netfilter: nf_tables: Eliminate duplicated code in nf_tables_table_enable()

If something fails in nf_tables_table_enable(), it unregisters the
chains. But the rollback code is the same as nf_tables_table_disable()
almostly, except there is one counter check.  Now create one wrapper
function to eliminate the duplicated codes.

Signed-off-by: Feng <fgao@ikuai8.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

path: root/privs.c

#include <unistd.h>
#include <sys/types.h>

#include "privs.h"
#include "die.h"

void drop_privileges(bool enforce, uid_t uid, gid_t gid)
{
	if (enforce) {
		if (uid == getuid())
			panic("Uid cannot be the same as the current user!\n");
		if (gid == getgid())
			panic("Gid cannot be the same as the current user!\n");
	}
	if (setgid(gid) != 0)
		panic("Unable to drop group privileges: %s!\n", strerror(errno));
	if (setuid(uid) != 0)
		panic("Unable to drop user privileges: %s!\n", strerror(errno));
}