On Wed, 22 Nov 2023, Ahelenia Ziemiańska wrote:
> Since e00ab3c0616fe6d83ab0710d9e7d989c299088f7, ss -l looks like this:
> u_seq LISTEN 0 5 @/run/fsid.sock@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 26989379 * 0
> with fsidd pushing all the addresses to 108 bytes wide, which is deeply
> egregious if you don't filter it out and recolumnate.
>
> This is because, naturally (unix(7)), "Null bytes in the name have
> no special significance": abstract addresses are binary blobs, but
> paths automatically terminate at the first NUL byte, since paths
> can't contain those.
>
> So just specify the correct address length when we're using the abstract domain:
> unix(7) recommends "offsetof(struct sockaddr_un, sun_path) + strlen(sun_path) + 1"
> for paths, but we don't want to include the terminating NUL, so it's just
> "offsetof(struct sockaddr_un, sun_path) + strlen(sun_path)".
> This brings the width back to order:
> -- >8 --
> $ ss -la | grep @
> u_str ESTAB 0 0 @45208536ec96909a/bus/systemd-timesyn/bus-api-timesync 18500238 * 18501249
> u_str ESTAB 0 0 @fecc9657d2315eb7/bus/systemd-network/bus-api-network 18495452 * 18494406
> u_seq LISTEN 0 5 @/run/fsid.sock 27168796 * 0
> u_str ESTAB 0 0 @ac308f35f50797a2/bus/systemd-logind/system 19406 * 15153
> u_str ESTAB 0 0 @b6606e0dfacbae75/bus/systemd/bus-api-system 18494353 * 18495334
> u_str ESTAB 0 0 @5880653d215718a7/bus/systemd/bus-system 26930876 * 26930003
> -- >8 --
>
> Fixes: e00ab3c0616fe6d83ab0710d9e7d989c299088f7 ("fsidd: provide
> better default socket name.")
> Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@xxxxxxxxxxxxxxxxxx>
> ---
> v1: <04f3fe71defa757d518468f04f08334a5d0dfbb9.1693754442.git.nabijaczleweli@xxxxxxxxxxxxxxxxxx>
> v2 NFC, addr_len declared at top of function
>
> support/reexport/fsidd.c | 9 ++++++---
> support/reexport/reexport.c | 8 ++++++--
> 2 files changed, 12 insertions(+), 5 deletions(-)
Reviewed-by: NeilBrown <neilb@xxxxxxx>
Thanks,
NeilBrown
>
> diff --git a/support/reexport/fsidd.c b/support/reexport/fsidd.c
> index 3e62b3fc..8a70b78f 100644
> --- a/support/reexport/fsidd.c
> +++ b/support/reexport/fsidd.c
> @@ -147,6 +147,7 @@ int main(void)
> {
> struct event *srv_ev;
> struct sockaddr_un addr;
> + socklen_t addr_len;
> char *sock_file;
> int srv;
>
> @@ -161,10 +162,12 @@ int main(void)
> memset(&addr, 0, sizeof(struct sockaddr_un));
> addr.sun_family = AF_UNIX;
> strncpy(addr.sun_path, sock_file, sizeof(addr.sun_path) - 1);
> - if (addr.sun_path[0] == '@')
> + addr_len = sizeof(struct sockaddr_un);
> + if (addr.sun_path[0] == '@') {
> /* "abstract" socket namespace */
> + addr_len = offsetof(struct sockaddr_un, sun_path) + strlen(addr.sun_path);
> addr.sun_path[0] = 0;
> - else
> + } else
> unlink(sock_file);
>
> srv = socket(AF_UNIX, SOCK_SEQPACKET | SOCK_NONBLOCK, 0);
> @@ -173,7 +176,7 @@ int main(void)
> return 1;
> }
>
> - if (bind(srv, (const struct sockaddr *)&addr, sizeof(struct sockaddr_un)) == -1) {
> + if (bind(srv, (const struct sockaddr *)&addr, addr_len) == -1) {
> xlog(L_WARNING, "Unable to bind %s: %m\n", sock_file);
> return 1;
> }
> diff --git a/support/reexport/reexport.c b/support/reexport/reexport.c
> index 78516586..0fb49a46 100644
> --- a/support/reexport/reexport.c
> +++ b/support/reexport/reexport.c
> @@ -21,6 +21,7 @@ static int fsidd_srv = -1;
> static bool connect_fsid_service(void)
> {
> struct sockaddr_un addr;
> + socklen_t addr_len;
> char *sock_file;
> int ret;
> int s;
> @@ -33,9 +34,12 @@ static bool connect_fsid_service(void)
> memset(&addr, 0, sizeof(struct sockaddr_un));
> addr.sun_family = AF_UNIX;
> strncpy(addr.sun_path, sock_file, sizeof(addr.sun_path) - 1);
> - if (addr.sun_path[0] == '@')
> + addr_len = sizeof(struct sockaddr_un);
> + if (addr.sun_path[0] == '@') {
> /* "abstract" socket namespace */
> + addr_len = offsetof(struct sockaddr_un, sun_path) + strlen(addr.sun_path);
> addr.sun_path[0] = 0;
> + }
>
> s = socket(AF_UNIX, SOCK_SEQPACKET, 0);
> if (s == -1) {
> @@ -43,7 +47,7 @@ static bool connect_fsid_service(void)
> return false;
> }
>
> - ret = connect(s, (const struct sockaddr *)&addr, sizeof(struct sockaddr_un));
> + ret = connect(s, (const struct sockaddr *)&addr, addr_len);
> if (ret == -1) {
> xlog(L_WARNING, "Unable to connect %s: %m, is fsidd running?\n", sock_file);
> return false;
> --
> 2.39.2
>
>
