From 62346217fd722510c3551858ad7d0fcfab8cce7e Mon Sep 17 00:00:00 2001 From: Benjamin Coddington Date: Wed, 25 Feb 2026 07:51:36 -0500 Subject: NFSD: Add a key for signing filehandles A future patch will enable NFSD to sign filehandles by appending a Message Authentication Code(MAC). To do this, NFSD requires a secret 128-bit key that can persist across reboots. A persisted key allows the server to accept filehandles after a restart. Enable NFSD to be configured with this key via the netlink interface. Link: https://lore.kernel.org/linux-nfs/cover.1772022373.git.bcodding@hammerspace.com Signed-off-by: Benjamin Coddington Reviewed-by: Jeff Layton Signed-off-by: Chuck Lever --- include/uapi/linux/nfsd_netlink.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/uapi') diff --git a/include/uapi/linux/nfsd_netlink.h b/include/uapi/linux/nfsd_netlink.h index e9efbc9e63d8..97c7447f4d14 100644 --- a/include/uapi/linux/nfsd_netlink.h +++ b/include/uapi/linux/nfsd_netlink.h @@ -36,6 +36,7 @@ enum { NFSD_A_SERVER_LEASETIME, NFSD_A_SERVER_SCOPE, NFSD_A_SERVER_MIN_THREADS, + NFSD_A_SERVER_FH_KEY, __NFSD_A_SERVER_MAX, NFSD_A_SERVER_MAX = (__NFSD_A_SERVER_MAX - 1) -- cgit v1.2.3 From a002ad8a9bc89c084bc40933065c88336700837e Mon Sep 17 00:00:00 2001 From: Benjamin Coddington Date: Wed, 25 Feb 2026 07:51:37 -0500 Subject: NFSD/export: Add sign_fh export option In order to signal that filehandles on this export should be signed, add a "sign_fh" export option. Filehandle signing can help the server defend against certain filehandle guessing attacks. Setting the "sign_fh" export option sets NFSEXP_SIGN_FH. In a future patch NFSD uses this signal to append a MAC onto filehandles for that export. While we're in here, tidy a few stray expflags to more closely align to the export flag order. Link: https://lore.kernel.org/linux-nfs/cover.1772022373.git.bcodding@hammerspace.com Signed-off-by: Benjamin Coddington Reviewed-by: Jeff Layton Signed-off-by: Chuck Lever --- fs/nfsd/export.c | 5 +++-- include/uapi/linux/nfsd/export.h | 4 ++-- 2 files changed, 5 insertions(+), 4 deletions(-) (limited to 'include/uapi') diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c index 8e8a76a44ff0..7f4a51b832ef 100644 --- a/fs/nfsd/export.c +++ b/fs/nfsd/export.c @@ -1362,13 +1362,14 @@ static struct flags { { NFSEXP_ASYNC, {"async", "sync"}}, { NFSEXP_GATHERED_WRITES, {"wdelay", "no_wdelay"}}, { NFSEXP_NOREADDIRPLUS, {"nordirplus", ""}}, + { NFSEXP_SECURITY_LABEL, {"security_label", ""}}, + { NFSEXP_SIGN_FH, {"sign_fh", ""}}, { NFSEXP_NOHIDE, {"nohide", ""}}, - { NFSEXP_CROSSMOUNT, {"crossmnt", ""}}, { NFSEXP_NOSUBTREECHECK, {"no_subtree_check", ""}}, { NFSEXP_NOAUTHNLM, {"insecure_locks", ""}}, + { NFSEXP_CROSSMOUNT, {"crossmnt", ""}}, { NFSEXP_V4ROOT, {"v4root", ""}}, { NFSEXP_PNFS, {"pnfs", ""}}, - { NFSEXP_SECURITY_LABEL, {"security_label", ""}}, { 0, {"", ""}} }; diff --git a/include/uapi/linux/nfsd/export.h b/include/uapi/linux/nfsd/export.h index a73ca3703abb..de647cf166c3 100644 --- a/include/uapi/linux/nfsd/export.h +++ b/include/uapi/linux/nfsd/export.h @@ -34,7 +34,7 @@ #define NFSEXP_GATHERED_WRITES 0x0020 #define NFSEXP_NOREADDIRPLUS 0x0040 #define NFSEXP_SECURITY_LABEL 0x0080 -/* 0x100 currently unused */ +#define NFSEXP_SIGN_FH 0x0100 #define NFSEXP_NOHIDE 0x0200 #define NFSEXP_NOSUBTREECHECK 0x0400 #define NFSEXP_NOAUTHNLM 0x0800 /* Don't authenticate NLM requests - just trust */ @@ -55,7 +55,7 @@ #define NFSEXP_PNFS 0x20000 /* All flags that we claim to support. (Note we don't support NOACL.) */ -#define NFSEXP_ALLFLAGS 0x3FEFF +#define NFSEXP_ALLFLAGS 0x3FFFF /* The flags that may vary depending on security flavor: */ #define NFSEXP_SECINFO_FLAGS (NFSEXP_READONLY | NFSEXP_ROOTSQUASH \ -- cgit v1.2.3