NFS: pass cred explicitly for access tests

Storing the 'struct cred *' in nfs_access_entry is problematic.
An active 'cred' can keep a 'struct key *' active, and a quota is
imposed on the number of such keys that a user can maintain.
Cached 'nfs_access_entry' structs have indefinite lifetime, and having
these keep 'struct key's alive imposes on that quota.

So a future patch will remove the ->cred ref from nfs_access_entry.

To prepare, change various functions to not assume there is a 'cred' in
the nfs_access_entry, but to pass the cred around explicitly.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 8487a6d..a34351c 100644 (file)
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -2758,7 +2758,9 @@ int nfs_access_get_cached(struct inode *inode, const struct cred *cred,
 }
 EXPORT_SYMBOL_GPL(nfs_access_get_cached);
 
-static void nfs_access_add_rbtree(struct inode *inode, struct nfs_access_entry *set)
+static void nfs_access_add_rbtree(struct inode *inode,
+                                 struct nfs_access_entry *set,
+                                 const struct cred *cred)
 {
        struct nfs_inode *nfsi = NFS_I(inode);
        struct rb_root *root_node = &nfsi->access_cache;
@@ -2771,7 +2773,7 @@ static void nfs_access_add_rbtree(struct inode *inode, struct nfs_access_entry *
        while (*p != NULL) {
                parent = *p;
                entry = rb_entry(parent, struct nfs_access_entry, rb_node);
-               cmp = cred_fscmp(set->cred, entry->cred);
+               cmp = cred_fscmp(cred, entry->cred);
 
                if (cmp < 0)
                        p = &parent->rb_left;
@@ -2793,13 +2795,14 @@ found:
        nfs_access_free_entry(entry);
 }
 
-void nfs_access_add_cache(struct inode *inode, struct nfs_access_entry *set)
+void nfs_access_add_cache(struct inode *inode, struct nfs_access_entry *set,
+                         const struct cred *cred)
 {
        struct nfs_access_entry *cache = kmalloc(sizeof(*cache), GFP_KERNEL);
        if (cache == NULL)
                return;
        RB_CLEAR_NODE(&cache->rb_node);
-       cache->cred = get_cred(set->cred);
+       cache->cred = get_cred(cred);
        cache->mask = set->mask;
 
        /* The above field assignments must be visible
@@ -2807,7 +2810,7 @@ void nfs_access_add_cache(struct inode *inode, struct nfs_access_entry *set)
         * use rcu_assign_pointer, so just force the memory barrier.
         */
        smp_wmb();
-       nfs_access_add_rbtree(inode, cache);
+       nfs_access_add_rbtree(inode, cache, cred);
 
        /* Update accounting */
        smp_mb__before_atomic();
@@ -2893,7 +2896,7 @@ static int nfs_do_access(struct inode *inode, const struct cred *cred, int mask)
        else
                cache.mask |= NFS_ACCESS_EXECUTE;
        cache.cred = cred;
-       status = NFS_PROTO(inode)->access(inode, &cache);
+       status = NFS_PROTO(inode)->access(inode, &cache, cred);
        if (status != 0) {
                if (status == -ESTALE) {
                        if (!S_ISDIR(inode->i_mode))
@@ -2903,7 +2906,7 @@ static int nfs_do_access(struct inode *inode, const struct cred *cred, int mask)
                }
                goto out;
        }
-       nfs_access_add_cache(inode, &cache);
+       nfs_access_add_cache(inode, &cache, cred);
 out_cached:
        cache_mask = nfs_access_calc_mask(cache.mask, inode->i_mode);
        if ((mask & ~cache_mask & (MAY_READ | MAY_WRITE | MAY_EXEC)) != 0)

diff --git a/fs/nfs/nfs3proc.c b/fs/nfs/nfs3proc.c
index 7100514..1597eef 100644 (file)
--- a/fs/nfs/nfs3proc.c
+++ b/fs/nfs/nfs3proc.c
@@ -220,7 +220,8 @@ static int nfs3_proc_lookupp(struct inode *inode, struct nfs_fh *fhandle,
                                  task_flags);
 }
 
-static int nfs3_proc_access(struct inode *inode, struct nfs_access_entry *entry)
+static int nfs3_proc_access(struct inode *inode, struct nfs_access_entry *entry,
+                           const struct cred *cred)
 {
        struct nfs3_accessargs  arg = {
                .fh             = NFS_FH(inode),
@@ -231,7 +232,7 @@ static int nfs3_proc_access(struct inode *inode, struct nfs_access_entry *entry)
                .rpc_proc       = &nfs3_procedures[NFS3PROC_ACCESS],
                .rpc_argp       = &arg,
                .rpc_resp       = &res,
-               .rpc_cred       = entry->cred,
+               .rpc_cred       = cred,
        };
        int status = -ENOMEM;
 

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 322ff45..f02aa98 100644 (file)
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -2655,7 +2655,7 @@ static int nfs4_opendata_access(const struct cred *cred,
 
        cache.cred = cred;
        nfs_access_set_mask(&cache, opendata->o_res.access_result);
-       nfs_access_add_cache(state->inode, &cache);
+       nfs_access_add_cache(state->inode, &cache, cred);
 
        flags = NFS4_ACCESS_READ | NFS4_ACCESS_EXECUTE | NFS4_ACCESS_LOOKUP;
        if ((mask & ~cache.mask & flags) == 0)
@@ -4441,7 +4441,8 @@ static int nfs4_proc_lookupp(struct inode *inode, struct nfs_fh *fhandle,
        return err;
 }
 
-static int _nfs4_proc_access(struct inode *inode, struct nfs_access_entry *entry)
+static int _nfs4_proc_access(struct inode *inode, struct nfs_access_entry *entry,
+                            const struct cred *cred)
 {
        struct nfs_server *server = NFS_SERVER(inode);
        struct nfs4_accessargs args = {
@@ -4455,7 +4456,7 @@ static int _nfs4_proc_access(struct inode *inode, struct nfs_access_entry *entry
                .rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_ACCESS],
                .rpc_argp = &args,
                .rpc_resp = &res,
-               .rpc_cred = entry->cred,
+               .rpc_cred = cred,
        };
        int status = 0;
 
@@ -4475,14 +4476,15 @@ static int _nfs4_proc_access(struct inode *inode, struct nfs_access_entry *entry
        return status;
 }
 
-static int nfs4_proc_access(struct inode *inode, struct nfs_access_entry *entry)
+static int nfs4_proc_access(struct inode *inode, struct nfs_access_entry *entry,
+                           const struct cred *cred)
 {
        struct nfs4_exception exception = {
                .interruptible = true,
        };
        int err;
        do {
-               err = _nfs4_proc_access(inode, entry);
+               err = _nfs4_proc_access(inode, entry, cred);
                trace_nfs4_access(inode, err);
                err = nfs4_handle_exception(NFS_SERVER(inode), err,
                                &exception);

diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index f33559a..c33b1b7 100644 (file)
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -396,7 +396,7 @@ extern int nfs_post_op_update_inode_force_wcc(struct inode *inode, struct nfs_fa
 extern int nfs_post_op_update_inode_force_wcc_locked(struct inode *inode, struct nfs_fattr *fattr);
 extern int nfs_getattr(struct user_namespace *, const struct path *,
                       struct kstat *, u32, unsigned int);
-extern void nfs_access_add_cache(struct inode *, struct nfs_access_entry *);
+extern void nfs_access_add_cache(struct inode *, struct nfs_access_entry *, const struct cred *);
 extern void nfs_access_set_mask(struct nfs_access_entry *, u32);
 extern int nfs_permission(struct user_namespace *, struct inode *, int);
 extern int nfs_open(struct inode *, struct file *);

diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index 967a009..9102bda 100644 (file)
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -1737,7 +1737,7 @@ struct nfs_rpc_ops {
                            struct nfs_fh *, struct nfs_fattr *);
        int     (*lookupp) (struct inode *, struct nfs_fh *,
                            struct nfs_fattr *);
-       int     (*access)  (struct inode *, struct nfs_access_entry *);
+       int     (*access)  (struct inode *, struct nfs_access_entry *, const struct cred *);
        int     (*readlink)(struct inode *, struct page *, unsigned int,
                            unsigned int);
        int     (*create)  (struct inode *, struct dentry *,