linux/fs/nfsd/nfs2acl.c
Ben Hutchings 999653786d nfsd: check permissions when setting ACLs
Use set_posix_acl, which includes proper permission checks, instead of
calling ->set_acl directly.  Without this anyone may be able to grant
themselves permissions to a file by setting the ACL.

Lock the inode to make the new checks atomic with respect to set_acl.
(Also, nfsd was the only caller of set_acl not locking the inode, so I
suspect this may fix other races.)

This also simplifies the code, and ensures our ACLs are checked by
posix_acl_valid.

The permission checks and the inode locking were lost with commit
4ac7249e, which changed nfsd to use the set_acl inode operation directly
instead of going through xattr handlers.

Reported-by: David Sinquin <david@sinquin.eu>
[agreunba@redhat.com: use set_posix_acl]
Fixes: 4ac7249e
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
2016-06-24 12:11:52 -04:00

381 lines
8.9 KiB
C

/*
* Process version 2 NFSACL requests.
*
* Copyright (C) 2002-2003 Andreas Gruenbacher <agruen@suse.de>
*/
#include "nfsd.h"
/* FIXME: nfsacl.h is a broken header */
#include <linux/nfsacl.h>
#include <linux/gfp.h>
#include "cache.h"
#include "xdr3.h"
#include "vfs.h"
#define NFSDDBG_FACILITY NFSDDBG_PROC
#define RETURN_STATUS(st) { resp->status = (st); return (st); }
/*
* NULL call.
*/
static __be32
nfsacld_proc_null(struct svc_rqst *rqstp, void *argp, void *resp)
{
return nfs_ok;
}
/*
* Get the Access and/or Default ACL of a file.
*/
static __be32 nfsacld_proc_getacl(struct svc_rqst * rqstp,
struct nfsd3_getaclargs *argp, struct nfsd3_getaclres *resp)
{
struct posix_acl *acl;
struct inode *inode;
svc_fh *fh;
__be32 nfserr = 0;
dprintk("nfsd: GETACL(2acl) %s\n", SVCFH_fmt(&argp->fh));
fh = fh_copy(&resp->fh, &argp->fh);
nfserr = fh_verify(rqstp, &resp->fh, 0, NFSD_MAY_NOP);
if (nfserr)
RETURN_STATUS(nfserr);
inode = d_inode(fh->fh_dentry);
if (argp->mask & ~NFS_ACL_MASK)
RETURN_STATUS(nfserr_inval);
resp->mask = argp->mask;
nfserr = fh_getattr(fh, &resp->stat);
if (nfserr)
RETURN_STATUS(nfserr);
if (resp->mask & (NFS_ACL|NFS_ACLCNT)) {
acl = get_acl(inode, ACL_TYPE_ACCESS);
if (acl == NULL) {
/* Solaris returns the inode's minimum ACL. */
acl = posix_acl_from_mode(inode->i_mode, GFP_KERNEL);
}
if (IS_ERR(acl)) {
nfserr = nfserrno(PTR_ERR(acl));
goto fail;
}
resp->acl_access = acl;
}
if (resp->mask & (NFS_DFACL|NFS_DFACLCNT)) {
/* Check how Solaris handles requests for the Default ACL
of a non-directory! */
acl = get_acl(inode, ACL_TYPE_DEFAULT);
if (IS_ERR(acl)) {
nfserr = nfserrno(PTR_ERR(acl));
goto fail;
}
resp->acl_default = acl;
}
/* resp->acl_{access,default} are released in nfssvc_release_getacl. */
RETURN_STATUS(0);
fail:
posix_acl_release(resp->acl_access);
posix_acl_release(resp->acl_default);
RETURN_STATUS(nfserr);
}
/*
* Set the Access and/or Default ACL of a file.
*/
static __be32 nfsacld_proc_setacl(struct svc_rqst * rqstp,
struct nfsd3_setaclargs *argp,
struct nfsd_attrstat *resp)
{
struct inode *inode;
svc_fh *fh;
__be32 nfserr = 0;
int error;
dprintk("nfsd: SETACL(2acl) %s\n", SVCFH_fmt(&argp->fh));
fh = fh_copy(&resp->fh, &argp->fh);
nfserr = fh_verify(rqstp, &resp->fh, 0, NFSD_MAY_SATTR);
if (nfserr)
goto out;
inode = d_inode(fh->fh_dentry);
error = fh_want_write(fh);
if (error)
goto out_errno;
fh_lock(fh);
error = set_posix_acl(inode, ACL_TYPE_ACCESS, argp->acl_access);
if (error)
goto out_drop_lock;
error = set_posix_acl(inode, ACL_TYPE_DEFAULT, argp->acl_default);
if (error)
goto out_drop_lock;
fh_unlock(fh);
fh_drop_write(fh);
nfserr = fh_getattr(fh, &resp->stat);
out:
/* argp->acl_{access,default} may have been allocated in
nfssvc_decode_setaclargs. */
posix_acl_release(argp->acl_access);
posix_acl_release(argp->acl_default);
return nfserr;
out_drop_lock:
fh_unlock(fh);
fh_drop_write(fh);
out_errno:
nfserr = nfserrno(error);
goto out;
}
/*
* Check file attributes
*/
static __be32 nfsacld_proc_getattr(struct svc_rqst * rqstp,
struct nfsd_fhandle *argp, struct nfsd_attrstat *resp)
{
__be32 nfserr;
dprintk("nfsd: GETATTR %s\n", SVCFH_fmt(&argp->fh));
fh_copy(&resp->fh, &argp->fh);
nfserr = fh_verify(rqstp, &resp->fh, 0, NFSD_MAY_NOP);
if (nfserr)
return nfserr;
nfserr = fh_getattr(&resp->fh, &resp->stat);
return nfserr;
}
/*
* Check file access
*/
static __be32 nfsacld_proc_access(struct svc_rqst *rqstp, struct nfsd3_accessargs *argp,
struct nfsd3_accessres *resp)
{
__be32 nfserr;
dprintk("nfsd: ACCESS(2acl) %s 0x%x\n",
SVCFH_fmt(&argp->fh),
argp->access);
fh_copy(&resp->fh, &argp->fh);
resp->access = argp->access;
nfserr = nfsd_access(rqstp, &resp->fh, &resp->access, NULL);
if (nfserr)
return nfserr;
nfserr = fh_getattr(&resp->fh, &resp->stat);
return nfserr;
}
/*
* XDR decode functions
*/
static int nfsaclsvc_decode_getaclargs(struct svc_rqst *rqstp, __be32 *p,
struct nfsd3_getaclargs *argp)
{
p = nfs2svc_decode_fh(p, &argp->fh);
if (!p)
return 0;
argp->mask = ntohl(*p); p++;
return xdr_argsize_check(rqstp, p);
}
static int nfsaclsvc_decode_setaclargs(struct svc_rqst *rqstp, __be32 *p,
struct nfsd3_setaclargs *argp)
{
struct kvec *head = rqstp->rq_arg.head;
unsigned int base;
int n;
p = nfs2svc_decode_fh(p, &argp->fh);
if (!p)
return 0;
argp->mask = ntohl(*p++);
if (argp->mask & ~NFS_ACL_MASK ||
!xdr_argsize_check(rqstp, p))
return 0;
base = (char *)p - (char *)head->iov_base;
n = nfsacl_decode(&rqstp->rq_arg, base, NULL,
(argp->mask & NFS_ACL) ?
&argp->acl_access : NULL);
if (n > 0)
n = nfsacl_decode(&rqstp->rq_arg, base + n, NULL,
(argp->mask & NFS_DFACL) ?
&argp->acl_default : NULL);
return (n > 0);
}
static int nfsaclsvc_decode_fhandleargs(struct svc_rqst *rqstp, __be32 *p,
struct nfsd_fhandle *argp)
{
p = nfs2svc_decode_fh(p, &argp->fh);
if (!p)
return 0;
return xdr_argsize_check(rqstp, p);
}
static int nfsaclsvc_decode_accessargs(struct svc_rqst *rqstp, __be32 *p,
struct nfsd3_accessargs *argp)
{
p = nfs2svc_decode_fh(p, &argp->fh);
if (!p)
return 0;
argp->access = ntohl(*p++);
return xdr_argsize_check(rqstp, p);
}
/*
* XDR encode functions
*/
/*
* There must be an encoding function for void results so svc_process
* will work properly.
*/
static int nfsaclsvc_encode_voidres(struct svc_rqst *rqstp, __be32 *p, void *dummy)
{
return xdr_ressize_check(rqstp, p);
}
/* GETACL */
static int nfsaclsvc_encode_getaclres(struct svc_rqst *rqstp, __be32 *p,
struct nfsd3_getaclres *resp)
{
struct dentry *dentry = resp->fh.fh_dentry;
struct inode *inode;
struct kvec *head = rqstp->rq_res.head;
unsigned int base;
int n;
int w;
/*
* Since this is version 2, the check for nfserr in
* nfsd_dispatch actually ensures the following cannot happen.
* However, it seems fragile to depend on that.
*/
if (dentry == NULL || d_really_is_negative(dentry))
return 0;
inode = d_inode(dentry);
p = nfs2svc_encode_fattr(rqstp, p, &resp->fh, &resp->stat);
*p++ = htonl(resp->mask);
if (!xdr_ressize_check(rqstp, p))
return 0;
base = (char *)p - (char *)head->iov_base;
rqstp->rq_res.page_len = w = nfsacl_size(
(resp->mask & NFS_ACL) ? resp->acl_access : NULL,
(resp->mask & NFS_DFACL) ? resp->acl_default : NULL);
while (w > 0) {
if (!*(rqstp->rq_next_page++))
return 0;
w -= PAGE_SIZE;
}
n = nfsacl_encode(&rqstp->rq_res, base, inode,
resp->acl_access,
resp->mask & NFS_ACL, 0);
if (n > 0)
n = nfsacl_encode(&rqstp->rq_res, base + n, inode,
resp->acl_default,
resp->mask & NFS_DFACL,
NFS_ACL_DEFAULT);
return (n > 0);
}
static int nfsaclsvc_encode_attrstatres(struct svc_rqst *rqstp, __be32 *p,
struct nfsd_attrstat *resp)
{
p = nfs2svc_encode_fattr(rqstp, p, &resp->fh, &resp->stat);
return xdr_ressize_check(rqstp, p);
}
/* ACCESS */
static int nfsaclsvc_encode_accessres(struct svc_rqst *rqstp, __be32 *p,
struct nfsd3_accessres *resp)
{
p = nfs2svc_encode_fattr(rqstp, p, &resp->fh, &resp->stat);
*p++ = htonl(resp->access);
return xdr_ressize_check(rqstp, p);
}
/*
* XDR release functions
*/
static int nfsaclsvc_release_getacl(struct svc_rqst *rqstp, __be32 *p,
struct nfsd3_getaclres *resp)
{
fh_put(&resp->fh);
posix_acl_release(resp->acl_access);
posix_acl_release(resp->acl_default);
return 1;
}
static int nfsaclsvc_release_attrstat(struct svc_rqst *rqstp, __be32 *p,
struct nfsd_attrstat *resp)
{
fh_put(&resp->fh);
return 1;
}
static int nfsaclsvc_release_access(struct svc_rqst *rqstp, __be32 *p,
struct nfsd3_accessres *resp)
{
fh_put(&resp->fh);
return 1;
}
#define nfsaclsvc_decode_voidargs NULL
#define nfsaclsvc_release_void NULL
#define nfsd3_fhandleargs nfsd_fhandle
#define nfsd3_attrstatres nfsd_attrstat
#define nfsd3_voidres nfsd3_voidargs
struct nfsd3_voidargs { int dummy; };
#define PROC(name, argt, rest, relt, cache, respsize) \
{ (svc_procfunc) nfsacld_proc_##name, \
(kxdrproc_t) nfsaclsvc_decode_##argt##args, \
(kxdrproc_t) nfsaclsvc_encode_##rest##res, \
(kxdrproc_t) nfsaclsvc_release_##relt, \
sizeof(struct nfsd3_##argt##args), \
sizeof(struct nfsd3_##rest##res), \
0, \
cache, \
respsize, \
}
#define ST 1 /* status*/
#define AT 21 /* attributes */
#define pAT (1+AT) /* post attributes - conditional */
#define ACL (1+NFS_ACL_MAX_ENTRIES*3) /* Access Control List */
static struct svc_procedure nfsd_acl_procedures2[] = {
PROC(null, void, void, void, RC_NOCACHE, ST),
PROC(getacl, getacl, getacl, getacl, RC_NOCACHE, ST+1+2*(1+ACL)),
PROC(setacl, setacl, attrstat, attrstat, RC_NOCACHE, ST+AT),
PROC(getattr, fhandle, attrstat, attrstat, RC_NOCACHE, ST+AT),
PROC(access, access, access, access, RC_NOCACHE, ST+AT+1),
};
struct svc_version nfsd_acl_version2 = {
.vs_vers = 2,
.vs_nproc = 5,
.vs_proc = nfsd_acl_procedures2,
.vs_dispatch = nfsd_dispatch,
.vs_xdrsize = NFS3_SVC_XDRSIZE,
.vs_hidden = 0,
};