sysctl.conf: prevent unintentional writes into attacker-controlled files and FIFOs
Commit Message
Similar to hard- and symlink protection introduced a while ago, this
patch enables protections against unintentional writes into
attacker-controlled regular files or FIFOs, where a program expected to
create new ones. This makes exploiting TOCTOU flaws harder.
See also: https://www.kernel.org/doc/Documentation/sysctl/fs.txt
Signed-off-by: Peter Müller <peter.mueller@ipfire.org>
---
config/etc/sysctl.conf | 5 +++++
1 file changed, 5 insertions(+)
@@ -49,6 +49,11 @@ kernel.dmesg_restrict = 1
fs.protected_symlinks = 1
fs.protected_hardlinks = 1
+# Don't allow writes to files and FIFOs that we don't own in world writable sticky
+# directories, unless they are owned by the owner of the directory.
+fs.protected_fifos = 2
+fs.protected_regular = 2
+
# Minimal preemption granularity for CPU-bound tasks:
# (default: 1 msec# (1 + ilog(ncpus)), units: nanoseconds)
kernel.sched_min_granularity_ns = 10000000