// SPDX-License-Identifier: GPL-2.0 /* * NFS server file handle treatment. * * Copyright (C) 1995, 1996 Olaf Kirch * Portions Copyright (C) 1999 G. Allen Morris III * Extensive rewrite by Neil Brown Southern-Spring 1999 * ... and again Southern-Winter 2001 to support export_operations */ #include #include #include "nfsd.h" #include "vfs.h" #include "auth.h" #include "trace.h" #define NFSDDBG_FACILITY NFSDDBG_FH /* * our acceptability function. * if NOSUBTREECHECK, accept anything * if not, require that we can walk up to exp->ex_dentry * doing some checks on the 'x' bits */ static int nfsd_acceptable(void *expv, struct dentry *dentry) { struct svc_export *exp = expv; int rv; struct dentry *tdentry; struct dentry *parent; if (exp->ex_flags & NFSEXP_NOSUBTREECHECK) return 1; tdentry = dget(dentry); while (tdentry != exp->ex_path.dentry && !IS_ROOT(tdentry)) { /* make sure parents give x permission to user */ int err; parent = dget_parent(tdentry); err = inode_permission(&nop_mnt_idmap, d_inode(parent), MAY_EXEC); if (err < 0) { dput(parent); break; } dput(tdentry); tdentry = parent; } if (tdentry != exp->ex_path.dentry) dprintk("nfsd_acceptable failed at %p %pd\n", tdentry, tdentry); rv = (tdentry == exp->ex_path.dentry); dput(tdentry); return rv; } /* Type check. The correct error return for type mismatches does not seem to be * generally agreed upon. SunOS seems to use EISDIR if file isn't S_IFREG; a * comment in the NFSv3 spec says this is incorrect (implementation notes for * the write call). */ static inline __be32 nfsd_mode_check(struct dentry *dentry, umode_t requested) { umode_t mode = d_inode(dentry)->i_mode & S_IFMT; if (requested == 0) /* the caller doesn't care */ return nfs_ok; if (mode == requested) { if (mode == S_IFDIR && !d_can_lookup(dentry)) { WARN_ON_ONCE(1); return nfserr_notdir; } return nfs_ok; } if (mode == S_IFLNK) { if (requested == S_IFDIR) return nfserr_symlink_not_dir; return nfserr_symlink; } if (requested == S_IFDIR) return nfserr_notdir; if (mode == S_IFDIR) return nfserr_isdir; return nfserr_wrong_type; } static bool nfsd_originating_port_ok(struct svc_rqst *rqstp, struct svc_cred *cred, struct svc_export *exp) { if (nfsexp_flags(cred, exp) & NFSEXP_INSECURE_PORT) return true; /* We don't require gss requests to use low ports: */ if (cred->cr_flavor >= RPC_AUTH_GSS) return true; return test_bit(RQ_SECURE, &rqstp->rq_flags); } static __be32 nfsd_setuser_and_check_port(struct svc_rqst *rqstp, struct svc_cred *cred, struct svc_export *exp) { /* Check if the request originated from a secure port. */ if (rqstp && !nfsd_originating_port_ok(rqstp, cred, exp)) { RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]); dprintk("nfsd: request from insecure port %s!\n", svc_print_addr(rqstp, buf, sizeof(buf))); return nfserr_perm; } /* Set user creds for this exportpoint */ return nfserrno(nfsd_setuser(cred, exp)); } static inline __be32 check_pseudo_root(struct dentry *dentry, struct svc_export *exp) { if (!(exp->ex_flags & NFSEXP_V4ROOT)) return nfs_ok; /* * We're exposing only the directories and symlinks that have to be * traversed on the way to real exports: */ if (unlikely(!d_is_dir(dentry) && !d_is_symlink(dentry))) return nfserr_stale; /* * A pseudoroot export gives permission to access only one * single directory; the kernel has to make another upcall * before granting access to anything else under it: */ if (unlikely(dentry != exp->ex_path.dentry)) return nfserr_stale; return nfs_ok; } /* * Use the given filehandle to look up the corresponding export and * dentry. On success, the results are used to set fh_export and * fh_dentry. */ static __be32 nfsd_set_fh_dentry(struct svc_rqst *rqstp, struct net *net, struct svc_cred *cred, struct auth_domain *client, struct auth_domain *gssclient, struct svc_fh *fhp) { struct knfsd_fh *fh = &fhp->fh_handle; struct fid *fid = NULL; struct svc_export *exp; struct dentry *dentry; int fileid_type; int data_left = fh->fh_size/4; int len; __be32 error; error = nfserr_badhandle; if (fh->fh_size == 0) return nfserr_nofilehandle; if (fh->fh_version != 1) return error; if (--data_left < 0) return error; if (fh->fh_auth_type != 0) return error; len = key_len(fh->fh_fsid_type) / 4; if (len == 0) return error; if (fh->fh_fsid_type == FSID_MAJOR_MINOR) { /* deprecated, convert to type 3 */ len = key_len(FSID_ENCODE_DEV)/4; fh->fh_fsid_type = FSID_ENCODE_DEV; /* * struct knfsd_fh uses host-endian fields, which are * sometimes used to hold net-endian values. This * confuses sparse, so we must use __force here to * keep it from complaining. */ fh->fh_fsid[0] = new_encode_dev(MKDEV(ntohl((__force __be32)fh->fh_fsid[0]), ntohl((__force __be32)fh->fh_fsid[1]))); fh->fh_fsid[1] = fh->fh_fsid[2]; } data_left -= len; if (data_left < 0) return error; exp = rqst_exp_find(rqstp ? &rqstp->rq_chandle : NULL, net, client, gssclient, fh->fh_fsid_type, fh->fh_fsid); fid = (struct fid *)(fh->fh_fsid + len); error = nfserr_stale; if (IS_ERR(exp)) { trace_nfsd_set_fh_dentry_badexport(rqstp, fhp, PTR_ERR(exp)); if (PTR_ERR(exp) == -ENOENT) return error; return nfserrno(PTR_ERR(exp)); } if (exp->ex_flags & NFSEXP_NOSUBTREECHECK) { /* Elevate privileges so that the lack of 'r' or 'x' * permission on some parent directory will * not stop exportfs_decode_fh from being able * to reconnect a directory into the dentry cache. * The same problem can affect "SUBTREECHECK" exports, * but as nfsd_acceptable depends on correct * access control settings being in effect, we cannot * fix that case easily. */ struct cred *new = prepare_creds(); if (!new) { error = nfserrno(-ENOMEM); goto out; } new->cap_effective = cap_raise_nfsd_set(new->cap_effective, new->cap_permitted); put_cred(override_creds(new)); put_cred(new); } else { error = nfsd_setuser_and_check_port(rqstp, cred, exp); if (error) goto out; } /* * Look up the dentry using the NFS file handle. */ error = nfserr_badhandle; fileid_type = fh->fh_fileid_type; if (fileid_type == FILEID_ROOT) dentry = dget(exp->ex_path.dentry); else { dentry = exportfs_decode_fh_raw(exp->ex_path.mnt, fid, data_left, fileid_type, 0, nfsd_acceptable, exp); if (IS_ERR_OR_NULL(dentry)) { trace_nfsd_set_fh_dentry_badhandle(rqstp, fhp, dentry ? PTR_ERR(dentry) : -ESTALE); switch (PTR_ERR(dentry)) { case -ENOMEM: case -ETIMEDOUT: break; default: dentry = ERR_PTR(-ESTALE); } } } if (dentry == NULL) goto out; if (IS_ERR(dentry)) { if (PTR_ERR(dentry) != -EINVAL) error = nfserrno(PTR_ERR(dentry)); goto out; } if (d_is_dir(dentry) && (dentry->d_flags & DCACHE_DISCONNECTED)) { printk("nfsd: find_fh_dentry returned a DISCONNECTED directory: %pd2\n", dentry); } fhp->fh_dentry = dentry; fhp->fh_export = exp; switch (fhp->fh_maxsize) { case NFS4_FHSIZE: if (dentry->d_sb->s_export_op->flags & EXPORT_OP_NOATOMIC_ATTR) fhp->fh_no_atomic_attr = true; fhp->fh_64bit_cookies = true; break; case NFS3_FHSIZE: if (dentry->d_sb->s_export_op->flags & EXPORT_OP_NOWCC) fhp->fh_no_wcc = true; fhp->fh_64bit_cookies = true; if (exp->ex_flags & NFSEXP_V4ROOT) goto out; break; case NFS_FHSIZE: fhp->fh_no_wcc = true; if (EX_WGATHER(exp)) fhp->fh_use_wgather = true; if (exp->ex_flags & NFSEXP_V4ROOT) goto out; } return 0; out: exp_put(exp); return error; } /** * __fh_verify - filehandle lookup and access checking * @rqstp: RPC transaction context, or NULL * @net: net namespace in which to perform the export lookup * @cred: RPC user credential * @client: RPC auth domain * @gssclient: RPC GSS auth domain, or NULL * @fhp: filehandle to be verified * @type: expected type of object pointed to by filehandle * @access: type of access needed to object * * See fh_verify() for further descriptions of @fhp, @type, and @access. */ static __be32 __fh_verify(struct svc_rqst *rqstp, struct net *net, struct svc_cred *cred, struct auth_domain *client, struct auth_domain *gssclient, struct svc_fh *fhp, umode_t type, int access) { struct nfsd_net *nn = net_generic(net, nfsd_net_id); struct svc_export *exp = NULL; bool may_bypass_gss = false; struct dentry *dentry; __be32 error; if (!fhp->fh_dentry) { error = nfsd_set_fh_dentry(rqstp, net, cred, client, gssclient, fhp); if (error) goto out; } dentry = fhp->fh_dentry; exp = fhp->fh_export; trace_nfsd_fh_verify(rqstp, fhp, type, access); /* * We still have to do all these permission checks, even when * fh_dentry is already set: * - fh_verify may be called multiple times with different * "access" arguments (e.g. nfsd_proc_create calls * fh_verify(...,NFSD_MAY_EXEC) first, then later (in * nfsd_create) calls fh_verify(...,NFSD_MAY_CREATE). * - in the NFSv4 case, the filehandle may have been filled * in by fh_compose, and given a dentry, but further * compound operations performed with that filehandle * still need permissions checks. In the worst case, a * mountpoint crossing may have changed the export * options, and we may now need to use a different uid * (for example, if different id-squashing options are in * effect on the new filesystem). */ error = check_pseudo_root(dentry, exp); if (error) goto out; error = nfsd_setuser_and_check_port(rqstp, cred, exp); if (error) goto out; error = nfsd_mode_check(dentry, type); if (error) goto out; if ((access & NFSD_MAY_NLM) && (exp->ex_flags & NFSEXP_NOAUTHNLM)) /* NLM is allowed to fully bypass authentication */ goto out; if (access & NFSD_MAY_BYPASS_GSS) may_bypass_gss = true; /* * Clients may expect to be able to use auth_sys during mount, * even if they use gss for everything else; see section 2.3.2 * of rfc 2623. */ if (access & NFSD_MAY_BYPASS_GSS_ON_ROOT && exp->ex_path.dentry == dentry) may_bypass_gss = true; error = check_nfsd_access(exp, rqstp, may_bypass_gss); if (error) goto out; /* Finally, check access permissions. */ error = nfsd_permission(cred, exp, dentry, access); out: trace_nfsd_fh_verify_err(rqstp, fhp, type, access, error); if (error == nfserr_stale) nfsd_stats_fh_stale_inc(nn, exp); return error; } /** * fh_verify_local - filehandle lookup and access checking * @net: net namespace in which to perform the export lookup * @cred: RPC user credential * @client: RPC auth domain * @fhp: filehandle to be verified * @type: expected type of object pointed to by filehandle * @access: type of access needed to object * * This API can be used by callers who do not have an RPC * transaction context (ie are not running in an nfsd thread). * * See fh_verify() for further descriptions of @fhp, @type, and @access. */ __be32 fh_verify_local(struct net *net, struct svc_cred *cred, struct auth_domain *client, struct svc_fh *fhp, umode_t type, int access) { return __fh_verify(NULL, net, cred, client, NULL, fhp, type, access); } /** * fh_verify - filehandle lookup and access checking * @rqstp: pointer to current rpc request * @fhp: filehandle to be verified * @type: expected type of object pointed to by filehandle * @access: type of access needed to object * * Look up a dentry from the on-the-wire filehandle, check the client's * access to the export, and set the current task's credentials. * * Regardless of success or failure of fh_verify(), fh_put() should be * called on @fhp when the caller is finished with the filehandle. * * fh_verify() may be called multiple times on a given filehandle, for * example, when processing an NFSv4 compound. The first call will look * up a dentry using the on-the-wire filehandle. Subsequent calls will * skip the lookup and just perform the other checks and possibly change * the current task's credentials. * * @type specifies the type of object expected using one of the S_IF* * constants defined in include/linux/stat.h. The caller may use zero * to indicate that it doesn't care, or a negative integer to indicate * that it expects something not of the given type. * * @access is formed from the NFSD_MAY_* constants defined in * fs/nfsd/vfs.h. */ __be32 fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, umode_t type, int access) { return __fh_verify(rqstp, SVC_NET(rqstp), &rqstp->rq_cred, rqstp->rq_client, rqstp->rq_gssclient, fhp, type, access); } /* * Compose a file handle for an NFS reply. * * Note that when first composed, the dentry may not yet have * an inode. In this case a call to fh_update should be made * before the fh goes out on the wire ... */ static void _fh_update(struct svc_fh *fhp, struct svc_export *exp, struct dentry *dentry) { if (dentry != exp->ex_path.dentry) { struct fid *fid = (struct fid *) (fhp->fh_handle.fh_fsid + fhp->fh_handle.fh_size/4 - 1); int maxsize = (fhp->fh_maxsize - fhp->fh_handle.fh_size)/4; int fh_flags = (exp->ex_flags & NFSEXP_NOSUBTREECHECK) ? 0 : EXPORT_FH_CONNECTABLE; int fileid_type = exportfs_encode_fh(dentry, fid, &maxsize, fh_flags); fhp->fh_handle.fh_fileid_type = fileid_type > 0 ? fileid_type : FILEID_INVALID; fhp->fh_handle.fh_size += maxsize * 4; } else { fhp->fh_handle.fh_fileid_type = FILEID_ROOT; } } static bool is_root_export(struct svc_export *exp) { return exp->ex_path.dentry == exp->ex_path.dentry->d_sb->s_root; } static struct super_block *exp_sb(struct svc_export *exp) { return exp->ex_path.dentry->d_sb; } static bool fsid_type_ok_for_exp(u8 fsid_type, struct svc_export *exp) { switch (fsid_type) { case FSID_DEV: if (!old_valid_dev(exp_sb(exp)->s_dev)) return false; fallthrough; case FSID_MAJOR_MINOR: case FSID_ENCODE_DEV: return exp_sb(exp)->s_type->fs_flags & FS_REQUIRES_DEV; case FSID_NUM: return exp->ex_flags & NFSEXP_FSID; case FSID_UUID8: case FSID_UUID16: if (!is_root_export(exp)) return false; fallthrough; case FSID_UUID4_INUM: case FSID_UUID16_INUM: return exp->ex_uuid != NULL; } return true; } static void set_version_and_fsid_type(struct svc_fh *fhp, struct svc_export *exp, struct svc_fh *ref_fh) { u8 version; u8 fsid_type; retry: version = 1; if (ref_fh && ref_fh->fh_export == exp) { version = ref_fh->fh_handle.fh_version; fsid_type = ref_fh->fh_handle.fh_fsid_type; ref_fh = NULL; switch (version) { case 0xca: fsid_type = FSID_DEV; break; case 1: break; default: goto retry; } /* * As the fsid -> filesystem mapping was guided by * user-space, there is no guarantee that the filesystem * actually supports that fsid type. If it doesn't we * loop around again without ref_fh set. */ if (!fsid_type_ok_for_exp(fsid_type, exp)) goto retry; } else if (exp->ex_flags & NFSEXP_FSID) { fsid_type = FSID_NUM; } else if (exp->ex_uuid) { if (fhp->fh_maxsize >= 64) { if (is_root_export(exp)) fsid_type = FSID_UUID16; else fsid_type = FSID_UUID16_INUM; } else { if (is_root_export(exp)) fsid_type = FSID_UUID8; else fsid_type = FSID_UUID4_INUM; } } else if (!old_valid_dev(exp_sb(exp)->s_dev)) /* for newer device numbers, we must use a newer fsid format */ fsid_type = FSID_ENCODE_DEV; else fsid_type = FSID_DEV; fhp->fh_handle.fh_version = version; if (version) fhp->fh_handle.fh_fsid_type = fsid_type; } __be32 fh_compose(struct svc_fh *fhp, struct svc_export *exp, struct dentry *dentry, struct svc_fh *ref_fh) { /* ref_fh is a reference file handle. * if it is non-null and for the same filesystem, then we should compose * a filehandle which is of the same version, where possible. */ struct inode * inode = d_inode(dentry); dev_t ex_dev = exp_sb(exp)->s_dev; dprintk("nfsd: fh_compose(exp %02x:%02x/%ld %pd2, ino=%ld)\n", MAJOR(ex_dev), MINOR(ex_dev), (long) d_inode(exp->ex_path.dentry)->i_ino, dentry, (inode ? inode->i_ino : 0)); /* Choose filehandle version and fsid type based on * the reference filehandle (if it is in the same export) * or the export options. */ set_version_and_fsid_type(fhp, exp, ref_fh); /* If we have a ref_fh, then copy the fh_no_wcc setting from it. */ fhp->fh_no_wcc = ref_fh ? ref_fh->fh_no_wcc : false; if (ref_fh == fhp) fh_put(ref_fh); if (fhp->fh_dentry) { printk(KERN_ERR "fh_compose: fh %pd2 not initialized!\n", dentry); } if (fhp->fh_maxsize < NFS_FHSIZE) printk(KERN_ERR "fh_compose: called with maxsize %d! %pd2\n", fhp->fh_maxsize, dentry); fhp->fh_dentry = dget(dentry); /* our internal copy */ fhp->fh_export = exp_get(exp); fhp->fh_handle.fh_size = key_len(fhp->fh_handle.fh_fsid_type) + 4; fhp->fh_handle.fh_auth_type = 0; mk_fsid(fhp->fh_handle.fh_fsid_type, fhp->fh_handle.fh_fsid, ex_dev, d_inode(exp->ex_path.dentry)->i_ino, exp->ex_fsid, exp->ex_uuid); if (inode) _fh_update(fhp, exp, dentry); if (fhp->fh_handle.fh_fileid_type == FILEID_INVALID) { fh_put(fhp); return nfserr_stale; } return 0; } /* * Update file handle information after changing a dentry. * This is only called by nfsd_create, nfsd_create_v3 and nfsd_proc_create */ __be32 fh_update(struct svc_fh *fhp) { struct dentry *dentry; if (!fhp->fh_dentry) goto out_bad; dentry = fhp->fh_dentry; if (d_really_is_negative(dentry)) goto out_negative; if (fhp->fh_handle.fh_fileid_type != FILEID_ROOT) return 0; _fh_update(fhp, fhp->fh_export, dentry); if (fhp->fh_handle.fh_fileid_type == FILEID_INVALID) return nfserr_stale; return 0; out_bad: printk(KERN_ERR "fh_update: fh not verified!\n"); return nfserr_serverfault; out_negative: printk(KERN_ERR "fh_update: %pd2 still negative!\n", dentry); return nfserr_serverfault; } /** * fh_fill_pre_attrs - Fill in pre-op attributes * @fhp: file handle to be updated * */ __be32 __must_check fh_fill_pre_attrs(struct svc_fh *fhp) { bool v4 = (fhp->fh_maxsize == NFS4_FHSIZE); struct kstat stat; __be32 err; if (fhp->fh_no_wcc || fhp->fh_pre_saved) return nfs_ok; err = fh_getattr(fhp, &stat); if (err) return err; if (v4) fhp->fh_pre_change = nfsd4_change_attribute(&stat); fhp->fh_pre_mtime = stat.mtime; fhp->fh_pre_ctime = stat.ctime; fhp->fh_pre_size = stat.size; fhp->fh_pre_saved = true; return nfs_ok; } /** * fh_fill_post_attrs - Fill in post-op attributes * @fhp: file handle to be updated * */ __be32 fh_fill_post_attrs(struct svc_fh *fhp) { bool v4 = (fhp->fh_maxsize == NFS4_FHSIZE); __be32 err; if (fhp->fh_no_wcc) return nfs_ok; if (fhp->fh_post_saved) printk("nfsd: inode locked twice during operation.\n"); err = fh_getattr(fhp, &fhp->fh_post_attr); if (err) return err; fhp->fh_post_saved = true; if (v4) fhp->fh_post_change = nfsd4_change_attribute(&fhp->fh_post_attr); return nfs_ok; } /** * fh_fill_both_attrs - Fill pre-op and post-op attributes * @fhp: file handle to be updated * * This is used when the directory wasn't changed, but wcc attributes * are needed anyway. */ __be32 __must_check fh_fill_both_attrs(struct svc_fh *fhp) { __be32 err; err = fh_fill_post_attrs(fhp); if (err) return err; fhp->fh_pre_change = fhp->fh_post_change; fhp->fh_pre_mtime = fhp->fh_post_attr.mtime; fhp->fh_pre_ctime = fhp->fh_post_attr.ctime; fhp->fh_pre_size = fhp->fh_post_attr.size; fhp->fh_pre_saved = true; return nfs_ok; } /* * Release a file handle. */ void fh_put(struct svc_fh *fhp) { struct dentry * dentry = fhp->fh_dentry; struct svc_export * exp = fhp->fh_export; if (dentry) { fhp->fh_dentry = NULL; dput(dentry); fh_clear_pre_post_attrs(fhp); } fh_drop_write(fhp); if (exp) { exp_put(exp); fhp->fh_export = NULL; } fhp->fh_no_wcc = false; return; } /* * Shorthand for dprintk()'s */ char * SVCFH_fmt(struct svc_fh *fhp) { struct knfsd_fh *fh = &fhp->fh_handle; static char buf[2+1+1+64*3+1]; if (fh->fh_size > 64) return "bad-fh"; sprintf(buf, "%d: %*ph", fh->fh_size, fh->fh_size, fh->fh_raw); return buf; } enum fsid_source fsid_source(const struct svc_fh *fhp) { if (fhp->fh_handle.fh_version != 1) return FSIDSOURCE_DEV; switch(fhp->fh_handle.fh_fsid_type) { case FSID_DEV: case FSID_ENCODE_DEV: case FSID_MAJOR_MINOR: if (exp_sb(fhp->fh_export)->s_type->fs_flags & FS_REQUIRES_DEV) return FSIDSOURCE_DEV; break; case FSID_NUM: if (fhp->fh_export->ex_flags & NFSEXP_FSID) return FSIDSOURCE_FSID; break; default: break; } /* either a UUID type filehandle, or the filehandle doesn't * match the export. */ if (fhp->fh_export->ex_flags & NFSEXP_FSID) return FSIDSOURCE_FSID; if (fhp->fh_export->ex_uuid) return FSIDSOURCE_UUID; return FSIDSOURCE_DEV; } /** * nfsd4_change_attribute - Generate an NFSv4 change_attribute value * @stat: inode attributes * * Caller must fill in @stat before calling, typically by invoking * vfs_getattr() with STATX_MODE, STATX_CTIME, and STATX_CHANGE_COOKIE. * Returns an unsigned 64-bit changeid4 value (RFC 8881 Section 3.2). * * We could use i_version alone as the change attribute. However, i_version * can go backwards on a regular file after an unclean shutdown. On its own * that doesn't necessarily cause a problem, but if i_version goes backwards * and then is incremented again it could reuse a value that was previously * used before boot, and a client who queried the two values might incorrectly * assume nothing changed. * * By using both ctime and the i_version counter we guarantee that as long as * time doesn't go backwards we never reuse an old value. If the filesystem * advertises STATX_ATTR_CHANGE_MONOTONIC, then this mitigation is not * needed. * * We only need to do this for regular files as well. For directories, we * assume that the new change attr is always logged to stable storage in some * fashion before the results can be seen. */ u64 nfsd4_change_attribute(const struct kstat *stat) { u64 chattr; if (stat->result_mask & STATX_CHANGE_COOKIE) { chattr = stat->change_cookie; if (S_ISREG(stat->mode) && !(stat->attributes & STATX_ATTR_CHANGE_MONOTONIC)) { chattr += (u64)stat->ctime.tv_sec << 30; chattr += stat->ctime.tv_nsec; } } else { chattr = time_to_chattr(&stat->ctime); } return chattr; }