// SPDX-License-Identifier: GPL-2.0
#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"
#include "nfs3_fs.h"

#define NFSDBG_FACILITY NFSDBG_PROC

/*
 * nfs3_prepare_get_acl, nfs3_complete_get_acl, nfs3_abort_get_acl: Helpers for
 * caching get_acl results in a race-free way.  See fs/posix_acl.c:get_acl()
 * for explanations.
 */
static void nfs3_prepare_get_acl(struct posix_acl **p)
{
        struct posix_acl *sentinel = uncached_acl_sentinel(current);

        /* If the ACL isn't being read yet, set our sentinel. */
        cmpxchg(p, ACL_NOT_CACHED, sentinel);
}

static void nfs3_complete_get_acl(struct posix_acl **p, struct posix_acl *acl)
{
        struct posix_acl *sentinel = uncached_acl_sentinel(current);

        /* Only cache the ACL if our sentinel is still in place. */
        posix_acl_dup(acl);
        if (cmpxchg(p, sentinel, acl) != sentinel)
                posix_acl_release(acl);
}

static void nfs3_abort_get_acl(struct posix_acl **p)
{
        struct posix_acl *sentinel = uncached_acl_sentinel(current);

        /* Remove our sentinel upon failure. */
        cmpxchg(p, sentinel, ACL_NOT_CACHED);
}

struct posix_acl *nfs3_get_acl(struct inode *inode, int type, bool rcu)
{
        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 = {
                NULL,
        };
        struct rpc_message msg = {
                .rpc_argp       = &args,
                .rpc_resp       = &res,
        };
        int status, count;

        if (rcu)
                return ERR_PTR(-ECHILD);

        if (!nfs_server_capable(inode, NFS_CAP_ACLS))
                return ERR_PTR(-EOPNOTSUPP);

        status = nfs_revalidate_inode(inode, NFS_INO_INVALID_CHANGE);
        if (status < 0)
                return ERR_PTR(status);

        /*
         * 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);

        if (args.mask & NFS_ACL)
                nfs3_prepare_get_acl(&inode->i_acl);
        if (args.mask & NFS_DFACL)
                nfs3_prepare_get_acl(&inode->i_default_acl);

        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:
                        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;
                        fallthrough;
                case -ENOTSUPP:
                        status = -EOPNOTSUPP;
                        goto getout;
                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) ||
                    res.acl_access->a_count == 0) {
                        posix_acl_release(res.acl_access);
                        res.acl_access = NULL;
                }
        }

        if (res.mask & NFS_ACL)
                nfs3_complete_get_acl(&inode->i_acl, res.acl_access);
        else
                forget_cached_acl(inode, ACL_TYPE_ACCESS);

        if (res.mask & NFS_DFACL)
                nfs3_complete_get_acl(&inode->i_default_acl, res.acl_default);
        else
                forget_cached_acl(inode, ACL_TYPE_DEFAULT);

        nfs_free_fattr(res.fattr);
        if (type == ACL_TYPE_ACCESS) {
                posix_acl_release(res.acl_default);
                return res.acl_access;
        } else {
                posix_acl_release(res.acl_access);
                return res.acl_default;
        }

getout:
        nfs3_abort_get_acl(&inode->i_acl);
        nfs3_abort_get_acl(&inode->i_default_acl);
        posix_acl_release(res.acl_access);
        posix_acl_release(res.acl_default);
        nfs_free_fattr(res.fattr);
        return ERR_PTR(status);
}

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 = 0;

        if (acl == NULL && (!S_ISDIR(inode->i_mode) || dfacl == NULL))
                goto out;

        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);
                        break;
                case -EPFNOSUPPORT:
                case -EPROTONOSUPPORT:
                        dprintk("NFS_V3_ACL SETACL RPC not supported"
                                        "(will not retry)\n");
                        server->caps &= ~NFS_CAP_ACLS;
                        fallthrough;
                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_setacls(struct inode *inode, struct posix_acl *acl,
                struct posix_acl *dfacl)
{
        int ret;
        ret = __nfs3_proc_setacls(inode, acl, dfacl);
        return (ret == -EOPNOTSUPP) ? 0 : ret;

}

int nfs3_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
                 struct posix_acl *acl, int type)
{
        struct posix_acl *orig = acl, *dfacl = NULL, *alloc;
        struct inode *inode = d_inode(dentry);
        int status;

        if (S_ISDIR(inode->i_mode)) {
                switch(type) {
                case ACL_TYPE_ACCESS:
                        alloc = get_inode_acl(inode, ACL_TYPE_DEFAULT);
                        if (IS_ERR(alloc))
                                goto fail;
                        dfacl = alloc;
                        break;

                case ACL_TYPE_DEFAULT:
                        alloc = get_inode_acl(inode, ACL_TYPE_ACCESS);
                        if (IS_ERR(alloc))
                                goto fail;
                        dfacl = acl;
                        acl = alloc;
                        break;
                }
        }

        if (acl == NULL) {
                alloc = posix_acl_from_mode(inode->i_mode, GFP_KERNEL);
                if (IS_ERR(alloc))
                        goto fail;
                acl = alloc;
        }
        status = __nfs3_proc_setacls(inode, acl, dfacl);
out:
        if (acl != orig)
                posix_acl_release(acl);
        if (dfacl != orig)
                posix_acl_release(dfacl);
        return status;

fail:
        status = PTR_ERR(alloc);
        goto out;
}

static int
nfs3_list_one_acl(struct inode *inode, int type, const char *name, void *data,
                size_t size, ssize_t *result)
{
        struct posix_acl *acl;
        char *p = data + *result;

        acl = get_inode_acl(inode, type);
        if (IS_ERR_OR_NULL(acl))
                return 0;

        posix_acl_release(acl);

        *result += strlen(name);
        *result += 1;
        if (!size)
                return 0;
        if (*result > size)
                return -ERANGE;

        strcpy(p, name);
        return 0;
}

ssize_t
nfs3_listxattr(struct dentry *dentry, char *data, size_t size)
{
        struct inode *inode = d_inode(dentry);
        ssize_t result = 0;
        int error;

        error = nfs3_list_one_acl(inode, ACL_TYPE_ACCESS,
                        XATTR_NAME_POSIX_ACL_ACCESS, data, size, &result);
        if (error)
                return error;

        error = nfs3_list_one_acl(inode, ACL_TYPE_DEFAULT,
                        XATTR_NAME_POSIX_ACL_DEFAULT, data, size, &result);
        if (error)
                return error;
        return result;
}