Magisk/sepolicy.c

#include "magiskpolicy.h"
#include "sepolicy.h"

policydb_t *policydb = NULL;

static void *cmalloc(size_t s) {
	void *t = calloc(s, 1);
	if (t == NULL) {
		fprintf(stderr, "Out of memory\n");
		exit(1);
	}
	return t;
}

static int get_attr(char *type, int value) {
	type_datum_t *attr = hashtab_search(policydb->p_types.table, type);
	if (!attr)
		return 1;

	if (attr->flavor != TYPE_ATTRIB)
		return 1;

	return !! ebitmap_get_bit(&policydb->attr_type_map[attr->s.value-1], value-1);
}

static int get_attr_id(char *type) {
	type_datum_t *attr = hashtab_search(policydb->p_types.table, type);
	if (!attr)
		return 1;

	if (attr->flavor != TYPE_ATTRIB)
		return 1;

	return attr->s.value;
}

static int set_attr(char *type, int value) {
	type_datum_t *attr = hashtab_search(policydb->p_types.table, type);
	if (!attr)
		return 1;

	if (attr->flavor != TYPE_ATTRIB)
		return 1;

	if(ebitmap_set_bit(&policydb->type_attr_map[value-1], attr->s.value-1, 1))
		return 1;
	if(ebitmap_set_bit(&policydb->attr_type_map[attr->s.value-1], value-1, 1))
		return 1;

	return 0;
}

static int add_irule(int s, int t, int c, int p, int effect, int not) {
	avtab_key_t key;
	avtab_datum_t *av;
	int new_rule = 0;

	key.source_type = s;
	key.target_type = t;
	key.target_class = c;
	key.specified = effect;

	av = avtab_search(&policydb->te_avtab, &key);
	if (av == NULL) {
		av = cmalloc(sizeof(*av));
		new_rule = 1;
	}

	if(not) {
		if (p < 0)
			av->data = 0U;
		else
			av->data &= ~(1U << (p - 1));
	} else {
		if (p < 0)
			av->data = ~0U;
		else
			av->data |= 1U << (p - 1);
	}

	if (new_rule) {
		if (avtab_insert(&policydb->te_avtab, &key, av)) {
			fprintf(stderr, "Error inserting into avtab\n");
			return 1;
		}
		free(av);
	}

	return 0;
}

static int add_rule_auto(type_datum_t *src, type_datum_t *tgt, class_datum_t *cls, perm_datum_t *perm, int effect, int not) {
	hashtab_ptr_t cur;
	int ret = 0;

	if (src == NULL) {
		hashtab_for_each(policydb->p_types.table, &cur) {
			src = cur->datum;
			ret |= add_rule_auto(src, tgt, cls, perm, effect, not);
		}
	} else if (tgt == NULL) {
		hashtab_for_each(policydb->p_types.table, &cur) {
			tgt = cur->datum;
			ret |= add_rule_auto(src, tgt, cls, perm, effect, not);
		}
	} else if (cls == NULL) {
		hashtab_for_each(policydb->p_classes.table, &cur) {
			cls = cur->datum;
			ret |= add_irule(src->s.value, tgt->s.value, cls->s.value, -1, effect, not);
		}
	} else {
		return add_irule(src->s.value, tgt->s.value, cls->s.value, perm ? perm->s.value : -1, effect, not);
	}
	return ret;
}

int load_policydb(const char *filename) {
	int fd;
	struct stat sb;
	struct policy_file pf;
	void *map;
	int ret;

	if (policydb)
		destroy_policydb();

	policydb = cmalloc(sizeof(*policydb));

	fd = open(filename, O_RDONLY);
	if (fd < 0) {
		fprintf(stderr, "Can't open '%s':  %s\n",
				filename, strerror(errno));
		return 1;
	}
	if (fstat(fd, &sb) < 0) {
		fprintf(stderr, "Can't stat '%s':  %s\n",
				filename, strerror(errno));
		return 1;
	}
	map = mmap(NULL, sb.st_size, PROT_READ | PROT_WRITE, MAP_PRIVATE,
				fd, 0);
	if (map == MAP_FAILED) {
		fprintf(stderr, "Can't mmap '%s':  %s\n",
				filename, strerror(errno));
		return 1;
	}

	policy_file_init(&pf);
	pf.type = PF_USE_MEMORY;
	pf.data = map;
	pf.len = sb.st_size;
	if (policydb_init(policydb)) {
		fprintf(stderr, "policydb_init: Out of memory!\n");
		return 1;
	}
	ret = policydb_read(policydb, &pf, 0);
	if (ret) {
		fprintf(stderr, "error(s) encountered while parsing configuration\n");
		return 1;
	}

	munmap(map, sb.st_size);
	close(fd);

	return 0;
}

int dump_policydb(const char *filename) {
	int fd, ret;
	void *data = NULL;
	size_t len;
	policydb_to_image(NULL, policydb, &data, &len);
	if (data == NULL) {
		fprintf(stderr, "Fail to dump policy image!");
		return 1;
	}

	fd = open(filename, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
	if (fd < 0) {
		fprintf(stderr, "Can't open '%s':  %s\n",
		        filename, strerror(errno));
		return 1;
	}
	ret = write(fd, data, len);
	close(fd);
	if (ret < 0) {
		fprintf(stderr, "Could not write policy to %s\n",
		        filename);
		return 1;
	}
	return 0;
}

void destroy_policydb() {
	policydb_destroy(policydb);
	free(policydb);
	policydb = NULL;
}

int create_domain(char *d) {
	symtab_datum_t *src = hashtab_search(policydb->p_types.table, d);
	if(src) {
		fprintf(stderr, "Domain %s already exists\n", d);
		return 1;
	}

	type_datum_t *typedatum = (type_datum_t *) malloc(sizeof(type_datum_t));
	type_datum_init(typedatum);
	typedatum->primary = 1;
	typedatum->flavor = TYPE_TYPE;

	uint32_t value = 0;
	int r = symtab_insert(policydb, SYM_TYPES, strdup(d), typedatum, SCOPE_DECL, 1, &value);
	typedatum->s.value = value;

	if (ebitmap_set_bit(&policydb->global->branch_list->declared.scope[SYM_TYPES], value - 1, 1)) {
		return 1;
	}

	policydb->type_attr_map = realloc(policydb->type_attr_map, sizeof(ebitmap_t) * policydb->p_types.nprim);
	policydb->attr_type_map = realloc(policydb->attr_type_map, sizeof(ebitmap_t) * policydb->p_types.nprim);
	ebitmap_init(&policydb->type_attr_map[value-1]);
	ebitmap_init(&policydb->attr_type_map[value-1]);
	ebitmap_set_bit(&policydb->type_attr_map[value-1], value-1, 1);

	//Add the domain to all roles
	for(unsigned i=0; i<policydb->p_roles.nprim; ++i) {
		//Not sure all those three calls are needed
		ebitmap_set_bit(&policydb->role_val_to_struct[i]->types.negset, value-1, 0);
		ebitmap_set_bit(&policydb->role_val_to_struct[i]->types.types, value-1, 1);
		type_set_expand(&policydb->role_val_to_struct[i]->types, &policydb->role_val_to_struct[i]->cache, policydb, 0);
	}

	src = hashtab_search(policydb->p_types.table, d);
	if(!src)
		return 1;

	if(policydb_index_decls(NULL, policydb))
		return 1;

	if(policydb_index_classes(policydb))
		return 1;

	if(policydb_index_others(NULL, policydb, 0))
		return 1;

	return set_attr("domain", value);
}

int set_domain_state(char* s, int state) {
	type_datum_t *type;
	hashtab_ptr_t cur;
	if (s == NULL) {
		hashtab_for_each(policydb->p_types.table, &cur) {
			type = cur->datum;
			if (ebitmap_set_bit(&policydb->permissive_map, type->s.value, state)) {
				fprintf(stderr, "Could not set bit in permissive map\n");
				return 1;
			}
		}
	} else {
		type = hashtab_search(policydb->p_types.table, s);
		if (type == NULL) {
				fprintf(stderr, "type %s does not exist\n", s);
				return 1;
		}
		if (ebitmap_set_bit(&policydb->permissive_map, type->s.value, state)) {
			fprintf(stderr, "Could not set bit in permissive map\n");
			return 1;
		}
	}
	
	return 0;
}

int add_transition(char *s, char *t, char *c, char *d) {
	type_datum_t *src, *tgt, *def;
	class_datum_t *cls;

	avtab_key_t key;
	avtab_datum_t *av;
	int new_rule = 0;

	src = hashtab_search(policydb->p_types.table, s);
	if (src == NULL) {
		fprintf(stderr, "source type %s does not exist\n", s);
		return 1;
	}
	tgt = hashtab_search(policydb->p_types.table, t);
	if (tgt == NULL) {
		fprintf(stderr, "target type %s does not exist\n", t);
		return 1;
	}
	cls = hashtab_search(policydb->p_classes.table, c);
	if (cls == NULL) {
		fprintf(stderr, "class %s does not exist\n", c);
		return 1;
	}
	def = hashtab_search(policydb->p_types.table, d);
	if (def == NULL) {
		fprintf(stderr, "default type %s does not exist\n", d);
		return 1;
	}

	key.source_type = src->s.value;
	key.target_type = tgt->s.value;
	key.target_class = cls->s.value;
	key.specified = AVTAB_TRANSITION;
	av = avtab_search(&policydb->te_avtab, &key);

	if (av == NULL) {
		av = cmalloc(sizeof(*av));
		new_rule = 1;
	}

	av->data = def->s.value;

	if (new_rule) {
		if (avtab_insert(&policydb->te_avtab, &key, av)) {
			fprintf(stderr, "Error inserting into avtab\n");
			return 1;
		}
		free(av);
	}
	return 0;
}

int add_file_transition(char *s, char *t, char *c, char *d, char* filename) {
	type_datum_t *src, *tgt, *def;
	class_datum_t *cls;

	src = hashtab_search(policydb->p_types.table, s);
	if (src == NULL) {
		fprintf(stderr, "source type %s does not exist\n", s);
		return 1;
	}
	tgt = hashtab_search(policydb->p_types.table, t);
	if (tgt == NULL) {
		fprintf(stderr, "target type %s does not exist\n", t);
		return 1;
	}
	cls = hashtab_search(policydb->p_classes.table, c);
	if (cls == NULL) {
		fprintf(stderr, "class %s does not exist\n", c);
		return 1;
	}
	def = hashtab_search(policydb->p_types.table, d);
	if (def == NULL) {
		fprintf(stderr, "default type %s does not exist\n", d);
		return 1;
	}

	filename_trans_t trans_key;
	trans_key.stype = src->s.value;
	trans_key.ttype = tgt->s.value;
	trans_key.tclass = cls->s.value;
	trans_key.name = filename;

	filename_trans_datum_t *trans_datum;
	trans_datum = hashtab_search(policydb->p_types.table, (hashtab_key_t) &trans_key);

	if (trans_datum == NULL) {
		trans_datum = cmalloc(sizeof(*trans_datum));
		hashtab_insert(policydb->filename_trans, (hashtab_key_t) &trans_key, trans_datum);
	}

	// Overwrite existing
	trans_datum->otype = def->s.value;
	return 0;
}

int add_typeattribute(char *domainS, char *attr) {
	type_datum_t *domain;

	domain = hashtab_search(policydb->p_types.table, domainS);
	if (domain == NULL) {
		fprintf(stderr, "source type %s does not exist\n", domainS);
		return 1;
	}

	set_attr(attr, domain->s.value);

	int typeId = get_attr_id(attr);
	//Now let's update all constraints!
	//(kernel doesn't support (yet?) type_names rules)
	for(int i=0; i<policydb->p_classes.nprim; ++i) {
		class_datum_t *cl = policydb->class_val_to_struct[i];
		for(constraint_node_t *n = cl->constraints; n ; n=n->next) {
			for(constraint_expr_t *e = n->expr; e; e=e->next) {
				if(e->expr_type == CEXPR_NAMES) {
					if(ebitmap_get_bit(&e->type_names->types, typeId-1)) {
						ebitmap_set_bit(&e->names, domain->s.value-1, 1);
					}
				}
			}
		}
	}
	return 0;
}

int add_rule(char *s, char *t, char *c, char *p, int effect, int not) {
	type_datum_t *src = NULL, *tgt = NULL;
	class_datum_t *cls = NULL;
	perm_datum_t *perm = NULL;

	if (s) {
		src = hashtab_search(policydb->p_types.table, s);
		if (src == NULL) {
			fprintf(stderr, "source type %s does not exist\n", s);
			return 1;
		}
	}

	if (t) {
		tgt = hashtab_search(policydb->p_types.table, t);
		if (tgt == NULL) {
			fprintf(stderr, "target type %s does not exist\n", t);
			return 1;
		}
	}

	if (c) {
		cls = hashtab_search(policydb->p_classes.table, c);
		if (cls == NULL) {
			fprintf(stderr, "class %s does not exist\n", c);
			return 1;
		}
	}

	if (p) {
		if (c == NULL) {
			fprintf(stderr, "No class is specified, cannot add perm [%s] \n", p);
			return 1;
		}
		
		if (cls != NULL) {
			perm = hashtab_search(cls->permissions.table, p);
			if (perm == NULL && cls->comdatum != NULL) {
				perm = hashtab_search(cls->comdatum->permissions.table, p);
			}
			if (perm == NULL) {
				fprintf(stderr, "perm %s does not exist in class %s\n", p, c);
				return 1;
			}
		}
	}
	return add_rule_auto(src, tgt, cls, perm, effect, not);
}