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         dst->range.level[0].sens = src->range.level[0].sens;
  45         rc = ebitmap_cpy(&dst->range.level[0].cat, &src->range.level[0].cat);
  46         if (rc)
  47                 goto out;
  48
  49         dst->range.level[1].sens = src->range.level[1].sens;
  50         rc = ebitmap_cpy(&dst->range.level[1].cat, &src->range.level[1].cat);
  51         if (rc)
  52                 ebitmap_destroy(&dst->range.level[0].cat);
  53 out:
  54         return rc;
  55 }
  56
  57 /*
  58  * Sets both levels in the MLS range of 'dst' to the low level of 'src'.
  59  */
  60 static inline int mls_context_cpy_low(struct context *dst, struct context *src)
  61 {
  62         int rc;
  63
  64         dst->range.level[0].sens = src->range.level[0].sens;
  65         rc = ebitmap_cpy(&dst->range.level[0].cat, &src->range.level[0].cat);
  66         if (rc)
  67                 goto out;
  68
  69         dst->range.level[1].sens = src->range.level[0].sens;
  70         rc = ebitmap_cpy(&dst->range.level[1].cat, &src->range.level[0].cat);
  71         if (rc)
  72                 ebitmap_destroy(&dst->range.level[0].cat);
  73 out:
  74         return rc;
  75 }
  76
  77 static inline int mls_context_cmp(struct context *c1, struct context *c2)
  78 {
  79         return ((c1->range.level[0].sens == c2->range.level[0].sens) &&
  80                 ebitmap_cmp(&c1->range.level[0].cat, &c2->range.level[0].cat) &&
  81                 (c1->range.level[1].sens == c2->range.level[1].sens) &&
  82                 ebitmap_cmp(&c1->range.level[1].cat, &c2->range.level[1].cat));
  83 }
  84
  85 static inline void mls_context_destroy(struct context *c)
  86 {
  87         ebitmap_destroy(&c->range.level[0].cat);
  88         ebitmap_destroy(&c->range.level[1].cat);
  89         mls_context_init(c);
  90 }
  91
  92 static inline void context_init(struct context *c)
  93 {
  94         memset(c, 0, sizeof(*c));
  95 }
  96
  97 static inline int context_cpy(struct context *dst, struct context *src)
  98 {
  99         int rc;
 100
 101         dst->user = src->user;
 102         dst->role = src->role;
 103         dst->type = src->type;
 104         if (src->str) {
 105                 dst->str = kstrdup(src->str, GFP_ATOMIC);
 106                 if (!dst->str)
 107                         return -ENOMEM;
 108                 dst->len = src->len;
 109         } else {
 110                 dst->str = NULL;
 111                 dst->len = 0;
 112         }
 113         rc = mls_context_cpy(dst, src);
 114         if (rc) {
 115                 kfree(dst->str);
 116                 return rc;
 117         }
 118         return 0;
 119 }
 120
 121 static inline void context_destroy(struct context *c)
 122 {
 123         c->user = c->role = c->type = 0;
 124         kfree(c->str);
 125         c->str = NULL;
 126         c->len = 0;
 127         mls_context_destroy(c);
 128 }
 129
 130 static inline int context_cmp(struct context *c1, struct context *c2)
 131 {
 132         if (c1->len && c2->len)
 133                 return (c1->len == c2->len && !strcmp(c1->str, c2->str));
 134         if (c1->len || c2->len)
 135                 return 0;
 136         return ((c1->user == c2->user) &&
 137                 (c1->role == c2->role) &&
 138                 (c1->type == c2->type) &&
 139                 mls_context_cmp(c1, c2));
 140 }
 141
 142 #endif  /* _SS_CONTEXT_H_ */
 143