +129,7 @@ static char *lookup_one(struct autofs_point *ap,
int distance;
int alloci = 1;
int status;
+ char *prefix;
mapent = (char *) malloc(MAPENT_MAX_LEN + 1);
if (!mapent) {
@@ -174,6 +175,17 @@ static char *lookup_one(struct autofs_point *ap,
warn(ap->logopt,
MODPREFIX "failed to set PWD to %s for map %s",
ap->path, ctxt->mapname);
+
+ /*
+ * By default use a prefix with standard environment
+ * variables to prevent system subversion by interpreted
+ * languages.
+ */
+ if (defaults_force_std_prog_map_env())
+ prefix = NULL;
+ else
+ prefix = "AUTOFS_";
+
/*
* MAPFMT_DEFAULT must be "sun" for ->parse_init() to have setup
* the macro table.
@@ -181,7 +193,7 @@ static char *lookup_one(struct autofs_point *ap,
if (ctxt->mapfmt && strcmp(ctxt->mapfmt, "MAPFMT_DEFAULT")) {
struct parse_context *pctxt = (struct parse_context *) ctxt->parse->context;
/* Add standard environment as seen by sun map parser */
- pctxt->subst = addstdenv(pctxt->subst, "AUTOFS_");
+ pctxt->subst = addstdenv(pctxt->subst, prefix);
macro_setenv(pctxt->subst);
}
execl(ctxt->mapname, ctxt->mapname, name, NULL);
diff --git a/redhat/autofs.conf.default.in b/redhat/autofs.conf.default.in
index 8ccd5d6..13bbb7e 100644
--- a/redhat/autofs.conf.default.in
+++ b/redhat/autofs.conf.default.in
@@ -53,6 +53,17 @@ mount_nfs_default_protocol = 4
#
#logging = none
#
+# force_standard_program_map_env - disable the use of the "AUTOFS_"
+# prefix for standard environemt variables when
+# executing a program map. Since program maps
+# are run as the privileded user this opens
+# automount(8) to potential user privilege
+# escalation when the program map is written
+# in a language that can load components from,
+# for example, a user home directory.
+#
+# force_standard_program_map_env = no
+#
# Define base dn for map dn lookup.
#
# Define server URIs
diff --git a/samples/autofs.conf.default.in b/samples/autofs.conf.default.in
index 934e411..441b68e 100644
--- a/samples/autofs.conf.default.in
+++ b/samples/autofs.conf.default.in
@@ -52,6 +52,17 @@ browse_mode = no
#
#logging = none
#
+# force_standard_program_map_env - disable the use of the "AUTOFS_"
+# prefix for standard environemt variables when
+# executing a program map. Since program maps
+# are run as the privileded user this opens
+# automount(8) to potential user privilege
+# escalation when the program map is written
+# in a language that can load components from,
+# for example, a user home directory.
+#
+# force_standard_program_map_env = no
+#
# Define base dn for map dn lookup.
#
# Define server URIs