Magisk/native/jni/magiskpolicy/sepolicy.cpp
2020-06-17 01:17:28 -07:00

700 lines
19 KiB
C++

#include <sepol/policydb/policydb.h>
#include <magiskpolicy.hpp>
#include <utils.hpp>
#include "sepolicy.hpp"
#if 0
// Print out all rules going through public API for debugging
template <typename ...Args>
static void dprint(const char *action, Args ...args) {
std::string s(action);
for (int i = 0; i < sizeof...(args); ++i) s += " %s";
s += "\n";
LOGD(s.data(), (args ? args : "*")...);
}
#else
#define dprint(...)
#endif
// Invert is adding rules for auditdeny; in other cases, invert is removing rules
#define strip_av(effect, invert) ((effect == AVTAB_AUDITDENY) == !invert)
// libsepol internal APIs
__BEGIN_DECLS
int policydb_index_decls(sepol_handle_t * handle, policydb_t * p);
int avtab_hash(struct avtab_key *keyp, uint32_t mask);
int type_set_expand(type_set_t * set, ebitmap_t * t, policydb_t * p, unsigned char alwaysexpand);
int context_from_string(
sepol_handle_t * handle,
const policydb_t * policydb,
context_struct_t ** cptr,
const char *con_str, size_t con_str_len);
__END_DECLS
template <typename T>
struct auto_cast_wrapper
{
auto_cast_wrapper(T *ptr) : ptr(ptr) {}
template <typename U>
operator U*() const { return static_cast<U*>(ptr); }
private:
T *ptr;
};
template <typename T>
static auto_cast_wrapper<T> auto_cast(T *p) {
return auto_cast_wrapper<T>(p);
}
static auto hashtab_find(hashtab_t h, const_hashtab_key_t key) {
return auto_cast(hashtab_search(h, key));
}
template <class Node, class Func>
static void hash_for_each(Node **node_ptr, int n_slot, const Func &fn) {
for (int i = 0; i < n_slot; ++i) {
for (Node *cur = node_ptr[i]; cur; cur = cur->next) {
fn(cur);
}
}
}
template <class Func>
static void hashtab_for_each(hashtab_t htab, const Func &fn) {
hash_for_each(htab->htable, htab->size, fn);
}
template <class Func>
static void avtab_for_each(avtab_t *avtab, const Func &fn) {
hash_for_each(avtab->htable, avtab->nslot, fn);
}
template <class Func>
static void for_each_attr(hashtab_t htab, const Func &fn) {
hashtab_for_each(htab, [&](hashtab_ptr_t node) {
auto type = static_cast<type_datum_t *>(node->datum);
if (type->flavor == TYPE_ATTRIB)
fn(type);
});
}
static int avtab_remove_node(avtab_t *h, avtab_ptr_t node) {
if (!h || !h->htable)
return SEPOL_ENOMEM;
int hvalue = avtab_hash(&node->key, h->mask);
avtab_ptr_t prev, cur;
for (prev = nullptr, cur = h->htable[hvalue]; cur; prev = cur, cur = cur->next) {
if (cur == node)
break;
}
if (cur == nullptr)
return SEPOL_ENOENT;
// Detach from hash table
if (prev)
prev->next = node->next;
else
h->htable[hvalue] = node->next;
h->nel--;
// Free memory
if (node->key.specified & AVTAB_XPERMS)
free(node->datum.xperms);
free(node);
return 0;
}
void sepol_impl::check_avtab_node(avtab_ptr_t node) {
bool redundant;
if (node->key.specified == AVTAB_AUDITDENY)
redundant = node->datum.data == ~0U;
else if (node->key.specified & AVTAB_XPERMS)
redundant = node->datum.xperms == nullptr;
else
redundant = node->datum.data == 0U;
if (redundant)
avtab_remove_node(&db->te_avtab, node);
}
avtab_ptr_t sepol_impl::get_avtab_node(avtab_key_t *key, avtab_extended_perms_t *xperms) {
avtab_ptr_t node;
/* AVTAB_XPERMS entries are not necessarily unique */
if (key->specified & AVTAB_XPERMS) {
bool match = false;
node = avtab_search_node(&db->te_avtab, key);
while (node) {
if ((node->datum.xperms->specified == xperms->specified) &&
(node->datum.xperms->driver == xperms->driver)) {
match = true;
break;
}
node = avtab_search_node_next(node, key->specified);
}
if (!match)
node = nullptr;
} else {
node = avtab_search_node(&db->te_avtab, key);
}
if (!node) {
avtab_datum_t avdatum{};
/*
* AUDITDENY, aka DONTAUDIT, are &= assigned, versus |= for
* others. Initialize the data accordingly.
*/
avdatum.data = key->specified == AVTAB_AUDITDENY ? ~0U : 0U;
/* this is used to get the node - insertion is actually unique */
node = avtab_insert_nonunique(&db->te_avtab, key, &avdatum);
}
return node;
}
void sepol_impl::add_rule(type_datum_t *src, type_datum_t *tgt, class_datum_t *cls, perm_datum_t *perm, int effect, bool invert) {
if (src == nullptr) {
if (strip_av(effect, invert)) {
// Stripping av, have to go through all types for correct results
hashtab_for_each(db->p_types.table, [&](hashtab_ptr_t node) {
add_rule(auto_cast(node->datum), tgt, cls, perm, effect, invert);
});
} else {
// If we are not stripping av, go through all attributes instead of types for optimization
for_each_attr(db->p_types.table, [&](type_datum_t *type) {
add_rule(type, tgt, cls, perm, effect, invert);
});
}
} else if (tgt == nullptr) {
if (strip_av(effect, invert)) {
hashtab_for_each(db->p_types.table, [&](hashtab_ptr_t node) {
add_rule(src, auto_cast(node->datum), cls, perm, effect, invert);
});
} else {
for_each_attr(db->p_types.table, [&](type_datum_t *type) {
add_rule(src, type, cls, perm, effect, invert);
});
}
} else if (cls == nullptr) {
hashtab_for_each(db->p_classes.table, [&](hashtab_ptr_t node) {
add_rule(src, tgt, auto_cast(node->datum), perm, effect, invert);
});
} else {
avtab_key_t key;
key.source_type = src->s.value;
key.target_type = tgt->s.value;
key.target_class = cls->s.value;
key.specified = effect;
avtab_ptr_t node = get_avtab_node(&key, nullptr);
if (invert) {
if (perm)
node->datum.data &= ~(1U << (perm->s.value - 1));
else
node->datum.data = 0U;
} else {
if (perm)
node->datum.data |= 1U << (perm->s.value - 1);
else
node->datum.data = ~0U;
}
check_avtab_node(node);
}
}
bool sepol_impl::add_rule(const char *s, const char *t, const char *c, const char *p, int effect, bool invert) {
type_datum_t *src = nullptr, *tgt = nullptr;
class_datum_t *cls = nullptr;
perm_datum_t *perm = nullptr;
if (s) {
src = hashtab_find(db->p_types.table, s);
if (src == nullptr) {
LOGW("source type %s does not exist\n", s);
return false;
}
}
if (t) {
tgt = hashtab_find(db->p_types.table, t);
if (tgt == nullptr) {
LOGW("target type %s does not exist\n", t);
return false;
}
}
if (c) {
cls = hashtab_find(db->p_classes.table, c);
if (cls == nullptr) {
LOGW("class %s does not exist\n", c);
return false;
}
}
if (p) {
if (c == nullptr) {
LOGW("No class is specified, cannot add perm [%s] \n", p);
return false;
}
perm = hashtab_find(cls->permissions.table, p);
if (perm == nullptr && cls->comdatum != nullptr) {
perm = hashtab_find(cls->comdatum->permissions.table, p);
}
if (perm == nullptr) {
LOGW("perm %s does not exist in class %s\n", p, c);
return false;
}
}
add_rule(src, tgt, cls, perm, effect, invert);
return true;
}
#define ioctl_driver(x) (x>>8 & 0xFF)
#define ioctl_func(x) (x & 0xFF)
void sepol_impl::add_xperm_rule(type_datum_t *src, type_datum_t *tgt,
class_datum_t *cls, uint16_t low, uint16_t high, int effect, bool invert) {
if (src == nullptr) {
for_each_attr(db->p_types.table, [&](type_datum_t *type) {
add_xperm_rule(type, tgt, cls, low, high, effect, invert);
});
} else if (tgt == nullptr) {
for_each_attr(db->p_types.table, [&](type_datum_t *type) {
add_xperm_rule(src, type, cls, low, high, effect, invert);
});
} else if (cls == nullptr) {
hashtab_for_each(db->p_classes.table, [&](hashtab_ptr_t node) {
add_xperm_rule(src, tgt, auto_cast(node->datum), low, high, effect, invert);
});
} else {
avtab_key_t key;
key.source_type = src->s.value;
key.target_type = tgt->s.value;
key.target_class = cls->s.value;
key.specified = effect;
avtab_datum_t *datum;
avtab_extended_perms_t xperms;
memset(&xperms, 0, sizeof(xperms));
if (ioctl_driver(low) != ioctl_driver(high)) {
xperms.specified = AVTAB_XPERMS_IOCTLDRIVER;
xperms.driver = 0;
} else {
xperms.specified = AVTAB_XPERMS_IOCTLFUNCTION;
xperms.driver = ioctl_driver(low);
}
if (xperms.specified == AVTAB_XPERMS_IOCTLDRIVER) {
for (int i = ioctl_driver(low); i <= ioctl_driver(high); ++i) {
if (invert)
xperm_clear(i, xperms.perms);
else
xperm_set(i, xperms.perms);
}
} else {
for (int i = ioctl_func(low); i <= ioctl_func(high); ++i) {
if (invert)
xperm_clear(i, xperms.perms);
else
xperm_set(i, xperms.perms);
}
}
datum = &get_avtab_node(&key, &xperms)->datum;
if (datum->xperms == nullptr)
datum->xperms = auto_cast(xmalloc(sizeof(xperms)));
memcpy(datum->xperms, &xperms, sizeof(xperms));
}
}
bool sepol_impl::add_xperm_rule(const char *s, const char *t, const char *c, const char *range, int effect, bool invert) {
type_datum_t *src = nullptr, *tgt = nullptr;
class_datum_t *cls = nullptr;
if (s) {
src = hashtab_find(db->p_types.table, s);
if (src == nullptr) {
LOGW("source type %s does not exist\n", s);
return false;
}
}
if (t) {
tgt = hashtab_find(db->p_types.table, t);
if (tgt == nullptr) {
LOGW("target type %s does not exist\n", t);
return false;
}
}
if (c) {
cls = hashtab_find(db->p_classes.table, c);
if (cls == nullptr) {
LOGW("class %s does not exist\n", c);
return false;
}
}
uint16_t low, high;
if (range) {
if (strchr(range, '-')){
sscanf(range, "%hx-%hx", &low, &high);
} else {
sscanf(range, "%hx", &low);
high = low;
}
} else {
low = 0;
high = 0xFFFF;
}
add_xperm_rule(src, tgt, cls, low, high, effect, invert);
return true;
}
bool sepol_impl::add_type_rule(const char *s, const char *t, const char *c, const char *d, int effect) {
type_datum_t *src, *tgt, *def;
class_datum_t *cls;
src = hashtab_find(db->p_types.table, s);
if (src == nullptr) {
LOGW("source type %s does not exist\n", s);
return false;
}
tgt = hashtab_find(db->p_types.table, t);
if (tgt == nullptr) {
LOGW("target type %s does not exist\n", t);
return false;
}
cls = hashtab_find(db->p_classes.table, c);
if (cls == nullptr) {
LOGW("class %s does not exist\n", c);
return false;
}
def = hashtab_find(db->p_types.table, d);
if (def == nullptr) {
LOGW("default type %s does not exist\n", d);
return false;
}
avtab_key_t key;
key.source_type = src->s.value;
key.target_type = tgt->s.value;
key.target_class = cls->s.value;
key.specified = effect;
avtab_ptr_t node = get_avtab_node(&key, nullptr);
node->datum.data = def->s.value;
return true;
}
bool sepol_impl::add_filename_trans(const char *s, const char *t, const char *c, const char *d, const char *o) {
type_datum_t *src, *tgt, *def;
class_datum_t *cls;
filename_trans_datum_t *trans;
src = hashtab_find(db->p_types.table, s);
if (src == nullptr) {
LOGW("source type %s does not exist\n", s);
return false;
}
tgt = hashtab_find(db->p_types.table, t);
if (tgt == nullptr) {
LOGW("target type %s does not exist\n", t);
return false;
}
cls = hashtab_find(db->p_classes.table, c);
if (cls == nullptr) {
LOGW("class %s does not exist\n", c);
return false;
}
def = hashtab_find(db->p_types.table, d);
if (def == nullptr) {
LOGW("default type %s does not exist\n", d);
return false;
}
filename_trans_t key;
key.stype = src->s.value;
key.ttype = tgt->s.value;
key.tclass = cls->s.value;
key.name = (char *) o;
trans = hashtab_find(db->filename_trans, (hashtab_key_t) &key);
if (trans == nullptr) {
trans = auto_cast(xcalloc(sizeof(*trans), 1));
hashtab_insert(db->filename_trans, (hashtab_key_t) &key, trans);
}
// Overwrite existing
trans->otype = def->s.value;
return true;
}
bool sepol_impl::add_genfscon(const char *fs_name, const char *path, const char *context) {
// First try to create context
context_struct_t *ctx;
if (context_from_string(nullptr, db, &ctx, context, strlen(context))) {
LOGW("Failed to create context from string [%s]\n", context);
return false;
}
// Allocate genfs context
ocontext_t *newc = auto_cast(xcalloc(sizeof(*newc), 1));
newc->u.name = strdup(path);
memcpy(&newc->context[0], ctx, sizeof(*ctx));
free(ctx);
// Find or allocate genfs
genfs_t *last_gen = nullptr;
genfs_t *newfs = nullptr;
for (genfs_t *node = db->genfs; node; node = node->next) {
if (strcmp(node->fstype, fs_name) == 0) {
newfs = node;
break;
}
last_gen = node;
}
if (newfs == nullptr) {
newfs = auto_cast(xcalloc(sizeof(*newfs), 1));
newfs->fstype = strdup(fs_name);
// Insert
if (last_gen)
last_gen->next = newfs;
else
db->genfs = newfs;
}
// Insert or replace genfs context
ocontext_t *last_ctx = nullptr;
for (ocontext_t *node = newfs->head; node; node = node->next) {
if (strcmp(node->u.name, path) == 0) {
// Unlink
if (last_ctx)
last_ctx->next = node->next;
else
newfs->head = nullptr;
// Destroy old node
free(node->u.name);
context_destroy(&node->context[0]);
free(node);
break;
}
last_ctx = node;
}
// Insert
if (last_ctx)
last_ctx->next = newc;
else
newfs->head = newc;
return true;
}
bool sepol_impl::add_type(const char *type_name, uint32_t flavor) {
type_datum_t *type = hashtab_find(db->p_types.table, type_name);
if (type) {
LOGW("Type %s already exists\n", type_name);
return true;
}
type = auto_cast(xmalloc(sizeof(type_datum_t)));
type_datum_init(type);
type->primary = 1;
type->flavor = flavor;
uint32_t value = 0;
if (symtab_insert(db, SYM_TYPES, strdup(type_name), type, SCOPE_DECL, 1, &value))
return false;
type->s.value = value;
ebitmap_set_bit(&db->global->branch_list->declared.p_types_scope, value - 1, 1);
auto new_size = sizeof(ebitmap_t) * db->p_types.nprim;
db->type_attr_map = auto_cast(xrealloc(db->type_attr_map, new_size));
db->attr_type_map = auto_cast(xrealloc(db->attr_type_map, new_size));
ebitmap_init(&db->type_attr_map[value - 1]);
ebitmap_init(&db->attr_type_map[value - 1]);
ebitmap_set_bit(&db->type_attr_map[value - 1], value - 1, 1);
// Re-index stuffs
if (policydb_index_decls(nullptr, db) ||
policydb_index_classes(db) || policydb_index_others(nullptr, db, 0))
return false;
// Add the type to all roles
for (int i = 0; i < db->p_roles.nprim; ++i) {
// Not sure all those three calls are needed
ebitmap_set_bit(&db->role_val_to_struct[i]->types.negset, value - 1, 0);
ebitmap_set_bit(&db->role_val_to_struct[i]->types.types, value - 1, 1);
type_set_expand(&db->role_val_to_struct[i]->types, &db->role_val_to_struct[i]->cache, db, 0);
}
return true;
}
bool sepol_impl::set_type_state(const char *type_name, bool permissive) {
type_datum_t *type;
if (type_name == nullptr) {
hashtab_for_each(db->p_types.table, [&](hashtab_ptr_t node) {
type = auto_cast(node->datum);
if (ebitmap_set_bit(&db->permissive_map, type->s.value, permissive))
LOGW("Could not set bit in permissive map\n");
});
} else {
type = hashtab_find(db->p_types.table, type_name);
if (type == nullptr) {
LOGW("type %s does not exist\n", type_name);
return false;
}
if (ebitmap_set_bit(&db->permissive_map, type->s.value, permissive)) {
LOGW("Could not set bit in permissive map\n");
return false;
}
}
return true;
}
void sepol_impl::add_typeattribute(type_datum_t *type, type_datum_t *attr) {
ebitmap_set_bit(&db->type_attr_map[type->s.value - 1], attr->s.value - 1, 1);
ebitmap_set_bit(&db->attr_type_map[attr->s.value - 1], type->s.value - 1, 1);
hashtab_for_each(db->p_classes.table, [&](hashtab_ptr_t node){
auto cls = static_cast<class_datum_t *>(node->datum);
for (constraint_node_t *n = cls->constraints; n ; n = n->next) {
for (constraint_expr_t *e = n->expr; e; e = e->next) {
if (e->expr_type == CEXPR_NAMES &&
ebitmap_get_bit(&e->type_names->types, attr->s.value - 1)) {
ebitmap_set_bit(&e->names, type->s.value - 1, 1);
}
}
}
});
}
bool sepol_impl::add_typeattribute(const char *type, const char *attr) {
type_datum_t *type_d = hashtab_find(db->p_types.table, type);
if (type_d == nullptr) {
LOGW("type %s does not exist\n", type);
return false;
} else if (type_d->flavor == TYPE_ATTRIB) {
LOGW("type %s is an attribute\n", attr);
return false;
}
type_datum *attr_d = hashtab_find(db->p_types.table, attr);
if (attr_d == nullptr) {
LOGW("attribute %s does not exist\n", type);
return false;
} else if (attr_d->flavor != TYPE_ATTRIB) {
LOGW("type %s is not an attribute \n", attr);
return false;
}
add_typeattribute(type_d, attr_d);
return true;
}
void sepol_impl::strip_dontaudit() {
avtab_for_each(&db->te_avtab, [=](avtab_ptr_t node) {
if (node->key.specified == AVTAB_AUDITDENY || node->key.specified == AVTAB_XPERMS_DONTAUDIT)
avtab_remove_node(&db->te_avtab, node);
});
}
bool sepolicy::allow(const char *s, const char *t, const char *c, const char *p) {
dprint(__FUNCTION__, s, t, c, p);
return impl->add_rule(s, t, c, p, AVTAB_ALLOWED, false);
}
bool sepolicy::deny(const char *s, const char *t, const char *c, const char *p) {
dprint(__FUNCTION__, s, t, c, p);
return impl->add_rule(s, t, c, p, AVTAB_ALLOWED, true);
}
bool sepolicy::auditallow(const char *s, const char *t, const char *c, const char *p) {
dprint(__FUNCTION__, s, t, c, p);
return impl->add_rule(s, t, c, p, AVTAB_AUDITALLOW, false);
}
bool sepolicy::dontaudit(const char *s, const char *t, const char *c, const char *p) {
dprint(__FUNCTION__, s, t, c, p);
return impl->add_rule(s, t, c, p, AVTAB_AUDITDENY, true);
}
bool sepolicy::allowxperm(const char *s, const char *t, const char *c, const char *range) {
dprint(__FUNCTION__, s, t, c, "ioctl", range);
return impl->add_xperm_rule(s, t, c, range, AVTAB_XPERMS_ALLOWED, false);
}
bool sepolicy::auditallowxperm(const char *s, const char *t, const char *c, const char *range) {
dprint(__FUNCTION__, s, t, c, "ioctl", range);
return impl->add_xperm_rule(s, t, c, range, AVTAB_XPERMS_AUDITALLOW, false);
}
bool sepolicy::dontauditxperm(const char *s, const char *t, const char *c, const char *range) {
dprint(__FUNCTION__, s, t, c, "ioctl", range);
return impl->add_xperm_rule(s, t, c, range, AVTAB_XPERMS_DONTAUDIT, false);
}
bool sepolicy::type_change(const char *s, const char *t, const char *c, const char *d) {
dprint(__FUNCTION__, s, t, c, d);
return impl->add_type_rule(s, t, c, d, AVTAB_CHANGE);
}
bool sepolicy::type_member(const char *s, const char *t, const char *c, const char *d) {
dprint(__FUNCTION__, s, t, c, d);
return impl->add_type_rule(s, t, c, d, AVTAB_MEMBER);
}
bool sepolicy::type_transition(const char *s, const char *t, const char *c, const char *d, const char *o) {
if (o) {
dprint(__FUNCTION__, s, t, c, d, o);
return impl->add_filename_trans(s, t, c, d, o);
} else {
dprint(__FUNCTION__, s, t, c, d);
return impl->add_type_rule(s, t, c, d, AVTAB_TRANSITION);
}
}
bool sepolicy::permissive(const char *s) {
dprint(__FUNCTION__, s);
return impl->set_type_state(s, true);
}
bool sepolicy::enforce(const char *s) {
dprint(__FUNCTION__, s);
return impl->set_type_state(s, false);
}
bool sepolicy::type(const char *name, const char *attr) {
dprint(__FUNCTION__, name, attr);
return impl->add_type(name, TYPE_TYPE) && impl->add_typeattribute(name, attr);
}
bool sepolicy::attribute(const char *name) {
dprint(__FUNCTION__, name);
return impl->add_type(name, TYPE_ATTRIB);
}
bool sepolicy::typeattribute(const char *type, const char *attr) {
dprint(__FUNCTION__, type, attr);
return impl->add_typeattribute(type, attr);
}
bool sepolicy::genfscon(const char *fs_name, const char *path, const char *ctx) {
dprint(__FUNCTION__, fs_name, path, ctx);
return impl->add_genfscon(fs_name, path, ctx);
}
bool sepolicy::exists(const char *source) {
return hashtab_search(db->p_types.table, source) != nullptr;
}