Relative clauses modifying a noun: passive voice?


Hopefully, the two following sentences are grammatically valid:

> 旅行の後で帰った時話を話す。
>
> 旅行の後で帰った時話が話される。

If so, can I use either as a basis for a relative clause modifying 話; are the
two following sentences valid? Do they differ in meaning?

> 土産話は旅行の後で帰った時話す話です。
>
> 土産話は旅行の後で帰った時話される話です。

What I mean to say is "Souvenir stories are stories told after coming back
from a trip". Does either sentence convey that meaning, or are they both wrong
altogether?




Your sentences have several flaws unrelated to your main concern. 話を話す ("to
talk a talk"?) is weird, and you have to say 話をする instead. 旅行の後で帰る sounds
clumsy and redundant, and it's better to say 旅行から帰る. When you introduce the
definition of a word, it's better to use
[とは](https://japanese.stackexchange.com/q/19310/5010) instead of は.

After fixing these, yes, you can say all of the following.

>   * 旅行から帰った時話をする。
>   * 旅行から帰った時話がされる。
>

>   * 土産話とは、旅行から帰った時する話です。
>   * 土産話とは、旅行から帰った時される話です。
>

する話 and される話 effectively refer to the same thing in this case because people
can automatically find the implicit subject that makes the most sense. [This
question](https://japanese.stackexchange.com/q/61710/5010) may be related.




Your sentences have several flaws unrelated to your main concern. 話を話す ("to
talk a talk"?) is weird, and you have to say 話をする instead. 旅行の後で帰る sounds
clumsy and redundant, and it's better to say 旅行から帰る. When you introduce the
definition of a word, it's better to use
[とは](https://japanese.stackexchange.com/q/19310/5010) instead of は.

After fixing these, yes, you can say all of the following.

>   * 旅行から帰った時話をする。
>   * 旅行から帰った時話がされる。
>

>   * 土産話とは、旅行から帰った時する話です。
>   * 土産話とは、旅行から帰った時される話です。
>

する話 and される話 effectively refer to the same thing in this case because people
can automatically find the implicit subject that makes the most sense. [This
question](https://japanese.stackexchange.com/q/61710/5010) may be related.

