exportfs: require ->fh_to_parent() to encode connectable file handles

When user requests a connectable file handle explicitly with the
AT_HANDLE_CONNECTABLE flag, fail the request if filesystem (e.g. nfs)
does not know how to decode a connected non-dir dentry.

Fixes: c374196b2b ("fs: name_to_handle_at() support for "explicit connectable" file handles")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/20250525104731.1461704-1-amir73il@gmail.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
pull/1255/head
Amir Goldstein 2025-05-25 12:47:31 +02:00 committed by Christian Brauner
parent 21fae34a27
commit 5402c4d4d2
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1 changed files with 10 additions and 0 deletions

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@ -314,6 +314,9 @@ static inline bool exportfs_can_decode_fh(const struct export_operations *nop)
static inline bool exportfs_can_encode_fh(const struct export_operations *nop, static inline bool exportfs_can_encode_fh(const struct export_operations *nop,
int fh_flags) int fh_flags)
{ {
if (!nop)
return false;
/* /*
* If a non-decodeable file handle was requested, we only need to make * If a non-decodeable file handle was requested, we only need to make
* sure that filesystem did not opt-out of encoding fid. * sure that filesystem did not opt-out of encoding fid.
@ -321,6 +324,13 @@ static inline bool exportfs_can_encode_fh(const struct export_operations *nop,
if (fh_flags & EXPORT_FH_FID) if (fh_flags & EXPORT_FH_FID)
return exportfs_can_encode_fid(nop); return exportfs_can_encode_fid(nop);
/*
* If a connectable file handle was requested, we need to make sure that
* filesystem can also decode connected file handles.
*/
if ((fh_flags & EXPORT_FH_CONNECTABLE) && !nop->fh_to_parent)
return false;
/* /*
* If a decodeable file handle was requested, we need to make sure that * If a decodeable file handle was requested, we need to make sure that
* filesystem can also decode file handles. * filesystem can also decode file handles.