On 09/16/2009 11:36 AM, Joshua Brindle wrote:
>
>
> Chad Sellers wrote:
>> On 8/28/09 1:58 PM, "Daniel J Walsh"<dwalsh@xxxxxxxxxx> wrote:
>>
>>
>>> The general idea is to relabel a disabled policy module as
>>> policymodule.pp.disabled
>>>
>>> Then make sure -u and -i update this name.
>>>
>>> Rebuilding policy does not include .disabled
>>>
>>> Listing shows disabled as disabled.
>>>
>>> semodule -r will remove disabled modules. If you reinstall they will
>>> come
>>> back.
>>>
>>> # /usr/sbin/semodule -d unconfined
>>> # /usr/sbin/semodule -l | grep unc
>>> unconfined 3.0.1 Disabled
>>> unconfineduser 1.0.0
>>> # ls -lZ /etc/selinux/targeted/modules/active/modules/unconfined.pp*
>>> -rw-------. root root staff_u:object_r:semanage_store_t:s0
>>> /etc/selinux/targeted/modules/active/modules/unconfined.pp.disabled
>>> # /usr/sbin/semodule -i /usr/share/selinux/targeted/unconfined.pp.bz2
>>> # /usr/sbin/semodule -l | grep unc
>>> unconfined 3.0.1 Disabled
>>> unconfineduser 1.0.0
>>> # /usr/sbin/semodule -e unconfined
>>> # /usr/sbin/semodule -l | grep unc
>>> unconfined 3.0.1
>>> unconfineduser 1.0.0
>>>
>>> This would allow an admin to disable a module and the module will stay
>>> disabled until he enables it.
>>>
>> <snip>
>>
>>> diff --git a/libsemanage/src/direct_api.c b/libsemanage/src/direct_api.c
>>> index f7d65eb..49a2357 100644
>>> --- a/libsemanage/src/direct_api.c
>>> +++ b/libsemanage/src/direct_api.c
>>> @@ -53,6 +53,8 @@
>>> #include "policy.h"
>>> #include<sys/mman.h>
>>>
>>> +static const char *DISABLESTR=".disabled";
>>> +
>>> static void semanage_direct_destroy(semanage_handle_t * sh);
>>> static int semanage_direct_disconnect(semanage_handle_t * sh);
>>> static int semanage_direct_begintrans(semanage_handle_t * sh);
>>> @@ -66,6 +68,8 @@ static int
>>> semanage_direct_upgrade_file(semanage_handle_t *
>>> sh, const char *modu
>>> static int semanage_direct_install_base(semanage_handle_t * sh, char
>>> *base_data,
>>> size_t data_len);
>>> static int semanage_direct_install_base_file(semanage_handle_t *
>>> sh, const
>>> char *module_name);
>>> +static int semanage_direct_enable(semanage_handle_t * sh, char
>>> *module_name);
>>> +static int semanage_direct_disable(semanage_handle_t * sh, char
>>> *module_name);
>>> static int semanage_direct_remove(semanage_handle_t * sh, char
>>> *module_name);
>>> static int semanage_direct_list(semanage_handle_t * sh,
>>> semanage_module_info_t ** modinfo,
>>> @@ -83,6 +87,8 @@ static struct semanage_policy_table direct_funcs = {
>>> .upgrade_file = semanage_direct_upgrade_file,
>>> .install_base = semanage_direct_install_base,
>>> .install_base_file = semanage_direct_install_base_file,
>>> + .enable = semanage_direct_enable,
>>> + .disable = semanage_direct_disable,
>>> .remove = semanage_direct_remove,
>>> .list = semanage_direct_list
>>> };
>>> @@ -1002,6 +1008,17 @@ static int
>>> semanage_direct_commit(semanage_handle_t *
>>> sh)
>>> return retval;
>>> }
>>>
>>> +static char * get_store_name(const char *file)
>>> +{
>>> + int len = strlen(file) + strlen(DISABLESTR) + 1;
>>> + char *storename = calloc(1, len);
>>> + if (! storename) return NULL;
>>> + snprintf(storename,len, "%s%s", file, DISABLESTR);
>>> + if ( access(storename, F_OK) == 0) return storename;
>>> + free(storename);
>>> + return strdup(file);
>>> +}
>>> +
>>> /* Writes a module to the sandbox's module directory, overwriting any
>>> * previous module stored within. Note that module data are not
>>> * free()d by this function; caller is responsible for deallocating it
>>> @@ -1019,11 +1036,20 @@ static int
>>> semanage_direct_install(semanage_handle_t *
>>> sh,
>>> &filename)) != 0) {
>>> goto cleanup;
>>> }
>>> - if (bzip(sh, filename, data, data_len)<= 0) {
>>> +
>>> + char *storename = get_store_name(filename);
>>> + if (!storename) {
>>> + ERR(sh, "Could not allocate memory");
>>> + retval = -1;
>>> + goto cleanup;
>>> + }
>>> + if (bzip(sh, storename, data, data_len)<= 0) {
>>>
>>
>> Should we present some sort of warning to the user if they
>> install/upgrade a
>> module that is disabled? This seems to maintain the disabled status
>> silently, which might confuse users (e.g. "I just installed that
>> module, why
>> isn't the policy working").
>>
>> Also, I see that you patched direct_install, but not direct_upgrade. So,
>> upgrade will try to re-enable the module if it has been disabled.
>>
>>
>>> ERR(sh, "Error while writing to %s.", filename);
>>> retval = -3;
>>> goto cleanup;
>>> }
>>> + free(storename);
>>> +
>>> retval = 0;
>>> cleanup:
>>> free(version);
>>> @@ -1268,6 +1294,107 @@ static int
>>> semanage_direct_install_base_file(semanage_handle_t * sh,
>>> return retval;
>>> }
>>>
>>> +/* Enables a module from the sandbox. Returns 0 on success, -1 if out
>>> + * of memory, -2 if module not found or could not be enabled. */
>>> +static int semanage_direct_enable(semanage_handle_t * sh, char
>>> *module_name)
>>> +{
>>> + int i, retval = -1;
>>> + char **module_filenames = NULL;
>>> + int num_mod_files;
>>> + size_t name_len = strlen(module_name);
>>> + if
>>> (semanage_get_modules_names(sh,&module_filenames,&num_mod_files) ==
>>> + -1) {
>>> + return -1;
>>> + }
>>> + for (i = 0; i< num_mod_files; i++) {
>>> + char *base = strrchr(module_filenames[i], '/');
>>> + if (base == NULL) {
>>> + ERR(sh, "Could not read module names.");
>>> + retval = -2;
>>> + goto cleanup;
>>> + }
>>> + base++;
>>> + if (memcmp(module_name, base, name_len) == 0&&
>>> + strcmp(base + name_len + 3, DISABLESTR) == 0) {
>>> + int len = strlen(module_filenames[i]) - strlen(DISABLESTR);
>>> + char *enabled_name = calloc(1, len+1);
>>> + if (!enabled_name) {
>>> + ERR(sh, "Could not allocate memory");
>>> + retval = -1;
>>> + goto cleanup;
>>> + }
>>> +
>>> + strncpy(enabled_name, module_filenames[i],len);
>>> +
>>> + if (rename(module_filenames[i], enabled_name) == -1) {
>>> + ERR(sh, "Could not enable module file %s.",
>>> + enabled_name);
>>> + retval = -2;
>>> + }
>>> + retval = 0;
>>> + free(enabled_name);
>>> + goto cleanup;
>>> + }
>>> + }
>>> + ERR(sh, "Module %s was not found.", module_name);
>>> + retval = -2; /* module not found */
>>> + cleanup:
>>> + for (i = 0; module_filenames != NULL&& i< num_mod_files; i++) {
>>> + free(module_filenames[i]);
>>> + }
>>> + free(module_filenames);
>>> + return retval;
>>> +}
>>> +
>>> +/* Enables a module from the sandbox. Returns 0 on success, -1 if out
>>> + * of memory, -2 if module not found or could not be enabled. */
>>> +static int semanage_direct_disable(semanage_handle_t * sh, char
>>> *module_name)
>>> +{
>>> + int i, retval = -1;
>>> + char **module_filenames = NULL;
>>> + int num_mod_files;
>>> + size_t name_len = strlen(module_name);
>>> + if
>>> (semanage_get_modules_names(sh,&module_filenames,&num_mod_files) ==
>>> + -1) {
>>> + return -1;
>>> + }
>>> + for (i = 0; i< num_mod_files; i++) {
>>> + char *base = strrchr(module_filenames[i], '/');
>>> + if (base == NULL) {
>>> + ERR(sh, "Could not read module names.");
>>> + retval = -2;
>>> + goto cleanup;
>>> + }
>>> + base++;
>>> + if (memcmp(module_name, base, name_len) == 0&&
>>> + strcmp(base + name_len, ".pp") == 0) {
>>> + char disabled_name[PATH_MAX];
>>> + if (snprintf(disabled_name, PATH_MAX, "%s%s",
>>> + module_filenames[i], DISABLESTR) == PATH_MAX) {
>>> + ERR(sh, "Could not disable module file %s.",
>>> + module_filenames[i]);
>>> + retval = -2;
>>> + goto cleanup;
>>> + }
>>> + if (rename(module_filenames[i], disabled_name) == -1) {
>>> + ERR(sh, "Could not disable module file %s.",
>>> + module_filenames[i]);
>>> + retval = -2;
>>> + }
>>> + retval = 0;
>>> + goto cleanup;
>>> + }
>>> + }
>>> + ERR(sh, "Module %s was not found.", module_name);
>>> + retval = -2; /* module not found */
>>> + cleanup:
>>> + for (i = 0; module_filenames != NULL&& i< num_mod_files; i++) {
>>> + free(module_filenames[i]);
>>> + }
>>> + free(module_filenames);
>>> + return retval;
>>> +}
>>> +
>>>
>> While this function does succeed in renaming a file, it does not
>> succeed in
>> preventing the module from being linked in. semanage_get_modules_names()
>> grabs everything in the modules directory, so the disabled modules
>> here are
>> still linked into the policy. A quick sesearch confirms this.
>>
>> To fix this, you'll either need to modify semanage_filename_select() to
>> filter out files ending in .disabled or perhaps just move them from the
>> modules directory to a disabled_modules directory (instead of the
>> rename).
>> The latter option has the advantage of not requiring filtering that
>> could go
>> wrong at some point, so I would lean toward it.
>>
>> Thanks,
>> Chad
>>
>>
>>
>
>
> Do you have an updated version of this?
>
Not yet, we need to hold off on this, Maybe we can hack it out next week. Moving to /disabled versus .disabled is not as easy as I would have liked.
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