security/apparmor/include/lib.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /*
   3  * AppArmor security module
   4  *
   5  * This file contains AppArmor lib definitions
   6  *
   7  * 2017 Canonical Ltd.
   8  */
   9
  10 #ifndef __AA_LIB_H
  11 #define __AA_LIB_H
  12
  13 #include <linux/slab.h>
  14 #include <linux/fs.h>
  15 #include <linux/lsm_hooks.h>
  16
  17 #include "match.h"
  18
  19 extern struct aa_dfa *stacksplitdfa;
  20
  21 /*
  22  * DEBUG remains global (no per profile flag) since it is mostly used in sysctl
  23  * which is not related to profile accesses.
  24  */
  25
  26 #define DEBUG_ON (aa_g_debug)
  27 /*
  28  * split individual debug cases out in preparation for finer grained
  29  * debug controls in the future.
  30  */
  31 #define AA_DEBUG_LABEL DEBUG_ON
  32 #define dbg_printk(__fmt, __args...) pr_debug(__fmt, ##__args)
  33 #define AA_DEBUG(fmt, args...)                                          \
  34         do {                                                            \
  35                 if (DEBUG_ON)                                           \
  36                         pr_debug_ratelimited("AppArmor: " fmt, ##args); \
  37         } while (0)
  38
  39 #define AA_WARN(X) WARN((X), "APPARMOR WARN %s: %s\n", __func__, #X)
  40
  41 #define AA_BUG(X, args...)                                                  \
  42         do {                                                                \
  43                 _Pragma("GCC diagnostic ignored \"-Wformat-zero-length\""); \
  44                 AA_BUG_FMT((X), "" args);                                   \
  45                 _Pragma("GCC diagnostic warning \"-Wformat-zero-length\""); \
  46         } while (0)
  47 #ifdef CONFIG_SECURITY_APPARMOR_DEBUG_ASSERTS
  48 #define AA_BUG_FMT(X, fmt, args...)                                     \
  49         WARN((X), "AppArmor WARN %s: (" #X "): " fmt, __func__, ##args)
  50 #else
  51 #define AA_BUG_FMT(X, fmt, args...) no_printk(fmt, ##args)
  52 #endif
  53
  54 #define AA_ERROR(fmt, args...)                                          \
  55         pr_err_ratelimited("AppArmor: " fmt, ##args)
  56
  57 /* Flag indicating whether initialization completed */
  58 extern int apparmor_initialized;
  59
  60 /* fn's in lib */
  61 const char *skipn_spaces(const char *str, size_t n);
  62 const char *aa_splitn_fqname(const char *fqname, size_t n, const char **ns_name,
  63                              size_t *ns_len);
  64 void aa_info_message(const char *str);
  65
  66 /* Security blob offsets */
  67 extern struct lsm_blob_sizes apparmor_blob_sizes;
  68
  69 /**
  70  * aa_strneq - compare null terminated @str to a non null terminated substring
  71  * @str: a null terminated string
  72  * @sub: a substring, not necessarily null terminated
  73  * @len: length of @sub to compare
  74  *
  75  * The @str string must be full consumed for this to be considered a match
  76  */
  77 static inline bool aa_strneq(const char *str, const char *sub, int len)
  78 {
  79         return !strncmp(str, sub, len) && !str[len];
  80 }
  81
  82 /**
  83  * aa_dfa_null_transition - step to next state after null character
  84  * @dfa: the dfa to match against
  85  * @start: the state of the dfa to start matching in
  86  *
  87  * aa_dfa_null_transition transitions to the next state after a null
  88  * character which is not used in standard matching and is only
  89  * used to separate pairs.
  90  */
  91 static inline aa_state_t aa_dfa_null_transition(struct aa_dfa *dfa,
  92                                                 aa_state_t start)
  93 {
  94         /* the null transition only needs the string's null terminator byte */
  95         return aa_dfa_next(dfa, start, 0);
  96 }
  97
  98 static inline bool path_mediated_fs(struct dentry *dentry)
  99 {
 100         return !(dentry->d_sb->s_flags & SB_NOUSER);
 101 }
 102
 103 struct aa_str_table {
 104         int size;
 105         char **table;
 106 };
 107
 108 void aa_free_str_table(struct aa_str_table *table);
 109
 110 struct counted_str {
 111         struct kref count;
 112         char name[];
 113 };
 114
 115 #define str_to_counted(str) \
 116         ((struct counted_str *)(str - offsetof(struct counted_str, name)))
 117
 118 #define __counted       /* atm just a notation */
 119
 120 void aa_str_kref(struct kref *kref);
 121 char *aa_str_alloc(int size, gfp_t gfp);
 122
 123
 124 static inline __counted char *aa_get_str(__counted char *str)
 125 {
 126         if (str)
 127                 kref_get(&(str_to_counted(str)->count));
 128
 129         return str;
 130 }
 131
 132 static inline void aa_put_str(__counted char *str)
 133 {
 134         if (str)
 135                 kref_put(&str_to_counted(str)->count, aa_str_kref);
 136 }
 137
 138
 139 /* struct aa_policy - common part of both namespaces and profiles
 140  * @name: name of the object
 141  * @hname - The hierarchical name
 142  * @list: list policy object is on
 143  * @profiles: head of the profiles list contained in the object
 144  */
 145 struct aa_policy {
 146         const char *name;
 147         __counted char *hname;
 148         struct list_head list;
 149         struct list_head profiles;
 150 };
 151
 152 /**
 153  * basename - find the last component of an hname
 154  * @name: hname to find the base profile name component of  (NOT NULL)
 155  *
 156  * Returns: the tail (base profile name) name component of an hname
 157  */
 158 static inline const char *basename(const char *hname)
 159 {
 160         char *split;
 161
 162         hname = strim((char *)hname);
 163         for (split = strstr(hname, "//"); split; split = strstr(hname, "//"))
 164                 hname = split + 2;
 165
 166         return hname;
 167 }
 168
 169 /**
 170  * __policy_find - find a policy by @name on a policy list
 171  * @head: list to search  (NOT NULL)
 172  * @name: name to search for  (NOT NULL)
 173  *
 174  * Requires: rcu_read_lock be held
 175  *
 176  * Returns: unrefcounted policy that match @name or NULL if not found
 177  */
 178 static inline struct aa_policy *__policy_find(struct list_head *head,
 179                                               const char *name)
 180 {
 181         struct aa_policy *policy;
 182
 183         list_for_each_entry_rcu(policy, head, list) {
 184                 if (!strcmp(policy->name, name))
 185                         return policy;
 186         }
 187         return NULL;
 188 }
 189
 190 /**
 191  * __policy_strn_find - find a policy that's name matches @len chars of @str
 192  * @head: list to search  (NOT NULL)
 193  * @str: string to search for  (NOT NULL)
 194  * @len: length of match required
 195  *
 196  * Requires: rcu_read_lock be held
 197  *
 198  * Returns: unrefcounted policy that match @str or NULL if not found
 199  *
 200  * if @len == strlen(@strlen) then this is equiv to __policy_find
 201  * other wise it allows searching for policy by a partial match of name
 202  */
 203 static inline struct aa_policy *__policy_strn_find(struct list_head *head,
 204                                             const char *str, int len)
 205 {
 206         struct aa_policy *policy;
 207
 208         list_for_each_entry_rcu(policy, head, list) {
 209                 if (aa_strneq(policy->name, str, len))
 210                         return policy;
 211         }
 212
 213         return NULL;
 214 }
 215
 216 bool aa_policy_init(struct aa_policy *policy, const char *prefix,
 217                     const char *name, gfp_t gfp);
 218 void aa_policy_destroy(struct aa_policy *policy);
 219
 220
 221 /*
 222  * fn_label_build - abstract out the build of a label transition
 223  * @L: label the transition is being computed for
 224  * @P: profile parameter derived from L by this macro, can be passed to FN
 225  * @GFP: memory allocation type to use
 226  * @FN: fn to call for each profile transition. @P is set to the profile
 227  *
 228  * Returns: new label on success
 229  *          ERR_PTR if build @FN fails
 230  *          NULL if label_build fails due to low memory conditions
 231  *
 232  * @FN must return a label or ERR_PTR on failure. NULL is not allowed
 233  */
 234 #define fn_label_build(L, P, GFP, FN)                                   \
 235 ({                                                                      \
 236         __label__ __do_cleanup, __done;                                 \
 237         struct aa_label *__new_;                                        \
 238                                                                         \
 239         if ((L)->size > 1) {                                            \
 240                 /* TODO: add cache of transitions already done */       \
 241                 struct label_it __i;                                    \
 242                 int __j, __k, __count;                                  \
 243                 DEFINE_VEC(label, __lvec);                              \
 244                 DEFINE_VEC(profile, __pvec);                            \
 245                 if (vec_setup(label, __lvec, (L)->size, (GFP))) {       \
 246                         __new_ = NULL;                                  \
 247                         goto __done;                                    \
 248                 }                                                       \
 249                 __j = 0;                                                \
 250                 label_for_each(__i, (L), (P)) {                         \
 251                         __new_ = (FN);                                  \
 252                         AA_BUG(!__new_);                                \
 253                         if (IS_ERR(__new_))                             \
 254                                 goto __do_cleanup;                      \
 255                         __lvec[__j++] = __new_;                         \
 256                 }                                                       \
 257                 for (__j = __count = 0; __j < (L)->size; __j++)         \
 258                         __count += __lvec[__j]->size;                   \
 259                 if (!vec_setup(profile, __pvec, __count, (GFP))) {      \
 260                         for (__j = __k = 0; __j < (L)->size; __j++) {   \
 261                                 label_for_each(__i, __lvec[__j], (P))   \
 262                                         __pvec[__k++] = aa_get_profile(P); \
 263                         }                                               \
 264                         __count -= aa_vec_unique(__pvec, __count, 0);   \
 265                         if (__count > 1) {                              \
 266                                 __new_ = aa_vec_find_or_create_label(__pvec,\
 267                                                      __count, (GFP));   \
 268                                 /* only fails if out of Mem */          \
 269                                 if (!__new_)                            \
 270                                         __new_ = NULL;                  \
 271                         } else                                          \
 272                                 __new_ = aa_get_label(&__pvec[0]->label); \
 273                         vec_cleanup(profile, __pvec, __count);          \
 274                 } else                                                  \
 275                         __new_ = NULL;                                  \
 276 __do_cleanup:                                                           \
 277                 vec_cleanup(label, __lvec, (L)->size);                  \
 278         } else {                                                        \
 279                 (P) = labels_profile(L);                                \
 280                 __new_ = (FN);                                          \
 281         }                                                               \
 282 __done:                                                                 \
 283         if (!__new_)                                                    \
 284                 AA_DEBUG("label build failed\n");                       \
 285         (__new_);                                                       \
 286 })
 287
 288
 289 #define __fn_build_in_ns(NS, P, NS_FN, OTHER_FN)                        \
 290 ({                                                                      \
 291         struct aa_label *__new;                                         \
 292         if ((P)->ns != (NS))                                            \
 293                 __new = (OTHER_FN);                                     \
 294         else                                                            \
 295                 __new = (NS_FN);                                        \
 296         (__new);                                                        \
 297 })
 298
 299 #define fn_label_build_in_ns(L, P, GFP, NS_FN, OTHER_FN)                \
 300 ({                                                                      \
 301         fn_label_build((L), (P), (GFP),                                 \
 302                 __fn_build_in_ns(labels_ns(L), (P), (NS_FN), (OTHER_FN))); \
 303 })
 304
 305 #endif /* __AA_LIB_H */