From 0189a2d367f49729622fdafaef5da73161591859 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Tue, 14 Jul 2020 14:45:41 +0200 Subject: fuse: use ->reconfigure() instead of ->remount_fs() s_op->remount_fs() is only called from legacy_reconfigure(), which is not used after being converted to the new API. Convert to using ->reconfigure(). This restores the previous behavior of syncing the filesystem and rejecting MS_MANDLOCK on remount. Fixes: c30da2e981a7 ("fuse: convert to use the new mount API") Cc: # v5.4 Signed-off-by: Miklos Szeredi --- fs/fuse/inode.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) (limited to 'fs/fuse/inode.c') diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c index 5b4aebf5821f..be39dff57c28 100644 --- a/fs/fuse/inode.c +++ b/fs/fuse/inode.c @@ -121,10 +121,12 @@ static void fuse_evict_inode(struct inode *inode) } } -static int fuse_remount_fs(struct super_block *sb, int *flags, char *data) +static int fuse_reconfigure(struct fs_context *fc) { + struct super_block *sb = fc->root->d_sb; + sync_filesystem(sb); - if (*flags & SB_MANDLOCK) + if (fc->sb_flags & SB_MANDLOCK) return -EINVAL; return 0; @@ -817,7 +819,6 @@ static const struct super_operations fuse_super_operations = { .evict_inode = fuse_evict_inode, .write_inode = fuse_write_inode, .drop_inode = generic_delete_inode, - .remount_fs = fuse_remount_fs, .put_super = fuse_put_super, .umount_begin = fuse_umount_begin, .statfs = fuse_statfs, @@ -1296,6 +1297,7 @@ static int fuse_get_tree(struct fs_context *fc) static const struct fs_context_operations fuse_context_ops = { .free = fuse_free_fc, .parse_param = fuse_parse_param, + .reconfigure = fuse_reconfigure, .get_tree = fuse_get_tree, }; -- cgit From e8b20a474cf2c42698d1942f939ff2128819f151 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Tue, 14 Jul 2020 14:45:41 +0200 Subject: fuse: ignore 'data' argument of mount(..., MS_REMOUNT) The command mount -o remount -o unknownoption /mnt/fuse succeeds on kernel versions prior to v5.4 and fails on kernel version at or after. This is because fuse_parse_param() rejects any unrecognised options in case of FS_CONTEXT_FOR_RECONFIGURE, just as for FS_CONTEXT_FOR_MOUNT. This causes a regression in case the fuse filesystem is in fstab, since remount sends all options found there to the kernel; even ones that are meant for the initial mount and are consumed by the userspace fuse server. Fix this by ignoring mount options, just as fuse_remount_fs() did prior to the conversion to the new API. Reported-by: Stefan Priebe Fixes: c30da2e981a7 ("fuse: convert to use the new mount API") Cc: # v5.4 Signed-off-by: Miklos Szeredi --- fs/fuse/inode.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'fs/fuse/inode.c') diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c index be39dff57c28..ba201bf5ffad 100644 --- a/fs/fuse/inode.c +++ b/fs/fuse/inode.c @@ -477,6 +477,13 @@ static int fuse_parse_param(struct fs_context *fc, struct fs_parameter *param) struct fuse_fs_context *ctx = fc->fs_private; int opt; + /* + * Ignore options coming from mount(MS_REMOUNT) for backward + * compatibility. + */ + if (fc->purpose == FS_CONTEXT_FOR_RECONFIGURE) + return 0; + opt = fs_parse(fc, fuse_fs_parameters, param, &result); if (opt < 0) return opt; -- cgit From b330966f79fb4fdc49183f58db113303695a750f Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Tue, 14 Jul 2020 14:45:41 +0200 Subject: fuse: reject options on reconfigure via fsconfig(2) Previous patch changed handling of remount/reconfigure to ignore all options, including those that are unknown to the fuse kernel fs. This was done for backward compatibility, but this likely only affects the old mount(2) API. The new fsconfig(2) based reconfiguration could possibly be improved. This would make the new API less of a drop in replacement for the old, OTOH this is a good chance to get rid of some weirdnesses in the old API. Several other behaviors might make sense: 1) unknown options are rejected, known options are ignored 2) unknown options are rejected, known options are rejected if the value is changed, allowed otherwise 3) all options are rejected Prior to the backward compatibility fix to ignore all options all known options were accepted (1), even if they change the value of a mount parameter; fuse_reconfigure() does not look at the config values set by fuse_parse_param(). To fix that we'd need to verify that the value provided is the same as set in the initial configuration (2). The major drawback is that this is much more complex than just rejecting all attempts at changing options (3); i.e. all options signify initial configuration values and don't make sense on reconfigure. This patch opts for (3) with the rationale that no mount options are reconfigurable in fuse. Signed-off-by: Miklos Szeredi --- fs/fuse/inode.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) (limited to 'fs/fuse/inode.c') diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c index ba201bf5ffad..bba747520e9b 100644 --- a/fs/fuse/inode.c +++ b/fs/fuse/inode.c @@ -477,12 +477,16 @@ static int fuse_parse_param(struct fs_context *fc, struct fs_parameter *param) struct fuse_fs_context *ctx = fc->fs_private; int opt; - /* - * Ignore options coming from mount(MS_REMOUNT) for backward - * compatibility. - */ - if (fc->purpose == FS_CONTEXT_FOR_RECONFIGURE) - return 0; + if (fc->purpose == FS_CONTEXT_FOR_RECONFIGURE) { + /* + * Ignore options coming from mount(MS_REMOUNT) for backward + * compatibility. + */ + if (fc->oldapi) + return 0; + + return invalfc(fc, "No changes allowed in reconfigure"); + } opt = fs_parse(fc, fuse_fs_parameters, param, &result); if (opt < 0) -- cgit