89 lines
3.6 KiB
Diff
89 lines
3.6 KiB
Diff
|
From 301f19f2ebd617e43e3a8e7bdcf694de580fe689 Mon Sep 17 00:00:00 2001
|
||
|
|
From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
|
||
|
|
Date: Tue, 5 May 2020 16:35:56 +0100
|
||
|
|
Subject: [PATCH 5/9] virtiofsd: stay below fs.file-max sysctl value
|
||
|
|
(CVE-2020-10717)
|
||
|
|
|
||
|
|
RH-Author: Dr. David Alan Gilbert <dgilbert@redhat.com>
|
||
|
|
Message-id: <20200505163600.22956-4-dgilbert@redhat.com>
|
||
|
|
Patchwork-id: 96271
|
||
|
|
O-Subject: [RHEL-AV-8.2.1 qemu-kvm PATCH 3/7] virtiofsd: stay below fs.file-max sysctl value (CVE-2020-10717)
|
||
|
|
Bugzilla: 1817445
|
||
|
|
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
|
||
|
|
RH-Acked-by: Max Reitz <mreitz@redhat.com>
|
||
|
|
RH-Acked-by: Michael S. Tsirkin <mst@redhat.com>
|
||
|
|
|
||
|
|
From: Stefan Hajnoczi <stefanha@redhat.com>
|
||
|
|
|
||
|
|
The system-wide fs.file-max sysctl value determines how many files can
|
||
|
|
be open. It defaults to a value calculated based on the machine's RAM
|
||
|
|
size. Previously virtiofsd would try to set RLIMIT_NOFILE to 1,000,000
|
||
|
|
and this allowed the FUSE client to exhaust the number of open files
|
||
|
|
system-wide on Linux hosts with less than 10 GB of RAM!
|
||
|
|
|
||
|
|
Take fs.file-max into account when choosing the default RLIMIT_NOFILE
|
||
|
|
value.
|
||
|
|
|
||
|
|
Fixes: CVE-2020-10717
|
||
|
|
Reported-by: Yuval Avrahami <yavrahami@paloaltonetworks.com>
|
||
|
|
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
|
||
|
|
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
|
||
|
|
Message-Id: <20200501140644.220940-3-stefanha@redhat.com>
|
||
|
|
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
|
||
|
|
(cherry picked from commit 8c1d353d107b4fc344e27f2f08ea7fa25de2eea2)
|
||
|
|
Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
|
||
|
|
---
|
||
|
|
tools/virtiofsd/helper.c | 26 +++++++++++++++++++++++++-
|
||
|
|
1 file changed, 25 insertions(+), 1 deletion(-)
|
||
|
|
|
||
|
|
diff --git a/tools/virtiofsd/helper.c b/tools/virtiofsd/helper.c
|
||
|
|
index 9b3eddc..5b222ea 100644
|
||
|
|
--- a/tools/virtiofsd/helper.c
|
||
|
|
+++ b/tools/virtiofsd/helper.c
|
||
|
|
@@ -176,7 +176,8 @@ void fuse_cmdline_help(void)
|
||
|
|
" default: no_xattr\n"
|
||
|
|
" --rlimit-nofile=<num> set maximum number of file descriptors\n"
|
||
|
|
" (0 leaves rlimit unchanged)\n"
|
||
|
|
- " default: 1,000,000 if the current rlimit is lower\n"
|
||
|
|
+ " default: min(1000000, fs.file-max - 16384)\n"
|
||
|
|
+ " if the current rlimit is lower\n"
|
||
|
|
);
|
||
|
|
}
|
||
|
|
|
||
|
|
@@ -199,9 +200,32 @@ static int fuse_helper_opt_proc(void *data, const char *arg, int key,
|
||
|
|
|
||
|
|
static unsigned long get_default_rlimit_nofile(void)
|
||
|
|
{
|
||
|
|
+ g_autofree gchar *file_max_str = NULL;
|
||
|
|
+ const rlim_t reserved_fds = 16384; /* leave at least this many fds free */
|
||
|
|
rlim_t max_fds = 1000000; /* our default RLIMIT_NOFILE target */
|
||
|
|
+ rlim_t file_max;
|
||
|
|
struct rlimit rlim;
|
||
|
|
|
||
|
|
+ /*
|
||
|
|
+ * Reduce max_fds below the system-wide maximum, if necessary. This
|
||
|
|
+ * ensures there are fds available for other processes so we don't
|
||
|
|
+ * cause resource exhaustion.
|
||
|
|
+ */
|
||
|
|
+ if (!g_file_get_contents("/proc/sys/fs/file-max", &file_max_str,
|
||
|
|
+ NULL, NULL)) {
|
||
|
|
+ fuse_log(FUSE_LOG_ERR, "can't read /proc/sys/fs/file-max\n");
|
||
|
|
+ exit(1);
|
||
|
|
+ }
|
||
|
|
+ file_max = g_ascii_strtoull(file_max_str, NULL, 10);
|
||
|
|
+ if (file_max < 2 * reserved_fds) {
|
||
|
|
+ fuse_log(FUSE_LOG_ERR,
|
||
|
|
+ "The fs.file-max sysctl is too low (%lu) to allow a "
|
||
|
|
+ "reasonable number of open files.\n",
|
||
|
|
+ (unsigned long)file_max);
|
||
|
|
+ exit(1);
|
||
|
|
+ }
|
||
|
|
+ max_fds = MIN(file_max - reserved_fds, max_fds);
|
||
|
|
+
|
||
|
|
if (getrlimit(RLIMIT_NOFILE, &rlim) < 0) {
|
||
|
|
fuse_log(FUSE_LOG_ERR, "getrlimit(RLIMIT_NOFILE): %m\n");
|
||
|
|
exit(1);
|
||
|
|
--
|
||
|
|
1.8.3.1
|
||
|
|
|