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138060ba92
The current way of setting and getting posix acls through the generic xattr interface is error prone and type unsafe. The vfs needs to interpret and fixup posix acls before storing or reporting it to userspace. Various hacks exist to make this work. The code is hard to understand and difficult to maintain in it's current form. Instead of making this work by hacking posix acls through xattr handlers we are building a dedicated posix acl api around the get and set inode operations. This removes a lot of hackiness and makes the codepaths easier to maintain. A lot of background can be found in [1]. Since some filesystem rely on the dentry being available to them when setting posix acls (e.g., 9p and cifs) they cannot rely on set acl inode operation. But since ->set_acl() is required in order to use the generic posix acl xattr handlers filesystems that do not implement this inode operation cannot use the handler and need to implement their own dedicated posix acl handlers. Update the ->set_acl() inode method to take a dentry argument. This allows all filesystems to rely on ->set_acl(). As far as I can tell all codepaths can be switched to rely on the dentry instead of just the inode. Note that the original motivation for passing the dentry separate from the inode instead of just the dentry in the xattr handlers was because of security modules that call security_d_instantiate(). This hook is called during d_instantiate_new(), d_add(), __d_instantiate_anon(), and d_splice_alias() to initialize the inode's security context and possibly to set security.* xattrs. Since this only affects security.* xattrs this is completely irrelevant for posix acls. Link: https://lore.kernel.org/all/20220801145520.1532837-1-brauner@kernel.org [1] Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
297 lines
7.1 KiB
C
297 lines
7.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Process version 3 NFSACL requests.
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*
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* Copyright (C) 2002-2003 Andreas Gruenbacher <agruen@suse.de>
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*/
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#include "nfsd.h"
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/* FIXME: nfsacl.h is a broken header */
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#include <linux/nfsacl.h>
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#include <linux/gfp.h>
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#include "cache.h"
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#include "xdr3.h"
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#include "vfs.h"
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/*
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* NULL call.
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*/
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static __be32
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nfsd3_proc_null(struct svc_rqst *rqstp)
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{
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return rpc_success;
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}
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/*
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* Get the Access and/or Default ACL of a file.
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*/
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static __be32 nfsd3_proc_getacl(struct svc_rqst *rqstp)
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{
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struct nfsd3_getaclargs *argp = rqstp->rq_argp;
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struct nfsd3_getaclres *resp = rqstp->rq_resp;
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struct posix_acl *acl;
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struct inode *inode;
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svc_fh *fh;
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fh = fh_copy(&resp->fh, &argp->fh);
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resp->status = fh_verify(rqstp, &resp->fh, 0, NFSD_MAY_NOP);
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if (resp->status != nfs_ok)
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goto out;
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inode = d_inode(fh->fh_dentry);
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if (argp->mask & ~NFS_ACL_MASK) {
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resp->status = nfserr_inval;
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goto out;
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}
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resp->mask = argp->mask;
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if (resp->mask & (NFS_ACL|NFS_ACLCNT)) {
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acl = get_acl(inode, ACL_TYPE_ACCESS);
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if (acl == NULL) {
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/* Solaris returns the inode's minimum ACL. */
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acl = posix_acl_from_mode(inode->i_mode, GFP_KERNEL);
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}
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if (IS_ERR(acl)) {
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resp->status = nfserrno(PTR_ERR(acl));
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goto fail;
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}
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resp->acl_access = acl;
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}
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if (resp->mask & (NFS_DFACL|NFS_DFACLCNT)) {
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/* Check how Solaris handles requests for the Default ACL
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of a non-directory! */
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acl = get_acl(inode, ACL_TYPE_DEFAULT);
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if (IS_ERR(acl)) {
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resp->status = nfserrno(PTR_ERR(acl));
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goto fail;
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}
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resp->acl_default = acl;
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}
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/* resp->acl_{access,default} are released in nfs3svc_release_getacl. */
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out:
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return rpc_success;
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fail:
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posix_acl_release(resp->acl_access);
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posix_acl_release(resp->acl_default);
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goto out;
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}
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/*
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* Set the Access and/or Default ACL of a file.
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*/
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static __be32 nfsd3_proc_setacl(struct svc_rqst *rqstp)
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{
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struct nfsd3_setaclargs *argp = rqstp->rq_argp;
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struct nfsd3_attrstat *resp = rqstp->rq_resp;
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struct inode *inode;
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svc_fh *fh;
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int error;
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fh = fh_copy(&resp->fh, &argp->fh);
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resp->status = fh_verify(rqstp, &resp->fh, 0, NFSD_MAY_SATTR);
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if (resp->status != nfs_ok)
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goto out;
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inode = d_inode(fh->fh_dentry);
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error = fh_want_write(fh);
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if (error)
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goto out_errno;
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inode_lock(inode);
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error = set_posix_acl(&init_user_ns, fh->fh_dentry, ACL_TYPE_ACCESS,
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argp->acl_access);
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if (error)
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goto out_drop_lock;
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error = set_posix_acl(&init_user_ns, fh->fh_dentry, ACL_TYPE_DEFAULT,
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argp->acl_default);
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out_drop_lock:
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inode_unlock(inode);
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fh_drop_write(fh);
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out_errno:
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resp->status = nfserrno(error);
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out:
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/* argp->acl_{access,default} may have been allocated in
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nfs3svc_decode_setaclargs. */
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posix_acl_release(argp->acl_access);
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posix_acl_release(argp->acl_default);
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return rpc_success;
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}
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/*
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* XDR decode functions
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*/
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static bool
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nfs3svc_decode_getaclargs(struct svc_rqst *rqstp, struct xdr_stream *xdr)
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{
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struct nfsd3_getaclargs *args = rqstp->rq_argp;
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if (!svcxdr_decode_nfs_fh3(xdr, &args->fh))
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return false;
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if (xdr_stream_decode_u32(xdr, &args->mask) < 0)
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return false;
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return true;
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}
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static bool
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nfs3svc_decode_setaclargs(struct svc_rqst *rqstp, struct xdr_stream *xdr)
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{
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struct nfsd3_setaclargs *argp = rqstp->rq_argp;
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if (!svcxdr_decode_nfs_fh3(xdr, &argp->fh))
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return false;
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if (xdr_stream_decode_u32(xdr, &argp->mask) < 0)
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return false;
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if (argp->mask & ~NFS_ACL_MASK)
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return false;
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if (!nfs_stream_decode_acl(xdr, NULL, (argp->mask & NFS_ACL) ?
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&argp->acl_access : NULL))
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return false;
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if (!nfs_stream_decode_acl(xdr, NULL, (argp->mask & NFS_DFACL) ?
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&argp->acl_default : NULL))
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return false;
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return true;
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}
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/*
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* XDR encode functions
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*/
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/* GETACL */
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static bool
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nfs3svc_encode_getaclres(struct svc_rqst *rqstp, struct xdr_stream *xdr)
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{
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struct nfsd3_getaclres *resp = rqstp->rq_resp;
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struct dentry *dentry = resp->fh.fh_dentry;
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struct kvec *head = rqstp->rq_res.head;
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struct inode *inode;
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unsigned int base;
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int n;
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int w;
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if (!svcxdr_encode_nfsstat3(xdr, resp->status))
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return false;
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switch (resp->status) {
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case nfs_ok:
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inode = d_inode(dentry);
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if (!svcxdr_encode_post_op_attr(rqstp, xdr, &resp->fh))
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return false;
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if (xdr_stream_encode_u32(xdr, resp->mask) < 0)
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return false;
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base = (char *)xdr->p - (char *)head->iov_base;
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rqstp->rq_res.page_len = w = nfsacl_size(
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(resp->mask & NFS_ACL) ? resp->acl_access : NULL,
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(resp->mask & NFS_DFACL) ? resp->acl_default : NULL);
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while (w > 0) {
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if (!*(rqstp->rq_next_page++))
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return false;
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w -= PAGE_SIZE;
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}
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n = nfsacl_encode(&rqstp->rq_res, base, inode,
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resp->acl_access,
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resp->mask & NFS_ACL, 0);
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if (n > 0)
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n = nfsacl_encode(&rqstp->rq_res, base + n, inode,
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resp->acl_default,
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resp->mask & NFS_DFACL,
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NFS_ACL_DEFAULT);
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if (n <= 0)
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return false;
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break;
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default:
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if (!svcxdr_encode_post_op_attr(rqstp, xdr, &resp->fh))
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return false;
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}
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return true;
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}
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/* SETACL */
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static bool
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nfs3svc_encode_setaclres(struct svc_rqst *rqstp, struct xdr_stream *xdr)
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{
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struct nfsd3_attrstat *resp = rqstp->rq_resp;
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return svcxdr_encode_nfsstat3(xdr, resp->status) &&
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svcxdr_encode_post_op_attr(rqstp, xdr, &resp->fh);
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}
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/*
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* XDR release functions
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*/
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static void nfs3svc_release_getacl(struct svc_rqst *rqstp)
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{
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struct nfsd3_getaclres *resp = rqstp->rq_resp;
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fh_put(&resp->fh);
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posix_acl_release(resp->acl_access);
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posix_acl_release(resp->acl_default);
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}
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struct nfsd3_voidargs { int dummy; };
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#define ST 1 /* status*/
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#define AT 21 /* attributes */
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#define pAT (1+AT) /* post attributes - conditional */
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#define ACL (1+NFS_ACL_MAX_ENTRIES*3) /* Access Control List */
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static const struct svc_procedure nfsd_acl_procedures3[3] = {
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[ACLPROC3_NULL] = {
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.pc_func = nfsd3_proc_null,
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.pc_decode = nfssvc_decode_voidarg,
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.pc_encode = nfssvc_encode_voidres,
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.pc_argsize = sizeof(struct nfsd_voidargs),
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.pc_argzero = sizeof(struct nfsd_voidargs),
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.pc_ressize = sizeof(struct nfsd_voidres),
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.pc_cachetype = RC_NOCACHE,
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.pc_xdrressize = ST,
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.pc_name = "NULL",
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},
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[ACLPROC3_GETACL] = {
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.pc_func = nfsd3_proc_getacl,
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.pc_decode = nfs3svc_decode_getaclargs,
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.pc_encode = nfs3svc_encode_getaclres,
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.pc_release = nfs3svc_release_getacl,
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.pc_argsize = sizeof(struct nfsd3_getaclargs),
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.pc_argzero = sizeof(struct nfsd3_getaclargs),
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.pc_ressize = sizeof(struct nfsd3_getaclres),
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.pc_cachetype = RC_NOCACHE,
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.pc_xdrressize = ST+1+2*(1+ACL),
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.pc_name = "GETACL",
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},
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[ACLPROC3_SETACL] = {
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.pc_func = nfsd3_proc_setacl,
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.pc_decode = nfs3svc_decode_setaclargs,
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.pc_encode = nfs3svc_encode_setaclres,
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.pc_release = nfs3svc_release_fhandle,
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.pc_argsize = sizeof(struct nfsd3_setaclargs),
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.pc_argzero = sizeof(struct nfsd3_setaclargs),
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.pc_ressize = sizeof(struct nfsd3_attrstat),
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.pc_cachetype = RC_NOCACHE,
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.pc_xdrressize = ST+pAT,
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.pc_name = "SETACL",
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},
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};
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static unsigned int nfsd_acl_count3[ARRAY_SIZE(nfsd_acl_procedures3)];
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const struct svc_version nfsd_acl_version3 = {
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.vs_vers = 3,
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.vs_nproc = 3,
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.vs_proc = nfsd_acl_procedures3,
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.vs_count = nfsd_acl_count3,
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.vs_dispatch = nfsd_dispatch,
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.vs_xdrsize = NFS3_SVC_XDRSIZE,
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};
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