* [PATCH v3 0/2] um: Protect memory mapped file
@ 2015-12-10 0:09 ` Mickaël Salaün
0 siblings, 0 replies; 7+ messages in thread
From: Mickaël Salaün @ 2015-12-10 0:09 UTC (permalink / raw)
To: linux-kernel
Cc: Mickaël Salaün, Jeff Dike, Richard Weinberger,
Tristan Schmelcher, Greg Kroah-Hartman, user-mode-linux-devel,
user-mode-linux-user
This series protect the memory mapped file.
Changes since v2; addressed Tristan Schmelcher's comment:
* remove the whole fchmod call [1/2]
Changes since v1; addressed Richard Weinberger's comments:
* add attacker model to the patch description [1/2]
* remove errno reset [2/2]
Regards,
Mickaël
Mickaël Salaün (2):
um: Do not set unsecure permission for temporary file
um: Use race-free temporary file creation
arch/um/os-Linux/mem.c | 17 +++++++++++------
1 file changed, 11 insertions(+), 6 deletions(-)
--
2.6.2
^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH v3 0/2] um: Protect memory mapped file
@ 2015-12-10 0:09 ` Mickaël Salaün
0 siblings, 0 replies; 7+ messages in thread
From: Mickaël Salaün @ 2015-12-10 0:09 UTC (permalink / raw)
To: linux-kernel
Cc: Mickaël Salaün, Jeff Dike, Richard Weinberger,
Tristan Schmelcher, Greg Kroah-Hartman, user-mode-linux-devel,
user-mode-linux-user
This series protect the memory mapped file.
Changes since v2; addressed Tristan Schmelcher's comment:
* remove the whole fchmod call [1/2]
Changes since v1; addressed Richard Weinberger's comments:
* add attacker model to the patch description [1/2]
* remove errno reset [2/2]
Regards,
Mickaël
Mickaël Salaün (2):
um: Do not set unsecure permission for temporary file
um: Use race-free temporary file creation
arch/um/os-Linux/mem.c | 17 +++++++++++------
1 file changed, 11 insertions(+), 6 deletions(-)
--
2.6.2
--
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^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH v3 1/2] um: Do not set unsecure permission for temporary file
2015-12-10 0:09 ` Mickaël Salaün
@ 2015-12-10 0:09 ` Mickaël Salaün
-1 siblings, 0 replies; 7+ messages in thread
From: Mickaël Salaün @ 2015-12-10 0:09 UTC (permalink / raw)
To: linux-kernel
Cc: Mickaël Salaün, Jeff Dike, Richard Weinberger,
Tristan Schmelcher, Greg Kroah-Hartman, user-mode-linux-devel,
user-mode-linux-user
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>
Cc: 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.
--
2.6.2
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [PATCH v3 1/2] um: Do not set unsecure permission for temporary file
@ 2015-12-10 0:09 ` Mickaël Salaün
0 siblings, 0 replies; 7+ messages in thread
From: Mickaël Salaün @ 2015-12-10 0:09 UTC (permalink / raw)
To: linux-kernel
Cc: Mickaël Salaün, Jeff Dike, Richard Weinberger,
Tristan Schmelcher, Greg Kroah-Hartman, user-mode-linux-devel,
user-mode-linux-user
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>
Cc: 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.
--
2.6.2
--
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Please read the FAQ at http://www.tux.org/lkml/
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [PATCH v3 2/2] um: Use race-free temporary file creation
2015-12-10 0:09 ` Mickaël Salaün
@ 2015-12-10 0:09 ` Mickaël Salaün
-1 siblings, 0 replies; 7+ messages in thread
From: Mickaël Salaün @ 2015-12-10 0:09 UTC (permalink / raw)
To: linux-kernel
Cc: Mickaël Salaün, Jeff Dike, Richard Weinberger,
Tristan Schmelcher, Greg Kroah-Hartman, user-mode-linux-devel,
user-mode-linux-user
Open the memory mapped file with the O_TMPFILE flag when available.
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 | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/arch/um/os-Linux/mem.c b/arch/um/os-Linux/mem.c
index 840d573..8b17676 100644
--- a/arch/um/os-Linux/mem.c
+++ b/arch/um/os-Linux/mem.c
@@ -106,6 +106,17 @@ static int __init make_tempfile(const char *template)
}
}
+#ifdef O_TMPFILE
+ fd = open(tempdir, O_CLOEXEC | O_RDWR | O_EXCL | O_TMPFILE, 0700);
+ /*
+ * If the running system does not support O_TMPFILE flag then retry
+ * without it.
+ */
+ if (fd != -1 || (errno != EINVAL && errno != EISDIR &&
+ errno != EOPNOTSUPP))
+ return fd;
+#endif
+
tempname = malloc(strlen(tempdir) + strlen(template) + 1);
if (tempname == NULL)
return -1;
--
2.6.2
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [PATCH v3 2/2] um: Use race-free temporary file creation
@ 2015-12-10 0:09 ` Mickaël Salaün
0 siblings, 0 replies; 7+ messages in thread
From: Mickaël Salaün @ 2015-12-10 0:09 UTC (permalink / raw)
To: linux-kernel
Cc: Mickaël Salaün, Jeff Dike, Richard Weinberger,
Tristan Schmelcher, Greg Kroah-Hartman, user-mode-linux-devel,
user-mode-linux-user
Open the memory mapped file with the O_TMPFILE flag when available.
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 | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/arch/um/os-Linux/mem.c b/arch/um/os-Linux/mem.c
index 840d573..8b17676 100644
--- a/arch/um/os-Linux/mem.c
+++ b/arch/um/os-Linux/mem.c
@@ -106,6 +106,17 @@ static int __init make_tempfile(const char *template)
}
}
+#ifdef O_TMPFILE
+ fd = open(tempdir, O_CLOEXEC | O_RDWR | O_EXCL | O_TMPFILE, 0700);
+ /*
+ * If the running system does not support O_TMPFILE flag then retry
+ * without it.
+ */
+ if (fd != -1 || (errno != EINVAL && errno != EISDIR &&
+ errno != EOPNOTSUPP))
+ return fd;
+#endif
+
tempname = malloc(strlen(tempdir) + strlen(template) + 1);
if (tempname == NULL)
return -1;
--
2.6.2
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
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Please read the FAQ at http://www.tux.org/lkml/
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH v3 1/2] um: Do not set unsecure permission for temporary file
2015-12-10 0:09 ` Mickaël Salaün
(?)
@ 2015-12-11 19:24 ` Tristan Schmelcher
-1 siblings, 0 replies; 7+ messages in thread
From: Tristan Schmelcher @ 2015-12-11 19:24 UTC (permalink / raw)
To: Mickaël Salaün
Cc: linux-kernel, Jeff Dike, Richard Weinberger, Greg Kroah-Hartman,
user-mode-linux-devel, user-mode-linux-user
Acked-by: Tristan Schmelcher <tschmelcher@google.com>
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2015-12-11 19:24 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
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2015-12-10 0:09 [PATCH v3 0/2] um: Protect memory mapped file Mickaël Salaün
2015-12-10 0:09 ` Mickaël Salaün
2015-12-10 0:09 ` [PATCH v3 1/2] um: Do not set unsecure permission for temporary file Mickaël Salaün
2015-12-10 0:09 ` Mickaël Salaün
2015-12-11 19:24 ` Tristan Schmelcher
2015-12-10 0:09 ` [PATCH v3 2/2] um: Use race-free temporary file creation Mickaël Salaün
2015-12-10 0:09 ` Mickaël Salaün
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