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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id s17-20020a17090a5d1100b001e0d4169365sm1921226pji.17.2022.06.15.08.01.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Jun 2022 08:02:00 -0700 (PDT) From: Kees Cook To: avagin@gmail.com, linux-kernel@vger.kernel.org, 0x7f454c46@gmail.com, brauner@kernel.org Cc: Kees Cook , ebiederm@xmission.com, linux-mm@kvack.org, fweimer@redhat.com Subject: Re: [PATCH 1/2] fs/exec: allow to unshare a time namespace on vfork+exec Date: Wed, 15 Jun 2022 08:01:48 -0700 Message-Id: <165530530544.261757.10728167525988459977.b4-ty@chromium.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20220613060723.197407-1-avagin@gmail.com> References: <20220613060723.197407-1-avagin@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1655305324; a=rsa-sha256; cv=none; b=DoPAxZFBJYsLqvzuQLIa0jNo1Dwj4Vk1b+WGWHvQuKUzwPzFe5sZAllLaniPY5v3ZQ8ohC STbO6KPywsQUFVFOYhcZ5khmM3cb6vqXwTHb0Sne+X/92pJtUuBXQpjV6bCCqPUy+yXgQ0 e03ndtdsWQOV4y1PnPcMh6i1vm32RSo= ARC-Authentication-Results: i=1; imf18.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=agBC36Od; spf=pass (imf18.hostedemail.com: domain of keescook@chromium.org designates 209.85.216.47 as permitted sender) smtp.mailfrom=keescook@chromium.org; dmarc=pass (policy=none) header.from=chromium.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1655305324; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=VeL22Tj/KeUMdZCI0ao7YL9Y2reNjsNfv6khr7OlAV0=; b=XdnlIKpg7Tzk2BsM7lCKfJYoJP36r13RuzcLFRZVsc1n3PwhD1xbrxUxMq8Fj5uK7X1hRE wLlFNPq9Pcu2yT4AwcOmbrNcw3I0R2FthV6C/y3EuJZK0dOJW0dgR8LXBt8UeWk0NyTN1l 4WgZVc7uRE0PnSBu9u9iflJWRSA9Iew= X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 22EFE1C00C3 X-Stat-Signature: 9646naetqdkkh6nge4mnjy4on3ey3kif Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=agBC36Od; spf=pass (imf18.hostedemail.com: domain of keescook@chromium.org designates 209.85.216.47 as permitted sender) smtp.mailfrom=keescook@chromium.org; dmarc=pass (policy=none) header.from=chromium.org X-HE-Tag: 1655305321-342878 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sun, 12 Jun 2022 23:07:22 -0700, Andrei Vagin wrote: > Right now, a new process can't be forked in another time namespace > if it shares mm with its parent. It is prohibited, because each time > namespace has its own vvar page that is mapped into a process address > space. > > When a process calls exec, it gets a new mm and so it could be "legal" > to switch time namespace in that case. This was not implemented and > now if we want to do this, we need to add another clone flag to not > break backward compatibility. > > [...] Applied to for-next/execve, thanks! [1/2] fs/exec: allow to unshare a time namespace on vfork+exec https://git.kernel.org/kees/c/133e2d3e81de [2/2] testing/timens: add a test for vfork+exit https://git.kernel.org/kees/c/6342140db660 -- Kees Cook