security/apparmor/include/path.h

   1 /*
   2  * AppArmor security module
   3  *
   4  * This file contains AppArmor basic path manipulation function definitions.
   5  *
   6  * Copyright (C) 1998-2008 Novell/SUSE
   7  * Copyright 2009-2010 Canonical Ltd.
   8  *
   9  * This program is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU General Public License as
  11  * published by the Free Software Foundation, version 2 of the
  12  * License.
  13  */
  14
  15 #ifndef __AA_PATH_H
  16 #define __AA_PATH_H
  17
  18
  19 enum path_flags {
  20         PATH_IS_DIR = 0x1,              /* path is a directory */
  21         PATH_SOCK_COND = 0x2,
  22         PATH_CONNECT_PATH = 0x4,        /* connect disconnected paths to / */
  23         PATH_CHROOT_REL = 0x8,          /* do path lookup relative to chroot */
  24         PATH_CHROOT_NSCONNECT = 0x10,   /* connect paths that are at ns root */
  25
  26         PATH_DELEGATE_DELETED = 0x08000, /* delegate deleted files */
  27         PATH_MEDIATE_DELETED = 0x10000,  /* mediate deleted paths */
  28 };
  29
  30 int aa_path_name(const struct path *path, int flags, char *buffer,
  31                  const char **name, const char **info,
  32                  const char *disconnected);
  33
  34 #define MAX_PATH_BUFFERS 2
  35
  36 /* Per cpu buffers used during mediation */
  37 /* preallocated buffers to use during path lookups */
  38 struct aa_buffers {
  39         char *buf[MAX_PATH_BUFFERS];
  40 };
  41
  42 #include <linux/percpu.h>
  43 #include <linux/preempt.h>
  44
  45 DECLARE_PER_CPU(struct aa_buffers, aa_buffers);
  46
  47 #define COUNT_ARGS(X...) COUNT_ARGS_HELPER(, ##X, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
  48 #define COUNT_ARGS_HELPER(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, n, X...) n
  49 #define CONCAT(X, Y) X ## Y
  50 #define CONCAT_AFTER(X, Y) CONCAT(X, Y)
  51
  52 #define ASSIGN(FN, X, N) ((X) = FN(N))
  53 #define EVAL1(FN, X) ASSIGN(FN, X, 0) /*X = FN(0)*/
  54 #define EVAL2(FN, X, Y...) do { ASSIGN(FN, X, 1);  EVAL1(FN, Y); } while (0)
  55 #define EVAL(FN, X...) CONCAT_AFTER(EVAL, COUNT_ARGS(X))(FN, X)
  56
  57 #define for_each_cpu_buffer(I) for ((I) = 0; (I) < MAX_PATH_BUFFERS; (I)++)
  58
  59 #ifdef CONFIG_DEBUG_PREEMPT
  60 #define AA_BUG_PREEMPT_ENABLED(X) AA_BUG(preempt_count() <= 0, X)
  61 #else
  62 #define AA_BUG_PREEMPT_ENABLED(X) /* nop */
  63 #endif
  64
  65 #define __get_buffer(N) ({                                      \
  66         struct aa_buffers *__cpu_var; \
  67         AA_BUG_PREEMPT_ENABLED("__get_buffer without preempt disabled");  \
  68         __cpu_var = this_cpu_ptr(&aa_buffers);                  \
  69         __cpu_var->buf[(N)]; })
  70
  71 #define __get_buffers(X...)    EVAL(__get_buffer, X)
  72
  73 #define __put_buffers(X, Y...) ((void)&(X))
  74
  75 #define get_buffers(X...)       \
  76 do {                            \
  77         preempt_disable();      \
  78         __get_buffers(X);       \
  79 } while (0)
  80
  81 #define put_buffers(X, Y...)    \
  82 do {                            \
  83         __put_buffers(X, Y);    \
  84         preempt_enable();       \
  85 } while (0)
  86
  87 #endif /* __AA_PATH_H */