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