From: Linus Torvalds <torvalds@linux-foundation.org>
To: Mimi Zohar <zohar@linux.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>,
Roberto Sassu <roberto.sassu@huawei.com>,
"linux-integrity@vger.kernel.org"
<linux-integrity@vger.kernel.org>,
"linux-security-module@vger.kernel.org"
<linux-security-module@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Silviu Vlasceanu <Silviu.Vlasceanu@huawei.com>,
"stable@vger.kernel.org" <stable@vger.kernel.org>,
"viro@zeniv.linux.org.uk" <viro@zeniv.linux.org.uk>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>
Subject: Re: [RESEND][PATCH] ima: Set and clear FMODE_CAN_READ in ima_calc_file_hash()
Date: Tue, 17 Nov 2020 10:23:58 -0800 [thread overview]
Message-ID: <CAHk-=wih-ibNUxeiKpuKrw3Rd2=QEAZ8zgRWt_CORAjbZykRWQ@mail.gmail.com> (raw)
In-Reply-To: <3f8cc7c9462353ac2eef58e39beee079bdd9c7b4.camel@linux.ibm.com>
On Mon, Nov 16, 2020 at 10:35 AM Mimi Zohar <zohar@linux.ibm.com> wrote:
>
> We need to differentiate between signed files, which by definition are
> immutable, and those that are mutable. Appending to a mutable file,
> for example, would result in the file hash not being updated.
> Subsequent reads would fail.
Why would that require any reading of the file at all AT WRITE TIME?
Don't do it. Really.
When opening the file write-only, you just invalidate the hash. It
doesn't matter anyway - you're only writing.
Later on, when reading, only at that point does the hash matter, and
then you can do the verification.
Although honestly, I don't even see the point. You know the hash won't
match, if you wrote to the file.
Linus
next prev parent reply other threads:[~2020-11-17 18:24 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-13 8:01 [RESEND][PATCH] ima: Set and clear FMODE_CAN_READ in ima_calc_file_hash() Roberto Sassu
2020-11-13 15:53 ` Mimi Zohar
2020-11-14 11:10 ` Christoph Hellwig
2020-11-16 8:52 ` Roberto Sassu
2020-11-16 16:22 ` Christoph Hellwig
2020-11-16 16:46 ` Mimi Zohar
2020-11-16 17:37 ` Linus Torvalds
2020-11-16 17:41 ` Christoph Hellwig
2020-11-16 18:09 ` Linus Torvalds
2020-11-16 18:35 ` Mimi Zohar
2020-11-17 18:23 ` Linus Torvalds [this message]
2020-11-17 18:54 ` Theodore Y. Ts'o
2020-11-17 23:23 ` Mimi Zohar
2020-11-17 23:29 ` Linus Torvalds
2020-11-17 23:36 ` Linus Torvalds
2020-11-18 18:28 ` Mimi Zohar
2020-11-20 12:52 ` Roberto Sassu
2020-11-16 18:21 ` Mimi Zohar
2020-11-16 18:08 ` Al Viro
2020-11-16 18:49 ` Mimi Zohar
2020-11-17 12:29 ` Roberto Sassu
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