security/selinux/ss/context.h

   1 /*
   2  * A security context is a set of security attributes
   3  * associated with each subject and object controlled
   4  * by the security policy.  Security contexts are
   5   * externally represented as variable-length strings
   6  * that can be interpreted by a user or application
   7  * with an understanding of the security policy.
   8  * Internally, the security server uses a simple
   9  * structure.  This structure is private to the
  10  * security server and can be changed without affecting
  11  * clients of the security server.
  12  *
  13  * Author : Stephen Smalley, <sds@epoch.ncsc.mil>
  14  */
  15 #ifndef _SS_CONTEXT_H_
  16 #define _SS_CONTEXT_H_
  17
  18 #include "ebitmap.h"
  19 #include "mls_types.h"
  20 #include "security.h"
  21
  22 /*
  23  * A security context consists of an authenticated user
  24  * identity, a role, a type and a MLS range.
  25  */
  26 struct context {
  27         u32 user;
  28         u32 role;
  29         u32 type;
  30         u32 len;        /* length of string in bytes */
  31         struct mls_range range;
  32         char *str;      /* string representation if context cannot be mapped. */
  33 };
  34
  35 static inline void mls_context_init(struct context *c)
  36 {
  37         memset(&c->range, 0, sizeof(c->range));
  38 }
  39
  40 static inline int mls_context_cpy(struct context *dst, struct context *src)
  41 {
  42         int rc;
  43
  44         if (!selinux_mls_enabled)
  45                 return 0;
  46
  47         dst->range.level[0].sens = src->range.level[0].sens;
  48         rc = ebitmap_cpy(&dst->range.level[0].cat, &src->range.level[0].cat);
  49         if (rc)
  50                 goto out;
  51
  52         dst->range.level[1].sens = src->range.level[1].sens;
  53         rc = ebitmap_cpy(&dst->range.level[1].cat, &src->range.level[1].cat);
  54         if (rc)
  55                 ebitmap_destroy(&dst->range.level[0].cat);
  56 out:
  57         return rc;
  58 }
  59
  60 /*
  61  * Sets both levels in the MLS range of 'dst' to the low level of 'src'.
  62  */
  63 static inline int mls_context_cpy_low(struct context *dst, struct context *src)
  64 {
  65         int rc;
  66
  67         if (!selinux_mls_enabled)
  68                 return 0;
  69
  70         dst->range.level[0].sens = src->range.level[0].sens;
  71         rc = ebitmap_cpy(&dst->range.level[0].cat, &src->range.level[0].cat);
  72         if (rc)
  73                 goto out;
  74
  75         dst->range.level[1].sens = src->range.level[0].sens;
  76         rc = ebitmap_cpy(&dst->range.level[1].cat, &src->range.level[0].cat);
  77         if (rc)
  78                 ebitmap_destroy(&dst->range.level[0].cat);
  79 out:
  80         return rc;
  81 }
  82
  83 static inline int mls_context_cmp(struct context *c1, struct context *c2)
  84 {
  85         if (!selinux_mls_enabled)
  86                 return 1;
  87
  88         return ((c1->range.level[0].sens == c2->range.level[0].sens) &&
  89                 ebitmap_cmp(&c1->range.level[0].cat, &c2->range.level[0].cat) &&
  90                 (c1->range.level[1].sens == c2->range.level[1].sens) &&
  91                 ebitmap_cmp(&c1->range.level[1].cat, &c2->range.level[1].cat));
  92 }
  93
  94 static inline void mls_context_destroy(struct context *c)
  95 {
  96         if (!selinux_mls_enabled)
  97                 return;
  98
  99         ebitmap_destroy(&c->range.level[0].cat);
 100         ebitmap_destroy(&c->range.level[1].cat);
 101         mls_context_init(c);
 102 }
 103
 104 static inline void context_init(struct context *c)
 105 {
 106         memset(c, 0, sizeof(*c));
 107 }
 108
 109 static inline int context_cpy(struct context *dst, struct context *src)
 110 {
 111         int rc;
 112
 113         dst->user = src->user;
 114         dst->role = src->role;
 115         dst->type = src->type;
 116         if (src->str) {
 117                 dst->str = kstrdup(src->str, GFP_ATOMIC);
 118                 if (!dst->str)
 119                         return -ENOMEM;
 120                 dst->len = src->len;
 121         } else {
 122                 dst->str = NULL;
 123                 dst->len = 0;
 124         }
 125         rc = mls_context_cpy(dst, src);
 126         if (rc) {
 127                 kfree(dst->str);
 128                 return rc;
 129         }
 130         return 0;
 131 }
 132
 133 static inline void context_destroy(struct context *c)
 134 {
 135         c->user = c->role = c->type = 0;
 136         kfree(c->str);
 137         c->str = NULL;
 138         c->len = 0;
 139         mls_context_destroy(c);
 140 }
 141
 142 static inline int context_cmp(struct context *c1, struct context *c2)
 143 {
 144         if (c1->len && c2->len)
 145                 return (c1->len == c2->len && !strcmp(c1->str, c2->str));
 146         if (c1->len || c2->len)
 147                 return 0;
 148         return ((c1->user == c2->user) &&
 149                 (c1->role == c2->role) &&
 150                 (c1->type == c2->type) &&
 151                 mls_context_cmp(c1, c2));
 152 }
 153
 154 #endif  /* _SS_CONTEXT_H_ */
 155