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