On Wed, Apr 29, 2020 at 11:52:08PM +0800, Wen Yang wrote:
As in commit 2045cdfa1b40 ("netfilter: nf_conntrack: Fix possible possible crash on module loading"),
Loading the nf_conntrack module with doubled hashsize parameter, i.e.
modprobe nf_conntrack hashsize=12345 hashsize=12345
causes NULL-ptr deref.
If 'hashsize' specified twice, the nf_conntrack_set_hashsize() function
will be called also twice.
In addition, we may also construct the doubled hashsize parameter scenario by using the following configuration:
$ cat /etc/modprobe.d/firewalld-sysctls.conf
install nf_conntrack /usr/sbin/modprobe --ignore-install nf_conntrack $CMDLINE_OPTS && /usr/sbin/sysctl --quiet --pattern 'net[.]netfilter[.]nf_conntrack.*' --system
$ cat /etc/modprobe.d/nf_conntrack.conf
options nf_conntrack hashsize=187600
$ sudo modprobe nf_conntrack -v
install /usr/sbin/modprobe --ignore-install nf_conntrack $CMDLINE_OPTS && /usr/sbin/sysctl --quiet --pattern 'net[.]netfilter[.]nf_conntrack.*' --system hashsize=187500
insmod /path/to/nf_conntrack.ko hashsize=187500 hashsize=187500
Passing multiple repeated parameters to the kernel may trigger kernel bugs
and affect the performance of loading kernel modules.
We introduce the nf_conntrack_set_hashsize() and hope to solve this problem.
Signed-off-by: Wen Yang <wenyang@xxxxxxxxxxxxxxxxx>
Cc: Lucas De Marchi <lucas.demarchi@xxxxxxxxx>
Cc: Lucas De Marchi <lucas.de.marchi@xxxxxxxxx>
Cc: Topi Miettinen <toiwoton@xxxxxxxxx>
Cc: Alexey Gladkov <gladkov.alexey@xxxxxxxxx>
Cc: linux-modules@xxxxxxxxxxxxxxx
---
libkmod/libkmod-module.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++++
libkmod/libkmod.h | 1 +
tools/insmod.c | 7 +++++
3 files changed, 80 insertions(+)
diff --git a/libkmod/libkmod-module.c b/libkmod/libkmod-module.c
index 76a6dc3..f42beb8 100644
--- a/libkmod/libkmod-module.c
+++ b/libkmod/libkmod-module.c
@@ -1076,6 +1076,72 @@ static char *module_options_concat(const char *opt, const char *xopt)
return r;
}
+static unsigned int module_options_cnt(const char *opts)
+{
+ int nr_opts = 0;
+ char *saveptr, *tok, *buf;
+
+ if (!opts)
+ return 0;
+
+ buf = strdup(opts);
+ for (tok = strtok_r(buf, " ", &saveptr); tok != NULL;
Why not use strchr() to find the " " and count them ?
+ tok = strtok_r(NULL, " ", &saveptr), nr_opts++) {}
+
Parameters can have spaces [1]. Is not it so ?
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/lib/cmdline.c#n196
+ free(buf);
+ return nr_opts;
+}
+
+KMOD_EXPORT int kmod_module_uniq_options(char **opts)
+{
+ char *buf;
+ char **array;
+ bool duplicated;
+ char *saveptr, *tok;
+ int nr_opts, len, i, j;
+
+ if (!opts || !*opts)
+ return 0;
+
+ buf = strdup(*opts);
We have the options passed as an argument. You doubled it here and tripled
in the module_options_cnt(). Can you reduce memory usage ?
+ if (!buf)
+ return -ENOMEM;
+
+ len = strlen(buf);
+ nr_opts = module_options_cnt(buf);
+ array = calloc(nr_opts, sizeof(char *));
+ if (!buf)
+ return -ENOMEM;
+
+ for (tok = strtok_r(buf, " ", &saveptr), i = 0; tok != NULL;
+ tok = strtok_r(NULL, " ", &saveptr), i++) {
+ array[i] = tok;
+ }
+
+ (*opts)[0] = '\0';
+ len = 0;
+ for (i = 0; i < nr_opts; i++) {
+ duplicated = false;
+ for (j = 0; j < i; j++) {
+ if (strcmp(array[i], array[j]) == 0) {
+ duplicated = true;
+ break;
+ }
+ }
+
+ if (!duplicated) {
+ strcat(*opts, array[i]);
+ strcat(*opts, " ");
+ len += strlen(array[i]) + 1;
+ }
+ }
+
+ (*opts)[len] = '\0';
+ free(buf);
+ free(array);
+ return 0;
+}
+
static int __kmod_module_get_probe_list(struct kmod_module *mod,
bool required,
bool ignorecmd,
@@ -1322,6 +1388,12 @@ KMOD_EXPORT int kmod_module_probe_insert_module(struct kmod_module *mod,
options = module_options_concat(moptions,
m == mod ? extra_options : NULL);
+ err = kmod_module_uniq_options(&options);
+ if (err < 0) {
+ free(options);
+ return err;
+ }
+
if (cmd != NULL && !m->ignorecmd) {
if (print_action != NULL)
print_action(m, true, options ?: "");
diff --git a/libkmod/libkmod.h b/libkmod/libkmod.h
index 3cab2e5..774e52a 100644
--- a/libkmod/libkmod.h
+++ b/libkmod/libkmod.h
@@ -186,6 +186,7 @@ int kmod_module_probe_insert_module(struct kmod_module *mod,
const char *kmod_module_get_name(const struct kmod_module *mod);
const char *kmod_module_get_path(const struct kmod_module *mod);
const char *kmod_module_get_options(const struct kmod_module *mod);
+int kmod_module_uniq_options(char **opts);
const char *kmod_module_get_install_commands(const struct kmod_module *mod);
const char *kmod_module_get_remove_commands(const struct kmod_module *mod);
struct kmod_list *kmod_module_get_dependencies(const struct kmod_module *mod);
diff --git a/tools/insmod.c b/tools/insmod.c
index c422971..2dc0c22 100644
--- a/tools/insmod.c
+++ b/tools/insmod.c
@@ -132,6 +132,13 @@ static int do_insmod(int argc, char *argv[])
opts[optslen] = '\0';
}
+ err = kmod_module_uniq_options(&opts);
+ if (err < 0) {
+ ERR("kmod_module_uniq_options() failed!\n");
+ free(opts);
+ return err;
+ }
+
ctx = kmod_new(NULL, &null_config);
if (!ctx) {
ERR("kmod_new() failed!\n");
--
1.8.3.1
