autofs-5.1.0 - add config option to force use of program map stdvars From: Ian Kent 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