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nfsd: Use MD5 library instead of crypto_shash 

Update NFSD's support for "legacy client tracking" (which uses MD5) to
use the MD5 library instead of crypto_shash.  This has several benefits:

- Simpler code.  Notably, much of the error-handling code is no longer
  needed, since the library functions can't fail.

- Improved performance due to reduced overhead.  A microbenchmark of
  nfs4_make_rec_clidname() shows a speedup from 1455 cycles to 425.

- The MD5 code can now safely be built as a loadable module when nfsd is
  built as a loadable module.  (Previously, nfsd forced the MD5 code to
  built-in, presumably to work around the unreliability of the
  name-based loading.)  Thus select MD5 from the tristate option NFSD if
  NFSD_LEGACY_CLIENT_TRACKING, instead of from the bool option NFSD_V4.

- Fixes a bug where legacy client tracking was not supported on kernels
  booted with "fips=1", due to crypto_shash not allowing MD5 to be used.
  This particular use of MD5 is not for a cryptographic purpose, though,
  so it is acceptable even when fips=1 (see
  https://lore.kernel.org/r/dae495a93cbcc482f4ca23c3a0d9360a1fd8c3a8.camel@redhat.com/).

Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Scott Mayhew <smayhew@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
pull/1354/merge
Eric Biggers 2025-10-16 11:15:34 -07:00 committed by Chuck Lever
parent fceb8734e7
commit 78cd170d03
2 changed files with 11 additions and 69 deletions
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4
fs/nfsd/Kconfig
View File

@ -5,6 +5,7 @@ config NFSD
depends on FILE_LOCKING
depends on FSNOTIFY
select CRC32
select CRYPTO_LIB_MD5 if NFSD_LEGACY_CLIENT_TRACKING
select CRYPTO_LIB_SHA256 if NFSD_V4
select LOCKD
select SUNRPC
@ -77,8 +78,7 @@ config NFSD_V4
depends on NFSD && PROC_FS
select FS_POSIX_ACL
select RPCSEC_GSS_KRB5
select CRYPTO
select CRYPTO_MD5
select CRYPTO # required by RPCSEC_GSS_KRB5
select GRACE_PERIOD
select NFS_V4_2_SSC_HELPER if NFS_V4_2
help

76
fs/nfsd/nfs4recover.c
View File

@ -32,7 +32,7 @@
*
*/
#include <crypto/hash.h>
#include <crypto/md5.h>
#include <crypto/sha2.h>
#include <linux/file.h>
#include <linux/slab.h>
@ -92,57 +92,18 @@ nfs4_reset_creds(const struct cred *original)
put_cred(revert_creds(original));
}
static int
static void
nfs4_make_rec_clidname(char dname[HEXDIR_LEN], const struct xdr_netobj *clname)
{
u8 digest[MD5_DIGEST_SIZE];
struct crypto_shash *tfm;
int status;
dprintk("NFSD: nfs4_make_rec_clidname for %.*s\n",
clname->len, clname->data);
tfm = crypto_alloc_shash("md5", 0, 0);
if (IS_ERR(tfm)) {
status = PTR_ERR(tfm);
goto out_no_tfm;
}
status = crypto_shash_tfm_digest(tfm, clname->data, clname->len,
digest);
if (status)
goto out;
md5(clname->data, clname->len, digest);
static_assert(HEXDIR_LEN == 2 * MD5_DIGEST_SIZE + 1);
sprintf(dname, "%*phN", MD5_DIGEST_SIZE, digest);
status = 0;
out:
crypto_free_shash(tfm);
out_no_tfm:
return status;
}
/*
* If we had an error generating the recdir name for the legacy tracker
* then warn the admin. If the error doesn't appear to be transient,
* then disable recovery tracking.
*/
static void
legacy_recdir_name_error(struct nfs4_client *clp, int error)
{
printk(KERN_ERR "NFSD: unable to generate recoverydir "
"name (%d).\n", error);
/*
* if the algorithm just doesn't exist, then disable the recovery
* tracker altogether. The crypto libs will generally return this if
* FIPS is enabled as well.
*/
if (error == -ENOENT) {
printk(KERN_ERR "NFSD: disabling legacy clientid tracking. "
"Reboot recovery will not function correctly!\n");
nfsd4_client_tracking_exit(clp->net);
}
}
static void
@ -171,9 +132,7 @@ nfsd4_create_clid_dir(struct nfs4_client *clp)
if (!nn->rec_file)
return;
status = nfs4_make_rec_clidname(dname, &clp->cl_name);
if (status)
return legacy_recdir_name_error(clp, status);
nfs4_make_rec_clidname(dname, &clp->cl_name);
status = nfs4_save_creds(&original_cred);
if (status < 0)
@ -354,9 +313,7 @@ nfsd4_remove_clid_dir(struct nfs4_client *clp)
if (!nn->rec_file || !test_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags))
return;
status = nfs4_make_rec_clidname(dname, &clp->cl_name);
if (status)
return legacy_recdir_name_error(clp, status);
nfs4_make_rec_clidname(dname, &clp->cl_name);
status = mnt_want_write_file(nn->rec_file);
if (status)
@ -636,7 +593,6 @@ nfs4_recoverydir(void)
static int
nfsd4_check_legacy_client(struct nfs4_client *clp)
{
int status;
char dname[HEXDIR_LEN];
struct nfs4_client_reclaim *crp;
struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);
@ -646,11 +602,7 @@ nfsd4_check_legacy_client(struct nfs4_client *clp)
if (test_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags))
return 0;
status = nfs4_make_rec_clidname(dname, &clp->cl_name);
if (status) {
legacy_recdir_name_error(clp, status);
return status;
}
nfs4_make_rec_clidname(dname, &clp->cl_name);
/* look for it in the reclaim hashtable otherwise */
name.data = kmemdup(dname, HEXDIR_LEN, GFP_KERNEL);
@ -1243,13 +1195,10 @@ nfsd4_cld_check(struct nfs4_client *clp)
#ifdef CONFIG_NFSD_LEGACY_CLIENT_TRACKING
if (nn->cld_net->cn_has_legacy) {
int status;
char dname[HEXDIR_LEN];
struct xdr_netobj name;
status = nfs4_make_rec_clidname(dname, &clp->cl_name);
if (status)
return -ENOENT;
nfs4_make_rec_clidname(dname, &clp->cl_name);
name.data = kmemdup(dname, HEXDIR_LEN, GFP_KERNEL);
if (!name.data) {
@ -1294,11 +1243,8 @@ nfsd4_cld_check_v2(struct nfs4_client *clp)
if (cn->cn_has_legacy) {
struct xdr_netobj name;
char dname[HEXDIR_LEN];
int status;
status = nfs4_make_rec_clidname(dname, &clp->cl_name);
if (status)
return -ENOENT;
nfs4_make_rec_clidname(dname, &clp->cl_name);
name.data = kmemdup(dname, HEXDIR_LEN, GFP_KERNEL);
if (!name.data) {
@ -1671,11 +1617,7 @@ nfsd4_cltrack_legacy_recdir(const struct xdr_netobj *name)
return NULL;
}
copied = nfs4_make_rec_clidname(result + copied, name);
if (copied) {
kfree(result);
return NULL;
}
nfs4_make_rec_clidname(result + copied, name);
return result;
}