NFS: use secinfo when crossing mountpoints
Bryan Schumaker [Thu, 24 Mar 2011 17:12:30 +0000 (17:12 +0000)]
A submount may use different security than the parent
mount does.  We should figure out what sec flavor the
submount uses at mount time.

Signed-off-by: Bryan Schumaker <bjschuma@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/inode.c
fs/nfs/internal.h
fs/nfs/namespace.c
fs/nfs/nfs4proc.c
fs/nfs/nfs4xdr.c
include/linux/nfs_xdr.h
net/sunrpc/auth_gss/gss_mech_switch.c

index 01768e5..058d7d6 100644 (file)
@@ -254,7 +254,9 @@ nfs_fhget(struct super_block *sb, struct nfs_fh *fh, struct nfs_fattr *fattr)
        struct inode *inode = ERR_PTR(-ENOENT);
        unsigned long hash;
 
-       if ((fattr->valid & NFS_ATTR_FATTR_FILEID) == 0)
+       nfs_attr_check_mountpoint(sb, fattr);
+
+       if ((fattr->valid & NFS_ATTR_FATTR_FILEID) == 0 && (fattr->valid & NFS_ATTR_FATTR_MOUNTPOINT) == 0)
                goto out_no_inode;
        if ((fattr->valid & NFS_ATTR_FATTR_TYPE) == 0)
                goto out_no_inode;
@@ -298,8 +300,8 @@ nfs_fhget(struct super_block *sb, struct nfs_fh *fh, struct nfs_fattr *fattr)
                        if (nfs_server_capable(inode, NFS_CAP_READDIRPLUS))
                                set_bit(NFS_INO_ADVISE_RDPLUS, &NFS_I(inode)->flags);
                        /* Deal with crossing mountpoints */
-                       if ((fattr->valid & NFS_ATTR_FATTR_FSID)
-                                       && !nfs_fsid_equal(&NFS_SB(sb)->fsid, &fattr->fsid)) {
+                       if (fattr->valid & NFS_ATTR_FATTR_MOUNTPOINT ||
+                                       fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL) {
                                if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL)
                                        inode->i_op = &nfs_referral_inode_operations;
                                else
index 1ec5d06..345d86b 100644 (file)
@@ -39,6 +39,12 @@ static inline int nfs4_has_persistent_session(const struct nfs_client *clp)
        return 0;
 }
 
+static inline void nfs_attr_check_mountpoint(struct super_block *parent, struct nfs_fattr *fattr)
+{
+       if (!nfs_fsid_equal(&NFS_SB(parent)->fsid, &fattr->fsid))
+               fattr->valid |= NFS_ATTR_FATTR_MOUNTPOINT;
+}
+
 struct nfs_clone_mount {
        const struct super_block *sb;
        const struct dentry *dentry;
@@ -214,6 +220,7 @@ extern const u32 nfs41_maxwrite_overhead;
 /* nfs4proc.c */
 #ifdef CONFIG_NFS_V4
 extern struct rpc_procinfo nfs4_procedures[];
+void nfs_fixup_secinfo_attributes(struct nfs_fattr *, struct nfs_fh *);
 #endif
 
 extern int nfs4_init_ds_session(struct nfs_client *clp);
index b027208..ad92bf7 100644 (file)
@@ -15,6 +15,7 @@
 #include <linux/string.h>
 #include <linux/sunrpc/clnt.h>
 #include <linux/vfs.h>
+#include <linux/sunrpc/gss_api.h>
 #include "internal.h"
 
 #define NFSDBG_FACILITY                NFSDBG_VFS
@@ -27,7 +28,8 @@ int nfs_mountpoint_expiry_timeout = 500 * HZ;
 
 static struct vfsmount *nfs_do_submount(struct dentry *dentry,
                                        struct nfs_fh *fh,
-                                       struct nfs_fattr *fattr);
+                                       struct nfs_fattr *fattr,
+                                       rpc_authflavor_t authflavor);
 
 /*
  * nfs_path - reconstruct the path given an arbitrary dentry
@@ -116,6 +118,100 @@ Elong:
        return ERR_PTR(-ENAMETOOLONG);
 }
 
+#ifdef CONFIG_NFS_V4
+static rpc_authflavor_t nfs_find_best_sec(struct nfs4_secinfo_flavors *flavors, struct inode *inode)
+{
+       struct gss_api_mech *mech;
+       struct xdr_netobj oid;
+       int i;
+       rpc_authflavor_t pseudoflavor = RPC_AUTH_UNIX;
+
+       for (i = 0; i < flavors->num_flavors; i++) {
+               struct nfs4_secinfo_flavor *flavor;
+               flavor = &flavors->flavors[i];
+
+               if (flavor->flavor == RPC_AUTH_NULL || flavor->flavor == RPC_AUTH_UNIX) {
+                       pseudoflavor = flavor->flavor;
+                       break;
+               } else if (flavor->flavor == RPC_AUTH_GSS) {
+                       oid.len  = flavor->gss.sec_oid4.len;
+                       oid.data = flavor->gss.sec_oid4.data;
+                       mech = gss_mech_get_by_OID(&oid);
+                       if (!mech)
+                               continue;
+                       pseudoflavor = gss_svc_to_pseudoflavor(mech, flavor->gss.service);
+                       gss_mech_put(mech);
+                       break;
+               }
+       }
+
+       return pseudoflavor;
+}
+
+static rpc_authflavor_t nfs_negotiate_security(const struct dentry *parent, const struct dentry *dentry)
+{
+       int status = 0;
+       struct page *page;
+       struct nfs4_secinfo_flavors *flavors;
+       int (*secinfo)(struct inode *, const struct qstr *, struct nfs4_secinfo_flavors *);
+       rpc_authflavor_t flavor = RPC_AUTH_UNIX;
+
+       secinfo = NFS_PROTO(parent->d_inode)->secinfo;
+       if (secinfo != NULL) {
+               page = alloc_page(GFP_KERNEL);
+               if (!page) {
+                       status = -ENOMEM;
+                       goto out;
+               }
+               flavors = page_address(page);
+               status = secinfo(parent->d_inode, &dentry->d_name, flavors);
+               flavor = nfs_find_best_sec(flavors, dentry->d_inode);
+               put_page(page);
+       }
+
+       return flavor;
+
+out:
+       status = -ENOMEM;
+       return status;
+}
+
+static rpc_authflavor_t nfs_lookup_with_sec(struct nfs_server *server, struct dentry *parent,
+                                    struct dentry *dentry, struct path *path,
+                                    struct nfs_fh *fh, struct nfs_fattr *fattr)
+{
+       rpc_authflavor_t flavor;
+       struct rpc_clnt *clone;
+       struct rpc_auth *auth;
+       int err;
+
+       flavor = nfs_negotiate_security(parent, path->dentry);
+       if (flavor < 0)
+               goto out;
+       clone  = rpc_clone_client(server->client);
+       auth   = rpcauth_create(flavor, clone);
+       if (!auth) {
+               flavor = -EIO;
+               goto out;
+       }
+       err = server->nfs_client->rpc_ops->lookup(clone, parent->d_inode,
+                                                 &path->dentry->d_name,
+                                                 fh, fattr);
+       if (err < 0)
+               flavor = err;
+out:
+       return flavor;
+}
+#else /* CONFIG_NFS_V4 */
+static inline rpc_authflavor_t nfs_lookup_with_sec(struct nfs_server *server,
+                                    struct dentry *parent, struct dentry *dentry,
+                                    struct path *path, struct nfs_fh *fh,
+                                    struct nfs_fattr *fattr)
+{
+       return -EPERM;
+}
+#endif /* CONFIG_NFS_V4 */
+
 /*
  * nfs_d_automount - Handle crossing a mountpoint on the server
  * @path - The mountpoint
@@ -136,6 +232,7 @@ struct vfsmount *nfs_d_automount(struct path *path)
        struct nfs_fh *fh = NULL;
        struct nfs_fattr *fattr = NULL;
        int err;
+       rpc_authflavor_t flavor = 1;
 
        dprintk("--> nfs_d_automount()\n");
 
@@ -156,6 +253,13 @@ struct vfsmount *nfs_d_automount(struct path *path)
        err = server->nfs_client->rpc_ops->lookup(server->client, parent->d_inode,
                                                  &path->dentry->d_name,
                                                  fh, fattr);
+       if (err == -EPERM) {
+               flavor = nfs_lookup_with_sec(server, parent, path->dentry, path, fh, fattr);
+               if (flavor < 0)
+                       err = flavor;
+               else
+                       err = 0;
+       }
        dput(parent);
        if (err != 0) {
                mnt = ERR_PTR(err);
@@ -165,7 +269,7 @@ struct vfsmount *nfs_d_automount(struct path *path)
        if (fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL)
                mnt = nfs_do_refmount(path->dentry);
        else
-               mnt = nfs_do_submount(path->dentry, fh, fattr);
+               mnt = nfs_do_submount(path->dentry, fh, fattr, flavor);
        if (IS_ERR(mnt))
                goto out;
 
@@ -232,17 +336,20 @@ static struct vfsmount *nfs_do_clone_mount(struct nfs_server *server,
  * @dentry - parent directory
  * @fh - filehandle for new root dentry
  * @fattr - attributes for new root inode
+ * @authflavor - security flavor to use when performing the mount
  *
  */
 static struct vfsmount *nfs_do_submount(struct dentry *dentry,
                                        struct nfs_fh *fh,
-                                       struct nfs_fattr *fattr)
+                                       struct nfs_fattr *fattr,
+                                       rpc_authflavor_t authflavor)
 {
        struct nfs_clone_mount mountdata = {
                .sb = dentry->d_sb,
                .dentry = dentry,
                .fh = fh,
                .fattr = fattr,
+               .authflavor = authflavor,
        };
        struct vfsmount *mnt = ERR_PTR(-ENOMEM);
        char *page = (char *) __get_free_page(GFP_USER);
index 0b8bae1..5634637 100644 (file)
@@ -87,6 +87,8 @@ static int nfs4_map_errors(int err)
        switch (err) {
        case -NFS4ERR_RESOURCE:
                return -EREMOTEIO;
+       case -NFS4ERR_WRONGSEC:
+               return -EPERM;
        case -NFS4ERR_BADOWNER:
        case -NFS4ERR_BADNAME:
                return -EINVAL;
@@ -2383,6 +2385,16 @@ static int _nfs4_proc_lookup(struct rpc_clnt *clnt, struct inode *dir,
        return status;
 }
 
+void nfs_fixup_secinfo_attributes(struct nfs_fattr *fattr, struct nfs_fh *fh)
+{
+       memset(fh, 0, sizeof(struct nfs_fh));
+       fattr->fsid.major = 1;
+       fattr->valid |= NFS_ATTR_FATTR_TYPE | NFS_ATTR_FATTR_MODE |
+               NFS_ATTR_FATTR_NLINK | NFS_ATTR_FATTR_FSID | NFS_ATTR_FATTR_MOUNTPOINT;
+       fattr->mode = S_IFDIR | S_IRUGO | S_IXUGO;
+       fattr->nlink = 2;
+}
+
 static int nfs4_proc_lookup(struct rpc_clnt *clnt, struct inode *dir, struct qstr *name,
                            struct nfs_fh *fhandle, struct nfs_fattr *fattr)
 {
@@ -2392,6 +2404,8 @@ static int nfs4_proc_lookup(struct rpc_clnt *clnt, struct inode *dir, struct qst
                err = nfs4_handle_exception(NFS_SERVER(dir),
                                _nfs4_proc_lookup(clnt, dir, name, fhandle, fattr),
                                &exception);
+               if (err == -EPERM)
+                       nfs_fixup_secinfo_attributes(fattr, fhandle);
        } while (exception.retry);
        return err;
 }
index 98afcf9..21c3004 100644 (file)
@@ -113,7 +113,7 @@ static int nfs4_stat_to_errno(int);
 #define encode_restorefh_maxsz  (op_encode_hdr_maxsz)
 #define decode_restorefh_maxsz  (op_decode_hdr_maxsz)
 #define encode_fsinfo_maxsz    (encode_getattr_maxsz)
-#define decode_fsinfo_maxsz    (op_decode_hdr_maxsz + 11)
+#define decode_fsinfo_maxsz    (op_decode_hdr_maxsz + 15)
 #define encode_renew_maxsz     (op_encode_hdr_maxsz + 3)
 #define decode_renew_maxsz     (op_decode_hdr_maxsz)
 #define encode_setclientid_maxsz \
@@ -2966,6 +2966,7 @@ static int decode_attr_error(struct xdr_stream *xdr, uint32_t *bitmap)
                if (unlikely(!p))
                        goto out_overflow;
                bitmap[0] &= ~FATTR4_WORD0_RDATTR_ERROR;
+               return -be32_to_cpup(p);
        }
        return 0;
 out_overflow:
@@ -3953,6 +3954,10 @@ static int decode_getfattr_attrs(struct xdr_stream *xdr, uint32_t *bitmap,
        fattr->valid |= status;
 
        status = decode_attr_error(xdr, bitmap);
+       if (status == -NFS4ERR_WRONGSEC) {
+               nfs_fixup_secinfo_attributes(fattr, fh);
+               status = 0;
+       }
        if (status < 0)
                goto xdr_error;
 
@@ -6314,10 +6319,6 @@ static struct {
        { NFS4ERR_SYMLINK,      -ELOOP          },
        { NFS4ERR_OP_ILLEGAL,   -EOPNOTSUPP     },
        { NFS4ERR_DEADLOCK,     -EDEADLK        },
-       { NFS4ERR_WRONGSEC,     -EPERM          }, /* FIXME: this needs
-                                                   * to be handled by a
-                                                   * middle-layer.
-                                                   */
        { -1,                   -EIO            }
 };
 
index 3f32bf1..fa1ba78 100644 (file)
@@ -82,6 +82,7 @@ struct nfs_fattr {
 #define NFS_ATTR_FATTR_CHANGE          (1U << 17)
 #define NFS_ATTR_FATTR_PRECHANGE       (1U << 18)
 #define NFS_ATTR_FATTR_V4_REFERRAL     (1U << 19)      /* NFSv4 referral */
+#define NFS_ATTR_FATTR_MOUNTPOINT      (1U << 20)      /* Treat as mountpoint */
 
 #define NFS_ATTR_FATTR (NFS_ATTR_FATTR_TYPE \
                | NFS_ATTR_FATTR_MODE \
index 8b40610..6c844b0 100644 (file)
@@ -160,6 +160,28 @@ gss_mech_get_by_name(const char *name)
 
 EXPORT_SYMBOL_GPL(gss_mech_get_by_name);
 
+struct gss_api_mech *
+gss_mech_get_by_OID(struct xdr_netobj *obj)
+{
+       struct gss_api_mech     *pos, *gm = NULL;
+
+       spin_lock(&registered_mechs_lock);
+       list_for_each_entry(pos, &registered_mechs, gm_list) {
+               if (obj->len == pos->gm_oid.len) {
+                       if (0 == memcmp(obj->data, pos->gm_oid.data, obj->len)) {
+                               if (try_module_get(pos->gm_owner))
+                                       gm = pos;
+                               break;
+                       }
+               }
+       }
+       spin_unlock(&registered_mechs_lock);
+       return gm;
+
+}
+
+EXPORT_SYMBOL_GPL(gss_mech_get_by_OID);
+
 static inline int
 mech_supports_pseudoflavor(struct gss_api_mech *gm, u32 pseudoflavor)
 {