security/apparmor/procattr.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * AppArmor security module
   4  *
   5  * This file contains AppArmor /proc/<pid>/attr/ interface functions
   6  *
   7  * Copyright (C) 1998-2008 Novell/SUSE
   8  * Copyright 2009-2010 Canonical Ltd.
   9  */
  10
  11 #include "include/apparmor.h"
  12 #include "include/cred.h"
  13 #include "include/policy.h"
  14 #include "include/policy_ns.h"
  15 #include "include/domain.h"
  16 #include "include/procattr.h"
  17
  18
  19 /**
  20  * aa_getprocattr - Return the label information for @label
  21  * @label: the label to print label info about  (NOT NULL)
  22  * @string: Returns - string containing the label info (NOT NULL)
  23  * @newline: indicates that a newline should be added
  24  *
  25  * Requires: label != NULL && string != NULL
  26  *
  27  * Creates a string containing the label information for @label.
  28  *
  29  * Returns: size of string placed in @string else error code on failure
  30  */
  31 int aa_getprocattr(struct aa_label *label, char **string, bool newline)
  32 {
  33         struct aa_ns *ns = labels_ns(label);
  34         struct aa_ns *current_ns = aa_get_current_ns();
  35         int len;
  36
  37         if (!aa_ns_visible(current_ns, ns, true)) {
  38                 aa_put_ns(current_ns);
  39                 return -EACCES;
  40         }
  41
  42         len = aa_label_snxprint(NULL, 0, current_ns, label,
  43                                 FLAG_SHOW_MODE | FLAG_VIEW_SUBNS |
  44                                 FLAG_HIDDEN_UNCONFINED);
  45         AA_BUG(len < 0);
  46
  47         *string = kmalloc(len + 2, GFP_KERNEL);
  48         if (!*string) {
  49                 aa_put_ns(current_ns);
  50                 return -ENOMEM;
  51         }
  52
  53         len = aa_label_snxprint(*string, len + 2, current_ns, label,
  54                                 FLAG_SHOW_MODE | FLAG_VIEW_SUBNS |
  55                                 FLAG_HIDDEN_UNCONFINED);
  56         if (len < 0) {
  57                 aa_put_ns(current_ns);
  58                 return len;
  59         }
  60
  61         if (newline)
  62                 (*string)[len++] = '\n';
  63         (*string)[len] = 0;
  64
  65         aa_put_ns(current_ns);
  66         return len;
  67 }
  68
  69 /**
  70  * split_token_from_name - separate a string of form  <token>^<name>
  71  * @op: operation being checked
  72  * @args: string to parse  (NOT NULL)
  73  * @token: stores returned parsed token value  (NOT NULL)
  74  *
  75  * Returns: start position of name after token else NULL on failure
  76  */
  77 static char *split_token_from_name(const char *op, char *args, u64 *token)
  78 {
  79         char *name;
  80
  81         *token = simple_strtoull(args, &name, 16);
  82         if ((name == args) || *name != '^') {
  83                 AA_ERROR("%s: Invalid input '%s'", op, args);
  84                 return ERR_PTR(-EINVAL);
  85         }
  86
  87         name++;                 /* skip ^ */
  88         if (!*name)
  89                 name = NULL;
  90         return name;
  91 }
  92
  93 /**
  94  * aa_setprocattr_changehat - handle procattr interface to change_hat
  95  * @args: args received from writing to /proc/<pid>/attr/current (NOT NULL)
  96  * @size: size of the args
  97  * @flags: set of flags governing behavior
  98  *
  99  * Returns: %0 or error code if change_hat fails
 100  */
 101 int aa_setprocattr_changehat(char *args, size_t size, int flags)
 102 {
 103         char *hat;
 104         u64 token;
 105         const char *hats[16];           /* current hard limit on # of names */
 106         int count = 0;
 107
 108         hat = split_token_from_name(OP_CHANGE_HAT, args, &token);
 109         if (IS_ERR(hat))
 110                 return PTR_ERR(hat);
 111
 112         if (!hat && !token) {
 113                 AA_ERROR("change_hat: Invalid input, NULL hat and NULL magic");
 114                 return -EINVAL;
 115         }
 116
 117         if (hat) {
 118                 /* set up hat name vector, args guaranteed null terminated
 119                  * at args[size] by setprocattr.
 120                  *
 121                  * If there are multiple hat names in the buffer each is
 122                  * separated by a \0.  Ie. userspace writes them pre tokenized
 123                  */
 124                 char *end = args + size;
 125                 for (count = 0; (hat < end) && count < 16; ++count) {
 126                         char *next = hat + strlen(hat) + 1;
 127                         hats[count] = hat;
 128                         AA_DEBUG("%s: (pid %d) Magic 0x%llx count %d hat '%s'\n"
 129                                  , __func__, current->pid, token, count, hat);
 130                         hat = next;
 131                 }
 132         } else
 133                 AA_DEBUG("%s: (pid %d) Magic 0x%llx count %d Hat '%s'\n",
 134                          __func__, current->pid, token, count, "<NULL>");
 135
 136         return aa_change_hat(hats, count, token, flags);
 137 }