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, <stephen.smalley.work@gmail.com> 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, const 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, const 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, const 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 99 static inline int mls_context_glblub(struct context *dst, 100 const struct context *c1, const struct context *c2) 101 { 102 struct mls_range *dr = &dst->range; 103 const struct mls_range *r1 = &c1->range, *r2 = &c2->range; 104 int rc = 0; 105 106 if (r1->level[1].sens < r2->level[0].sens || 107 r2->level[1].sens < r1->level[0].sens) 108 /* These ranges have no common sensitivities */ 109 return -EINVAL; 110 111 /* Take the greatest of the low */ 112 dr->level[0].sens = max(r1->level[0].sens, r2->level[0].sens); 113 114 /* Take the least of the high */ 115 dr->level[1].sens = min(r1->level[1].sens, r2->level[1].sens); 116 117 rc = ebitmap_and(&dr->level[0].cat, 118 &r1->level[0].cat, &r2->level[0].cat); 119 if (rc) 120 goto out; 121 122 rc = ebitmap_and(&dr->level[1].cat, 123 &r1->level[1].cat, &r2->level[1].cat); 124 if (rc) 125 goto out; 126 127 out: 128 return rc; 129 } 130 131 static inline int mls_context_cmp(const struct context *c1, const struct context *c2) 132 { 133 return ((c1->range.level[0].sens == c2->range.level[0].sens) && 134 ebitmap_cmp(&c1->range.level[0].cat, &c2->range.level[0].cat) && 135 (c1->range.level[1].sens == c2->range.level[1].sens) && 136 ebitmap_cmp(&c1->range.level[1].cat, &c2->range.level[1].cat)); 137 } 138 139 static inline void mls_context_destroy(struct context *c) 140 { 141 ebitmap_destroy(&c->range.level[0].cat); 142 ebitmap_destroy(&c->range.level[1].cat); 143 mls_context_init(c); 144 } 145 146 static inline void context_init(struct context *c) 147 { 148 memset(c, 0, sizeof(*c)); 149 } 150 151 static inline int context_cpy(struct context *dst, const struct context *src) 152 { 153 int rc; 154 155 dst->user = src->user; 156 dst->role = src->role; 157 dst->type = src->type; 158 if (src->str) { 159 dst->str = kstrdup(src->str, GFP_ATOMIC); 160 if (!dst->str) 161 return -ENOMEM; 162 dst->len = src->len; 163 } else { 164 dst->str = NULL; 165 dst->len = 0; 166 } 167 rc = mls_context_cpy(dst, src); 168 if (rc) { 169 kfree(dst->str); 170 dst->str = NULL; 171 dst->len = 0; 172 return rc; 173 } 174 return 0; 175 } 176 177 static inline void context_destroy(struct context *c) 178 { 179 c->user = c->role = c->type = 0; 180 kfree(c->str); 181 c->str = NULL; 182 c->len = 0; 183 mls_context_destroy(c); 184 } 185 186 static inline int context_cmp(const struct context *c1, const struct context *c2) 187 { 188 if (c1->len && c2->len) 189 return (c1->len == c2->len && !strcmp(c1->str, c2->str)); 190 if (c1->len || c2->len) 191 return 0; 192 return ((c1->user == c2->user) && 193 (c1->role == c2->role) && 194 (c1->type == c2->type) && 195 mls_context_cmp(c1, c2)); 196 } 197 198 u32 context_compute_hash(const struct context *c); 199 200 #endif /* _SS_CONTEXT_H_ */ 201 202