// SPDX-License-Identifier: GPL-2.0-only
/*
* AppArmor security module
*
* This file contains basic common functions used in AppArmor
*
* Copyright (C) 1998-2008 Novell/SUSE
* Copyright 2009-2010 Canonical Ltd.
*/
#include <linux/ctype.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/vmalloc.h>
#include "include/audit.h"
#include "include/apparmor.h"
#include "include/lib.h"
#include "include/perms.h"
#include "include/policy.h"
struct aa_perms nullperms;
struct aa_perms allperms = { .allow = ALL_PERMS_MASK,
.quiet = ALL_PERMS_MASK,
.hide = ALL_PERMS_MASK };
/**
* aa_free_str_table - free entries str table
* @t: the string table to free (MAYBE NULL)
*/
void aa_free_str_table(struct aa_str_table *t)
{
int i;
if (t) {
if (!t->table)
return;
for (i = 0; i < t->size; i++)
kfree_sensitive(t->table[i]);
kfree_sensitive(t->table);
t->table = NULL;
t->size = 0;
}
}
/**
* aa_split_fqname - split a fqname into a profile and namespace name
* @fqname: a full qualified name in namespace profile format (NOT NULL)
* @ns_name: pointer to portion of the string containing the ns name (NOT NULL)
*
* Returns: profile name or NULL if one is not specified
*
* Split a namespace name from a profile name (see policy.c for naming
* description). If a portion of the name is missing it returns NULL for
* that portion.
*
* NOTE: may modify the @fqname string. The pointers returned point
* into the @fqname string.
*/
char *aa_split_fqname(char *fqname, char **ns_name)
{
char *name = strim(fqname);
*ns_name = NULL;
if (name[0] == ':') {
char *split = strchr(&name[1], ':');
*ns_name = skip_spaces(&name[1]);
if (split) {
/* overwrite ':' with \0 */
*split++ = 0;
if (strncmp(split, "//", 2) == 0)
split += 2;
name = skip_spaces(split);
} else
/* a ns name without a following profile is allowed */
name = NULL;
}
if (name && *name == 0)
name = NULL;
return name;
}
/**
* skipn_spaces - Removes leading whitespace from @str.
* @str: The string to be stripped.
* @n: length of str to parse, will stop at \0 if encountered before n
*
* Returns a pointer to the first non-whitespace character in @str.
* if all whitespace will return NULL
*/
const char *skipn_spaces(const char *str, size_t n)
{
for (; n && isspace(*str); --n)
++str;
if (n)
return (char *)str;
return NULL;
}
const char *aa_splitn_fqname(const char *fqname, size_t n, const char **ns_name,
size_t *ns_len)
{
const char *end = fqname + n;
const char *name = skipn_spaces(fqname, n);
*ns_name = NULL;
*ns_len = 0;
if (!name)
return NULL;
if (name[0] == ':') {
char *split = strnchr(&name[1], end - &name[1], ':');
*ns_name = skipn_spaces(&name[1], end - &name[1]);
if (!*ns_name)
return NULL;
if (split) {
*ns_len = split - *ns_name;
if (*ns_len == 0)
*ns_name = NULL;
split++;
if (end - split > 1 && strncmp(split, "//", 2) == 0)
split += 2;
name = skipn_spaces(split, end - split);
} else {
/* a ns name without a following profile is allowed */
name = NULL;
*ns_len = end - *ns_name;
}
}
if (name && *name == 0)
name = NULL;
return name;
}
/**
* aa_info_message - log a none profile related status message
* @str: message to log
*/
void aa_info_message(const char *str)
{
if (audit_enabled) {
DEFINE_AUDIT_DATA(ad, LSM_AUDIT_DATA_NONE, AA_CLASS_NONE, NULL);
ad.info = str;
aa_audit_msg(AUDIT_APPARMOR_STATUS, &ad, NULL);
}
printk(KERN_INFO "AppArmor: %s\n", str);
}
__counted char *aa_str_alloc(int size, gfp_t gfp)
{
struct counted_str *str;
str = kmalloc(struct_size(str, name, size), gfp);
if (!str)
return NULL;
kref_init(&str->count);
return str->name;
}
void aa_str_kref(struct kref *kref)
{
kfree(container_of(kref, struct counted_str, count));
}
const char aa_file_perm_chrs[] = "xwracd km l ";
const char *aa_file_perm_names[] = {
"exec",
"write",
"read",
"append",
"create",
"delete",
"open",
"rename",
"setattr",
"getattr",
"setcred",
"getcred",
"chmod",
"chown",
"chgrp",
"lock",
"mmap",
"mprot",
"link",
"snapshot",
"unknown",
"unknown",
"unknown",
"unknown",
"unknown",
"unknown",
"unknown",
"unknown",
"stack",
"change_onexec",
"change_profile",
"change_hat",
};
/**
* aa_perm_mask_to_str - convert a perm mask to its short string
* @str: character buffer to store string in (at least 10 characters)
* @str_size: size of the @str buffer
* @chrs: NUL-terminated character buffer of permission characters
* @mask: permission mask to convert
*/
void aa_perm_mask_to_str(char *str, size_t str_size, const char *chrs, u32 mask)
{
unsigned int i, perm = 1;
size_t num_chrs = strlen(chrs);
for (i = 0; i < num_chrs; perm <<= 1, i++) {
if (mask & perm) {
/* Ensure that one byte is left for NUL-termination */
if (WARN_ON_ONCE(str_size <= 1))
break;
*str++ = chrs[i];
str_size--;
}
}
*str = '\0';
}
void aa_audit_perm_names(struct audit_buffer *ab, const char * const *names,
u32 mask)
{
const char *fmt = "%s";
unsigned int i, perm = 1;
bool prev = false;
for (i = 0; i < 32; perm <<= 1, i++) {
if (mask & perm) {
audit_log_format(ab, fmt, names[i]);
if (!prev) {
prev = true;
fmt = " %s";
}
}
}
}
void aa_audit_perm_mask(struct audit_buffer *ab, u32 mask, const char *chrs,
u32 chrsmask, const char * const *names, u32 namesmask)
{
char str[33];
audit_log_format(ab, "\"");
if ((mask & chrsmask) && chrs) {
aa_perm_mask_to_str(str, sizeof(str), chrs, mask & chrsmask);
mask &= ~chrsmask;
audit_log_format(ab, "%s", str);
if (mask & namesmask)
audit_log_format(ab, " ");
}
if ((mask & namesmask) && names)
aa_audit_perm_names(ab, names, mask & namesmask);
audit_log_format(ab, "\"");
}
/**
* aa_audit_perms_cb - generic callback fn for auditing perms
* @ab: audit buffer (NOT NULL)
* @va: audit struct to audit values of (NOT NULL)
*/
static void aa_audit_perms_cb(struct audit_buffer *ab, void *va)
{
struct common_audit_data *sa = va;
struct apparmor_audit_data *ad = aad(sa);
if (ad->request) {
audit_log_format(ab, " requested_mask=");
aa_audit_perm_mask(ab, ad->request, aa_file_perm_chrs,
PERMS_CHRS_MASK, aa_file_perm_names,
PERMS_NAMES_MASK);
}
if (ad->denied) {
audit_log_format(ab, "denied_mask=");
aa_audit_perm_mask(ab, ad->denied, aa_file_perm_chrs,
PERMS_CHRS_MASK, aa_file_perm_names,
PERMS_NAMES_MASK);
}
audit_log_format(ab, " peer=");
aa_label_xaudit(ab, labels_ns(ad->subj_label), ad->peer,
FLAGS_NONE, GFP_ATOMIC);
}
/**
* aa_apply_modes_to_perms - apply namespace and profile flags to perms
* @profile: that perms where computed from
* @perms: perms to apply mode modifiers to
*
* TODO: split into profile and ns based flags for when accumulating perms
*/
void aa_apply_modes_to_perms(struct aa_profile *profile, struct aa_perms *perms)
{
switch (AUDIT_MODE(profile)) {
case AUDIT_ALL:
perms->audit = ALL_PERMS_MASK;
fallthrough;
case AUDIT_NOQUIET:
perms->quiet = 0;
break;
case AUDIT_QUIET:
perms->audit = 0;
fallthrough;
case AUDIT_QUIET_DENIED:
perms->quiet = ALL_PERMS_MASK;
break;
}
if (KILL_MODE(profile))
perms->kill = ALL_PERMS_MASK;
else if (COMPLAIN_MODE(profile))
perms->complain = ALL_PERMS_MASK;
else if (USER_MODE(profile))
perms->prompt = ALL_PERMS_MASK;
}
void aa_profile_match_label(struct aa_profile *profile,
struct aa_ruleset *rules,
struct aa_label *label,
int type, u32 request, struct aa_perms *perms)
{
/* TODO: doesn't yet handle extended types */
aa_state_t state;
state = aa_dfa_next(rules->policy->dfa,
rules->policy->start[AA_CLASS_LABEL],
type);
aa_label_match(profile, rules, label, state, false, request, perms);
}
/* currently unused */
int aa_profile_label_perm(struct aa_profile *profile, struct aa_profile *target,
u32 request, int type, u32 *deny,
struct apparmor_audit_data *ad)
{
struct aa_ruleset *rules = list_first_entry(&profile->rules,
typeof(*rules), list);
struct aa_perms perms;
ad->peer = &target->label;
ad->request = request;
aa_profile_match_label(profile, rules, &target->label, type, request,
&perms);
aa_apply_modes_to_perms(profile, &perms);
*deny |= request & perms.deny;
return aa_check_perms(profile, &perms, request, ad, aa_audit_perms_cb);
}
/**
* aa_check_perms - do audit mode selection based on perms set
* @profile: profile being checked
* @perms: perms computed for the request
* @request: requested perms
* @ad: initialized audit structure (MAY BE NULL if not auditing)
* @cb: callback fn for type specific fields (MAY BE NULL)
*
* Returns: 0 if permission else error code
*
* Note: profile audit modes need to be set before calling by setting the
* perm masks appropriately.
*
* If not auditing then complain mode is not enabled and the
* error code will indicate whether there was an explicit deny
* with a positive value.
*/
int aa_check_perms(struct aa_profile *profile, struct aa_perms *perms,
u32 request, struct apparmor_audit_data *ad,
void (*cb)(struct audit_buffer *, void *))
{
int type, error;
u32 denied = request & (~perms->allow | perms->deny);
if (likely(!denied)) {
/* mask off perms that are not being force audited */
request &= perms->audit;
if (!request || !ad)
return 0;
type = AUDIT_APPARMOR_AUDIT;
error = 0;
} else {
error = -EACCES;
if (denied & perms->kill)
type = AUDIT_APPARMOR_KILL;
else if (denied == (denied & perms->complain))
type = AUDIT_APPARMOR_ALLOWED;
else
type = AUDIT_APPARMOR_DENIED;
if (denied == (denied & perms->hide))
error = -ENOENT;
denied &= ~perms->quiet;
if (!ad || !denied)
return error;
}
if (ad) {
ad->subj_label = &profile->label;
ad->request = request;
ad->denied = denied;
ad->error = error;
aa_audit_msg(type, ad, cb);
}
if (type == AUDIT_APPARMOR_ALLOWED)
error = 0;
return error;
}
/**
* aa_policy_init - initialize a policy structure
* @policy: policy to initialize (NOT NULL)
* @prefix: prefix name if any is required. (MAYBE NULL)
* @name: name of the policy, init will make a copy of it (NOT NULL)
* @gfp: allocation mode
*
* Note: this fn creates a copy of strings passed in
*
* Returns: true if policy init successful
*/
bool aa_policy_init(struct aa_policy *policy, const char *prefix,
const char *name, gfp_t gfp)
{
char *hname;
/* freed by policy_free */
if (prefix) {
hname = aa_str_alloc(strlen(prefix) + strlen(name) + 3, gfp);
if (hname)
sprintf(hname, "%s//%s", prefix, name);
} else {
hname = aa_str_alloc(strlen(name) + 1, gfp);
if (hname)
strcpy(hname, name);
}
if (!hname)
return false;
policy->hname = hname;
/* base.name is a substring of fqname */
policy->name = basename(policy->hname);
INIT_LIST_HEAD(&policy->list);
INIT_LIST_HEAD(&policy->profiles);
return true;
}
/**
* aa_policy_destroy - free the elements referenced by @policy
* @policy: policy that is to have its elements freed (NOT NULL)
*/
void aa_policy_destroy(struct aa_policy *policy)
{
AA_BUG(on_list_rcu(&policy->profiles));
AA_BUG(on_list_rcu(&policy->list));
/* don't free name as its a subset of hname */
aa_put_str(policy->hname);
}
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