security/apparmor/include/lib.h

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