From: Todd Kjos <tkjos@xxxxxxxxxx> commit 656e01f3ab54afe71bed066996fc2640881e1220 upstream. This patch is to prepare for an up coming patch where we read pre-translated fds from the sender buffer and translate them before copying them to the target. It does not change run time. The patch adds two new parameters to binder_translate_fd_array() to hold the sender buffer and sender buffer parent. These parameters let us call copy_from_user() directly from the sender instead of using binder_alloc_copy_from_buffer() to copy from the target. Also the patch adds some new alignment checks. Previously the alignment checks would have been done in a different place, but this lets us print more useful error messages. Reviewed-by: Martijn Coenen <maco@xxxxxxxxxxx> Acked-by: Christian Brauner <christian.brauner@xxxxxxxxxx> Signed-off-by: Todd Kjos <tkjos@xxxxxxxxxx> Link: https://lore.kernel.org/r/20211130185152.437403-4-tkjos@xxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Carlos Llamas <cmllamas@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/android/binder.c | 39 ++++++++++++++++++++++++++++++++------- 1 file changed, 32 insertions(+), 7 deletions(-) --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -2637,15 +2637,17 @@ err_fd_not_accepted: } static int binder_translate_fd_array(struct binder_fd_array_object *fda, + const void __user *sender_ubuffer, struct binder_buffer_object *parent, + struct binder_buffer_object *sender_uparent, struct binder_transaction *t, struct binder_thread *thread, struct binder_transaction *in_reply_to) { binder_size_t fdi, fd_buf_size; binder_size_t fda_offset; + const void __user *sender_ufda_base; struct binder_proc *proc = thread->proc; - struct binder_proc *target_proc = t->to_proc; fd_buf_size = sizeof(u32) * fda->num_fds; if (fda->num_fds >= SIZE_MAX / sizeof(u32)) { @@ -2669,7 +2671,10 @@ static int binder_translate_fd_array(str */ fda_offset = (parent->buffer - (uintptr_t)t->buffer->user_data) + fda->parent_offset; - if (!IS_ALIGNED((unsigned long)fda_offset, sizeof(u32))) { + sender_ufda_base = (void __user *)sender_uparent->buffer + fda->parent_offset; + + if (!IS_ALIGNED((unsigned long)fda_offset, sizeof(u32)) || + !IS_ALIGNED((unsigned long)sender_ufda_base, sizeof(u32))) { binder_user_error("%d:%d parent offset not aligned correctly.\n", proc->pid, thread->pid); return -EINVAL; @@ -2678,10 +2683,9 @@ static int binder_translate_fd_array(str u32 fd; int ret; binder_size_t offset = fda_offset + fdi * sizeof(fd); + binder_size_t sender_uoffset = fdi * sizeof(fd); - ret = binder_alloc_copy_from_buffer(&target_proc->alloc, - &fd, t->buffer, - offset, sizeof(fd)); + ret = copy_from_user(&fd, sender_ufda_base + sender_uoffset, sizeof(fd)); if (!ret) ret = binder_translate_fd(fd, offset, t, thread, in_reply_to); @@ -3348,6 +3352,8 @@ static void binder_transaction(struct bi case BINDER_TYPE_FDA: { struct binder_object ptr_object; binder_size_t parent_offset; + struct binder_object user_object; + size_t user_parent_size; struct binder_fd_array_object *fda = to_binder_fd_array_object(hdr); size_t num_valid = (buffer_offset - off_start_offset) / @@ -3379,8 +3385,27 @@ static void binder_transaction(struct bi return_error_line = __LINE__; goto err_bad_parent; } - ret = binder_translate_fd_array(fda, parent, t, thread, - in_reply_to); + /* + * We need to read the user version of the parent + * object to get the original user offset + */ + user_parent_size = + binder_get_object(proc, user_buffer, t->buffer, + parent_offset, &user_object); + if (user_parent_size != sizeof(user_object.bbo)) { + binder_user_error("%d:%d invalid ptr object size: %zd vs %zd\n", + proc->pid, thread->pid, + user_parent_size, + sizeof(user_object.bbo)); + return_error = BR_FAILED_REPLY; + return_error_param = -EINVAL; + return_error_line = __LINE__; + goto err_bad_parent; + } + ret = binder_translate_fd_array(fda, user_buffer, + parent, + &user_object.bbo, t, + thread, in_reply_to); if (!ret) ret = binder_alloc_copy_to_buffer(&target_proc->alloc, t->buffer,
