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 /*
  78  * Sets both levels in the MLS range of 'dst' to the high level of 'src'.
  79  */
  80 static inline int mls_context_cpy_high(struct context *dst, struct context *src)
  81 {
  82         int rc;
  83
  84         dst->range.level[0].sens = src->range.level[1].sens;
  85         rc = ebitmap_cpy(&dst->range.level[0].cat, &src->range.level[1].cat);
  86         if (rc)
  87                 goto out;
  88
  89         dst->range.level[1].sens = src->range.level[1].sens;
  90         rc = ebitmap_cpy(&dst->range.level[1].cat, &src->range.level[1].cat);
  91         if (rc)
  92                 ebitmap_destroy(&dst->range.level[0].cat);
  93 out:
  94         return rc;
  95 }
  96
  97 static inline int mls_context_cmp(struct context *c1, struct context *c2)
  98 {
  99         return ((c1->range.level[0].sens == c2->range.level[0].sens) &&
 100                 ebitmap_cmp(&c1->range.level[0].cat, &c2->range.level[0].cat) &&
 101                 (c1->range.level[1].sens == c2->range.level[1].sens) &&
 102                 ebitmap_cmp(&c1->range.level[1].cat, &c2->range.level[1].cat));
 103 }
 104
 105 static inline void mls_context_destroy(struct context *c)
 106 {
 107         ebitmap_destroy(&c->range.level[0].cat);
 108         ebitmap_destroy(&c->range.level[1].cat);
 109         mls_context_init(c);
 110 }
 111
 112 static inline void context_init(struct context *c)
 113 {
 114         memset(c, 0, sizeof(*c));
 115 }
 116
 117 static inline int context_cpy(struct context *dst, struct context *src)
 118 {
 119         int rc;
 120
 121         dst->user = src->user;
 122         dst->role = src->role;
 123         dst->type = src->type;
 124         if (src->str) {
 125                 dst->str = kstrdup(src->str, GFP_ATOMIC);
 126                 if (!dst->str)
 127                         return -ENOMEM;
 128                 dst->len = src->len;
 129         } else {
 130                 dst->str = NULL;
 131                 dst->len = 0;
 132         }
 133         rc = mls_context_cpy(dst, src);
 134         if (rc) {
 135                 kfree(dst->str);
 136                 return rc;
 137         }
 138         return 0;
 139 }
 140
 141 static inline void context_destroy(struct context *c)
 142 {
 143         c->user = c->role = c->type = 0;
 144         kfree(c->str);
 145         c->str = NULL;
 146         c->len = 0;
 147         mls_context_destroy(c);
 148 }
 149
 150 static inline int context_cmp(struct context *c1, struct context *c2)
 151 {
 152         if (c1->len && c2->len)
 153                 return (c1->len == c2->len && !strcmp(c1->str, c2->str));
 154         if (c1->len || c2->len)
 155                 return 0;
 156         return ((c1->user == c2->user) &&
 157                 (c1->role == c2->role) &&
 158                 (c1->type == c2->type) &&
 159                 mls_context_cmp(c1, c2));
 160 }
 161
 162 #endif  /* _SS_CONTEXT_H_ */
 163