Add O_EXCL flag when opening segment for creation

Security fix. One could potentially pass a wrong argument in xseg_create
and destroy an already initialized segment. Ensuring creation
exclusiveness makes xseg less error-prone.

diff --git a/xseg/drivers/user/xseg_posix.c b/xseg/drivers/user/xseg_posix.c
index 523900b..69b4783 100644 (file)
--- a/xseg/drivers/user/xseg_posix.c
+++ b/xseg/drivers/user/xseg_posix.c
@@ -54,7 +54,7 @@ char errbuf[ERRSIZE];
 static long posix_allocate(const char *name, uint64_t size)
 {
        int fd, r;
-       fd = shm_open(name, O_RDWR | O_CREAT, 0770);
+       fd = shm_open(name, O_RDWR | O_CREAT | O_EXCL, 0770);
        if (fd < 0) {
                XSEGLOG("Cannot create shared segment: %s\n",
                        strerror_r(errno, errbuf, ERRSIZE));

diff --git a/xseg/drivers/user/xseg_pthread.c b/xseg/drivers/user/xseg_pthread.c
index 55168bc..d1ddc98 100644 (file)
--- a/xseg/drivers/user/xseg_pthread.c
+++ b/xseg/drivers/user/xseg_pthread.c
@@ -57,7 +57,7 @@ static void pthread_mfree(void *mem);
 static long pthread_allocate(const char *name, uint64_t size)
 {
        int fd, r;
-       fd = shm_open(name, O_RDWR | O_CREAT, 0770);
+       fd = shm_open(name, O_RDWR | O_CREAT | O_EXCL, 0770);
        if (fd < 0) {
                XSEGLOG("Cannot create shared segment: %s\n",
                        strerror_r(errno, errbuf, ERRSIZE));