linux-hardened/security/tomoyo/environ.c
Tetsuo Handa d58e0da854 TOMOYO: Add environment variable name restriction support.
This patch adds support for checking environment variable's names.
Although TOMOYO already provides ability to check argv[]/envp[] passed to
execve() requests,

  file execute /bin/sh exec.envp["LD_LIBRARY_PATH"]="bar"

will reject execution of /bin/sh if environment variable LD_LIBRARY_PATH is not
defined. To grant execution of /bin/sh if LD_LIBRARY_PATH is not defined,
administrators have to specify like

  file execute /bin/sh exec.envp["LD_LIBRARY_PATH"]="/system/lib"
  file execute /bin/sh exec.envp["LD_LIBRARY_PATH"]=NULL

. Since there are many environment variables whereas conditional checks are
applied as "&&", it is difficult to cover all combinations. Therefore, this
patch supports conditional checks that are applied as "||", by specifying like

  file execute /bin/sh
  misc env LD_LIBRARY_PATH exec.envp["LD_LIBRARY_PATH"]="/system/lib"

which means "grant execution of /bin/sh if environment variable is not defined
or is defined and its value is /system/lib".

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: James Morris <jmorris@namei.org>
2011-09-14 08:27:05 +10:00

122 lines
3 KiB
C

/*
* security/tomoyo/environ.c
*
* Copyright (C) 2005-2011 NTT DATA CORPORATION
*/
#include "common.h"
/**
* tomoyo_check_env_acl - Check permission for environment variable's name.
*
* @r: Pointer to "struct tomoyo_request_info".
* @ptr: Pointer to "struct tomoyo_acl_info".
*
* Returns true if granted, false otherwise.
*/
static bool tomoyo_check_env_acl(struct tomoyo_request_info *r,
const struct tomoyo_acl_info *ptr)
{
const struct tomoyo_env_acl *acl =
container_of(ptr, typeof(*acl), head);
return tomoyo_path_matches_pattern(r->param.environ.name, acl->env);
}
/**
* tomoyo_audit_env_log - Audit environment variable name log.
*
* @r: Pointer to "struct tomoyo_request_info".
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_audit_env_log(struct tomoyo_request_info *r)
{
return tomoyo_supervisor(r, "misc env %s\n",
r->param.environ.name->name);
}
/**
* tomoyo_env_perm - Check permission for environment variable's name.
*
* @r: Pointer to "struct tomoyo_request_info".
* @env: The name of environment variable.
*
* Returns 0 on success, negative value otherwise.
*
* Caller holds tomoyo_read_lock().
*/
int tomoyo_env_perm(struct tomoyo_request_info *r, const char *env)
{
struct tomoyo_path_info environ;
int error;
if (!env || !*env)
return 0;
environ.name = env;
tomoyo_fill_path_info(&environ);
r->param_type = TOMOYO_TYPE_ENV_ACL;
r->param.environ.name = &environ;
do {
tomoyo_check_acl(r, tomoyo_check_env_acl);
error = tomoyo_audit_env_log(r);
} while (error == TOMOYO_RETRY_REQUEST);
return error;
}
/**
* tomoyo_same_env_acl - Check for duplicated "struct tomoyo_env_acl" entry.
*
* @a: Pointer to "struct tomoyo_acl_info".
* @b: Pointer to "struct tomoyo_acl_info".
*
* Returns true if @a == @b, false otherwise.
*/
static bool tomoyo_same_env_acl(const struct tomoyo_acl_info *a,
const struct tomoyo_acl_info *b)
{
const struct tomoyo_env_acl *p1 = container_of(a, typeof(*p1), head);
const struct tomoyo_env_acl *p2 = container_of(b, typeof(*p2), head);
return p1->env == p2->env;
}
/**
* tomoyo_write_env - Write "struct tomoyo_env_acl" list.
*
* @param: Pointer to "struct tomoyo_acl_param".
*
* Returns 0 on success, negative value otherwise.
*
* Caller holds tomoyo_read_lock().
*/
static int tomoyo_write_env(struct tomoyo_acl_param *param)
{
struct tomoyo_env_acl e = { .head.type = TOMOYO_TYPE_ENV_ACL };
int error = -ENOMEM;
const char *data = tomoyo_read_token(param);
if (!tomoyo_correct_word(data) || strchr(data, '='))
return -EINVAL;
e.env = tomoyo_get_name(data);
if (!e.env)
return error;
error = tomoyo_update_domain(&e.head, sizeof(e), param,
tomoyo_same_env_acl, NULL);
tomoyo_put_name(e.env);
return error;
}
/**
* tomoyo_write_misc - Update environment variable list.
*
* @param: Pointer to "struct tomoyo_acl_param".
*
* Returns 0 on success, negative value otherwise.
*/
int tomoyo_write_misc(struct tomoyo_acl_param *param)
{
if (tomoyo_str_starts(&param->data, "env "))
return tomoyo_write_env(param);
return -EINVAL;
}