security/selinux/ss/context.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * A security context is a set of security attributes
   4  * associated with each subject and object controlled
   5  * by the security policy.  Security contexts are
   6   * externally represented as variable-length strings
   7  * that can be interpreted by a user or application
   8  * with an understanding of the security policy.
   9  * Internally, the security server uses a simple
  10  * structure.  This structure is private to the
  11  * security server and can be changed without affecting
  12  * clients of the security server.
  13  *
  14  * Author : Stephen Smalley, <sds@tycho.nsa.gov>
  15  */
  16 #ifndef _SS_CONTEXT_H_
  17 #define _SS_CONTEXT_H_
  18
  19 #include "ebitmap.h"
  20 #include "mls_types.h"
  21 #include "security.h"
  22
  23 /*
  24  * A security context consists of an authenticated user
  25  * identity, a role, a type and a MLS range.
  26  */
  27 struct context {
  28         u32 user;
  29         u32 role;
  30         u32 type;
  31         u32 len;        /* length of string in bytes */
  32         struct mls_range range;
  33         char *str;      /* string representation if context cannot be mapped. */
  34 };
  35
  36 static inline void mls_context_init(struct context *c)
  37 {
  38         memset(&c->range, 0, sizeof(c->range));
  39 }
  40
  41 static inline int mls_context_cpy(struct context *dst, struct context *src)
  42 {
  43         int rc;
  44
  45         dst->range.level[0].sens = src->range.level[0].sens;
  46         rc = ebitmap_cpy(&dst->range.level[0].cat, &src->range.level[0].cat);
  47         if (rc)
  48                 goto out;
  49
  50         dst->range.level[1].sens = src->range.level[1].sens;
  51         rc = ebitmap_cpy(&dst->range.level[1].cat, &src->range.level[1].cat);
  52         if (rc)
  53                 ebitmap_destroy(&dst->range.level[0].cat);
  54 out:
  55         return rc;
  56 }
  57
  58 /*
  59  * Sets both levels in the MLS range of 'dst' to the low level of 'src'.
  60  */
  61 static inline int mls_context_cpy_low(struct context *dst, struct context *src)
  62 {
  63         int rc;
  64
  65         dst->range.level[0].sens = src->range.level[0].sens;
  66         rc = ebitmap_cpy(&dst->range.level[0].cat, &src->range.level[0].cat);
  67         if (rc)
  68                 goto out;
  69
  70         dst->range.level[1].sens = src->range.level[0].sens;
  71         rc = ebitmap_cpy(&dst->range.level[1].cat, &src->range.level[0].cat);
  72         if (rc)
  73                 ebitmap_destroy(&dst->range.level[0].cat);
  74 out:
  75         return rc;
  76 }
  77
  78 /*
  79  * Sets both levels in the MLS range of 'dst' to the high level of 'src'.
  80  */
  81 static inline int mls_context_cpy_high(struct context *dst, struct context *src)
  82 {
  83         int rc;
  84
  85         dst->range.level[0].sens = src->range.level[1].sens;
  86         rc = ebitmap_cpy(&dst->range.level[0].cat, &src->range.level[1].cat);
  87         if (rc)
  88                 goto out;
  89
  90         dst->range.level[1].sens = src->range.level[1].sens;
  91         rc = ebitmap_cpy(&dst->range.level[1].cat, &src->range.level[1].cat);
  92         if (rc)
  93                 ebitmap_destroy(&dst->range.level[0].cat);
  94 out:
  95         return rc;
  96 }
  97
  98 static inline int mls_context_cmp(struct context *c1, struct context *c2)
  99 {
 100         return ((c1->range.level[0].sens == c2->range.level[0].sens) &&
 101                 ebitmap_cmp(&c1->range.level[0].cat, &c2->range.level[0].cat) &&
 102                 (c1->range.level[1].sens == c2->range.level[1].sens) &&
 103                 ebitmap_cmp(&c1->range.level[1].cat, &c2->range.level[1].cat));
 104 }
 105
 106 static inline void mls_context_destroy(struct context *c)
 107 {
 108         ebitmap_destroy(&c->range.level[0].cat);
 109         ebitmap_destroy(&c->range.level[1].cat);
 110         mls_context_init(c);
 111 }
 112
 113 static inline void context_init(struct context *c)
 114 {
 115         memset(c, 0, sizeof(*c));
 116 }
 117
 118 static inline int context_cpy(struct context *dst, struct context *src)
 119 {
 120         int rc;
 121
 122         dst->user = src->user;
 123         dst->role = src->role;
 124         dst->type = src->type;
 125         if (src->str) {
 126                 dst->str = kstrdup(src->str, GFP_ATOMIC);
 127                 if (!dst->str)
 128                         return -ENOMEM;
 129                 dst->len = src->len;
 130         } else {
 131                 dst->str = NULL;
 132                 dst->len = 0;
 133         }
 134         rc = mls_context_cpy(dst, src);
 135         if (rc) {
 136                 kfree(dst->str);
 137                 return rc;
 138         }
 139         return 0;
 140 }
 141
 142 static inline void context_destroy(struct context *c)
 143 {
 144         c->user = c->role = c->type = 0;
 145         kfree(c->str);
 146         c->str = NULL;
 147         c->len = 0;
 148         mls_context_destroy(c);
 149 }
 150
 151 static inline int context_cmp(struct context *c1, struct context *c2)
 152 {
 153         if (c1->len && c2->len)
 154                 return (c1->len == c2->len && !strcmp(c1->str, c2->str));
 155         if (c1->len || c2->len)
 156                 return 0;
 157         return ((c1->user == c2->user) &&
 158                 (c1->role == c2->role) &&
 159                 (c1->type == c2->type) &&
 160                 mls_context_cmp(c1, c2));
 161 }
 162
 163 #endif  /* _SS_CONTEXT_H_ */
 164