From: "Mickaël Salaün" <mic@digikod.net> To: linux-kernel@vger.kernel.org Cc: "Mickaël Salaün" <mic@digikod.net>, "Jeff Dike" <jdike@addtoit.com>, "Richard Weinberger" <richard@nod.at>, "Tristan Schmelcher" <tschmelcher@google.com>, "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>, user-mode-linux-devel@lists.sourceforge.net, user-mode-linux-user@lists.sourceforge.net Subject: [PATCH v4 1/2] um: Do not set unsecure permission for temporary file Date: Sat, 19 Dec 2015 19:18:30 +0100 [thread overview] Message-ID: <1450549111-1297-2-git-send-email-mic@digikod.net> (raw) In-Reply-To: <1450549111-1297-1-git-send-email-mic@digikod.net> Remove the insecure 0777 mode for temporary file to prohibit other users to change the executable mapped code. An attacker could gain access to the mapped file descriptor from the temporary file (before it is unlinked) in a read-only mode but it should not be accessible in write mode to avoid arbitrary code execution. To not change the hostfs behavior, the temporary file creation permission now depend on the current umask(2) and the implementation of mkstemp(3). Signed-off-by: Mickaël Salaün <mic@digikod.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Richard Weinberger <richard@nod.at> Acked-by: Tristan Schmelcher <tschmelcher@google.com> --- arch/um/os-Linux/mem.c | 6 ------ 1 file changed, 6 deletions(-) diff --git a/arch/um/os-Linux/mem.c b/arch/um/os-Linux/mem.c index 897e9ad..840d573 100644 --- a/arch/um/os-Linux/mem.c +++ b/arch/um/os-Linux/mem.c @@ -142,12 +142,6 @@ static int __init create_tmp_file(unsigned long long len) if (fd < 0) exit(1); - err = fchmod(fd, 0777); - if (err < 0) { - perror("fchmod"); - exit(1); - } - /* * Seek to len - 1 because writing a character there will * increase the file size by one byte, to the desired length. -- 2.6.4
WARNING: multiple messages have this Message-ID (diff)
From: "Mickaël Salaün" <mic@digikod.net> To: linux-kernel@vger.kernel.org Cc: "Mickaël Salaün" <mic@digikod.net>, "Jeff Dike" <jdike@addtoit.com>, "Richard Weinberger" <richard@nod.at>, "Tristan Schmelcher" <tschmelcher@google.com>, "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>, user-mode-linux-devel@lists.sourceforge.net, user-mode-linux-user@lists.sourceforge.net Subject: [PATCH v4 1/2] um: Do not set unsecure permission for temporary file Date: Sat, 19 Dec 2015 19:18:30 +0100 [thread overview] Message-ID: <1450549111-1297-2-git-send-email-mic@digikod.net> (raw) In-Reply-To: <1450549111-1297-1-git-send-email-mic@digikod.net> Remove the insecure 0777 mode for temporary file to prohibit other users to change the executable mapped code. An attacker could gain access to the mapped file descriptor from the temporary file (before it is unlinked) in a read-only mode but it should not be accessible in write mode to avoid arbitrary code execution. To not change the hostfs behavior, the temporary file creation permission now depend on the current umask(2) and the implementation of mkstemp(3). Signed-off-by: Mickaël Salaün <mic@digikod.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Richard Weinberger <richard@nod.at> Acked-by: Tristan Schmelcher <tschmelcher@google.com> --- arch/um/os-Linux/mem.c | 6 ------ 1 file changed, 6 deletions(-) diff --git a/arch/um/os-Linux/mem.c b/arch/um/os-Linux/mem.c index 897e9ad..840d573 100644 --- a/arch/um/os-Linux/mem.c +++ b/arch/um/os-Linux/mem.c @@ -142,12 +142,6 @@ static int __init create_tmp_file(unsigned long long len) if (fd < 0) exit(1); - err = fchmod(fd, 0777); - if (err < 0) { - perror("fchmod"); - exit(1); - } - /* * Seek to len - 1 because writing a character there will * increase the file size by one byte, to the desired length. -- 2.6.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
next prev parent reply other threads:[~2015-12-19 19:37 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-12-19 18:18 [PATCH v4 0/2] um: Protect memory mapped file Mickaël Salaün 2015-12-19 18:18 ` Mickaël Salaün 2015-12-19 18:18 ` Mickaël Salaün [this message] 2015-12-19 18:18 ` [PATCH v4 1/2] um: Do not set unsecure permission for temporary file Mickaël Salaün 2015-12-19 18:18 ` [PATCH v4 2/2] um: Use race-free temporary file creation Mickaël Salaün 2015-12-19 18:18 ` Mickaël Salaün
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