Using the creat() function overwrites existing files which is
unintended when it comes to making sure the target of a single-file
mount exists. Instead, use open() with the O_EXCL flag to make sure
mount targets are only created if actually needed.
While at it also clean up various error paths of the do_mounts
function, making sure the additionally allocated string being created
for the path inside the jail's root filesystem is always freed
and also making it a bit more readable and less bloated.
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
struct stat s;
char new[PATH_MAX];
char *source = (char *)orig_source;
struct stat s;
char new[PATH_MAX];
char *source = (char *)orig_source;
bool is_bind = (orig_mountflags & MS_BIND);
bool is_mask = (source == (void *)(-1));
unsigned long mountflags = orig_mountflags;
bool is_bind = (orig_mountflags & MS_BIND);
bool is_mask = (source == (void *)(-1));
unsigned long mountflags = orig_mountflags;
+ assert(!(inner && is_mask));
+ assert(!(inner && !orig_source));
+
if (source && is_bind && stat(source, &s)) {
ERROR("stat(%s) failed: %m\n", source);
return error;
}
if (source && is_bind && stat(source, &s)) {
ERROR("stat(%s) failed: %m\n", source);
return error;
}
- if (!is_mask && orig_source && inner) {
if (asprintf(&source, "%s%s", root, orig_source) < 0)
return ENOMEM;
if (asprintf(&source, "%s%s", root, orig_source) < 0)
return ENOMEM;
snprintf(new, sizeof(new), "%s%s", root, target?target:source);
snprintf(new, sizeof(new), "%s%s", root, target?target:source);
return 0; /* doesn't exists, nothing to mask */
if (S_ISDIR(s.st_mode)) {/* use empty 0-sized tmpfs for directories */
return 0; /* doesn't exists, nothing to mask */
if (S_ISDIR(s.st_mode)) {/* use empty 0-sized tmpfs for directories */
- if (mount(NULL, new, "tmpfs", MS_RDONLY | MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_NOATIME, "size=0,mode=000"))
+ if (mount("none", new, "tmpfs", MS_RDONLY | MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_NOATIME, "size=0,mode=000"))
return error;
} else {
/* mount-bind 0-sized file having mode 000 */
return error;
} else {
/* mount-bind 0-sized file having mode 000 */
} else if (is_bind && source) {
mkdir_p(dirname(new), 0755);
snprintf(new, sizeof(new), "%s%s", root, target?target:source);
} else if (is_bind && source) {
mkdir_p(dirname(new), 0755);
snprintf(new, sizeof(new), "%s%s", root, target?target:source);
- fd = creat(new, 0644);
- if (fd < 0) {
- ERROR("creat(%s) failed: %m\n", new);
- return error;
+ fd = open(new, O_CREAT|O_WRONLY|O_TRUNC|O_EXCL, 0644);
+ if (fd >= 0)
+ close(fd);
+
+ if (error && fd < 0 && errno != EEXIST) {
+ ERROR("failed to create mount target %s: %m\n", new);
+
+ ret = errno;
+ goto free_source_out;
if (error)
ERROR("failed to mount -B %s %s: %m\n", source, new);
if (error)
ERROR("failed to mount -B %s %s: %m\n", source, new);
- if (inner)
- free(source);
-
- return error;
+ ret = error;
+ goto free_source_out;
}
mountflags |= MS_REMOUNT;
}
}
mountflags |= MS_REMOUNT;
}
if (error)
ERROR("failed to mount %s %s: %m\n", source, new);
if (error)
ERROR("failed to mount %s %s: %m\n", source, new);
- if (inner)
- free(source);
-
- return error;
+ ret = error;
+ goto free_source_out;
}
DEBUG("mount %s%s %s (%s)\n", (mountflags & MS_BIND)?"-B ":"", source, new,
}
DEBUG("mount %s%s %s (%s)\n", (mountflags & MS_BIND)?"-B ":"", source, new,
if (error)
ERROR("failed to mount --make-... %s \n", new);
if (error)
ERROR("failed to mount --make-... %s \n", new);
- if (inner)
- free(source);
-
- return error;
}
static int _add_mount(const char *source, const char *target, const char *filesystemtype,
}
static int _add_mount(const char *source, const char *target, const char *filesystemtype,