77 lines
2.9 KiB
Diff
77 lines
2.9 KiB
Diff
|
From 75e73778dce1cb7a2816a936240ef75adfbd6ed9 Mon Sep 17 00:00:00 2001
|
||
|
|
From: Prasanna Kumar Kalever <prasanna.kalever@redhat.com>
|
||
|
|
Date: Thu, 16 Jul 2020 17:21:28 +0530
|
||
|
|
Subject: [PATCH] rtslib: safely call shutil.copy()
|
||
|
|
|
||
|
|
Previously we had to replace shutil.copyfile() with shutil.copy(),
|
||
|
|
because we want to copy the file permissions to the destination file
|
||
|
|
along with the data.
|
||
|
|
|
||
|
|
It appears that shutil.copy() is opening the destination file with
|
||
|
|
wide access (0666) first, and then it starts copying the data and
|
||
|
|
at the end it is copying the permissions from source file to destination.
|
||
|
|
|
||
|
|
If we closely notice there appears a window between destination file
|
||
|
|
is opened vs permissions are set on the destination file, which could
|
||
|
|
allow a user to get the contents of the file when opening it at the
|
||
|
|
right time.
|
||
|
|
|
||
|
|
The behavior is a bit unsteady here, it is noticed that, when
|
||
|
|
saveconfig.json file exists, then on shutil.copy(), destination file is
|
||
|
|
opened and a mask 0600 is applied on the file, in case shutil.copy() had
|
||
|
|
to open a new destination saveconfig.json file, then mask 0644 is applied.
|
||
|
|
|
||
|
|
Thanks and Credits to 'Stefan Cornelius <scorneli@redhat.com>' for
|
||
|
|
reporting this, here is the strace he shared from RHEL-7/python-2.7.5
|
||
|
|
env:
|
||
|
|
|
||
|
|
Case 1: When /etc/target/saveconfig.json doesn't exist:
|
||
|
|
|
||
|
|
open("/etc/target/saveconfig.json.temp", O_RDONLY) = 3
|
||
|
|
open("/etc/target/saveconfig.json", O_WRONLY|O_CREAT|O_TRUNC, 0666) = 4
|
||
|
|
fstat(3, {st_mode=S_IFREG|0600, st_size=71, ...}) = 0
|
||
|
|
fstat(4, {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
|
||
|
|
[...]
|
||
|
|
chmod("/etc/target/saveconfig.json", 0600) = 0}")")}")
|
||
|
|
|
||
|
|
Case 2: When /etc/target/saveconfig.json already exist:
|
||
|
|
|
||
|
|
open("/etc/target/saveconfig.json.temp", O_RDONLY) = 3
|
||
|
|
open("/etc/target/saveconfig.json", O_WRONLY|O_CREAT|O_TRUNC, 0666) = 4
|
||
|
|
fstat(3, {st_mode=S_IFREG|0600, st_size=71, ...}) = 0
|
||
|
|
fstat(4, {st_mode=S_IFREG|0600, st_size=0, ...}) = 0
|
||
|
|
[...]
|
||
|
|
chmod("/etc/target/saveconfig.json", 0600) = 0}")")}")
|
||
|
|
|
||
|
|
Signed-off-by: Prasanna Kumar Kalever <prasanna.kalever@redhat.com>
|
||
|
|
---
|
||
|
|
rtslib/root.py | 5 +++--
|
||
|
|
1 file changed, 3 insertions(+), 2 deletions(-)
|
||
|
|
|
||
|
|
diff --git a/rtslib/root.py b/rtslib/root.py
|
||
|
|
index 2c5cf43..4ecc03c 100644
|
||
|
|
--- a/rtslib/root.py
|
||
|
|
+++ b/rtslib/root.py
|
||
|
|
@@ -476,8 +476,8 @@ class RTSRoot(CFSNode):
|
||
|
|
# prevent the file from being created if it exists due to a race
|
||
|
|
try:
|
||
|
|
fdesc = os.open(tmp_file, os.O_WRONLY | os.O_CREAT | os.O_EXCL, mode)
|
||
|
|
- finally:
|
||
|
|
- os.umask(umask_original)
|
||
|
|
+ except OSError:
|
||
|
|
+ raise ExecutionError("Could not open %s" % tmp_file)
|
||
|
|
|
||
|
|
with os.fdopen(fdesc, 'w') as f:
|
||
|
|
f.write(json.dumps(saveconf, sort_keys=True, indent=2))
|
||
|
|
@@ -488,6 +488,7 @@ class RTSRoot(CFSNode):
|
||
|
|
|
||
|
|
# copy along with permissions
|
||
|
|
shutil.copy(tmp_file, save_file)
|
||
|
|
+ os.umask(umask_original)
|
||
|
|
os.remove(tmp_file)
|
||
|
|
|
||
|
|
def restore_from_file(self, restore_file=None, clear_existing=True,
|
||
|
|
--
|
||
|
|
2.26.2
|
||
|
|
|