u-boot/env/flags.c
Marek Vasut d045cbacf2 env: Add support for explicit write access list
This option marks any U-Boot variable which does not have explicit 'w'
writeable flag set as read-only. This way the environment can be locked
down and only variables explicitly configured to be writeable can ever
be changed by either 'env import', 'env set' or loading user environment
from environment storage.

Signed-off-by: Marek Vasut <marex@denx.de>
Reviewed-by: Tom Rini <trini@konsulko.com>
2020-07-31 10:13:00 -04:00

608 lines
14 KiB
C

// SPDX-License-Identifier: GPL-2.0+
/*
* (C) Copyright 2012
* Joe Hershberger, National Instruments, joe.hershberger@ni.com
*/
#include <env.h>
#include <linux/string.h>
#include <linux/ctype.h>
#ifdef USE_HOSTCC /* Eliminate "ANSI does not permit..." warnings */
#include <stdint.h>
#include <stdio.h>
#include "fw_env_private.h"
#include "fw_env.h"
#include <env_attr.h>
#include <env_flags.h>
#define env_get fw_getenv
#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
#else
#include <common.h>
#include <env_internal.h>
#endif
#ifdef CONFIG_CMD_NET
#define ENV_FLAGS_NET_VARTYPE_REPS "im"
#else
#define ENV_FLAGS_NET_VARTYPE_REPS ""
#endif
#ifdef CONFIG_ENV_WRITEABLE_LIST
#define ENV_FLAGS_WRITEABLE_VARACCESS_REPS "w"
#else
#define ENV_FLAGS_WRITEABLE_VARACCESS_REPS ""
#endif
static const char env_flags_vartype_rep[] = "sdxb" ENV_FLAGS_NET_VARTYPE_REPS;
static const char env_flags_varaccess_rep[] =
"aroc" ENV_FLAGS_WRITEABLE_VARACCESS_REPS;
static const int env_flags_varaccess_mask[] = {
0,
ENV_FLAGS_VARACCESS_PREVENT_DELETE |
ENV_FLAGS_VARACCESS_PREVENT_CREATE |
ENV_FLAGS_VARACCESS_PREVENT_OVERWR,
ENV_FLAGS_VARACCESS_PREVENT_DELETE |
ENV_FLAGS_VARACCESS_PREVENT_OVERWR,
ENV_FLAGS_VARACCESS_PREVENT_DELETE |
ENV_FLAGS_VARACCESS_PREVENT_NONDEF_OVERWR,
#ifdef CONFIG_ENV_WRITEABLE_LIST
ENV_FLAGS_VARACCESS_WRITEABLE,
#endif
};
#ifdef CONFIG_CMD_ENV_FLAGS
static const char * const env_flags_vartype_names[] = {
"string",
"decimal",
"hexadecimal",
"boolean",
#ifdef CONFIG_CMD_NET
"IP address",
"MAC address",
#endif
};
static const char * const env_flags_varaccess_names[] = {
"any",
"read-only",
"write-once",
"change-default",
#ifdef CONFIG_ENV_WRITEABLE_LIST
"writeable",
#endif
};
/*
* Print the whole list of available type flags.
*/
void env_flags_print_vartypes(void)
{
enum env_flags_vartype curtype = (enum env_flags_vartype)0;
while (curtype != env_flags_vartype_end) {
printf("\t%c -\t%s\n", env_flags_vartype_rep[curtype],
env_flags_vartype_names[curtype]);
curtype++;
}
}
/*
* Print the whole list of available access flags.
*/
void env_flags_print_varaccess(void)
{
enum env_flags_varaccess curaccess = (enum env_flags_varaccess)0;
while (curaccess != env_flags_varaccess_end) {
printf("\t%c -\t%s\n", env_flags_varaccess_rep[curaccess],
env_flags_varaccess_names[curaccess]);
curaccess++;
}
}
/*
* Return the name of the type.
*/
const char *env_flags_get_vartype_name(enum env_flags_vartype type)
{
return env_flags_vartype_names[type];
}
/*
* Return the name of the access.
*/
const char *env_flags_get_varaccess_name(enum env_flags_varaccess access)
{
return env_flags_varaccess_names[access];
}
#endif /* CONFIG_CMD_ENV_FLAGS */
/*
* Parse the flags string from a .flags attribute list into the vartype enum.
*/
enum env_flags_vartype env_flags_parse_vartype(const char *flags)
{
char *type;
if (strlen(flags) <= ENV_FLAGS_VARTYPE_LOC)
return env_flags_vartype_string;
type = strchr(env_flags_vartype_rep,
flags[ENV_FLAGS_VARTYPE_LOC]);
if (type != NULL)
return (enum env_flags_vartype)
(type - &env_flags_vartype_rep[0]);
printf("## Warning: Unknown environment variable type '%c'\n",
flags[ENV_FLAGS_VARTYPE_LOC]);
return env_flags_vartype_string;
}
/*
* Parse the flags string from a .flags attribute list into the varaccess enum.
*/
enum env_flags_varaccess env_flags_parse_varaccess(const char *flags)
{
enum env_flags_varaccess va_default = env_flags_varaccess_any;
enum env_flags_varaccess va;
char *access;
if (strlen(flags) <= ENV_FLAGS_VARACCESS_LOC)
return va_default;
access = strchr(env_flags_varaccess_rep,
flags[ENV_FLAGS_VARACCESS_LOC]);
if (access != NULL) {
va = (enum env_flags_varaccess)
(access - &env_flags_varaccess_rep[0]);
return va;
}
printf("## Warning: Unknown environment variable access method '%c'\n",
flags[ENV_FLAGS_VARACCESS_LOC]);
return va_default;
}
/*
* Parse the binary flags from a hash table entry into the varaccess enum.
*/
enum env_flags_varaccess env_flags_parse_varaccess_from_binflags(int binflags)
{
enum env_flags_varaccess va_default = env_flags_varaccess_any;
enum env_flags_varaccess va;
int i;
for (i = 0; i < ARRAY_SIZE(env_flags_varaccess_mask); i++)
if (env_flags_varaccess_mask[i] ==
(binflags & ENV_FLAGS_VARACCESS_BIN_MASK)) {
va = (enum env_flags_varaccess)i;
return va;
}
printf("Warning: Non-standard access flags. (0x%x)\n",
binflags & ENV_FLAGS_VARACCESS_BIN_MASK);
return va_default;
}
static inline int is_hex_prefix(const char *value)
{
return value[0] == '0' && (value[1] == 'x' || value[1] == 'X');
}
static void skip_num(int hex, const char *value, const char **end,
int max_digits)
{
int i;
if (hex && is_hex_prefix(value))
value += 2;
for (i = max_digits; i != 0; i--) {
if (hex && !isxdigit(*value))
break;
if (!hex && !isdigit(*value))
break;
value++;
}
if (end != NULL)
*end = value;
}
#ifdef CONFIG_CMD_NET
int eth_validate_ethaddr_str(const char *addr)
{
const char *end;
const char *cur;
int i;
cur = addr;
for (i = 0; i < 6; i++) {
skip_num(1, cur, &end, 2);
if (cur == end)
return -1;
if (cur + 2 == end && is_hex_prefix(cur))
return -1;
if (i != 5 && *end != ':')
return -1;
if (i == 5 && *end != '\0')
return -1;
cur = end + 1;
}
return 0;
}
#endif
/*
* Based on the declared type enum, validate that the value string complies
* with that format
*/
static int _env_flags_validate_type(const char *value,
enum env_flags_vartype type)
{
const char *end;
#ifdef CONFIG_CMD_NET
const char *cur;
int i;
#endif
switch (type) {
case env_flags_vartype_string:
break;
case env_flags_vartype_decimal:
skip_num(0, value, &end, -1);
if (*end != '\0')
return -1;
break;
case env_flags_vartype_hex:
skip_num(1, value, &end, -1);
if (*end != '\0')
return -1;
if (value + 2 == end && is_hex_prefix(value))
return -1;
break;
case env_flags_vartype_bool:
if (value[0] != '1' && value[0] != 'y' && value[0] != 't' &&
value[0] != 'Y' && value[0] != 'T' &&
value[0] != '0' && value[0] != 'n' && value[0] != 'f' &&
value[0] != 'N' && value[0] != 'F')
return -1;
if (value[1] != '\0')
return -1;
break;
#ifdef CONFIG_CMD_NET
case env_flags_vartype_ipaddr:
cur = value;
for (i = 0; i < 4; i++) {
skip_num(0, cur, &end, 3);
if (cur == end)
return -1;
if (i != 3 && *end != '.')
return -1;
if (i == 3 && *end != '\0')
return -1;
cur = end + 1;
}
break;
case env_flags_vartype_macaddr:
if (eth_validate_ethaddr_str(value))
return -1;
break;
#endif
case env_flags_vartype_end:
return -1;
}
/* OK */
return 0;
}
/*
* Look for flags in a provided list and failing that the static list
*/
static inline int env_flags_lookup(const char *flags_list, const char *name,
char *flags)
{
int ret = 1;
if (!flags)
/* bad parameter */
return -1;
/* try the env first */
if (flags_list)
ret = env_attr_lookup(flags_list, name, flags);
if (ret != 0)
/* if not found in the env, look in the static list */
ret = env_attr_lookup(ENV_FLAGS_LIST_STATIC, name, flags);
return ret;
}
#ifdef USE_HOSTCC /* Functions only used from tools/env */
/*
* Look up any flags directly from the .flags variable and the static list
* and convert them to the vartype enum.
*/
enum env_flags_vartype env_flags_get_type(const char *name)
{
const char *flags_list = env_get(ENV_FLAGS_VAR);
char flags[ENV_FLAGS_ATTR_MAX_LEN + 1];
if (env_flags_lookup(flags_list, name, flags))
return env_flags_vartype_string;
if (strlen(flags) <= ENV_FLAGS_VARTYPE_LOC)
return env_flags_vartype_string;
return env_flags_parse_vartype(flags);
}
/*
* Look up the access of a variable directly from the .flags var.
*/
enum env_flags_varaccess env_flags_get_varaccess(const char *name)
{
const char *flags_list = env_get(ENV_FLAGS_VAR);
enum env_flags_varaccess va_default = env_flags_varaccess_any;
char flags[ENV_FLAGS_ATTR_MAX_LEN + 1];
if (env_flags_lookup(flags_list, name, flags))
return va_default;
if (strlen(flags) <= ENV_FLAGS_VARACCESS_LOC)
return va_default;
return env_flags_parse_varaccess(flags);
}
/*
* Validate that the proposed new value for "name" is valid according to the
* defined flags for that variable, if any.
*/
int env_flags_validate_type(const char *name, const char *value)
{
enum env_flags_vartype type;
if (value == NULL)
return 0;
type = env_flags_get_type(name);
if (_env_flags_validate_type(value, type) < 0) {
printf("## Error: flags type check failure for "
"\"%s\" <= \"%s\" (type: %c)\n",
name, value, env_flags_vartype_rep[type]);
return -1;
}
return 0;
}
/*
* Validate that the proposed access to variable "name" is valid according to
* the defined flags for that variable, if any.
*/
int env_flags_validate_varaccess(const char *name, int check_mask)
{
enum env_flags_varaccess access;
int access_mask;
access = env_flags_get_varaccess(name);
access_mask = env_flags_varaccess_mask[access];
return (check_mask & access_mask) != 0;
}
/*
* Validate the parameters to "env set" directly
*/
int env_flags_validate_env_set_params(char *name, char * const val[], int count)
{
if ((count >= 1) && val[0] != NULL) {
enum env_flags_vartype type = env_flags_get_type(name);
/*
* we don't currently check types that need more than
* one argument
*/
if (type != env_flags_vartype_string && count > 1) {
printf("## Error: too many parameters for setting \"%s\"\n",
name);
return -1;
}
return env_flags_validate_type(name, val[0]);
}
/* ok */
return 0;
}
#else /* !USE_HOSTCC - Functions only used from lib/hashtable.c */
/*
* Parse the flag charachters from the .flags attribute list into the binary
* form to be stored in the environment entry->flags field.
*/
static int env_parse_flags_to_bin(const char *flags)
{
int binflags;
binflags = env_flags_parse_vartype(flags) & ENV_FLAGS_VARTYPE_BIN_MASK;
binflags |= env_flags_varaccess_mask[env_flags_parse_varaccess(flags)];
return binflags;
}
static int first_call = 1;
static const char *flags_list;
/*
* Look for possible flags for a newly added variable
* This is called specifically when the variable did not exist in the hash
* previously, so the blanket update did not find this variable.
*/
void env_flags_init(struct env_entry *var_entry)
{
const char *var_name = var_entry->key;
char flags[ENV_FLAGS_ATTR_MAX_LEN + 1] = "";
int ret = 1;
if (first_call) {
#ifdef CONFIG_ENV_WRITEABLE_LIST
flags_list = ENV_FLAGS_LIST_STATIC;
#else
flags_list = env_get(ENV_FLAGS_VAR);
#endif
first_call = 0;
}
/* look in the ".flags" and static for a reference to this variable */
ret = env_flags_lookup(flags_list, var_name, flags);
/* if any flags were found, set the binary form to the entry */
if (!ret && strlen(flags))
var_entry->flags = env_parse_flags_to_bin(flags);
}
/*
* Called on each existing env var prior to the blanket update since removing
* a flag in the flag list should remove its flags.
*/
static int clear_flags(struct env_entry *entry)
{
entry->flags = 0;
return 0;
}
/*
* Call for each element in the list that defines flags for a variable
*/
static int set_flags(const char *name, const char *value, void *priv)
{
struct env_entry e, *ep;
e.key = name;
e.data = NULL;
hsearch_r(e, ENV_FIND, &ep, &env_htab, 0);
/* does the env variable actually exist? */
if (ep != NULL) {
/* the flag list is empty, so clear the flags */
if (value == NULL || strlen(value) == 0)
ep->flags = 0;
else
/* assign the requested flags */
ep->flags = env_parse_flags_to_bin(value);
}
return 0;
}
static int on_flags(const char *name, const char *value, enum env_op op,
int flags)
{
/* remove all flags */
hwalk_r(&env_htab, clear_flags);
/* configure any static flags */
env_attr_walk(ENV_FLAGS_LIST_STATIC, set_flags, NULL);
/* configure any dynamic flags */
env_attr_walk(value, set_flags, NULL);
return 0;
}
U_BOOT_ENV_CALLBACK(flags, on_flags);
/*
* Perform consistency checking before creating, overwriting, or deleting an
* environment variable. Called as a callback function by hsearch_r() and
* hdelete_r(). Returns 0 in case of success, 1 in case of failure.
* When (flag & H_FORCE) is set, do not print out any error message and force
* overwriting of write-once variables.
*/
int env_flags_validate(const struct env_entry *item, const char *newval,
enum env_op op, int flag)
{
const char *name;
const char *oldval = NULL;
if (op != env_op_create)
oldval = item->data;
name = item->key;
/* Default value for NULL to protect string-manipulating functions */
newval = newval ? : "";
/* validate the value to match the variable type */
if (op != env_op_delete) {
enum env_flags_vartype type = (enum env_flags_vartype)
(ENV_FLAGS_VARTYPE_BIN_MASK & item->flags);
if (_env_flags_validate_type(newval, type) < 0) {
printf("## Error: flags type check failure for "
"\"%s\" <= \"%s\" (type: %c)\n",
name, newval, env_flags_vartype_rep[type]);
return -1;
}
}
/* check for access permission */
#ifdef CONFIG_ENV_WRITEABLE_LIST
if (flag & H_DEFAULT)
return 0; /* Default env is always OK */
/*
* External writeable variables can be overwritten by external env,
* anything else can not be overwritten by external env.
*/
if ((flag & H_EXTERNAL) &&
!(item->flags & ENV_FLAGS_VARACCESS_WRITEABLE))
return 1;
#endif
#ifndef CONFIG_ENV_ACCESS_IGNORE_FORCE
if (flag & H_FORCE) {
printf("## Error: Can't force access to \"%s\"\n", name);
return 0;
}
#endif
switch (op) {
case env_op_delete:
if (item->flags & ENV_FLAGS_VARACCESS_PREVENT_DELETE) {
printf("## Error: Can't delete \"%s\"\n", name);
return 1;
}
break;
case env_op_overwrite:
if (item->flags & ENV_FLAGS_VARACCESS_PREVENT_OVERWR) {
printf("## Error: Can't overwrite \"%s\"\n", name);
return 1;
} else if (item->flags &
ENV_FLAGS_VARACCESS_PREVENT_NONDEF_OVERWR) {
const char *defval = env_get_default(name);
if (defval == NULL)
defval = "";
printf("oldval: %s defval: %s\n", oldval, defval);
if (strcmp(oldval, defval) != 0) {
printf("## Error: Can't overwrite \"%s\"\n",
name);
return 1;
}
}
break;
case env_op_create:
if (item->flags & ENV_FLAGS_VARACCESS_PREVENT_CREATE) {
printf("## Error: Can't create \"%s\"\n", name);
return 1;
}
break;
}
return 0;
}
#endif