Magisk/sepolicy-inject.c

/*
 * This was derived from public domain works with updates to
 * work with more modern SELinux libraries.
 *
 * It is released into the public domain.
 *
 */

#include <getopt.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <sepol/debug.h>
#include <sepol/policydb/policydb.h>
#include <sepol/policydb/expand.h>
#include <sepol/policydb/link.h>
#include <sepol/policydb/services.h>
#include <sepol/policydb/avrule_block.h>
#include <sepol/policydb/conditional.h>
#include <sepol/policydb/constraint.h>

void usage(char *arg0) {
	fprintf(stderr, "%s -s <source type> -t <target type> -c <class> -p <perm> -P <policy file> -o <output file>\n", arg0);
	fprintf(stderr, "%s -Z permissive_type -P <policy file> -o <output file>\n", arg0);
	exit(1);
}

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

int get_attr(char *type, int value, policydb_t *policy) {
	type_datum_t *attr = hashtab_search(policy->p_types.table, type);
	if (!attr)
		exit(1);

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

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

int get_attr_id(char *type, policydb_t *policy) {
	type_datum_t *attr = hashtab_search(policy->p_types.table, type);
	if (!attr)
		exit(1);

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

	return attr->s.value;
}

int set_attr(char *type, int value, policydb_t *policy) {
	type_datum_t *attr = hashtab_search(policy->p_types.table, type);
	if (!attr)
		exit(1);

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

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

	return 0;
}

void create_domain(char *d, policydb_t *policy) {
	symtab_datum_t *src = hashtab_search(policy->p_types.table, d);
	if(src)
		return;

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

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

	fprintf(stderr, "source type %s does not exist: %d,%d\n", d, r, value);
	if (ebitmap_set_bit(&policy->global->branch_list->declared.scope[SYM_TYPES], value - 1, 1)) {
		exit(1);
	}

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

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


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

	extern int policydb_index_decls(policydb_t * p);
	if(policydb_index_decls(policy))
		exit(1);

	if(policydb_index_classes(policy))
		exit(1);

	if(policydb_index_others(NULL, policy, 1))
		exit(1);

	set_attr("domain", value, policy);
}

int add_rule(char *s, char *t, char *c, char *p, int effect, policydb_t *policy) {
	type_datum_t *src, *tgt;
	class_datum_t *cls;
	perm_datum_t *perm;
	avtab_datum_t *av;
	avtab_key_t key;

	src = hashtab_search(policy->p_types.table, s);
	if (src == NULL) {
		fprintf(stderr, "source type %s does not exist\n", s);
		return 1;
	}
	tgt = hashtab_search(policy->p_types.table, t);
	if (tgt == NULL) {
		fprintf(stderr, "target type %s does not exist\n", t);
		return 1;
	}
	cls = hashtab_search(policy->p_classes.table, c);
	if (cls == NULL) {
		fprintf(stderr, "class %s does not exist\n", c);
		return 1;
	}
	perm = hashtab_search(cls->permissions.table, p);
	if (perm == NULL) {
		if (cls->comdatum == NULL) {
			fprintf(stderr, "perm %s does not exist in class %s\n", p, c);
			return 1;
		}
		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;
		}
	}

	// See if there is already a rule
	key.source_type = src->s.value;
	key.target_type = tgt->s.value;
	key.target_class = cls->s.value;
	key.specified = effect;
	av = avtab_search(&policy->te_avtab, &key);

	if (av == NULL) {
		av = cmalloc(sizeof(*av));
		av->data |= 1U << (perm->s.value - 1);
		int ret = avtab_insert(&policy->te_avtab, &key, av);
		if (ret) {
			fprintf(stderr, "Error inserting into avtab\n");
			return 1;
		}
	}

	av->data |= 1U << (perm->s.value - 1);

	return 0;
}

int add_transition(char *srcS, char *origS, char *tgtS, char *c, policydb_t *policy) {
	type_datum_t *src, *tgt, *orig;
	class_datum_t *cls;

	avtab_datum_t *av;
	avtab_key_t key;

	src = hashtab_search(policy->p_types.table, srcS);
	if (src == NULL) {
		fprintf(stderr, "source type %s does not exist\n", srcS);
		return 1;
	}
	tgt = hashtab_search(policy->p_types.table, tgtS);
	if (tgt == NULL) {
		fprintf(stderr, "target type %s does not exist\n", tgtS);
		return 1;
	}
	cls = hashtab_search(policy->p_classes.table, c);
	if (cls == NULL) {
		fprintf(stderr, "class %s does not exist\n", c);
		return 1;
	}
	orig = hashtab_search(policy->p_types.table, origS);
	if (cls == NULL) {
		fprintf(stderr, "class %s does not exist\n", origS);
		return 1;
	}

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

	if (av == NULL) {
		av = cmalloc(sizeof(*av));
		av->data = tgt->s.value;
		int ret = avtab_insert(&policy->te_avtab, &key, av);
		if (ret) {
			fprintf(stderr, "Error inserting into avtab\n");
			return 1;
		}
	} else {
		fprintf(stderr, "Warning, rule already defined! Won't override.\n");
		fprintf(stderr, "Previous value = %d, wanted value = %d\n", av->data, tgt->s.value);
	}

	return 0;
}

int add_file_transition(char *srcS, char *origS, char *tgtS, char *c, char* filename, policydb_t *policy) {
	type_datum_t *src, *tgt, *orig;
	class_datum_t *cls;

	src = hashtab_search(policy->p_types.table, srcS);
	if (src == NULL) {
		fprintf(stderr, "source type %s does not exist\n", srcS);
		return 1;
	}
	tgt = hashtab_search(policy->p_types.table, tgtS);
	if (tgt == NULL) {
		fprintf(stderr, "target type %s does not exist\n", tgtS);
		return 1;
	}
	cls = hashtab_search(policy->p_classes.table, c);
	if (cls == NULL) {
		fprintf(stderr, "class %s does not exist\n", c);
		return 1;
	}
	orig = hashtab_search(policy->p_types.table, origS);
	if (cls == NULL) {
		fprintf(stderr, "class %s does not exist\n", origS);
		return 1;
	}

	filename_trans_t *new_transition = cmalloc(sizeof(*new_transition));
	new_transition->stype = src->s.value;
	new_transition->ttype = orig->s.value;
	new_transition->tclass = cls->s.value;
	new_transition->otype = tgt->s.value;
	new_transition->name = strdup(filename);
	new_transition->next = policy->filename_trans;

	policy->filename_trans = new_transition;

	return 0;
}

int add_type(char *domainS, char *typeS, policydb_t *policy) {
	type_datum_t *domain;

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

	set_attr(typeS, domain->s.value, policy);

	int typeId = get_attr_id(typeS, policy);
	//Now let's update all constraints!
	//(kernel doesn't support (yet?) type_names rules)
	for(int i=0; i<policy->p_classes.nprim; ++i) {
		class_datum_t *cl = policy->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 load_policy(char *filename, policydb_t *policydb, struct policy_file *pf) {
	int fd;
	struct stat sb;
	void *map;
	int ret;

	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, 1);
	if (ret) {
		fprintf(stderr, "error(s) encountered while parsing configuration\n");
		return 1;
	}

	return 0;
}

int main(int argc, char **argv)
{
	char *policy = NULL, *source = NULL, *target = NULL, *class = NULL, *perm = NULL;
	char *fcon = NULL, *outfile = NULL, *permissive = NULL, *attr = NULL, *filetrans = NULL;
	policydb_t policydb;
	struct policy_file pf, outpf;
	sidtab_t sidtab;
	int ch;
	FILE *fp;
	int permissive_value = 0, noaudit = 0;

        struct option long_options[] = {
                {"attr", required_argument, NULL, 'a'},
                {"source", required_argument, NULL, 's'},
                {"target", required_argument, NULL, 't'},
                {"class", required_argument, NULL, 'c'},
                {"perm", required_argument, NULL, 'p'},
                {"fcon", required_argument, NULL, 'f'},
                {"filetransition", required_argument, NULL, 'g'},
                {"noaudit", no_argument, NULL, 'n'},
                {"policy", required_argument, NULL, 'P'},
                {"output", required_argument, NULL, 'o'},
                {"permissive", required_argument, NULL, 'Z'},
                {"not-permissive", required_argument, NULL, 'z'},
                {NULL, 0, NULL, 0}
        };

        while ((ch = getopt_long(argc, argv, "a:f:g:s:t:c:p:P:o:Z:z:n", long_options, NULL)) != -1) {
                switch (ch) {
                case 'a':
                        attr = optarg;
                        break;
                case 'f':
                        fcon = optarg;
                        break;
                case 'g':
                        filetrans = optarg;
                        break;
                case 's':
                        source = optarg;
                        break;
                case 't':
                        target = optarg;
                        break;
                case 'c':
                        class = optarg;
                        break;
                case 'p':
                        perm = optarg;
                        break;
                case 'P':
                        policy = optarg;
                        break;
		case 'o':
			outfile = optarg;
			break;
		case 'Z':
			permissive = optarg;
			permissive_value = 1;
			break;
		case 'z':
			permissive = optarg;
			permissive_value = 0;
			break;
		case 'n':
			noaudit = 1;
			break;
		default:
			usage(argv[0]);
		}
	}

	if (((!source || !target || !class || !perm) && !permissive && !fcon && !attr &&!filetrans) || !policy)
		usage(argv[0]);

	if(!outfile)
		outfile = policy;

	sepol_set_policydb(&policydb);
        sepol_set_sidtab(&sidtab);

	if (load_policy(policy, &policydb, &pf)) {
		fprintf(stderr, "Could not load policy\n");
		return 1;
	}

        if (policydb_load_isids(&policydb, &sidtab))
		return 1;


	if (permissive) {
		type_datum_t *type;
		create_domain(permissive, &policydb);
        	type = hashtab_search(policydb.p_types.table, permissive);
        	if (type == NULL) {
                	fprintf(stderr, "type %s does not exist\n", permissive);
                	return 1;
        	}
		if (ebitmap_set_bit(&policydb.permissive_map, type->s.value, permissive_value)) {
			fprintf(stderr, "Could not set bit in permissive map\n");
			return 1;
		}
	} else if(filetrans) {
		add_file_transition(source, fcon, target, class, filetrans, &policydb);
	} else if(fcon) {
		add_transition(source, fcon, target, class, &policydb);
	} else if(attr) {
		add_type(source, attr, &policydb);
	} else if(noaudit) {
		add_rule(source, target, class, perm, AVTAB_AUDITDENY, &policydb);
	} else {
		char *saveptr = NULL;

		char *p = strtok_r(perm, ",", &saveptr);
		do {
			if (add_rule(source, target, class, p, AVTAB_ALLOWED, &policydb)) {
				fprintf(stderr, "Could not add rule\n");
				return 1;
			}
		} while( (p = strtok_r(NULL, ",", &saveptr)) != NULL);
	}

	fp = fopen(outfile, "w");
	if (!fp) {
		fprintf(stderr, "Could not open outfile\n");
		return 1;
	}

	policy_file_init(&outpf);
	outpf.type = PF_USE_STDIO;
	outpf.fp = fp;

	if (policydb_write(&policydb, &outpf)) {
		fprintf(stderr, "Could not write policy\n");
		return 1;
	}

	policydb_destroy(&policydb);
	fclose(fp);

	return 0;
}