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