mount_service: use the fsmount API helpers from mount_fsmount.c

The new fsmount API code in mount_service.c should use the new helper
functions that were recently added to mount_fsmount.c.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>

lib/mount_fsmount.c

@@ -35,17 +35,8 @@
 #define MOUNT_ATTR_NOSYMFOLLOW  0x00200000
 #endif
 
-/*
+unsigned long ms_flags_to_mount_attrs(unsigned long ms_flags,
- * Convert MS_* mount flags to MOUNT_ATTR_* mount attributes.
+				      unsigned int *mount_attrs)
- * These flags are passed to fsmount(), not fsconfig().
- * Mount attributes control mount-point level behavior.
- * To called after set_ms_flags() which consumes the fsconfig flags.
- *
- * @mount_attrs MOUNT_ATTR flags, built from MS_ flags
- * @return remaining MS_* flags
- */
-static unsigned long ms_flags_to_mount_attrs(unsigned long ms_flags,
-					     unsigned int *mount_attrs)
 {
 	int i;
 
@@ -65,12 +56,7 @@ static unsigned long ms_flags_to_mount_attrs(unsigned long ms_flags,
 	return ms_flags;
 }
 
-/*
+void log_fsconfig_kmsg(int fd)
- * Read and print kernel error messages from fsopen fd.
- * The kernel can provide detailed error/warning/info messages via the
- * filesystem context fd that are more informative than strerror(errno).
- */
-static void log_fsconfig_kmsg(int fd)
 {
 	char buf[4096];
 	int err, sz = 0;
@@ -107,19 +93,7 @@ static void log_fsconfig_kmsg(int fd)
 	errno = err;
 }
 
-/*
+int set_fsconfig_ms_flags(int fsfd, unsigned long *ms_flags)
- * Apply VFS superblock (fsconfig) flags to the filesystem context.
- * Handles the fsconfig leg of every entry whose is_fsconfig is set
- * (ro, rw, sync, async, dirsync). Mount attributes (nosuid, nodev, etc.)
- * are handled separately via fsmount().
- *
- * Entries that have *both* legs (ro/rw) leave the MS_ bit in *ms_flags
- * so that ms_flags_to_mount_attrs() can also pick them up.
- *
- * @ms_flags flags to set, outvalue are the remaining flags
- * @return 0 on success, negative error code on failure
- */
-static int set_ms_flags(int fsfd, unsigned long *ms_flags)
 {
 	int ret, flags = *ms_flags;
 	int i;
@@ -155,16 +129,7 @@ static int set_ms_flags(int fsfd, unsigned long *ms_flags)
 	return 0;
 }
 
-/*
+int apply_fsconfig_opt_fd(int fsfd, const char *value)
- * Apply the "fd" parameter via fsconfig
- *
- * Special handler for the "fd" mount option. Note that despite the name,
- * the fd parameter is passed as a u32 string value, not as a file descriptor
- * to pass to the kernel. Uses FSCONFIG_SET_STRING rather than FSCONFIG_SET_FD.
- *
- * Returns 0 on success, negative error code on failure.
- */
-static int apply_opt_fd(int fsfd, const char *value)
 {
 	int res;
 
@@ -181,15 +146,7 @@ static int apply_opt_fd(int fsfd, const char *value)
 	return 0;
 }
 
-/*
+int apply_fsconfig_opt_string(int fsfd, const char *key, const char *value)
- * Apply a key=value string option via fsconfig
- *
- * Applies a mount option that consists of a key-value pair (e.g., "rootmode=40000").
- * Uses FSCONFIG_SET_STRING to pass the key and value to the filesystem configuration.
- *
- * Returns 0 on success, negative error code on failure.
- */
-static int apply_opt_string(int fsfd, const char *key, const char *value)
 {
 	int res, save_errno;
 
@@ -210,6 +167,8 @@ static int apply_opt_string(int fsfd, const char *key, const char *value)
  * Applies a mount option that is a simple flag without a value (e.g., "rw").
  * Uses FSCONFIG_SET_FLAG to set the flag in the filesystem configuration.
  *
+ * @fsfd fsopen fd
+ * @opt name of filesystem mount flag option
  * Returns 0 on success, negative error code on failure.
  */
 static int apply_opt_flag(int fsfd, const char *opt)
@@ -227,7 +186,6 @@ static int apply_opt_flag(int fsfd, const char *opt)
 	return 0;
 }
 
-
 /*
  * Parse and apply a single mount option via fsconfig
  *
@@ -238,6 +196,8 @@ static int apply_opt_flag(int fsfd, const char *opt)
  * Special handling for the "fd" parameter which is treated as a string
  * value rather than a file descriptor to pass.
  *
+ * @fsfd fsopen fd
+ * @opt filesystem mount option, may be modified
  * Returns 0 on success, negative error code on failure.
  */
 static int apply_opt_key_value(int fsfd, char *opt)
@@ -255,9 +215,9 @@ static int apply_opt_key_value(int fsfd, char *opt)
 	value = eq + 1;
 
 	if (strcmp(key, "fd") == 0)
-		return apply_opt_fd(fsfd, value);
+		return apply_fsconfig_opt_fd(fsfd, value);
 
-	return apply_opt_string(fsfd, key, value);
+	return apply_fsconfig_opt_string(fsfd, key, value);
 }
 
 /*
@@ -287,11 +247,7 @@ static int is_mtab_only_opt(const char *opt)
 	       strcmp(opt, "rw") == 0;
 }
 
-/*
+int apply_fsconfig_mount_opts(int fsfd, const char *opts)
- * Parse kernel options string and apply via fsconfig
- * Options are comma-separated key=value pairs
- */
-static int apply_mount_opts(int fsfd, const char *opts)
 {
 	char *opts_copy;
 	char *opt;
@@ -393,12 +349,12 @@ int fuse_kern_fsmount(const char *mnt, unsigned long flags, int blkdev,
 	}
 
 	/* Apply VFS superblock (fsconfig) flags (ro, sync, dirsync) */
-	res = set_ms_flags(fsfd, &flags);
+	res = set_fsconfig_ms_flags(fsfd, &flags);
 	if (res != 0)
 		goto out_free;
 
 	/* Apply kernel options */
-	err = apply_mount_opts(fsfd, kernel_opts);
+	err = apply_fsconfig_mount_opts(fsfd, kernel_opts);
 	if (err < 0) {
 		log_fsconfig_kmsg(fsfd);
 		fprintf(stderr,
@@ -408,7 +364,7 @@ int fuse_kern_fsmount(const char *mnt, unsigned long flags, int blkdev,
 	}
 
 	/* Apply mtab options (overlap with kernel_opts is filtered and tolerated) */
-	err = apply_mount_opts(fsfd, mtab_opts);
+	err = apply_fsconfig_mount_opts(fsfd, mtab_opts);
 	if (err < 0) {
 		log_fsconfig_kmsg(fsfd);
 		fprintf(stderr,

lib/mount_i_linux.h

@@ -65,4 +65,76 @@ int mount_fusermount_obtain_fd(const char *mountpoint,
 
 int fuse_fusermount_proceed_mnt(int sock_fd);
 
+/**
+ * Convert MS_* mount flags to MOUNT_ATTR_* mount attributes.
+ * These flags are passed to fsmount(), not fsconfig().
+ * Mount attributes control mount-point level behavior.
+ * To called after set_ms_flags() which consumes the fsconfig flags.
+ *
+ * @mount_attrs MOUNT_ATTR flags, built from MS_ flags
+ * @return remaining MS_* flags
+ */
+unsigned long ms_flags_to_mount_attrs(unsigned long ms_flags,
+				      unsigned int *mount_attrs);
+
+/**
+ * Read and print kernel error messages from fsopen fd.
+ * The kernel can provide detailed error/warning/info messages via the
+ * filesystem context fd that are more informative than strerror(errno).
+ * 
+ * @fd fsopen fd
+ */
+void log_fsconfig_kmsg(int fd);
+
+/**
+ * Apply VFS superblock (fsconfig) flags to the filesystem context.
+ * Handles the fsconfig leg of every entry whose is_fsconfig is set
+ * (ro, rw, sync, async, dirsync). Mount attributes (nosuid, nodev, etc.)
+ * are handled separately via fsmount().
+ *
+ * Entries that have *both* legs (ro/rw) leave the MS_ bit in *ms_flags
+ * so that ms_flags_to_mount_attrs() can also pick them up.
+ *
+ * @fsfd fsopen fd
+ * @ms_flags flags to set, outvalue are the remaining flags
+ * @return 0 on success, negative error code on failure
+ */
+int set_fsconfig_ms_flags(int fsfd, unsigned long *ms_flags);
+
+/**
+ * Apply the "fd" parameter via fsconfig
+ *
+ * Special handler for the "fd" mount option. Note that despite the name,
+ * the fd parameter is passed as a u32 string value, not as a file descriptor
+ * to pass to the kernel. Uses FSCONFIG_SET_STRING rather than FSCONFIG_SET_FD.
+ *
+ * @fsfd fsopen fd
+ * @value fd number of /dev/fuse, as a string
+ * Returns 0 on success, negative error code on failure.
+ */
+int apply_fsconfig_opt_fd(int fsfd, const char *value);
+
+/**
+ * Apply a key=value string option via fsconfig
+ *
+ * Applies a mount option that consists of a key-value pair (e.g., "rootmode=40000").
+ * Uses FSCONFIG_SET_STRING to pass the key and value to the filesystem configuration.
+ *
+ * @fsfd fsopen fd
+ * @key name of filesystem mount option
+ * @value value of mount option
+ * Returns 0 on success, negative error code on failure.
+ */
+int apply_fsconfig_opt_string(int fsfd, const char *key, const char *value);
+
+/**
+ * Parse kernel options string and apply via fsconfig
+ * Options are comma-separated key=value pairs
+ *
+ * @fsfd fsopen fd
+ * @opt filesystem mount option string
+ * Returns 0 on success, negative error code on failure.
+ */
+int apply_fsconfig_mount_opts(int fsfd, const char *opts);
+
 #endif /* FUSE_MOUNT_I_LINUX_H_ */

util/meson.build

@@ -11,6 +11,9 @@ mount_service_sources = []
 mount_service_cflags = []
 if private_cfg.get('HAVE_SERVICEMOUNT', false)
   mount_service_sources += ['mount_service.c', '../lib/mount_util.c', 'fuser_conf.c']
+  if private_cfg.get('HAVE_NEW_MOUNT_API', false)
+    mount_service_sources += [ '../lib/mount_fsmount.c' ]
+  endif
   mount_service_cflags += ['-DFUSE_CONF="@0@"'.format(fuseconf_path)]
   fuservicemount_path = join_paths(get_option('prefix'), get_option('sbindir'))
   mount_service_cflags += ['-DFUSERVICEMOUNT_DIR="@0@"'.format(fuservicemount_path)]

util/mount_service.c

@@ -39,6 +39,9 @@
 #include "fuse_service_priv.h"
 #include "mount_service.h"
 #include "fuser_conf.h"
+#ifdef HAVE_NEW_MOUNT_API
+#include "mount_i_linux.h"
+#endif
 
 struct mount_service {
 	/* prefix for printing error messages */
@@ -875,40 +878,6 @@ static int mount_service_handle_fsopen_cmd(struct mount_service *mo,
 	return mount_service_send_reply(mo, 0);
 }
 
-#ifdef HAVE_NEW_MOUNT_API
-/* callers must preserve errno */
-static void emit_fsconfig_messages(const struct mount_service *mo)
-{
-	uint8_t buf[BUFSIZ];
-	ssize_t sz;
-
-	while ((sz = read(mo->fsopenfd, buf, sizeof(buf) - 1)) >= 1) {
-		if (buf[sz - 1] == '\n')
-			buf[--sz] = '\0';
-		else
-			buf[sz] = '\0';
-
-		if (!*buf)
-			continue;
-
-		switch (buf[0]) {
-		case 'e':
-			fprintf(stderr, "Error: %s\n", buf + 2);
-			break;
-		case 'w':
-			fprintf(stderr, "Warning: %s\n", buf + 2);
-			break;
-		case 'i':
-			fprintf(stderr, "Info: %s\n", buf + 2);
-			break;
-		default:
-			fprintf(stderr, " %s\n", buf);
-			break;
-		}
-	}
-}
-#endif
-
 static int mount_service_handle_source_cmd(struct mount_service *mo,
 					   const struct fuse_service_packet *p,
 					   size_t psz)
@@ -946,16 +915,11 @@ static int mount_service_handle_source_cmd(struct mount_service *mo,
 
 #ifdef HAVE_NEW_MOUNT_API
 	if (mo->fsopenfd >= 0) {
-		int ret = fsconfig(mo->fsopenfd, FSCONFIG_SET_STRING, "source",
+		int ret = apply_fsconfig_opt_string(mo->fsopenfd, "source",
-			       oc->value, 0);
+						    oc->value);
-		if (ret) {
+		if (ret < 0) {
-			int error = errno;
-
-			fprintf(stderr, "%s: fsconfig source: %s\n",
-				mo->msgtag, strerror(error));
-			emit_fsconfig_messages(mo);
 			free(source);
-			return mount_service_send_reply(mo, error);
+			return mount_service_send_reply(mo, -ret);
 		}
 	}
 #endif
@@ -1002,53 +966,30 @@ static int mount_service_handle_mntopts_cmd(struct mount_service *mo,
 	}
 
 	/* strtok_r mutates tokstr aka oc->value */
-	while ((tok = strtok_r(tokstr, ",", &savetok)) != NULL) {
+	if (getuid() != 0 && !user_allow_other) {
-		char *equals = strchr(tok, '=');
+		while ((tok = strtok_r(tokstr, ",", &savetok)) != NULL) {
-		char oldchar = 0;
+			if (!strcmp(tok, "allow_other") ||
+			    !strcmp(tok, "allow_root")) {
+				fprintf(stderr,
+	"%s: option %s only allowed if 'user_allow_other' is set in %s\n",
+					mo->msgtag, tok, FUSE_CONF);
+				return mount_service_send_reply(mo, EPERM);
+			}
 
-		if (equals) {
+			tokstr = NULL;
-			oldchar = *equals;
-			*equals = 0;
-		}
-
-		if (getuid() != 0 && !user_allow_other &&
-		    (!strcmp(tok, "allow_other") ||
-		     !strcmp(tok, "allow_root"))) {
-			fprintf(stderr,
-"%s: option %s only allowed if 'user_allow_other' is set in %s\n",
-				mo->msgtag, tok, FUSE_CONF);
-			return mount_service_send_reply(mo, EPERM);
 		}
+	}
 
 #ifdef HAVE_NEW_MOUNT_API
-		if (mo->fsopenfd >= 0) {
+	if (mo->fsopenfd >= 0) {
-			int ret;
+		int ret = apply_fsconfig_mount_opts(mo->fsopenfd, oc->value);
 
-			if (equals)
+		if (ret < 0) {
-				ret = fsconfig(mo->fsopenfd,
+			free(mntopts);
-					       FSCONFIG_SET_STRING, tok,
+			return mount_service_send_reply(mo, -ret);
-					       equals + 1, 0);
-			else
-				ret = fsconfig(mo->fsopenfd,
-					       FSCONFIG_SET_FLAG, tok,
-					       NULL, 0);
-			if (ret) {
-				int error = errno;
-
-				fprintf(stderr, "%s: set mount option: %s\n",
-					mo->msgtag, strerror(error));
-				emit_fsconfig_messages(mo);
-				free(mntopts);
-				return mount_service_send_reply(mo, error);
-			}
 		}
-#endif
-
-		if (equals)
-			*equals = oldchar;
-
-		tokstr = NULL;
 	}
+#endif
 
 	mo->mntopts = mntopts;
 	return mount_service_send_reply(mo, 0);
@@ -1452,66 +1393,6 @@ out_realmopts:
 }
 
 #ifdef HAVE_NEW_MOUNT_API
-struct ms_to_mount_map {
-	unsigned long ms_flag;
-	unsigned int mount_attr_flag;
-};
-
-static void get_mount_attr_flags(const struct fuse_service_mount_command *oc,
-				 unsigned int *attr_flags,
-				 unsigned long *leftover_ms_flags)
-{
-	const struct mount_flags *i;
-	unsigned int ms_flags = ntohl(oc->ms_flags);
-	unsigned int mount_attr_flags = 0;
-
-	for (i = mount_flags; i->opt != NULL; i++) {
-		if (!i->on || !(ms_flags & i->flag))
-			continue;
-
-		mount_attr_flags |= i->mount_attr;
-		ms_flags &= ~i->flag;
-	}
-
-	*leftover_ms_flags = ms_flags;
-	*attr_flags = mount_attr_flags;
-}
-
-static int set_ms_flags(struct mount_service *mo, unsigned long ms_flags)
-{
-	const struct mount_flags *i;
-	int ret;
-
-	for (i = mount_flags; i->opt != NULL; i++) {
-		if (!i->on || !(ms_flags & i->flag))
-			continue;
-
-		ret = fsconfig(mo->fsopenfd, FSCONFIG_SET_FLAG, i->opt,
-			       NULL, 0);
-		if (ret) {
-			int error = errno;
-
-			fprintf(stderr, "%s: set %s option: %s\n",
-				mo->msgtag, i->opt, strerror(error));
-			emit_fsconfig_messages(mo);
-
-			errno = error;
-			return -1;
-		}
-		ms_flags &= ~i->flag;
-	}
-
-	/*
-	 * We can't translate all the supplied MS_ flags into MOUNT_ATTR_ flags
-	 * or string flags!  Return a magic code so the caller will fall back
-	 * to regular mount(2).
-	 */
-	if (ms_flags)
-		return FUSE_MOUNT_FALLBACK_NEEDED;
-
-	return 0;
-}
-
 static int mount_service_fsopen_mount(struct mount_service *mo,
 				      const struct fuse_service_mount_command *oc,
 				      const struct stat *stbuf)
@@ -1523,63 +1404,57 @@ static int mount_service_fsopen_mount(struct mount_service *mo,
 	int error;
 	int ret;
 
-	get_mount_attr_flags(oc, &attr_flags, &ms_flags);
+	ms_flags = ms_flags_to_mount_attrs(ntohl(oc->ms_flags), &attr_flags);
 
-	ret = set_ms_flags(mo, ms_flags);
+	ret = set_fsconfig_ms_flags(mo->fsopenfd, &ms_flags);
-	if (ret == FUSE_MOUNT_FALLBACK_NEEDED)
-		return ret;
 	if (ret) {
 		error = errno;
 		goto fail_mount;
 	}
 
-	ret = fsconfig(mo->fsopenfd, FSCONFIG_SET_STRING, "subtype",
+	/*
-		       mo->subtype, 0);
+	 * We can't translate all the supplied MS_ flags into MOUNT_ATTR_ flags
-	if (ret) {
+	 * or string flags!  Return a magic code so the caller will fall back
-		error = errno;
+	 * to regular mount(2).
+	 */
+	if (ms_flags)
+		return FUSE_MOUNT_FALLBACK_NEEDED;
 
+	ret = apply_fsconfig_opt_string(mo->fsopenfd, "subtype", mo->subtype);
+	if (ret < 0) {
 		/* The subtype option was merged after fsopen */
-		if (error == EINVAL)
+		if (ret == -EINVAL)
 			return FUSE_MOUNT_FALLBACK_NEEDED;
 
-		fprintf(stderr, "%s: set subtype option: %s\n",
+		error = -ret;
-			mo->msgtag, strerror(error));
 		goto fail_fsconfig;
 	}
 
 	snprintf(tmp, sizeof(tmp), "%i", mo->fusedevfd);
-	ret = fsconfig(mo->fsopenfd, FSCONFIG_SET_STRING, "fd", tmp, 0);
+	ret = apply_fsconfig_opt_fd(mo->fsopenfd, tmp);
-	if (ret) {
+	if (ret < 0) {
-		error = errno;
+		error = -ret;
-		fprintf(stderr, "%s: set fd option: %s\n",
-			mo->msgtag, strerror(error));
 		goto fail_fsconfig;
 	}
 
 	snprintf(tmp, sizeof(tmp), "%o", stbuf->st_mode & S_IFMT);
-	ret = fsconfig(mo->fsopenfd, FSCONFIG_SET_STRING, "rootmode", tmp, 0);
+	ret = apply_fsconfig_opt_string(mo->fsopenfd, "rootmode", tmp);
-	if (ret) {
+	if (ret < 0) {
-		error = errno;
+		error = -ret;
-		fprintf(stderr, "%s: set rootmode option: %s\n",
-			mo->msgtag, strerror(error));
 		goto fail_fsconfig;
 	}
 
 	snprintf(tmp, sizeof(tmp), "%u", getuid());
-	ret = fsconfig(mo->fsopenfd, FSCONFIG_SET_STRING, "user_id", tmp, 0);
+	ret = apply_fsconfig_opt_string(mo->fsopenfd, "user_id", tmp);
-	if (ret) {
+	if (ret < 0) {
-		error = errno;
+		error = -ret;
-		fprintf(stderr, "%s: set user_id option: %s\n",
-			mo->msgtag, strerror(error));
 		goto fail_fsconfig;
 	}
 
 	snprintf(tmp, sizeof(tmp), "%u", getgid());
-	ret = fsconfig(mo->fsopenfd, FSCONFIG_SET_STRING, "group_id", tmp, 0);
+	ret = apply_fsconfig_opt_string(mo->fsopenfd, "group_id", tmp);
-	if (ret) {
+	if (ret < 0) {
-		error = errno;
+		error = -ret;
-		fprintf(stderr, "%s: set group_id option: %s\n",
-			mo->msgtag, strerror(error));
 		goto fail_fsconfig;
 	}
 
@@ -1629,7 +1504,7 @@ static int mount_service_fsopen_mount(struct mount_service *mo,
 	return mount_service_send_reply(mo, 0);
 
 fail_fsconfig:
-	emit_fsconfig_messages(mo);
+	log_fsconfig_kmsg(mo->fsopenfd);
 fail_mount:
 	return mount_service_send_reply(mo, error);
 }