/* * NFS server file handle treatment. * * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de> * Portions Copyright (C) 1999 G. Allen Morris III <gam3@acm.org> * Extensive rewrite by Neil Brown <neilb@cse.unsw.edu.au> Southern-Spring 1999 * ... and again Southern-Winter 2001 to support export_operations */ #include <linux/exportfs.h> #include <linux/sunrpc/svcauth_gss.h> #include "nfsd.h" #include "vfs.h" #include "auth.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(parent->d_inode, MAY_EXEC); if (err < 0) { dput(parent); break; } dput(tdentry); tdentry = parent; } if (tdentry != exp->ex_path.dentry) dprintk("nfsd_acceptable failed at %p %s\n", tdentry, tdentry->d_name.name); 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 svc_rqst *rqstp, umode_t mode, int type) { /* Type can be negative when creating hardlinks - not to a dir */ if (type > 0 && (mode & S_IFMT) != type) { if (rqstp->rq_vers == 4 && (mode & S_IFMT) == S_IFLNK) return nfserr_symlink; else if (type == S_IFDIR) return nfserr_notdir; else if ((mode & S_IFMT) == S_IFDIR) return nfserr_isdir; else return nfserr_inval; } if (type < 0 && (mode & S_IFMT) == -type) { if (rqstp->rq_vers == 4 && (mode & S_IFMT) == S_IFLNK) return nfserr_symlink; else if (type == -S_IFDIR) return nfserr_isdir; else return nfserr_notdir; } return 0; } static __be32 nfsd_setuser_and_check_port(struct svc_rqst *rqstp, struct svc_export *exp) { int flags = nfsexp_flags(rqstp, exp); /* Check if the request originated from a secure port. */ if (!rqstp->rq_secure && !(flags & NFSEXP_INSECURE_PORT)) { RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]); dprintk(KERN_WARNING "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(rqstp, exp)); } static inline __be32 check_pseudo_root(struct svc_rqst *rqstp, struct dentry *dentry, struct svc_export *exp) { if (!(exp->ex_flags & NFSEXP_V4ROOT)) return nfs_ok; /* * v2/v3 clients have no need for the V4ROOT export--they use * the mount protocl instead; also, further V4ROOT checks may be * in v4-specific code, in which case v2/v3 clients could bypass * them. */ if (!nfsd_v4client(rqstp)) return nfserr_stale; /* * We're exposing only the directories and symlinks that have to be * traversed on the way to real exports: */ if (unlikely(!S_ISDIR(dentry->d_inode->i_mode) && !S_ISLNK(dentry->d_inode->i_mode))) 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 svc_fh *fhp) { struct knfsd_fh *fh = &fhp->fh_handle; struct fid *fid = NULL, sfid; struct svc_export *exp; struct dentry *dentry; int fileid_type; int data_left = fh->fh_size/4; __be32 error; error = nfserr_stale; if (rqstp->rq_vers > 2) error = nfserr_badhandle; if (rqstp->rq_vers == 4 && fh->fh_size == 0) return nfserr_nofilehandle; if (fh->fh_version == 1) { int len; 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; fh->fh_fsid[0] = new_encode_dev(MKDEV(ntohl(fh->fh_fsid[0]), ntohl(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, fh->fh_fsid_type, fh->fh_auth); fid = (struct fid *)(fh->fh_auth + len); } else { __u32 tfh[2]; dev_t xdev; ino_t xino; if (fh->fh_size != NFS_FHSIZE) return error; /* assume old filehandle format */ xdev = old_decode_dev(fh->ofh_xdev); xino = u32_to_ino_t(fh->ofh_xino); mk_fsid(FSID_DEV, tfh, xdev, xino, 0, NULL); exp = rqst_exp_find(rqstp, FSID_DEV, tfh); } error = nfserr_stale; if (PTR_ERR(exp) == -ENOENT) return error; if (IS_ERR(exp)) 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) return nfserrno(-ENOMEM); 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, exp); if (error) goto out; } /* * Look up the dentry using the NFS file handle. */ error = nfserr_stale; if (rqstp->rq_vers > 2) error = nfserr_badhandle; if (fh->fh_version != 1) { sfid.i32.ino = fh->ofh_ino; sfid.i32.gen = fh->ofh_generation; sfid.i32.parent_ino = fh->ofh_dirino; fid = &sfid; data_left = 3; if (fh->ofh_dirino == 0) fileid_type = FILEID_INO32_GEN; else fileid_type = FILEID_INO32_GEN_PARENT; } else fileid_type = fh->fh_fileid_type; if (fileid_type == FILEID_ROOT) dentry = dget(exp->ex_path.dentry); else { dentry = exportfs_decode_fh(exp->ex_path.mnt, fid, data_left, fileid_type, nfsd_acceptable, exp); } if (dentry == NULL) goto out; if (IS_ERR(dentry)) { if (PTR_ERR(dentry) != -EINVAL) error = nfserrno(PTR_ERR(dentry)); goto out; } if (S_ISDIR(dentry->d_inode->i_mode) && (dentry->d_flags & DCACHE_DISCONNECTED)) { printk("nfsd: find_fh_dentry returned a DISCONNECTED directory: %s/%s\n", dentry->d_parent->d_name.name, dentry->d_name.name); } fhp->fh_dentry = dentry; fhp->fh_export = exp; return 0; out: exp_put(exp); return error; } /** * 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 * include/linux/nfsd/nfsd.h. */ __be32 fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, int type, int access) { struct svc_export *exp; struct dentry *dentry; __be32 error; dprintk("nfsd: fh_verify(%s)\n", SVCFH_fmt(fhp)); if (!fhp->fh_dentry) { error = nfsd_set_fh_dentry(rqstp, fhp); if (error) goto out; } dentry = fhp->fh_dentry; exp = fhp->fh_export; /* * 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(rqstp, dentry, exp); if (error) goto out; error = nfsd_setuser_and_check_port(rqstp, exp); if (error) goto out; error = nfsd_mode_check(rqstp, dentry->d_inode->i_mode, type); if (error) goto out; /* * pseudoflavor restrictions are not enforced on NLM, * which clients virtually always use auth_sys for, * even while using RPCSEC_GSS for NFS. */ if (access & NFSD_MAY_LOCK) goto skip_pseudoflavor_check; /* * 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) goto skip_pseudoflavor_check; error = check_nfsd_access(exp, rqstp); if (error) goto out; skip_pseudoflavor_check: /* Finally, check access permissions. */ error = nfsd_permission(rqstp, exp, dentry, access); if (error) { dprintk("fh_verify: %s/%s permission failure, " "acc=%x, error=%d\n", dentry->d_parent->d_name.name, dentry->d_name.name, access, ntohl(error)); } out: if (error == nfserr_stale) nfsdstats.fh_stale++; return error; } /* * 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_auth + fhp->fh_handle.fh_size/4 - 1); int maxsize = (fhp->fh_maxsize - fhp->fh_handle.fh_size)/4; int subtreecheck = !(exp->ex_flags & NFSEXP_NOSUBTREECHECK); fhp->fh_handle.fh_fileid_type = exportfs_encode_fh(dentry, fid, &maxsize, subtreecheck); fhp->fh_handle.fh_size += maxsize * 4; } else { fhp->fh_handle.fh_fileid_type = FILEID_ROOT; } } /* * for composing old style file handles */ static inline void _fh_update_old(struct dentry *dentry, struct svc_export *exp, struct knfsd_fh *fh) { fh->ofh_ino = ino_t_to_u32(dentry->d_inode->i_ino); fh->ofh_generation = dentry->d_inode->i_generation; if (S_ISDIR(dentry->d_inode->i_mode) || (exp->ex_flags & NFSEXP_NOSUBTREECHECK)) fh->ofh_dirino = 0; } 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_inode->i_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 0; /* FALL THROUGH */ 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 0; /* fall through */ case FSID_UUID4_INUM: case FSID_UUID16_INUM: return exp->ex_uuid != NULL; } return 1; } 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. * Currently, that means that if ref_fh->fh_handle.fh_version == 0xca * Then create a 32byte filehandle using nfs_fhbase_old * */ struct inode * inode = dentry->d_inode; struct dentry *parent = dentry->d_parent; __u32 *datap; dev_t ex_dev = exp_sb(exp)->s_dev; dprintk("nfsd: fh_compose(exp %02x:%02x/%ld %s/%s, ino=%ld)\n", MAJOR(ex_dev), MINOR(ex_dev), (long) exp->ex_path.dentry->d_inode->i_ino, parent->d_name.name, dentry->d_name.name, (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 (ref_fh == fhp) fh_put(ref_fh); if (fhp->fh_locked || fhp->fh_dentry) { printk(KERN_ERR "fh_compose: fh %s/%s not initialized!\n", parent->d_name.name, dentry->d_name.name); } if (fhp->fh_maxsize < NFS_FHSIZE) printk(KERN_ERR "fh_compose: called with maxsize %d! %s/%s\n", fhp->fh_maxsize, parent->d_name.name, dentry->d_name.name); fhp->fh_dentry = dget(dentry); /* our internal copy */ fhp->fh_export = exp; cache_get(&exp->h); if (fhp->fh_handle.fh_version == 0xca) { /* old style filehandle please */ memset(&fhp->fh_handle.fh_base, 0, NFS_FHSIZE); fhp->fh_handle.fh_size = NFS_FHSIZE; fhp->fh_handle.ofh_dcookie = 0xfeebbaca; fhp->fh_handle.ofh_dev = old_encode_dev(ex_dev); fhp->fh_handle.ofh_xdev = fhp->fh_handle.ofh_dev; fhp->fh_handle.ofh_xino = ino_t_to_u32(exp->ex_path.dentry->d_inode->i_ino); fhp->fh_handle.ofh_dirino = ino_t_to_u32(parent_ino(dentry)); if (inode) _fh_update_old(dentry, exp, &fhp->fh_handle); } else { int len; fhp->fh_handle.fh_auth_type = 0; datap = fhp->fh_handle.fh_auth+0; mk_fsid(fhp->fh_handle.fh_fsid_type, datap, ex_dev, exp->ex_path.dentry->d_inode->i_ino, exp->ex_fsid, exp->ex_uuid); len = key_len(fhp->fh_handle.fh_fsid_type); datap += len/4; fhp->fh_handle.fh_size = 4 + len; if (inode) _fh_update(fhp, exp, dentry); if (fhp->fh_handle.fh_fileid_type == 255) { fh_put(fhp); return nfserr_opnotsupp; } } 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 (!dentry->d_inode) goto out_negative; if (fhp->fh_handle.fh_version != 1) { _fh_update_old(dentry, fhp->fh_export, &fhp->fh_handle); } else { if (fhp->fh_handle.fh_fileid_type != FILEID_ROOT) goto out; _fh_update(fhp, fhp->fh_export, dentry); if (fhp->fh_handle.fh_fileid_type == 255) return nfserr_opnotsupp; } out: return 0; out_bad: printk(KERN_ERR "fh_update: fh not verified!\n"); goto out; out_negative: printk(KERN_ERR "fh_update: %s/%s still negative!\n", dentry->d_parent->d_name.name, dentry->d_name.name); goto out; } /* * 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) { fh_unlock(fhp); fhp->fh_dentry = NULL; dput(dentry); #ifdef CONFIG_NFSD_V3 fhp->fh_pre_saved = 0; fhp->fh_post_saved = 0; #endif } if (exp) { cache_put(&exp->h, &svc_export_cache); fhp->fh_export = NULL; } return; } /* * Shorthand for dprintk()'s */ char * SVCFH_fmt(struct svc_fh *fhp) { struct knfsd_fh *fh = &fhp->fh_handle; static char buf[80]; sprintf(buf, "%d: %08x %08x %08x %08x %08x %08x", fh->fh_size, fh->fh_base.fh_pad[0], fh->fh_base.fh_pad[1], fh->fh_base.fh_pad[2], fh->fh_base.fh_pad[3], fh->fh_base.fh_pad[4], fh->fh_base.fh_pad[5]); return buf; } enum fsid_source fsid_source(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; }