From 5105e844c2ff6a3e320bf8cdadc5094d4eaef2b7 Mon Sep 17 00:00:00 2001 From: Giuseppe Scrivano Date: Fri, 17 Jul 2020 10:39:40 +0200 Subject: iptables: accept lock file name at runtime allow users to override at runtime the lock file to use through the XTABLES_LOCKFILE environment variable. It allows to use iptables when the user has granted enough capabilities (e.g. a user+network namespace) to configure the network but that lacks access to the XT_LOCK_NAME (by default placed under /run). $ XTABLES_LOCKFILE=/tmp/xtables unshare -rn iptables ... Signed-off-by: Giuseppe Scrivano Signed-off-by: Pablo Neira Ayuso --- configure.ac | 1 + iptables/iptables.8.in | 8 ++++++++ iptables/xshared.c | 11 ++++++++--- 3 files changed, 17 insertions(+), 3 deletions(-) diff --git a/configure.ac b/configure.ac index 31a8bb26..d37752a2 100644 --- a/configure.ac +++ b/configure.ac @@ -219,6 +219,7 @@ AC_SUBST([libxtables_vmajor]) AC_DEFINE_UNQUOTED([XT_LOCK_NAME], "${xt_lock_name}", [Location of the iptables lock file]) +AC_SUBST([XT_LOCK_NAME], "${xt_lock_name}") AC_CONFIG_FILES([Makefile extensions/GNUmakefile include/Makefile iptables/Makefile iptables/xtables.pc diff --git a/iptables/iptables.8.in b/iptables/iptables.8.in index 054564b3..999cf339 100644 --- a/iptables/iptables.8.in +++ b/iptables/iptables.8.in @@ -397,6 +397,14 @@ corresponding to that rule's position in the chain. \fB\-\-modprobe=\fP\fIcommand\fP When adding or inserting rules into a chain, use \fIcommand\fP to load any necessary modules (targets, match extensions, etc). + +.SH LOCK FILE +iptables uses the \fI@XT_LOCK_NAME@\fP file to take an exclusive lock at +launch. + +The \fBXTABLES_LOCKFILE\fP environment variable can be used to override +the default setting. + .SH MATCH AND TARGET EXTENSIONS .PP iptables can use extended packet matching and target modules. diff --git a/iptables/xshared.c b/iptables/xshared.c index c1d1371a..7d97637f 100644 --- a/iptables/xshared.c +++ b/iptables/xshared.c @@ -249,15 +249,20 @@ void xs_init_match(struct xtables_match *match) static int xtables_lock(int wait, struct timeval *wait_interval) { struct timeval time_left, wait_time; + const char *lock_file; int fd, i = 0; time_left.tv_sec = wait; time_left.tv_usec = 0; - fd = open(XT_LOCK_NAME, O_CREAT, 0600); + lock_file = getenv("XTABLES_LOCKFILE"); + if (lock_file == NULL || lock_file[0] == '\0') + lock_file = XT_LOCK_NAME; + + fd = open(lock_file, O_CREAT, 0600); if (fd < 0) { fprintf(stderr, "Fatal: can't open lock file %s: %s\n", - XT_LOCK_NAME, strerror(errno)); + lock_file, strerror(errno)); return XT_LOCK_FAILED; } @@ -265,7 +270,7 @@ static int xtables_lock(int wait, struct timeval *wait_interval) if (flock(fd, LOCK_EX) == 0) return fd; - fprintf(stderr, "Can't lock %s: %s\n", XT_LOCK_NAME, + fprintf(stderr, "Can't lock %s: %s\n", lock_file, strerror(errno)); return XT_LOCK_BUSY; } -- cgit v1.2.3