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linux-pinenote/fs/nfs/nfs3acl.c
Chuck Lever f61f6da0d5 NFS: Prevent memory allocation failure in nfsacl_encode() 
nfsacl_encode() allocates memory in certain cases.  This of course
is not guaranteed to work.

Since commit 9f06c719 "SUNRPC: New xdr_streams XDR encoder API", the
kernel's XDR encoders can't return a result indicating possibly a
failure, so a memory allocation failure in nfsacl_encode() has become
fatal (ie, the XDR code Oopses) in some cases.

However, the allocated memory is a tiny fixed amount, on the order
of 40-50 bytes.  We can easily use a stack-allocated buffer for
this, with only a wee bit of nose-holding.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2011-01-25 15:24:47 -05:00

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#include <linux/fs.h>
#include <linux/gfp.h>
#include <linux/nfs.h>
#include <linux/nfs3.h>
#include <linux/nfs_fs.h>
#include <linux/posix_acl_xattr.h>
#include <linux/nfsacl.h>
#include "internal.h"
#define NFSDBG_FACILITY NFSDBG_PROC
ssize_t nfs3_listxattr(struct dentry *dentry, char *buffer, size_t size)
{
struct inode *inode = dentry->d_inode;
struct posix_acl *acl;
int pos=0, len=0;
# define output(s) do { \
if (pos + sizeof(s) <= size) { \
memcpy(buffer + pos, s, sizeof(s)); \
pos += sizeof(s); \
} \
len += sizeof(s); \
} while(0)
acl = nfs3_proc_getacl(inode, ACL_TYPE_ACCESS);
if (IS_ERR(acl))
return PTR_ERR(acl);
if (acl) {
output("system.posix_acl_access");
posix_acl_release(acl);
}
if (S_ISDIR(inode->i_mode)) {
acl = nfs3_proc_getacl(inode, ACL_TYPE_DEFAULT);
if (IS_ERR(acl))
return PTR_ERR(acl);
if (acl) {
output("system.posix_acl_default");
posix_acl_release(acl);
}
}
# undef output
if (!buffer || len <= size)
return len;
return -ERANGE;
}
ssize_t nfs3_getxattr(struct dentry *dentry, const char *name,
void *buffer, size_t size)
{
struct inode *inode = dentry->d_inode;
struct posix_acl *acl;
int type, error = 0;
if (strcmp(name, POSIX_ACL_XATTR_ACCESS) == 0)
type = ACL_TYPE_ACCESS;
else if (strcmp(name, POSIX_ACL_XATTR_DEFAULT) == 0)
type = ACL_TYPE_DEFAULT;
else
return -EOPNOTSUPP;
acl = nfs3_proc_getacl(inode, type);
if (IS_ERR(acl))
return PTR_ERR(acl);
else if (acl) {
if (type == ACL_TYPE_ACCESS && acl->a_count == 0)
error = -ENODATA;
else
error = posix_acl_to_xattr(acl, buffer, size);
posix_acl_release(acl);
} else
error = -ENODATA;
return error;
}
int nfs3_setxattr(struct dentry *dentry, const char *name,
const void *value, size_t size, int flags)
{
struct inode *inode = dentry->d_inode;
struct posix_acl *acl;
int type, error;
if (strcmp(name, POSIX_ACL_XATTR_ACCESS) == 0)
type = ACL_TYPE_ACCESS;
else if (strcmp(name, POSIX_ACL_XATTR_DEFAULT) == 0)
type = ACL_TYPE_DEFAULT;
else
return -EOPNOTSUPP;
acl = posix_acl_from_xattr(value, size);
if (IS_ERR(acl))
return PTR_ERR(acl);
error = nfs3_proc_setacl(inode, type, acl);
posix_acl_release(acl);
return error;
}
int nfs3_removexattr(struct dentry *dentry, const char *name)
{
struct inode *inode = dentry->d_inode;
int type;
if (strcmp(name, POSIX_ACL_XATTR_ACCESS) == 0)
type = ACL_TYPE_ACCESS;
else if (strcmp(name, POSIX_ACL_XATTR_DEFAULT) == 0)
type = ACL_TYPE_DEFAULT;
else
return -EOPNOTSUPP;
return nfs3_proc_setacl(inode, type, NULL);
}
static void __nfs3_forget_cached_acls(struct nfs_inode *nfsi)
{
if (!IS_ERR(nfsi->acl_access)) {
posix_acl_release(nfsi->acl_access);
nfsi->acl_access = ERR_PTR(-EAGAIN);
}
if (!IS_ERR(nfsi->acl_default)) {
posix_acl_release(nfsi->acl_default);
nfsi->acl_default = ERR_PTR(-EAGAIN);
}
}
void nfs3_forget_cached_acls(struct inode *inode)
{
dprintk("NFS: nfs3_forget_cached_acls(%s/%ld)\n", inode->i_sb->s_id,
inode->i_ino);
spin_lock(&inode->i_lock);
__nfs3_forget_cached_acls(NFS_I(inode));
spin_unlock(&inode->i_lock);
}
static struct posix_acl *nfs3_get_cached_acl(struct inode *inode, int type)
{
struct nfs_inode *nfsi = NFS_I(inode);
struct posix_acl *acl = ERR_PTR(-EINVAL);
spin_lock(&inode->i_lock);
switch(type) {
case ACL_TYPE_ACCESS:
acl = nfsi->acl_access;
break;
case ACL_TYPE_DEFAULT:
acl = nfsi->acl_default;
break;
default:
goto out;
}
if (IS_ERR(acl))
acl = ERR_PTR(-EAGAIN);
else
acl = posix_acl_dup(acl);
out:
spin_unlock(&inode->i_lock);
dprintk("NFS: nfs3_get_cached_acl(%s/%ld, %d) = %p\n", inode->i_sb->s_id,
inode->i_ino, type, acl);
return acl;
}
static void nfs3_cache_acls(struct inode *inode, struct posix_acl *acl,
struct posix_acl *dfacl)
{
struct nfs_inode *nfsi = NFS_I(inode);
dprintk("nfs3_cache_acls(%s/%ld, %p, %p)\n", inode->i_sb->s_id,
inode->i_ino, acl, dfacl);
spin_lock(&inode->i_lock);
__nfs3_forget_cached_acls(NFS_I(inode));
if (!IS_ERR(acl))
nfsi->acl_access = posix_acl_dup(acl);
if (!IS_ERR(dfacl))
nfsi->acl_default = posix_acl_dup(dfacl);
spin_unlock(&inode->i_lock);
}
struct posix_acl *nfs3_proc_getacl(struct inode *inode, int type)
{
struct nfs_server *server = NFS_SERVER(inode);
struct page *pages[NFSACL_MAXPAGES] = { };
struct nfs3_getaclargs args = {
.fh = NFS_FH(inode),
/* The xdr layer may allocate pages here. */
.pages = pages,
};
struct nfs3_getaclres res = {
0
};
struct rpc_message msg = {
.rpc_argp = &args,
.rpc_resp = &res,
};
struct posix_acl *acl;
int status, count;
if (!nfs_server_capable(inode, NFS_CAP_ACLS))
return ERR_PTR(-EOPNOTSUPP);
status = nfs_revalidate_inode(server, inode);
if (status < 0)
return ERR_PTR(status);
acl = nfs3_get_cached_acl(inode, type);
if (acl != ERR_PTR(-EAGAIN))
return acl;
acl = NULL;
/*
* Only get the access acl when explicitly requested: We don't
* need it for access decisions, and only some applications use
* it. Applications which request the access acl first are not
* penalized from this optimization.
*/
if (type == ACL_TYPE_ACCESS)
args.mask |= NFS_ACLCNT|NFS_ACL;
if (S_ISDIR(inode->i_mode))
args.mask |= NFS_DFACLCNT|NFS_DFACL;
if (args.mask == 0)
return NULL;
dprintk("NFS call getacl\n");
msg.rpc_proc = &server->client_acl->cl_procinfo[ACLPROC3_GETACL];
res.fattr = nfs_alloc_fattr();
if (res.fattr == NULL)
return ERR_PTR(-ENOMEM);
status = rpc_call_sync(server->client_acl, &msg, 0);
dprintk("NFS reply getacl: %d\n", status);
/* pages may have been allocated at the xdr layer. */
for (count = 0; count < NFSACL_MAXPAGES && args.pages[count]; count++)
__free_page(args.pages[count]);
switch (status) {
case 0:
status = nfs_refresh_inode(inode, res.fattr);
break;
case -EPFNOSUPPORT:
case -EPROTONOSUPPORT:
dprintk("NFS_V3_ACL extension not supported; disabling\n");
server->caps &= ~NFS_CAP_ACLS;
case -ENOTSUPP:
status = -EOPNOTSUPP;
default:
goto getout;
}
if ((args.mask & res.mask) != args.mask) {
status = -EIO;
goto getout;
}
if (res.acl_access != NULL) {
if (posix_acl_equiv_mode(res.acl_access, NULL) == 0) {
posix_acl_release(res.acl_access);
res.acl_access = NULL;
}
}
nfs3_cache_acls(inode,
(res.mask & NFS_ACL) ? res.acl_access : ERR_PTR(-EINVAL),
(res.mask & NFS_DFACL) ? res.acl_default : ERR_PTR(-EINVAL));
switch(type) {
case ACL_TYPE_ACCESS:
acl = res.acl_access;
res.acl_access = NULL;
break;
case ACL_TYPE_DEFAULT:
acl = res.acl_default;
res.acl_default = NULL;
}
getout:
posix_acl_release(res.acl_access);
posix_acl_release(res.acl_default);
nfs_free_fattr(res.fattr);
if (status != 0) {
posix_acl_release(acl);
acl = ERR_PTR(status);
}
return acl;
}
static int nfs3_proc_setacls(struct inode *inode, struct posix_acl *acl,
struct posix_acl *dfacl)
{
struct nfs_server *server = NFS_SERVER(inode);
struct nfs_fattr *fattr;
struct page *pages[NFSACL_MAXPAGES];
struct nfs3_setaclargs args = {
.inode = inode,
.mask = NFS_ACL,
.acl_access = acl,
.pages = pages,
};
struct rpc_message msg = {
.rpc_argp = &args,
.rpc_resp = &fattr,
};
int status;
status = -EOPNOTSUPP;
if (!nfs_server_capable(inode, NFS_CAP_ACLS))
goto out;
/* We are doing this here because XDR marshalling does not
* return any results, it BUGs. */
status = -ENOSPC;
if (acl != NULL && acl->a_count > NFS_ACL_MAX_ENTRIES)
goto out;
if (dfacl != NULL && dfacl->a_count > NFS_ACL_MAX_ENTRIES)
goto out;
if (S_ISDIR(inode->i_mode)) {
args.mask |= NFS_DFACL;
args.acl_default = dfacl;
args.len = nfsacl_size(acl, dfacl);
} else
args.len = nfsacl_size(acl, NULL);
if (args.len > NFS_ACL_INLINE_BUFSIZE) {
unsigned int npages = 1 + ((args.len - 1) >> PAGE_SHIFT);
status = -ENOMEM;
do {
args.pages[args.npages] = alloc_page(GFP_KERNEL);
if (args.pages[args.npages] == NULL)
goto out_freepages;
args.npages++;
} while (args.npages < npages);
}
dprintk("NFS call setacl\n");
status = -ENOMEM;
fattr = nfs_alloc_fattr();
if (fattr == NULL)
goto out_freepages;
msg.rpc_proc = &server->client_acl->cl_procinfo[ACLPROC3_SETACL];
msg.rpc_resp = fattr;
status = rpc_call_sync(server->client_acl, &msg, 0);
nfs_access_zap_cache(inode);
nfs_zap_acl_cache(inode);
dprintk("NFS reply setacl: %d\n", status);
switch (status) {
case 0:
status = nfs_refresh_inode(inode, fattr);
nfs3_cache_acls(inode, acl, dfacl);
break;
case -EPFNOSUPPORT:
case -EPROTONOSUPPORT:
dprintk("NFS_V3_ACL SETACL RPC not supported"
"(will not retry)\n");
server->caps &= ~NFS_CAP_ACLS;
case -ENOTSUPP:
status = -EOPNOTSUPP;
}
nfs_free_fattr(fattr);
out_freepages:
while (args.npages != 0) {
args.npages--;
__free_page(args.pages[args.npages]);
}
out:
return status;
}
int nfs3_proc_setacl(struct inode *inode, int type, struct posix_acl *acl)
{
struct posix_acl *alloc = NULL, *dfacl = NULL;
int status;
if (S_ISDIR(inode->i_mode)) {
switch(type) {
case ACL_TYPE_ACCESS:
alloc = dfacl = nfs3_proc_getacl(inode,
ACL_TYPE_DEFAULT);
if (IS_ERR(alloc))
goto fail;
break;
case ACL_TYPE_DEFAULT:
dfacl = acl;
alloc = acl = nfs3_proc_getacl(inode,
ACL_TYPE_ACCESS);
if (IS_ERR(alloc))
goto fail;
break;
default:
return -EINVAL;
}
} else if (type != ACL_TYPE_ACCESS)
return -EINVAL;
if (acl == NULL) {
alloc = acl = posix_acl_from_mode(inode->i_mode, GFP_KERNEL);
if (IS_ERR(alloc))
goto fail;
}
status = nfs3_proc_setacls(inode, acl, dfacl);
posix_acl_release(alloc);
return status;
fail:
return PTR_ERR(alloc);
}
int nfs3_proc_set_default_acl(struct inode *dir, struct inode *inode,
mode_t mode)
{
struct posix_acl *dfacl, *acl;
int error = 0;
dfacl = nfs3_proc_getacl(dir, ACL_TYPE_DEFAULT);
if (IS_ERR(dfacl)) {
error = PTR_ERR(dfacl);
return (error == -EOPNOTSUPP) ? 0 : error;
}
if (!dfacl)
return 0;
acl = posix_acl_clone(dfacl, GFP_KERNEL);
error = -ENOMEM;
if (!acl)
goto out_release_dfacl;
error = posix_acl_create_masq(acl, &mode);
if (error < 0)
goto out_release_acl;
error = nfs3_proc_setacls(inode, acl, S_ISDIR(inode->i_mode) ?
dfacl : NULL);
out_release_acl:
posix_acl_release(acl);
out_release_dfacl:
posix_acl_release(dfacl);
return error;
}
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