1 | #include <assert.h> |
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2 | #include <stdlib.h> |
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3 | |
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4 | #include "abac_graph.h" |
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5 | |
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6 | #include "abac_set.h" |
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7 | #include "abac_util.h" |
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8 | |
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9 | #include "uthash.h" |
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10 | |
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11 | // vertex |
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12 | struct _abac_vertex_t { |
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13 | abac_role_t *role; |
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14 | char *name; |
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15 | |
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16 | abac_list_t *edges; |
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17 | |
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18 | UT_hash_handle hh; |
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19 | }; |
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20 | |
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21 | // edge |
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22 | typedef struct _abac_edge_t { |
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23 | abac_vertex_t *vertex; |
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24 | abac_credential_t *credential; |
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25 | } abac_edge_t; |
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26 | |
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27 | // derived edge |
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28 | typedef struct _abac_derived_key_t { |
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29 | abac_vertex_t *head; |
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30 | abac_edge_t *tail; |
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31 | } abac_derived_key_t; |
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32 | |
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33 | typedef struct _abac_derived_t { |
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34 | abac_derived_key_t key; |
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35 | UT_hash_handle hh; |
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36 | } abac_derived_t; |
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37 | |
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38 | // graph |
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39 | struct _abac_graph_t { |
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40 | abac_vertex_t *vertices; |
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41 | abac_derived_t *derived; |
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42 | int dirty; |
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43 | }; |
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44 | |
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45 | /** |
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46 | * Create a new graph. |
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47 | */ |
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48 | abac_graph_t *abac_graph_new(void) { |
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49 | abac_graph_t *graph = abac_xmalloc(sizeof(abac_graph_t)); |
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50 | |
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51 | graph->vertices = NULL; |
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52 | graph->derived = NULL; |
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53 | graph->dirty = 0; |
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54 | |
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55 | return graph; |
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56 | } |
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57 | |
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58 | /** |
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59 | * Deep copy a graph. |
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60 | */ |
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61 | abac_graph_t *abac_graph_dup(abac_graph_t *graph) { |
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62 | abac_vertex_t *vertex; |
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63 | abac_edge_t *edge; |
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64 | |
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65 | abac_graph_t *clone = abac_graph_new(); |
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66 | |
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67 | // copy the vertices edge by edge |
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68 | for (vertex = graph->vertices; vertex != NULL; vertex = vertex->hh.next) |
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69 | abac_list_foreach(vertex->edges, edge, |
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70 | // only copy non-derived edges |
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71 | if (edge->credential != NULL) |
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72 | abac_graph_add_credential(clone, edge->credential); |
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73 | ); |
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74 | |
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75 | return clone; |
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76 | } |
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77 | |
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78 | /** |
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79 | * Add a vertex to the graph. Should only be called by abac_graph_add_credential. |
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80 | */ |
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81 | static abac_vertex_t *_get_vertex(abac_graph_t *graph, abac_role_t *role) { |
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82 | abac_vertex_t *vertex; |
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83 | char *string; |
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84 | |
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85 | string = abac_role_string(role); |
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86 | HASH_FIND_STR(graph->vertices, string, vertex); |
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87 | |
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88 | // add the vertex if it doesn't exist |
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89 | if (vertex == NULL) { |
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90 | vertex = abac_xmalloc(sizeof(abac_vertex_t)); |
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91 | vertex->role = abac_role_dup(role); |
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92 | vertex->name = abac_role_string(vertex->role); |
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93 | |
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94 | // create the list of edges |
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95 | vertex->edges = abac_list_new(); |
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96 | |
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97 | // add it to the vertices |
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98 | HASH_ADD_KEYPTR(hh, graph->vertices, vertex->name, strlen(vertex->name), vertex); |
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99 | } |
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100 | |
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101 | return vertex; |
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102 | } |
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103 | |
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104 | /** |
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105 | * Add a credential to the credential graph. |
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106 | */ |
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107 | int abac_graph_add_credential(abac_graph_t *graph, abac_credential_t *cred) { |
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108 | abac_vertex_t *head_vertex, *tail_vertex; |
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109 | abac_edge_t *edge; |
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110 | |
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111 | assert(cred != NULL); |
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112 | |
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113 | abac_role_t *head = abac_credential_head(cred); |
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114 | abac_role_t *tail = abac_credential_tail(cred); |
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115 | |
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116 | // TODO: handle intersections properly |
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117 | if (tail == NULL) |
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118 | return 0; |
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119 | |
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120 | // a valid credential must have a role for the head |
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121 | if (!abac_role_is_role(head)) return 0; |
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122 | |
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123 | head_vertex = _get_vertex(graph, head); |
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124 | tail_vertex = _get_vertex(graph, tail); |
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125 | |
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126 | // make sure we don't insert the same edge twice (ugh) |
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127 | abac_list_foreach(head_vertex->edges, edge, |
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128 | if (edge->vertex == tail_vertex) |
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129 | return 0; |
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130 | ); |
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131 | |
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132 | // create the edge and add it |
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133 | edge = abac_xmalloc(sizeof(abac_edge_t)); |
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134 | edge->vertex = tail_vertex; |
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135 | edge->credential = abac_credential_dup(cred); |
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136 | |
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137 | abac_list_add(head_vertex->edges, edge); |
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138 | |
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139 | // must re-derive edges |
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140 | graph->dirty = 1; |
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141 | |
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142 | return 1; |
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143 | } |
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144 | |
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145 | // find the principals that have a role |
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146 | static abac_set_t *_find_principals(abac_graph_t *graph, abac_vertex_t *start_vertex) { |
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147 | abac_set_t *principals = abac_set_new(); |
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148 | |
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149 | abac_list_t *traversal = abac_graph_postorder(graph, start_vertex->role); |
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150 | abac_vertex_t *vertex; |
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151 | |
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152 | abac_list_foreach(traversal, vertex, |
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153 | if (abac_role_is_principal(vertex->role)) |
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154 | abac_set_add(principals, abac_role_string(vertex->role)); |
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155 | ); |
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156 | |
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157 | abac_list_free(traversal); |
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158 | return principals; |
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159 | } |
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160 | |
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161 | // remove any derived edges from the graph |
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162 | void _clear_derived(abac_graph_t *graph) { |
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163 | abac_derived_t *current; |
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164 | |
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165 | while (graph->derived) { |
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166 | current = graph->derived; |
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167 | |
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168 | HASH_DEL(graph->derived, current); |
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169 | |
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170 | abac_vertex_t *head = current->key.head; |
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171 | abac_edge_t *tail = current->key.tail; |
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172 | assert(tail->credential == NULL); |
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173 | |
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174 | // this can fail, but we assume the data structures are consistent |
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175 | abac_list_remove(head->edges, tail); |
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176 | |
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177 | free(current); |
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178 | free(tail); |
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179 | } |
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180 | } |
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181 | |
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182 | void abac_graph_derive_links(abac_graph_t *graph) { |
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183 | abac_vertex_t *vertex; |
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184 | |
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185 | if (!graph->dirty) |
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186 | return; |
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187 | |
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188 | for (vertex = graph->vertices; vertex != NULL; vertex = vertex->hh.next) { |
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189 | // we only care about linking roles |
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190 | if (!abac_role_is_linking(vertex->role)) |
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191 | continue; |
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192 | |
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193 | // linking roles take the form A.r1.r2 |
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194 | char *A_r1 = abac_role_linked_role(vertex->role); |
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195 | char *r2 = abac_role_role_name(vertex->role); |
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196 | |
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197 | // find the linked role in the graph |
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198 | abac_vertex_t *A_r1_vertex; |
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199 | HASH_FIND_STR(graph->vertices, A_r1, A_r1_vertex); |
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200 | if (A_r1_vertex == NULL) |
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201 | continue; |
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202 | |
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203 | // find the principals that have A.r1 |
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204 | abac_set_t *principals = _find_principals(graph, A_r1_vertex); |
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205 | char *B; |
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206 | |
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207 | abac_list_t *elts = abac_set_elements(principals); |
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208 | |
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209 | // and add a link for each B.r2 to A.r1.r2 |
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210 | abac_list_foreach(elts, B, |
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211 | int B_len = strlen(B); |
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212 | int r2_len = strlen(r2); |
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213 | |
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214 | // create the string B.r2, thx C |
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215 | char *B_r2 = malloc(B_len + r2_len + 2); |
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216 | memcpy(B_r2, B, B_len); |
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217 | B_r2[B_len] = '.'; |
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218 | memcpy(B_r2 + B_len + 1, r2, r2_len); |
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219 | B_r2[B_len + r2_len + 1] = 0; |
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220 | |
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221 | abac_vertex_t *B_r2_vertex; |
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222 | HASH_FIND_STR(graph->vertices, B_r2, B_r2_vertex); |
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223 | |
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224 | // add an edge if the principal's granted it to someone |
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225 | if (B_r2_vertex) { |
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226 | debug_printf("adding edge from %s to %s\n", B_r2, abac_role_string(vertex->role)); |
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227 | abac_edge_t *edge = abac_xmalloc(sizeof(abac_edge_t)); |
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228 | edge->vertex = B_r2_vertex; |
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229 | edge->credential = NULL; |
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230 | abac_list_add(vertex->edges, edge); |
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231 | |
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232 | // add to list of derived edges |
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233 | abac_derived_t *derived = abac_xmalloc(sizeof(abac_derived_t)); |
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234 | derived->key.head = vertex; |
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235 | derived->key.tail = edge; |
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236 | HASH_ADD(hh, graph->derived, key, sizeof(abac_derived_key_t), derived); |
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237 | } |
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238 | |
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239 | #ifdef DEBUG |
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240 | debug_printf(" incoming edges for %s\n", abac_role_string(vertex->role)); |
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241 | abac_edge_t *cur; |
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242 | abac_list_foreach(vertex->edges, cur, |
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243 | debug_printf(" %s (%s)\n", abac_role_string(cur->vertex->role), cur->vertex->name); |
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244 | ); |
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245 | #endif |
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246 | |
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247 | free(B_r2); |
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248 | ); |
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249 | |
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250 | abac_list_free(elts); |
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251 | abac_set_free(principals); |
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252 | } |
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253 | |
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254 | graph->dirty = 0; |
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255 | } |
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256 | |
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257 | static void _order_recurse(abac_vertex_t *vertex, abac_set_t *seen, int preorder, abac_list_t *stack) { |
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258 | abac_edge_t *incoming; |
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259 | |
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260 | // don't revisit nodes |
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261 | if (!abac_set_add(seen, abac_role_string(vertex->role))) |
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262 | return; |
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263 | |
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264 | if (preorder) |
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265 | abac_list_add(stack, vertex); |
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266 | |
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267 | // recurse along the incoming vertices |
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268 | abac_list_foreach(vertex->edges, incoming, |
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269 | _order_recurse(incoming->vertex, seen, preorder, stack); |
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270 | ); |
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271 | |
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272 | if (!preorder) |
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273 | abac_list_add(stack, vertex); |
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274 | } |
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275 | |
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276 | static abac_list_t *_order(abac_graph_t *graph, abac_role_t *start, int preorder) { |
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277 | debug_printf("%sorder at %s\n", preorder ? "pre" : "post", abac_role_string(start)); |
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278 | |
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279 | abac_vertex_t *start_vertex = _get_vertex(graph, start); |
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280 | abac_set_t *seen = abac_set_new(); |
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281 | |
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282 | // create the return list |
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283 | abac_list_t *stack = abac_list_new(); |
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284 | |
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285 | _order_recurse(start_vertex, seen, preorder, stack); |
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286 | |
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287 | abac_set_free(seen); |
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288 | |
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289 | return stack; |
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290 | } |
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291 | |
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292 | abac_list_t *abac_graph_postorder(abac_graph_t *graph, abac_role_t *start) { |
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293 | return _order(graph, start, 0); |
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294 | } |
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295 | |
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296 | /** |
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297 | * Postorder traverse the graph and return all the credentials within. |
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298 | */ |
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299 | abac_list_t *abac_graph_postorder_credentials(abac_graph_t *graph, char *start) { |
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300 | abac_vertex_t *vertex; |
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301 | abac_edge_t *incoming; |
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302 | |
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303 | // get the postorder of vertices |
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304 | abac_role_t *role = abac_role_from_string(start); |
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305 | abac_list_t *order = abac_graph_postorder(graph, role); |
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306 | |
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307 | // go through the list and dup all the credentials |
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308 | abac_list_t *credentials = abac_list_new(); |
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309 | abac_list_foreach(order, vertex, |
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310 | abac_list_foreach(vertex->edges, incoming, |
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311 | if (incoming->credential != NULL) |
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312 | abac_list_add(credentials, abac_credential_dup(incoming->credential)); |
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313 | ); |
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314 | ); |
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315 | |
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316 | abac_role_free(role); |
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317 | abac_list_free(order); |
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318 | |
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319 | return credentials; |
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320 | } |
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321 | |
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322 | static void _query(abac_graph_t *graph, char *role_name, char *principal, abac_graph_t *return_graph) { |
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323 | abac_vertex_t *vertex; |
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324 | abac_edge_t *incoming; |
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325 | |
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326 | abac_role_t *role = abac_role_from_string(role_name); |
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327 | abac_role_t *prin_role = abac_role_from_string(principal); |
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328 | |
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329 | // give up on bogus roles |
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330 | if (role == NULL || prin_role == NULL) { |
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331 | free(role); |
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332 | free(prin_role); |
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333 | return; |
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334 | } |
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335 | |
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336 | abac_set_t *on_path = abac_set_new(); |
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337 | abac_set_add(on_path, abac_role_string(prin_role)); |
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338 | |
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339 | abac_list_t *traversal = abac_graph_postorder(graph, role); |
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340 | abac_list_foreach(traversal, vertex, |
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341 | abac_role_t *role = vertex->role; |
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342 | |
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343 | abac_list_foreach(vertex->edges, incoming, |
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344 | abac_role_t *incoming_role = incoming->vertex->role; |
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345 | |
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346 | if (!abac_set_contains(on_path, abac_role_string(incoming_role))) |
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347 | continue; |
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348 | |
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349 | abac_set_add(on_path, abac_role_string(role)); |
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350 | |
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351 | // add non-derived edges to the proof graph |
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352 | if (!abac_role_is_linking(role)) |
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353 | abac_graph_add_credential(return_graph, incoming->credential); |
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354 | |
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355 | // recursively find linked roles |
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356 | else { |
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357 | char *linked_role = abac_role_linked_role(role); |
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358 | char *principal = abac_role_principal(incoming_role); |
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359 | |
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360 | _query(graph, linked_role, principal, return_graph); |
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361 | } |
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362 | ); |
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363 | ); |
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364 | |
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365 | abac_list_free(traversal); |
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366 | abac_set_free(on_path); |
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367 | abac_role_free(role); |
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368 | abac_role_free(prin_role); |
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369 | } |
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370 | |
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371 | abac_graph_t *abac_graph_query(abac_graph_t *graph, char *role, char *principal) { |
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372 | abac_graph_derive_links(graph); |
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373 | |
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374 | abac_graph_t *return_graph = abac_graph_new(); |
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375 | _query(graph, role, principal, return_graph); |
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376 | abac_graph_derive_links(return_graph); |
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377 | return return_graph; |
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378 | } |
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379 | |
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380 | /** |
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381 | * Get all the credentials (attribute/issuer cert pairs) from the graph. |
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382 | */ |
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383 | abac_list_t *abac_graph_credentials(abac_graph_t *graph) { |
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384 | abac_list_t *credentials = abac_list_new(); |
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385 | |
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386 | abac_vertex_t *vertex; |
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387 | |
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388 | for (vertex = graph->vertices; vertex != NULL; vertex = vertex->hh.next) { |
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389 | abac_edge_t *edge; |
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390 | abac_list_foreach(vertex->edges, edge, |
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391 | if (edge->credential != NULL) |
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392 | abac_list_add(credentials, abac_credential_dup(edge->credential)); |
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393 | ); |
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394 | } |
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395 | |
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396 | return credentials; |
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397 | } |
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398 | |
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399 | void abac_graph_free(abac_graph_t *graph) { |
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400 | abac_vertex_t *vertex; |
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401 | abac_edge_t *edge; |
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402 | |
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403 | // kill derived edges |
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404 | _clear_derived(graph); |
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405 | |
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406 | // delete vertices |
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407 | while ((vertex = graph->vertices) != NULL) { |
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408 | HASH_DEL(graph->vertices, vertex); |
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409 | |
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410 | abac_role_free(vertex->role); |
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411 | |
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412 | abac_list_foreach(vertex->edges, edge, |
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413 | if (edge->credential != NULL) |
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414 | abac_credential_free(edge->credential); |
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415 | free(edge); |
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416 | ); |
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417 | abac_list_free(vertex->edges); |
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418 | free(vertex); |
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419 | } |
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420 | |
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421 | free(graph); |
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422 | } |
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423 | |
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424 | abac_role_t *abac_vertex_role(abac_vertex_t *vertex) { |
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425 | return vertex->role; |
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426 | } |
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