xref: /aosp_15_r20/external/libfuse/lib/mount_bsd.c (revision 9e5649576b786774a32d7b0252c9cd8c6538fa49)

/*
  FUSE: Filesystem in Userspace
  Copyright (C) 2005-2008 Csaba Henk <[email protected]>

  Architecture specific file system mounting (FreeBSD).

  This program can be distributed under the terms of the GNU LGPLv2.
  See the file COPYING.LIB.
*/

#include "fuse_config.h"
#include "fuse_i.h"
#include "fuse_misc.h"
#include "fuse_opt.h"

#include <sys/param.h>
#include "fuse_mount_compat.h"

#include <sys/stat.h>
#include <sys/wait.h>
#include <sys/sysctl.h>
#include <sys/user.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <stddef.h>
#include <fcntl.h>
#include <errno.h>
#include <string.h>
#include <paths.h>
#include <limits.h>

#define FUSERMOUNT_PROG		"mount_fusefs"
#define FUSE_DEV_TRUNK		"/dev/fuse"

enum {
	KEY_RO,
	KEY_KERN
};

struct mount_opts {
	int allow_other;
	char *kernel_opts;
	unsigned max_read;
};

#define FUSE_DUAL_OPT_KEY(templ, key)				\
	FUSE_OPT_KEY(templ, key), FUSE_OPT_KEY("no" templ, key)

static const struct fuse_opt fuse_mount_opts[] = {
	{ "allow_other", offsetof(struct mount_opts, allow_other), 1 },
	{ "max_read=%u", offsetof(struct mount_opts, max_read), 1 },
	FUSE_OPT_KEY("-r",			KEY_RO),
	/* standard FreeBSD mount options */
	FUSE_DUAL_OPT_KEY("dev",		KEY_KERN),
	FUSE_DUAL_OPT_KEY("async",		KEY_KERN),
	FUSE_DUAL_OPT_KEY("atime",		KEY_KERN),
	FUSE_DUAL_OPT_KEY("dev",		KEY_KERN),
	FUSE_DUAL_OPT_KEY("exec",		KEY_KERN),
	FUSE_DUAL_OPT_KEY("suid",		KEY_KERN),
	FUSE_DUAL_OPT_KEY("symfollow",		KEY_KERN),
	FUSE_DUAL_OPT_KEY("rdonly",		KEY_KERN),
	FUSE_DUAL_OPT_KEY("sync",		KEY_KERN),
	FUSE_DUAL_OPT_KEY("union",		KEY_KERN),
	FUSE_DUAL_OPT_KEY("userquota",		KEY_KERN),
	FUSE_DUAL_OPT_KEY("groupquota",		KEY_KERN),
	FUSE_DUAL_OPT_KEY("clusterr",		KEY_KERN),
	FUSE_DUAL_OPT_KEY("clusterw",		KEY_KERN),
	FUSE_DUAL_OPT_KEY("suiddir",		KEY_KERN),
	FUSE_DUAL_OPT_KEY("snapshot",		KEY_KERN),
	FUSE_DUAL_OPT_KEY("multilabel",		KEY_KERN),
	FUSE_DUAL_OPT_KEY("acls",		KEY_KERN),
	FUSE_DUAL_OPT_KEY("force",		KEY_KERN),
	FUSE_DUAL_OPT_KEY("update",		KEY_KERN),
	FUSE_DUAL_OPT_KEY("ro",			KEY_KERN),
	FUSE_DUAL_OPT_KEY("rw",			KEY_KERN),
	FUSE_DUAL_OPT_KEY("auto",		KEY_KERN),
	FUSE_DUAL_OPT_KEY("automounted",	KEY_KERN),
	/* options supported under both Linux and FBSD */
	FUSE_DUAL_OPT_KEY("allow_other",	KEY_KERN),
	FUSE_DUAL_OPT_KEY("default_permissions",KEY_KERN),
	FUSE_OPT_KEY("max_read=",		KEY_KERN),
	FUSE_OPT_KEY("subtype=",		KEY_KERN),
	/* FBSD FUSE specific mount options */
	FUSE_DUAL_OPT_KEY("private",		KEY_KERN),
	FUSE_DUAL_OPT_KEY("neglect_shares",	KEY_KERN),
	FUSE_DUAL_OPT_KEY("push_symlinks_in",	KEY_KERN),
	FUSE_OPT_KEY("nosync_unmount",		KEY_KERN),
#if __FreeBSD_version >= 1200519
	FUSE_DUAL_OPT_KEY("intr",		KEY_KERN),
#endif
	/* stock FBSD mountopt parsing routine lets anything be negated... */
	/*
	 * Linux specific mount options, but let just the mount util
	 * handle them
	 */
	FUSE_OPT_KEY("fsname=",			KEY_KERN),
	FUSE_OPT_END
};

void fuse_mount_version(void)
{
	system(FUSERMOUNT_PROG " --version");
}

unsigned get_max_read(struct mount_opts *o)
{
	return o->max_read;
}

static int fuse_mount_opt_proc(void *data, const char *arg, int key,
			       struct fuse_args *outargs)
{
	(void) outargs;
	struct mount_opts *mo = data;

	switch (key) {
	case KEY_RO:
		arg = "ro";
		/* fall through */

	case KEY_KERN:
		return fuse_opt_add_opt(&mo->kernel_opts, arg);
	}

	/* Pass through unknown options */
	return 1;
}

void fuse_kern_unmount(const char *mountpoint, int fd)
{
	close(fd);
	unmount(mountpoint, MNT_FORCE);
}

/* Check if kernel is doing init in background */
static int init_backgrounded(void)
{
	unsigned ibg;
	size_t len;

	len = sizeof(ibg);

	if (sysctlbyname("vfs.fuse.init_backgrounded", &ibg, &len, NULL, 0))
		return 0;

	return ibg;
}


static int fuse_mount_core(const char *mountpoint, const char *opts)
{
	const char *mountprog = FUSERMOUNT_PROG;
	int fd;
	char *fdnam, *dev;
	pid_t pid, cpid;
	int status;

	fdnam = getenv("FUSE_DEV_FD");

	if (fdnam) {
		char *ep;

		fd = strtol(fdnam, &ep, 10);

		if (*ep != '\0') {
			fuse_log(FUSE_LOG_ERR, "invalid value given in FUSE_DEV_FD\n");
			return -1;
		}

		if (fd < 0)
			return -1;

		goto mount;
	}

	dev = getenv("FUSE_DEV_NAME");

	if (! dev)
		dev = (char *)FUSE_DEV_TRUNK;

	if ((fd = open(dev, O_RDWR)) < 0) {
		perror("fuse: failed to open fuse device");
		return -1;
	}

mount:
	if (getenv("FUSE_NO_MOUNT") || ! mountpoint)
		goto out;

	pid = fork();
	cpid = pid;

	if (pid == -1) {
		perror("fuse: fork() failed");
		close(fd);
		return -1;
	}

	if (pid == 0) {
		if (! init_backgrounded()) {
			/*
			 * If init is not backgrounded, we have to
			 * call the mount util backgrounded, to avoid
			 * deadlock.
			 */

			pid = fork();

			if (pid == -1) {
				perror("fuse: fork() failed");
				close(fd);
				exit(1);
			}
		}

		if (pid == 0) {
			const char *argv[32];
			int a = 0;
			int ret = -1;

			if (! fdnam)
			{
				ret = asprintf(&fdnam, "%d", fd);
				if(ret == -1)
				{
					perror("fuse: failed to assemble mount arguments");
					close(fd);
					exit(1);
				}
			}

			argv[a++] = mountprog;
			if (opts) {
				argv[a++] = "-o";
				argv[a++] = opts;
			}
			argv[a++] = fdnam;
			argv[a++] = mountpoint;
			argv[a++] = NULL;
			execvp(mountprog, (char **) argv);
			perror("fuse: failed to exec mount program");
			free(fdnam);
			exit(1);
		}

		exit(0);
	}

	if (waitpid(cpid, &status, 0) == -1 || WEXITSTATUS(status) != 0) {
		perror("fuse: failed to mount file system");
		close(fd);
		return -1;
	}

out:
	return fd;
}

struct mount_opts *parse_mount_opts(struct fuse_args *args)
{
	struct mount_opts *mo;

	mo = (struct mount_opts*) malloc(sizeof(struct mount_opts));
	if (mo == NULL)
		return NULL;

	memset(mo, 0, sizeof(struct mount_opts));

	if (args &&
	    fuse_opt_parse(args, mo, fuse_mount_opts, fuse_mount_opt_proc) == -1)
		goto err_out;

	return mo;

err_out:
	destroy_mount_opts(mo);
	return NULL;
}

void destroy_mount_opts(struct mount_opts *mo)
{
	free(mo->kernel_opts);
	free(mo);
}

int fuse_kern_mount(const char *mountpoint, struct mount_opts *mo)
{
	/* mount util should not try to spawn the daemon */
	setenv("MOUNT_FUSEFS_SAFE", "1", 1);
	/* to notify the mount util it's called from lib */
	setenv("MOUNT_FUSEFS_CALL_BY_LIB", "1", 1);

	return fuse_mount_core(mountpoint, mo->kernel_opts);
}