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SubjectRe: [RFC PATCH] NFS: Fix the access mask checks in NFSv4
Anna, Trond,

On Fri, Jul 28, 2017 at 06:54:52PM +0100, Catalin Marinas wrote:
> --- a/fs/nfs/nfs4proc.c
> +++ b/fs/nfs/nfs4proc.c
> @@ -2236,7 +2236,7 @@ static int nfs4_opendata_access(struct rpc_cred *cred,
> int openflags)
> {
> struct nfs_access_entry cache;
> - u32 mask;
> + int mask, cache_mask;
>
> /* access call failed or for some reason the server doesn't
> * support any access modes -- defer access call until later */
> @@ -2259,7 +2259,8 @@ static int nfs4_opendata_access(struct rpc_cred *cred,
> nfs_access_set_mask(&cache, opendata->o_res.access_result);
> nfs_access_add_cache(state->inode, &cache);
>
> - if ((mask & ~cache.mask & (MAY_READ | MAY_EXEC)) == 0)
> + cache_mask = nfs_access_calc_mask(cache.mask, state->inode->i_mode);
> + if ((mask & ~cache_mask & (MAY_READ | MAY_EXEC)) == 0)
> return 0;
>
> return -EACCES;

I noticed -rc3 already has a fix here, commit 1e6f209515a0 ("NFS: Use
raw NFS access mask in nfs4_opendata_access()"), without having to
export nfs_access_calc_mask().

> @@ -3870,25 +3871,9 @@ static int _nfs4_proc_access(struct inode *inode, struct nfs_access_entry *entry
> .rpc_resp = &res,
> .rpc_cred = entry->cred,
> };
> - int mode = entry->mask;
> int status = 0;
>
> - /*
> - * Determine which access bits we want to ask for...
> - */
> - if (mode & MAY_READ)
> - args.access |= NFS4_ACCESS_READ;
> - if (S_ISDIR(inode->i_mode)) {
> - if (mode & MAY_WRITE)
> - args.access |= NFS4_ACCESS_MODIFY | NFS4_ACCESS_EXTEND | NFS4_ACCESS_DELETE;
> - if (mode & MAY_EXEC)
> - args.access |= NFS4_ACCESS_LOOKUP;
> - } else {
> - if (mode & MAY_WRITE)
> - args.access |= NFS4_ACCESS_MODIFY | NFS4_ACCESS_EXTEND;
> - if (mode & MAY_EXEC)
> - args.access |= NFS4_ACCESS_EXECUTE;
> - }
> + args.access = entry->mask;

However, AFAICT, 'entry->mask' already uses the NFS4_* bits, so checking
'mode' against MAY_READ etc. to build up args.access is incorrect. Is
this hunk still needed?

--
Catalin

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