On NixOS[1] - a Linux distribution which allows to configure a full OS
declaratively - it's possible to configure SSIDs for `wpa_supplicant`
like this:
networking.wireless.networks = {
myssid = {
pskRaw = "<redacted>";
};
};
It's also possible to add networks "imperatively" using `wpa_gui` or
`wpa_cli`. However it's not possible to do both because if the first
option is used, NixOS creates a read-only symlink at
`/etc/wpa_supplicant.conf` and then it's not possible for
`wpa_supplicant` anymore to write to it.
This patch aims to help us changing this: while "declarative" SSID
configuration can be quite useful, it's a bad idea for e.g. sensitive
stuff like a WPA2 enterprise network.
The original idea was to use `-I`[2] for immutable configs (including
"declarative" networks) on NixOS and `-c /etc/wpa_supplicant.conf` for
anything "imperative".
However this doesn't really work out because if a wifi network from a
config file specified with `-I` is changed by e.g. `wpa_gui`, it's
silently overwritten in `/etc/wpa_supplicant.conf` (specified with
`-c`) which is IMHO unintuitive (in our case at least). This patch
basically declares each network defined in a config file passed via `-I`
to `wpa_supplicant` as "read-only" and doesn't write these "read-only"
networks to `/etc/wpa_supplicant.conf`.
A bit more context can be found on GitHub in the PR where I implemented
this[3].
I know that this is a fairly distro-specific thing and has a rather low
chance to actually land in upstream because of that. However I figured
that it's still worth a try, especially because `-I` seems to be
designed for "global" configuration options only and its behavior if
SSIDs are defined in there doesn't seem explicitly defined to me.
Last but not least, I'm not a subscriber of this mailing list so while
reviewing this, it'd be good if you could leave my email explicitly in
the `To:`-section.
[1] https://nixos.org/
[2] Added in e6304cad47251e88d073553042f1ea7805a858d1
[3] https://github.com/NixOS/nixpkgs/pull/113716
Signed-off-by: Maximilian Bosch <maximilian@xxxxxxxxx>
---
wpa_supplicant/config.h | 2 +-
wpa_supplicant/config_file.c | 5 +++--
wpa_supplicant/config_none.c | 2 +-
wpa_supplicant/config_ssid.h | 15 +++++++++++++++
wpa_supplicant/wpa_supplicant.c | 8 ++++----
5 files changed, 24 insertions(+), 8 deletions(-)
diff --git a/wpa_supplicant/config.h b/wpa_supplicant/config.h
index 68679c6e3..8e0a692c5 100644
--- a/wpa_supplicant/config.h
+++ b/wpa_supplicant/config.h
@@ -1731,7 +1731,7 @@ const char * wpa_config_get_global_field_name(unsigned int i, int *no_var);
*
* Each configuration backend needs to implement this function.
*/
-struct wpa_config * wpa_config_read(const char *name, struct wpa_config *cfgp);
+struct wpa_config * wpa_config_read(const char *name, struct wpa_config *cfgp, int ro);
/**
* wpa_config_write - Write or update configuration data
diff --git a/wpa_supplicant/config_file.c b/wpa_supplicant/config_file.c
index a535e3f08..0ad5594fc 100644
--- a/wpa_supplicant/config_file.c
+++ b/wpa_supplicant/config_file.c
@@ -289,7 +289,7 @@ static int wpa_config_process_blob(struct wpa_config *config, FILE *f,
#endif /* CONFIG_NO_CONFIG_BLOBS */
-struct wpa_config * wpa_config_read(const char *name, struct wpa_config *cfgp)
+struct wpa_config * wpa_config_read(const char *name, struct wpa_config *cfgp, int ro)
{
FILE *f;
char buf[512], *pos;
@@ -331,6 +331,7 @@ struct wpa_config * wpa_config_read(const char *name, struct wpa_config *cfgp)
while (wpa_config_get_line(buf, sizeof(buf), f, &line, &pos)) {
if (os_strcmp(pos, "network={") == 0) {
ssid = wpa_config_read_network(f, &line, id++);
+ ssid->ro = ro;
if (ssid == NULL) {
wpa_printf(MSG_ERROR, "Line %d: failed to "
"parse network block.", line);
@@ -1581,7 +1582,7 @@ int wpa_config_write(const char *name, struct wpa_config *config)
}
for (ssid = config->ssid; ssid; ssid = ssid->next) {
- if (ssid->key_mgmt == WPA_KEY_MGMT_WPS || ssid->temporary)
+ if (ssid->key_mgmt == WPA_KEY_MGMT_WPS || ssid->temporary || ssid->ro)
continue; /* do not save temporary networks */
if (wpa_key_mgmt_wpa_psk_no_sae(ssid->key_mgmt) &&
!ssid->psk_set && !ssid->passphrase)
diff --git a/wpa_supplicant/config_none.c b/wpa_supplicant/config_none.c
index 2aac28fa3..02191b425 100644
--- a/wpa_supplicant/config_none.c
+++ b/wpa_supplicant/config_none.c
@@ -17,7 +17,7 @@
#include "base64.h"
-struct wpa_config * wpa_config_read(const char *name, struct wpa_config *cfgp)
+struct wpa_config * wpa_config_read(const char *name, struct wpa_config *cfgp, int ro)
{
struct wpa_config *config;
diff --git a/wpa_supplicant/config_ssid.h b/wpa_supplicant/config_ssid.h
index 3f7b31480..73f113391 100644
--- a/wpa_supplicant/config_ssid.h
+++ b/wpa_supplicant/config_ssid.h
@@ -104,6 +104,21 @@ struct wpa_ssid {
*/
int id;
+ /**
+ * ro - whether a network is declared as read-only
+ *
+ * Every network which is defined in a config file that is passed to
+ * `wpa_supplicant` using the `-I`-option will be marked as read-only
+ * using this flag. It has the effect that it won't be written to
+ * `/etc/wpa_supplicant.conf` if e.g. `wpa_gui` tells the daemon to
+ * save all changed configs.
+ *
+ * This is necessary because networks from `/etc/wpa_supplicant.conf`
+ * have a higher priority and changes from an alternative file would be
+ * silently overwritten without this.
+ */
+ int ro;
+
/**
* priority - Priority group
*
diff --git a/wpa_supplicant/wpa_supplicant.c b/wpa_supplicant/wpa_supplicant.c
index 835b33575..278e8b8c2 100644
--- a/wpa_supplicant/wpa_supplicant.c
+++ b/wpa_supplicant/wpa_supplicant.c
@@ -1137,14 +1137,14 @@ int wpa_supplicant_reload_configuration(struct wpa_supplicant *wpa_s)
if (wpa_s->confname == NULL)
return -1;
- conf = wpa_config_read(wpa_s->confname, NULL);
+ conf = wpa_config_read(wpa_s->confname, NULL, 0);
if (conf == NULL) {
wpa_msg(wpa_s, MSG_ERROR, "Failed to parse the configuration "
"file '%s' - exiting", wpa_s->confname);
return -1;
}
if (wpa_s->confanother &&
- !wpa_config_read(wpa_s->confanother, conf)) {
+ !wpa_config_read(wpa_s->confanother, conf, 1)) {
wpa_msg(wpa_s, MSG_ERROR,
"Failed to parse the configuration file '%s' - exiting",
wpa_s->confanother);
@@ -6342,7 +6342,7 @@ static int wpa_supplicant_init_iface(struct wpa_supplicant *wpa_s,
#else /* CONFIG_BACKEND_FILE */
wpa_s->confname = os_strdup(iface->confname);
#endif /* CONFIG_BACKEND_FILE */
- wpa_s->conf = wpa_config_read(wpa_s->confname, NULL);
+ wpa_s->conf = wpa_config_read(wpa_s->confname, NULL, 0);
if (wpa_s->conf == NULL) {
wpa_printf(MSG_ERROR, "Failed to read or parse "
"configuration '%s'.", wpa_s->confname);
@@ -6350,7 +6350,7 @@ static int wpa_supplicant_init_iface(struct wpa_supplicant *wpa_s,
}
wpa_s->confanother = os_rel2abs_path(iface->confanother);
if (wpa_s->confanother &&
- !wpa_config_read(wpa_s->confanother, wpa_s->conf)) {
+ !wpa_config_read(wpa_s->confanother, wpa_s->conf, 1)) {
wpa_printf(MSG_ERROR,
"Failed to read or parse configuration '%s'.",
wpa_s->confanother);
--
2.29.3
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