// SPDX-License-Identifier: GPL-2.0-only
/*
 * AppArmor security module
 *
 * This file contains AppArmor /proc/<pid>/attr/ interface functions
 *
 * Copyright (C) 1998-2008 Novell/SUSE
 * Copyright 2009-2010 Canonical Ltd.
 */

#include "include/apparmor.h"
#include "include/cred.h"
#include "include/policy.h"
#include "include/policy_ns.h"
#include "include/domain.h"
#include "include/procattr.h"


/**
 * aa_getprocattr - Return the label information for @label
 * @label: the label to print label info about  (NOT NULL)
 * @string: Returns - string containing the label info (NOT NULL)
 * @newline: indicates that a newline should be added
 *
 * Requires: label != NULL && string != NULL
 *
 * Creates a string containing the label information for @label.
 *
 * Returns: size of string placed in @string else error code on failure
 */
int aa_getprocattr(struct aa_label *label, char **string, bool newline)
{
        struct aa_ns *ns = labels_ns(label);
        struct aa_ns *current_ns = aa_get_current_ns();
        int len;

        if (!aa_ns_visible(current_ns, ns, true)) {
                aa_put_ns(current_ns);
                return -EACCES;
        }

        len = aa_label_snxprint(NULL, 0, current_ns, label,
                                FLAG_SHOW_MODE | FLAG_VIEW_SUBNS |
                                FLAG_HIDDEN_UNCONFINED);
        AA_BUG(len < 0);

        *string = kmalloc(len + 2, GFP_KERNEL);
        if (!*string) {
                aa_put_ns(current_ns);
                return -ENOMEM;
        }

        len = aa_label_snxprint(*string, len + 2, current_ns, label,
                                FLAG_SHOW_MODE | FLAG_VIEW_SUBNS |
                                FLAG_HIDDEN_UNCONFINED);
        if (len < 0) {
                aa_put_ns(current_ns);
                return len;
        }

        if (newline)
                (*string)[len++] = '\n';
        (*string)[len] = 0;

        aa_put_ns(current_ns);
        return len;
}

/**
 * split_token_from_name - separate a string of form  <token>^<name>
 * @op: operation being checked
 * @args: string to parse  (NOT NULL)
 * @token: stores returned parsed token value  (NOT NULL)
 *
 * Returns: start position of name after token else NULL on failure
 */
static char *split_token_from_name(const char *op, char *args, u64 *token)
{
        char *name;

        *token = simple_strtoull(args, &name, 16);
        if ((name == args) || *name != '^') {
                AA_ERROR("%s: Invalid input '%s'", op, args);
                return ERR_PTR(-EINVAL);
        }

        name++;                 /* skip ^ */
        if (!*name)
                name = NULL;
        return name;
}

/**
 * aa_setprocattr_changehat - handle procattr interface to change_hat
 * @args: args received from writing to /proc/<pid>/attr/current (NOT NULL)
 * @size: size of the args
 * @flags: set of flags governing behavior
 *
 * Returns: %0 or error code if change_hat fails
 */
int aa_setprocattr_changehat(char *args, size_t size, int flags)
{
        char *hat;
        u64 token;
        const char *hats[16];           /* current hard limit on # of names */
        int count = 0;

        hat = split_token_from_name(OP_CHANGE_HAT, args, &token);
        if (IS_ERR(hat))
                return PTR_ERR(hat);

        if (!hat && !token) {
                AA_ERROR("change_hat: Invalid input, NULL hat and NULL magic");
                return -EINVAL;
        }

        if (hat) {
                /* set up hat name vector, args guaranteed null terminated
                 * at args[size] by setprocattr.
                 *
                 * If there are multiple hat names in the buffer each is
                 * separated by a \0.  Ie. userspace writes them pre tokenized
                 */
                char *end = args + size;
                for (count = 0; (hat < end) && count < 16; ++count) {
                        char *next = hat + strlen(hat) + 1;
                        hats[count] = hat;
                        AA_DEBUG(DEBUG_DOMAIN,
                                 "%s: (pid %d) Magic 0x%llx count %d hat '%s'\n"
                                 , __func__, current->pid, token, count, hat);
                        hat = next;
                }
        } else
                AA_DEBUG(DEBUG_DOMAIN,
                         "%s: (pid %d) Magic 0x%llx count %d Hat '%s'\n",
                         __func__, current->pid, token, count, "<NULL>");

        return aa_change_hat(hats, count, token, flags);
}