security/apparmor/include/lib.h

   1 /*
   2  * AppArmor security module
   3  *
   4  * This file contains AppArmor lib definitions
   5  *
   6  * 2016 Canonical Ltd.
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License as
  10  * published by the Free Software Foundation, version 2 of the
  11  * License.
  12  */
  13
  14 #ifndef __AA_LIB_H
  15 #define __AA_LIB_H
  16
  17 #include <linux/slab.h>
  18 #include <linux/fs.h>
  19
  20 #include "match.h"
  21
  22 /* Provide our own test for whether a write lock is held for asserts
  23  * this is because on none SMP systems write_can_lock will always
  24  * resolve to true, which is what you want for code making decisions
  25  * based on it, but wrong for asserts checking that the lock is held
  26  */
  27 #ifdef CONFIG_SMP
  28 #define write_is_locked(X) !write_can_lock(X)
  29 #else
  30 #define write_is_locked(X) (1)
  31 #endif /* CONFIG_SMP */
  32
  33 /*
  34  * DEBUG remains global (no per profile flag) since it is mostly used in sysctl
  35  * which is not related to profile accesses.
  36  */
  37
  38 #define DEBUG_ON (aa_g_debug && printk_ratelimit())
  39 #define dbg_printk(__fmt, __args...) printk(KERN_DEBUG __fmt, ##__args)
  40 #define AA_DEBUG(fmt, args...)                                          \
  41         do {                                                            \
  42                 if (DEBUG_ON)                                           \
  43                         dbg_printk("AppArmor: " fmt, ##args);           \
  44         } while (0)
  45
  46 #define AA_WARN(X) WARN((X), "APPARMOR WARN %s: %s\n", __FUNCTION__, #X)
  47
  48 #define AA_BUG(X, args...) AA_BUG_FMT((X), "" args )
  49 #define AA_BUG_FMT(X, fmt, args...)                                     \
  50         WARN((X), "AppArmor WARN %s: (" #X "): " fmt, __FUNCTION__ , ##args )
  51
  52 #define AA_ERROR(fmt, args...)                                          \
  53         do {                                                            \
  54                 if (printk_ratelimit())                                 \
  55                         printk(KERN_ERR "AppArmor: " fmt, ##args);      \
  56         } while (0)
  57
  58 /* Flag indicating whether initialization completed */
  59 extern int apparmor_initialized __initdata;
  60
  61 /* fn's in lib */
  62 const char *skipn_spaces(const char *str, size_t n);
  63 char *aa_split_fqname(char *args, char **ns_name);
  64 const char *aa_splitn_fqname(const char *fqname, size_t n, const char **ns_name,
  65                              size_t *ns_len);
  66 void aa_info_message(const char *str);
  67 void *__aa_kvmalloc(size_t size, gfp_t flags);
  68
  69 static inline void *kvmalloc(size_t size)
  70 {
  71         return __aa_kvmalloc(size, 0);
  72 }
  73
  74 static inline void *kvzalloc(size_t size)
  75 {
  76         return __aa_kvmalloc(size, __GFP_ZERO);
  77 }
  78
  79 /* returns 0 if kref not incremented */
  80 static inline int kref_get_not0(struct kref *kref)
  81 {
  82         return atomic_inc_not_zero(&kref->refcount);
  83 }
  84
  85 /**
  86  * aa_strneq - compare null terminated @str to a non null terminated substring
  87  * @str: a null terminated string
  88  * @sub: a substring, not necessarily null terminated
  89  * @len: length of @sub to compare
  90  *
  91  * The @str string must be full consumed for this to be considered a match
  92  */
  93 static inline bool aa_strneq(const char *str, const char *sub, int len)
  94 {
  95         return !strncmp(str, sub, len) && !str[len];
  96 }
  97
  98 /**
  99  * aa_dfa_null_transition - step to next state after null character
 100  * @dfa: the dfa to match against
 101  * @start: the state of the dfa to start matching in
 102  *
 103  * aa_dfa_null_transition transitions to the next state after a null
 104  * character which is not used in standard matching and is only
 105  * used to separate pairs.
 106  */
 107 static inline unsigned int aa_dfa_null_transition(struct aa_dfa *dfa,
 108                                                   unsigned int start)
 109 {
 110         /* the null transition only needs the string's null terminator byte */
 111         return aa_dfa_next(dfa, start, 0);
 112 }
 113
 114 static inline bool path_mediated_fs(struct dentry *dentry)
 115 {
 116         return !(dentry->d_sb->s_flags & MS_NOUSER);
 117 }
 118
 119
 120 struct counted_str {
 121         struct kref count;
 122         char name[];
 123 };
 124
 125 #define str_to_counted(str) \
 126         ((struct counted_str *)(str - offsetof(struct counted_str,name)))
 127
 128 #define __counted       /* atm just a notation */
 129
 130 void aa_str_kref(struct kref *kref);
 131 char *aa_str_alloc(int size, gfp_t gfp);
 132
 133
 134 static inline __counted char *aa_get_str(__counted char *str)
 135 {
 136         if (str)
 137                 kref_get(&(str_to_counted(str)->count));
 138
 139         return str;
 140 }
 141
 142 static inline void aa_put_str(__counted char *str)
 143 {
 144         if (str)
 145                 kref_put(&str_to_counted(str)->count, aa_str_kref);
 146 }
 147
 148 const char *aa_imode_name(umode_t mode);
 149
 150
 151 /* struct aa_policy - common part of both namespaces and profiles
 152  * @name: name of the object
 153  * @hname - The hierarchical name, NOTE: is .name of struct counted_str
 154  * @list: list policy object is on
 155  * @profiles: head of the profiles list contained in the object
 156  */
 157 struct aa_policy {
 158         const char *name;
 159         __counted char *hname;
 160         struct list_head list;
 161         struct list_head profiles;
 162 };
 163
 164 #define aa_peer_name(peer) (peer)->base.hname
 165
 166 /**
 167  * basename - find the last component of an hname
 168  * @name: hname to find the base profile name component of  (NOT NULL)
 169  *
 170  * Returns: the tail (base profile name) name component of an hname
 171  */
 172 static inline const char *basename(const char *hname)
 173 {
 174         char *split;
 175         hname = strim((char *)hname);
 176         for (split = strstr(hname, "//"); split; split = strstr(hname, "//"))
 177                 hname = split + 2;
 178
 179         return hname;
 180 }
 181
 182 /**
 183  * __policy_find - find a policy by @name on a policy list
 184  * @head: list to search  (NOT NULL)
 185  * @name: name to search for  (NOT NULL)
 186  *
 187  * Requires: rcu_read_lock be held
 188  *
 189  * Returns: unrefcounted policy that match @name or NULL if not found
 190  */
 191 static inline struct aa_policy *__policy_find(struct list_head *head,
 192                                               const char *name)
 193 {
 194         struct aa_policy *policy;
 195
 196         list_for_each_entry_rcu(policy, head, list) {
 197                 if (!strcmp(policy->name, name))
 198                         return policy;
 199         }
 200         return NULL;
 201 }
 202
 203 /**
 204  * __policy_strn_find - find a policy that's name matches @len chars of @str
 205  * @head: list to search  (NOT NULL)
 206  * @str: string to search for  (NOT NULL)
 207  * @len: length of match required
 208  *
 209  * Requires: rcu_read_lock be held
 210  *
 211  * Returns: unrefcounted policy that match @str or NULL if not found
 212  *
 213  * if @len == strlen(@strlen) then this is equiv to __policy_find
 214  * other wise it allows searching for policy by a partial match of name
 215  */
 216 static inline struct aa_policy *__policy_strn_find(struct list_head *head,
 217                                                    const char *str, int len)
 218 {
 219         struct aa_policy *policy;
 220
 221         list_for_each_entry_rcu(policy, head, list) {
 222                 if (aa_strneq(policy->name, str, len))
 223                         return policy;
 224         }
 225
 226         return NULL;
 227 }
 228
 229 bool aa_policy_init(struct aa_policy *policy, const char *prefix,
 230                     const char *name, gfp_t gfp);
 231 void aa_policy_destroy(struct aa_policy *policy);
 232
 233
 234 /*
 235  * fn_label_build - abstract out the build of a label transition
 236  * @L: label the transition is being computed for
 237  * @P: profile parameter derived from L by this macro, can be passed to FN
 238  * @GFP: memory allocation type to use
 239  * @FN: fn to call for each profile transition. @P is set to the profile
 240  *
 241  * Returns: new label on success
 242  *          ERR_PTR if build @FN fails
 243  *          NULL if label_build fails due to low memory conditions
 244  *
 245  * @FN must return a label or ERR_PTR on failure. NULL is not allowed
 246  */
 247 #define fn_label_build(L, P, GFP, FN)                                   \
 248 ({                                                                      \
 249         __label__ __cleanup, __done;                                    \
 250         struct aa_label *__new_;                                        \
 251                                                                         \
 252         if ((L)->size > 1) {                                            \
 253                 /* TODO: add cache of transitions already done */       \
 254                 struct label_it __i;                                    \
 255                 int __j, __k, __count;                                  \
 256                 DEFINE_VEC(label, __lvec);                              \
 257                 DEFINE_VEC(profile, __pvec);                            \
 258                 if (vec_setup(label, __lvec, (L)->size, (GFP))) {       \
 259                         __new_ = NULL;                                  \
 260                         goto __done;                                    \
 261                 }                                                       \
 262                 __j = 0;                                                \
 263                 label_for_each(__i, (L), (P)) {                         \
 264                         __new_ = (FN);                                  \
 265                         AA_BUG(!__new_);                                \
 266                         if (IS_ERR(__new_))                             \
 267                                 goto __cleanup;                         \
 268                         __lvec[__j++] = __new_;                         \
 269                 }                                                       \
 270                 for (__j = __count = 0; __j < (L)->size; __j++)         \
 271                         __count += __lvec[__j]->size;                   \
 272                 if (!vec_setup(profile, __pvec, __count, (GFP))) {      \
 273                         for (__j = __k = 0; __j < (L)->size; __j++) {   \
 274                                 label_for_each(__i, __lvec[__j], (P))   \
 275                                         __pvec[__k++] = aa_get_profile(P); \
 276                         }                                               \
 277                         __count -= aa_vec_unique(__pvec, __count, 0);   \
 278                         if (__count > 1) {                              \
 279                                 __new_ = aa_vec_find_or_create_label(__pvec,\
 280                                                      __count, (GFP));   \
 281                                 /* only fails if out of Mem */          \
 282                                 if (!__new_)                            \
 283                                         __new_ = NULL;                  \
 284                         } else                                          \
 285                                 __new_ = aa_get_label(&__pvec[0]->label); \
 286                         vec_cleanup(profile, __pvec, __count);          \
 287                 } else                                                  \
 288                         __new_ = NULL;                                  \
 289         __cleanup:                                                      \
 290                 vec_cleanup(label, __lvec, (L)->size);                  \
 291         } else {                                                        \
 292                 (P) = labels_profile(L);                                \
 293                 __new_ = (FN);                                          \
 294         }                                                               \
 295 __done:                                                                 \
 296         if (!__new_)                                                    \
 297                 AA_DEBUG("label build failed\n");                       \
 298         (__new_);                                                       \
 299 })
 300
 301
 302 #define __fn_build_in_ns(NS, P, NS_FN, OTHER_FN)                        \
 303 ({                                                                      \
 304         struct aa_label *__new;                                         \
 305         if ((P)->ns != (NS))                                            \
 306                 __new = (OTHER_FN);                                     \
 307         else                                                            \
 308                 __new = (NS_FN);                                        \
 309         (__new);                                                        \
 310 })
 311
 312 #define fn_label_build_in_ns(L, P, GFP, NS_FN, OTHER_FN)                \
 313 ({                                                                      \
 314         fn_label_build((L), (P), (GFP),                                 \
 315                 __fn_build_in_ns(labels_ns(L), (P), (NS_FN), (OTHER_FN))); \
 316 })
 317
 318 #endif /* __AA_LIB_H */