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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>
This commit is contained in:
Tetsuo Handa 2011-09-10 15:22:48 +09:00 committed by James Morris
parent 5dbe3040c7
commit d58e0da854
7 changed files with 266 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
security/tomoyo/Makefile
View File

@ -1,4 +1,4 @@
obj-y = audit.o common.o condition.o domain.o file.o gc.o group.o load_policy.o memory.o mount.o realpath.o securityfs_if.o tomoyo.o util.o
obj-y = audit.o common.o condition.o domain.o environ.o file.o gc.o group.o load_policy.o memory.o mount.o realpath.o securityfs_if.o tomoyo.o util.o
$(obj)/policy/profile.conf:
@mkdir -p $(obj)/policy/

20
security/tomoyo/common.c
View File

@ -20,6 +20,7 @@ const char * const tomoyo_mode[TOMOYO_CONFIG_MAX_MODE] = {
/* String table for /sys/kernel/security/tomoyo/profile */
const char * const tomoyo_mac_keywords[TOMOYO_MAX_MAC_INDEX
+ TOMOYO_MAX_MAC_CATEGORY_INDEX] = {
/* CONFIG::file group */
[TOMOYO_MAC_FILE_EXECUTE] = "execute",
[TOMOYO_MAC_FILE_OPEN] = "open",
[TOMOYO_MAC_FILE_CREATE] = "create",
@ -43,7 +44,11 @@ const char * const tomoyo_mac_keywords[TOMOYO_MAX_MAC_INDEX
[TOMOYO_MAC_FILE_MOUNT] = "mount",
[TOMOYO_MAC_FILE_UMOUNT] = "unmount",
[TOMOYO_MAC_FILE_PIVOT_ROOT] = "pivot_root",
/* CONFIG::misc group */
[TOMOYO_MAC_ENVIRON] = "env",
/* CONFIG group */
[TOMOYO_MAX_MAC_INDEX + TOMOYO_MAC_CATEGORY_FILE] = "file",
[TOMOYO_MAX_MAC_INDEX + TOMOYO_MAC_CATEGORY_MISC] = "misc",
};
/* String table for conditions. */
@ -133,7 +138,8 @@ const char * const tomoyo_path_keyword[TOMOYO_MAX_PATH_OPERATION] = {
/* String table for categories. */
static const char * const tomoyo_category_keywords
[TOMOYO_MAX_MAC_CATEGORY_INDEX] = {
[TOMOYO_MAC_CATEGORY_FILE] = "file",
[TOMOYO_MAC_CATEGORY_FILE] = "file",
[TOMOYO_MAC_CATEGORY_MISC] = "misc",
};
/* Permit policy management by non-root user? */
@ -1036,11 +1042,13 @@ static int tomoyo_write_domain2(struct tomoyo_policy_namespace *ns,
static const struct {
const char *keyword;
int (*write) (struct tomoyo_acl_param *);
} tomoyo_callback[1] = {
} tomoyo_callback[2] = {
{ "file ", tomoyo_write_file },
{ "misc ", tomoyo_write_misc },
};
u8 i;
for (i = 0; i < 1; i++) {
for (i = 0; i < ARRAY_SIZE(tomoyo_callback); i++) {
if (!tomoyo_str_starts(&param.data,
tomoyo_callback[i].keyword))
continue;
@ -1375,6 +1383,12 @@ static bool tomoyo_print_entry(struct tomoyo_io_buffer *head,
tomoyo_print_name_union(head, &ptr->dir_name);
tomoyo_print_name_union(head, &ptr->fs_type);
tomoyo_print_number_union(head, &ptr->flags);
} else if (acl_type == TOMOYO_TYPE_ENV_ACL) {
struct tomoyo_env_acl *ptr =
container_of(acl, typeof(*ptr), head);
tomoyo_set_group(head, "misc env ");
tomoyo_set_string(head, ptr->env->name);
}
if (acl->cond) {
head->r.print_cond_part = true;

14
security/tomoyo/common.h
View File

@ -196,6 +196,7 @@ enum tomoyo_acl_entry_type_index {
TOMOYO_TYPE_PATH_NUMBER_ACL,
TOMOYO_TYPE_MKDEV_ACL,
TOMOYO_TYPE_MOUNT_ACL,
TOMOYO_TYPE_ENV_ACL,
};
/* Index numbers for access controls with one pathname. */
@ -300,12 +301,14 @@ enum tomoyo_mac_index {
TOMOYO_MAC_FILE_MOUNT,
TOMOYO_MAC_FILE_UMOUNT,
TOMOYO_MAC_FILE_PIVOT_ROOT,
TOMOYO_MAC_ENVIRON,
TOMOYO_MAX_MAC_INDEX
};
/* Index numbers for category of functionality. */
enum tomoyo_mac_category_index {
TOMOYO_MAC_CATEGORY_FILE,
TOMOYO_MAC_CATEGORY_MISC,
TOMOYO_MAX_MAC_CATEGORY_INDEX
};
@ -396,6 +399,9 @@ struct tomoyo_request_info {
*/
u8 operation;
} path_number;
struct {
const struct tomoyo_path_info *name;
} environ;
struct {
const struct tomoyo_path_info *type;
const struct tomoyo_path_info *dir;
@ -638,6 +644,12 @@ struct tomoyo_mount_acl {
struct tomoyo_number_union flags;
};
/* Structure for "misc env" directive in domain policy. */
struct tomoyo_env_acl {
struct tomoyo_acl_info head; /* type = TOMOYO_TYPE_ENV_ACL */
const struct tomoyo_path_info *env; /* environment variable */
};
/* Structure for holding a line from /sys/kernel/security/tomoyo/ interface. */
struct tomoyo_acl_param {
char *data;
@ -820,6 +832,7 @@ const struct tomoyo_path_info *tomoyo_path_matches_group
int tomoyo_check_open_permission(struct tomoyo_domain_info *domain,
struct path *path, const int flag);
int tomoyo_close_control(struct tomoyo_io_buffer *head);
int tomoyo_env_perm(struct tomoyo_request_info *r, const char *env);
int tomoyo_find_next_domain(struct linux_binprm *bprm);
int tomoyo_get_mode(const struct tomoyo_policy_namespace *ns, const u8 profile,
const u8 index);
@ -860,6 +873,7 @@ int tomoyo_update_policy(struct tomoyo_acl_head *new_entry, const int size,
int tomoyo_write_aggregator(struct tomoyo_acl_param *param);
int tomoyo_write_file(struct tomoyo_acl_param *param);
int tomoyo_write_group(struct tomoyo_acl_param *param, const u8 type);
int tomoyo_write_misc(struct tomoyo_acl_param *param);
int tomoyo_write_transition_control(struct tomoyo_acl_param *param,
const u8 type);
ssize_t tomoyo_read_control(struct tomoyo_io_buffer *head, char __user *buffer,

95
security/tomoyo/domain.c
View File

@ -562,6 +562,92 @@ out:
return entry;
}
/**
* tomoyo_environ - Check permission for environment variable names.
*
* @ee: Pointer to "struct tomoyo_execve".
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_environ(struct tomoyo_execve *ee)
{
struct tomoyo_request_info *r = &ee->r;
struct linux_binprm *bprm = ee->bprm;
/* env_page.data is allocated by tomoyo_dump_page(). */
struct tomoyo_page_dump env_page = { };
char *arg_ptr; /* Size is TOMOYO_EXEC_TMPSIZE bytes */
int arg_len = 0;
unsigned long pos = bprm->p;
int offset = pos % PAGE_SIZE;
int argv_count = bprm->argc;
int envp_count = bprm->envc;
int error = -ENOMEM;
ee->r.type = TOMOYO_MAC_ENVIRON;
ee->r.profile = r->domain->profile;
ee->r.mode = tomoyo_get_mode(r->domain->ns, ee->r.profile,
TOMOYO_MAC_ENVIRON);
if (!r->mode || !envp_count)
return 0;
arg_ptr = kzalloc(TOMOYO_EXEC_TMPSIZE, GFP_NOFS);
if (!arg_ptr)
goto out;
while (error == -ENOMEM) {
if (!tomoyo_dump_page(bprm, pos, &env_page))
goto out;
pos += PAGE_SIZE - offset;
/* Read. */
while (argv_count && offset < PAGE_SIZE) {
if (!env_page.data[offset++])
argv_count--;
}
if (argv_count) {
offset = 0;
continue;
}
while (offset < PAGE_SIZE) {
const unsigned char c = env_page.data[offset++];
if (c && arg_len < TOMOYO_EXEC_TMPSIZE - 10) {
if (c == '=') {
arg_ptr[arg_len++] = '\0';
} else if (c == '\\') {
arg_ptr[arg_len++] = '\\';
arg_ptr[arg_len++] = '\\';
} else if (c > ' ' && c < 127) {
arg_ptr[arg_len++] = c;
} else {
arg_ptr[arg_len++] = '\\';
arg_ptr[arg_len++] = (c >> 6) + '0';
arg_ptr[arg_len++]
= ((c >> 3) & 7) + '0';
arg_ptr[arg_len++] = (c & 7) + '0';
}
} else {
arg_ptr[arg_len] = '\0';
}
if (c)
continue;
if (tomoyo_env_perm(r, arg_ptr)) {
error = -EPERM;
break;
}
if (!--envp_count) {
error = 0;
break;
}
arg_len = 0;
}
offset = 0;
}
out:
if (r->mode != TOMOYO_CONFIG_ENFORCING)
error = 0;
kfree(env_page.data);
kfree(arg_ptr);
return error;
}
/**
* tomoyo_find_next_domain - Find a domain.
*
@ -581,6 +667,7 @@ int tomoyo_find_next_domain(struct linux_binprm *bprm)
bool reject_on_transition_failure = false;
struct tomoyo_path_info rn = { }; /* real name */
struct tomoyo_execve *ee = kzalloc(sizeof(*ee), GFP_NOFS);
if (!ee)
return -ENOMEM;
ee->tmp = kzalloc(TOMOYO_EXEC_TMPSIZE, GFP_NOFS);
@ -713,6 +800,10 @@ int tomoyo_find_next_domain(struct linux_binprm *bprm)
bprm->cred->security = domain;
if (need_kfree)
kfree(rn.name);
if (!retval) {
ee->r.domain = domain;
retval = tomoyo_environ(ee);
}
kfree(ee->tmp);
kfree(ee->dump.data);
kfree(ee);
@ -732,7 +823,8 @@ bool tomoyo_dump_page(struct linux_binprm *bprm, unsigned long pos,
struct tomoyo_page_dump *dump)
{
struct page *page;
/* dump->data is released by tomoyo_finish_execve(). */
/* dump->data is released by tomoyo_find_next_domain(). */
if (!dump->data) {
dump->data = kzalloc(PAGE_SIZE, GFP_NOFS);
if (!dump->data)
@ -753,6 +845,7 @@ bool tomoyo_dump_page(struct linux_binprm *bprm, unsigned long pos,
* So do I.
*/
char *kaddr = kmap_atomic(page, KM_USER0);
dump->page = page;
memcpy(dump->data + offset, kaddr + offset,
PAGE_SIZE - offset);

122
security/tomoyo/environ.c Normal file
View File

@ -0,0 +1,122 @@
/*
* 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;
}

9
security/tomoyo/gc.c
View File

@ -36,6 +36,7 @@ static const u8 tomoyo_acl_size[] = {
[TOMOYO_TYPE_PATH_NUMBER_ACL] = sizeof(struct tomoyo_path_number_acl),
[TOMOYO_TYPE_MKDEV_ACL] = sizeof(struct tomoyo_mkdev_acl),
[TOMOYO_TYPE_MOUNT_ACL] = sizeof(struct tomoyo_mount_acl),
[TOMOYO_TYPE_ENV_ACL] = sizeof(struct tomoyo_env_acl),
};
/**
@ -293,6 +294,14 @@ static void tomoyo_del_acl(struct list_head *element)
tomoyo_put_number_union(&entry->flags);
}
break;
case TOMOYO_TYPE_ENV_ACL:
{
struct tomoyo_env_acl *entry =
container_of(acl, typeof(*entry), head);
tomoyo_put_name(entry->env);
}
break;
}
}

14
security/tomoyo/util.c
View File

@ -42,6 +42,8 @@ const u8 tomoyo_index2category[TOMOYO_MAX_MAC_INDEX] = {
[TOMOYO_MAC_FILE_MOUNT] = TOMOYO_MAC_CATEGORY_FILE,
[TOMOYO_MAC_FILE_UMOUNT] = TOMOYO_MAC_CATEGORY_FILE,
[TOMOYO_MAC_FILE_PIVOT_ROOT] = TOMOYO_MAC_CATEGORY_FILE,
/* CONFIG::misc group */
[TOMOYO_MAC_ENVIRON] = TOMOYO_MAC_CATEGORY_MISC,
};
/**
@ -920,15 +922,17 @@ int tomoyo_get_mode(const struct tomoyo_policy_namespace *ns, const u8 profile,
const u8 index)
{
u8 mode;
const u8 category = TOMOYO_MAC_CATEGORY_FILE;
struct tomoyo_profile *p;
if (!tomoyo_policy_loaded)
return TOMOYO_CONFIG_DISABLED;
mode = tomoyo_profile(ns, profile)->config[index];
p = tomoyo_profile(ns, profile);
mode = p->config[index];
if (mode == TOMOYO_CONFIG_USE_DEFAULT)
mode = tomoyo_profile(ns, profile)->config
[category + TOMOYO_MAX_MAC_INDEX];
mode = p->config[tomoyo_index2category[index]
+ TOMOYO_MAX_MAC_INDEX];
if (mode == TOMOYO_CONFIG_USE_DEFAULT)
mode = tomoyo_profile(ns, profile)->default_config;
mode = p->default_config;
return mode & 3;
}