* same reference to the socket, to determine proper reference freeing.
*/
u32 id;
+ /* PTR_TO_SOCKET and PTR_TO_TCP_SOCK could be a ptr returned
+ * from a pointer-cast helper, bpf_sk_fullsock() and
+ * bpf_tcp_sock().
+ *
+ * Consider the following where "sk" is a reference counted
+ * pointer returned from "sk = bpf_sk_lookup_tcp();":
+ *
+ * 1: sk = bpf_sk_lookup_tcp();
+ * 2: if (!sk) { return 0; }
+ * 3: fullsock = bpf_sk_fullsock(sk);
+ * 4: if (!fullsock) { bpf_sk_release(sk); return 0; }
+ * 5: tp = bpf_tcp_sock(fullsock);
+ * 6: if (!tp) { bpf_sk_release(sk); return 0; }
+ * 7: bpf_sk_release(sk);
+ * 8: snd_cwnd = tp->snd_cwnd; // verifier will complain
+ *
+ * After bpf_sk_release(sk) at line 7, both "fullsock" ptr and
+ * "tp" ptr should be invalidated also. In order to do that,
+ * the reg holding "fullsock" and "sk" need to remember
+ * the original refcounted ptr id (i.e. sk_reg->id) in ref_obj_id
+ * such that the verifier can reset all regs which have
+ * ref_obj_id matching the sk_reg->id.
+ *
+ * sk_reg->ref_obj_id is set to sk_reg->id at line 1.
+ * sk_reg->id will stay as NULL-marking purpose only.
+ * After NULL-marking is done, sk_reg->id can be reset to 0.
+ *
+ * After "fullsock = bpf_sk_fullsock(sk);" at line 3,
+ * fullsock_reg->ref_obj_id is set to sk_reg->ref_obj_id.
+ *
+ * After "tp = bpf_tcp_sock(fullsock);" at line 5,
+ * tp_reg->ref_obj_id is set to fullsock_reg->ref_obj_id
+ * which is the same as sk_reg->ref_obj_id.
+ *
+ * From the verifier perspective, if sk, fullsock and tp
+ * are not NULL, they are the same ptr with different
+ * reg->type. In particular, bpf_sk_release(tp) is also
+ * allowed and has the same effect as bpf_sk_release(sk).
+ */
+ u32 ref_obj_id;
/* For scalar types (SCALAR_VALUE), this represents our knowledge of
* the actual value.
* For pointer types, this represents the variable part of the offset
int access_size;
s64 msize_smax_value;
u64 msize_umax_value;
- int ptr_id;
+ int ref_obj_id;
int func_id;
};
type == PTR_TO_TCP_SOCK_OR_NULL;
}
-static bool type_is_refcounted(enum bpf_reg_type type)
-{
- return type == PTR_TO_SOCKET;
-}
-
-static bool type_is_refcounted_or_null(enum bpf_reg_type type)
-{
- return type == PTR_TO_SOCKET || type == PTR_TO_SOCKET_OR_NULL;
-}
-
-static bool reg_is_refcounted(const struct bpf_reg_state *reg)
-{
- return type_is_refcounted(reg->type);
-}
-
static bool reg_may_point_to_spin_lock(const struct bpf_reg_state *reg)
{
return reg->type == PTR_TO_MAP_VALUE &&
map_value_has_spin_lock(reg->map_ptr);
}
-static bool reg_is_refcounted_or_null(const struct bpf_reg_state *reg)
+static bool arg_type_may_be_refcounted(enum bpf_arg_type type)
{
- return type_is_refcounted_or_null(reg->type);
-}
-
-static bool arg_type_is_refcounted(enum bpf_arg_type type)
-{
- return type == ARG_PTR_TO_SOCKET;
+ return type == ARG_PTR_TO_SOCK_COMMON;
}
/* Determine whether the function releases some resources allocated by another
func_id == BPF_FUNC_sk_lookup_udp;
}
+static bool is_ptr_cast_function(enum bpf_func_id func_id)
+{
+ return func_id == BPF_FUNC_tcp_sock ||
+ func_id == BPF_FUNC_sk_fullsock;
+}
+
/* string representation of 'enum bpf_reg_type' */
static const char * const reg_type_str[] = {
[NOT_INIT] = "?",
if (t == PTR_TO_STACK)
verbose(env, ",call_%d", func(env, reg)->callsite);
} else {
- verbose(env, "(id=%d", reg->id);
+ verbose(env, "(id=%d ref_obj_id=%d", reg->id,
+ reg->ref_obj_id);
if (t != SCALAR_VALUE)
verbose(env, ",off=%d", reg->off);
if (type_is_pkt_pointer(t))
/* Any sk pointer can be ARG_PTR_TO_SOCK_COMMON */
if (!type_is_sk_pointer(type))
goto err_type;
- } else if (arg_type == ARG_PTR_TO_SOCKET) {
- expected_type = PTR_TO_SOCKET;
- if (type != expected_type)
- goto err_type;
- if (meta->ptr_id || !reg->id) {
- verbose(env, "verifier internal error: mismatched references meta=%d, reg=%d\n",
- meta->ptr_id, reg->id);
- return -EFAULT;
+ if (reg->ref_obj_id) {
+ if (meta->ref_obj_id) {
+ verbose(env, "verifier internal error: more than one arg with ref_obj_id R%d %u %u\n",
+ regno, reg->ref_obj_id,
+ meta->ref_obj_id);
+ return -EFAULT;
+ }
+ meta->ref_obj_id = reg->ref_obj_id;
}
- meta->ptr_id = reg->id;
} else if (arg_type == ARG_PTR_TO_SPIN_LOCK) {
if (meta->func_id == BPF_FUNC_spin_lock) {
if (process_spin_lock(env, regno, true))
return true;
}
-static bool check_refcount_ok(const struct bpf_func_proto *fn)
+static bool check_refcount_ok(const struct bpf_func_proto *fn, int func_id)
{
int count = 0;
- if (arg_type_is_refcounted(fn->arg1_type))
+ if (arg_type_may_be_refcounted(fn->arg1_type))
count++;
- if (arg_type_is_refcounted(fn->arg2_type))
+ if (arg_type_may_be_refcounted(fn->arg2_type))
count++;
- if (arg_type_is_refcounted(fn->arg3_type))
+ if (arg_type_may_be_refcounted(fn->arg3_type))
count++;
- if (arg_type_is_refcounted(fn->arg4_type))
+ if (arg_type_may_be_refcounted(fn->arg4_type))
count++;
- if (arg_type_is_refcounted(fn->arg5_type))
+ if (arg_type_may_be_refcounted(fn->arg5_type))
count++;
+ /* A reference acquiring function cannot acquire
+ * another refcounted ptr.
+ */
+ if (is_acquire_function(func_id) && count)
+ return false;
+
/* We only support one arg being unreferenced at the moment,
* which is sufficient for the helper functions we have right now.
*/
return count <= 1;
}
-static int check_func_proto(const struct bpf_func_proto *fn)
+static int check_func_proto(const struct bpf_func_proto *fn, int func_id)
{
return check_raw_mode_ok(fn) &&
check_arg_pair_ok(fn) &&
- check_refcount_ok(fn) ? 0 : -EINVAL;
+ check_refcount_ok(fn, func_id) ? 0 : -EINVAL;
}
/* Packet data might have moved, any old PTR_TO_PACKET[_META,_END]
}
static void release_reg_references(struct bpf_verifier_env *env,
- struct bpf_func_state *state, int id)
+ struct bpf_func_state *state,
+ int ref_obj_id)
{
struct bpf_reg_state *regs = state->regs, *reg;
int i;
for (i = 0; i < MAX_BPF_REG; i++)
- if (regs[i].id == id)
+ if (regs[i].ref_obj_id == ref_obj_id)
mark_reg_unknown(env, regs, i);
bpf_for_each_spilled_reg(i, state, reg) {
if (!reg)
continue;
- if (reg_is_refcounted(reg) && reg->id == id)
+ if (reg->ref_obj_id == ref_obj_id)
__mark_reg_unknown(reg);
}
}
* resources. Identify all copies of the same pointer and clear the reference.
*/
static int release_reference(struct bpf_verifier_env *env,
- struct bpf_call_arg_meta *meta)
+ int ref_obj_id)
{
struct bpf_verifier_state *vstate = env->cur_state;
+ int err;
int i;
+ err = release_reference_state(cur_func(env), ref_obj_id);
+ if (err)
+ return err;
+
for (i = 0; i <= vstate->curframe; i++)
- release_reg_references(env, vstate->frame[i], meta->ptr_id);
+ release_reg_references(env, vstate->frame[i], ref_obj_id);
- return release_reference_state(cur_func(env), meta->ptr_id);
+ return 0;
}
static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
memset(&meta, 0, sizeof(meta));
meta.pkt_access = fn->pkt_access;
- err = check_func_proto(fn);
+ err = check_func_proto(fn, func_id);
if (err) {
verbose(env, "kernel subsystem misconfigured func %s#%d\n",
func_id_name(func_id), func_id);
return err;
}
} else if (is_release_function(func_id)) {
- err = release_reference(env, &meta);
+ err = release_reference(env, meta.ref_obj_id);
if (err) {
verbose(env, "func %s#%d reference has not been acquired before\n",
func_id_name(func_id), func_id);
if (id < 0)
return id;
- /* For release_reference() */
+ /* For mark_ptr_or_null_reg() */
regs[BPF_REG_0].id = id;
+ /* For release_reference() */
+ regs[BPF_REG_0].ref_obj_id = id;
} else {
/* For mark_ptr_or_null_reg() */
regs[BPF_REG_0].id = ++env->id_gen;
return -EINVAL;
}
+ if (is_ptr_cast_function(func_id))
+ /* For release_reference() */
+ regs[BPF_REG_0].ref_obj_id = meta.ref_obj_id;
+
do_refine_retval_range(regs, fn->ret_type, func_id, &meta);
err = check_map_func_compatibility(env, meta.map_ptr, func_id);
} else if (reg->type == PTR_TO_TCP_SOCK_OR_NULL) {
reg->type = PTR_TO_TCP_SOCK;
}
- if (is_null || !(reg_is_refcounted(reg) ||
- reg_may_point_to_spin_lock(reg))) {
- /* We don't need id from this point onwards anymore,
- * thus we should better reset it, so that state
- * pruning has chances to take effect.
+ if (is_null) {
+ /* We don't need id and ref_obj_id from this point
+ * onwards anymore, thus we should better reset it,
+ * so that state pruning has chances to take effect.
+ */
+ reg->id = 0;
+ reg->ref_obj_id = 0;
+ } else if (!reg_may_point_to_spin_lock(reg)) {
+ /* For not-NULL ptr, reg->ref_obj_id will be reset
+ * in release_reg_references().
+ *
+ * reg->id is still used by spin_lock ptr. Other
+ * than spin_lock ptr type, reg->id can be reset.
*/
reg->id = 0;
}
{
struct bpf_func_state *state = vstate->frame[vstate->curframe];
struct bpf_reg_state *reg, *regs = state->regs;
+ u32 ref_obj_id = regs[regno].ref_obj_id;
u32 id = regs[regno].id;
int i, j;
- if (reg_is_refcounted_or_null(®s[regno]) && is_null)
- release_reference_state(state, id);
+ if (ref_obj_id && ref_obj_id == id && is_null)
+ /* regs[regno] is in the " == NULL" branch.
+ * No one could have freed the reference state before
+ * doing the NULL check.
+ */
+ WARN_ON_ONCE(release_reference_state(state, id));
for (i = 0; i < MAX_BPF_REG; i++)
mark_ptr_or_null_reg(state, ®s[i], id, is_null);
projects / mirror_ubuntu-kernels.git / commitdiff