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-rw-r--r--security/apparmor/lib.c484
1 files changed, 484 insertions, 0 deletions
diff --git a/security/apparmor/lib.c b/security/apparmor/lib.c
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+++ b/security/apparmor/lib.c
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+// 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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