1 files changed, 136 insertions, 233 deletions

diff --git a/fs/nfs/nfs3acl.c b/fs/nfs/nfs3acl.c
index 4a1aafba6a20..a126eb31f62f 100644
--- a/fs/nfs/nfs3acl.c
+++ b/fs/nfs/nfs3acl.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 #include <linux/fs.h>
 #include <linux/gfp.h>
 #include <linux/nfs.h>
@@ -7,182 +8,42 @@
 #include <linux/nfsacl.h>
 
 #include "internal.h"
+#include "nfs3_fs.h"
 
 #define NFSDBG_FACILITY	NFSDBG_PROC
 
-ssize_t nfs3_listxattr(struct dentry *dentry, char *buffer, size_t size)
+/*
+ * 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 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);
-	}
+	struct posix_acl *sentinel = uncached_acl_sentinel(current);
 
-	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;
+	/* If the ACL isn't being read yet, set our sentinel. */
+	cmpxchg(p, ACL_NOT_CACHED, sentinel);
 }
 
-ssize_t nfs3_getxattr(struct dentry *dentry, const char *name,
-		void *buffer, size_t size)
+static void nfs3_complete_get_acl(struct posix_acl **p, struct posix_acl *acl)
 {
-	struct inode *inode = dentry->d_inode;
-	struct posix_acl *acl;
-	int type, error = 0;
+	struct posix_acl *sentinel = uncached_acl_sentinel(current);
 
-	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(&init_user_ns, acl, buffer, size);
+	/* 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);
-	} 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(&init_user_ns, 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)
+static void nfs3_abort_get_acl(struct posix_acl **p)
 {
-	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);
-	}
-}
+	struct posix_acl *sentinel = uncached_acl_sentinel(current);
 
-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);
+	/* Remove our sentinel upon failure. */
+	cmpxchg(p, sentinel, ACL_NOT_CACHED);
 }
 
-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 posix_acl *nfs3_get_acl(struct inode *inode, int type, bool rcu)
 {
 	struct nfs_server *server = NFS_SERVER(inode);
 	struct page *pages[NFSACL_MAXPAGES] = { };
@@ -198,19 +59,17 @@ struct posix_acl *nfs3_proc_getacl(struct inode *inode, int type)
 		.rpc_argp	= &args,
 		.rpc_resp	= &res,
 	};
-	struct posix_acl *acl;
 	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(server, inode);
+	status = nfs_revalidate_inode(inode, NFS_INO_INVALID_CHANGE);
 	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
@@ -231,6 +90,11 @@ struct posix_acl *nfs3_proc_getacl(struct inode *inode, int type)
 	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);
 
@@ -240,14 +104,16 @@ struct posix_acl *nfs3_proc_getacl(struct inode *inode, int type)
 
 	switch (status) {
 		case 0:
-			status = nfs_refresh_inode(inode, res.fattr);
+			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;
 	}
@@ -257,40 +123,43 @@ struct posix_acl *nfs3_proc_getacl(struct inode *inode, int type)
 	}
 
 	if (res.acl_access != NULL) {
-		if (posix_acl_equiv_mode(res.acl_access, NULL) == 0) {
+		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;
 		}
 	}
-	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;
+	if (res.mask & NFS_ACL)
+		nfs3_complete_get_acl(&inode->i_acl, res.acl_access);
+	else
+		forget_cached_acl(inode, ACL_TYPE_ACCESS);
 
-		case ACL_TYPE_DEFAULT:
-			acl = res.acl_default;
-			res.acl_default = NULL;
+	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);
-
-	if (status != 0) {
-		posix_acl_release(acl);
-		acl = ERR_PTR(status);
-	}
-	return acl;
+	return ERR_PTR(status);
 }
 
-static int nfs3_proc_setacls(struct inode *inode, struct posix_acl *acl,
-		  struct posix_acl *dfacl)
+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;
@@ -305,7 +174,10 @@ static int nfs3_proc_setacls(struct inode *inode, struct posix_acl *acl,
 		.rpc_argp	= &args,
 		.rpc_resp	= &fattr,
 	};
-	int status;
+	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))
@@ -353,13 +225,13 @@ static int nfs3_proc_setacls(struct inode *inode, struct posix_acl *acl,
 	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;
+			fallthrough;
 		case -ENOTSUPP:
 			status = -EOPNOTSUPP;
 	}
@@ -373,68 +245,99 @@ out:
 	return status;
 }
 
-int nfs3_proc_setacl(struct inode *inode, int type, struct posix_acl *acl)
+int nfs3_proc_setacls(struct inode *inode, struct posix_acl *acl,
+		struct posix_acl *dfacl)
 {
-	struct posix_acl *alloc = NULL, *dfacl = NULL;
+	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 = 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;
+		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;
 		}
-	} else if (type != ACL_TYPE_ACCESS)
-			return -EINVAL;
+	}
 
 	if (acl == NULL) {
-		alloc = acl = posix_acl_from_mode(inode->i_mode, GFP_KERNEL);
+		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);
-	posix_acl_release(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:
-	return PTR_ERR(alloc);
+	status = PTR_ERR(alloc);
+	goto out;
 }
 
-int nfs3_proc_set_default_acl(struct inode *dir, struct inode *inode,
-		umode_t mode)
+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 *dfacl, *acl;
-	int error = 0;
+	struct posix_acl *acl;
+	char *p = data + *result;
 
-	dfacl = nfs3_proc_getacl(dir, ACL_TYPE_DEFAULT);
-	if (IS_ERR(dfacl)) {
-		error = PTR_ERR(dfacl);
-		return (error == -EOPNOTSUPP) ? 0 : error;
-	}
-	if (!dfacl)
+	acl = get_inode_acl(inode, type);
+	if (IS_ERR_OR_NULL(acl))
 		return 0;
-	acl = posix_acl_dup(dfacl);
-	error = posix_acl_create(&acl, GFP_KERNEL, &mode);
-	if (error < 0)
-		goto out_release_dfacl;
-	error = nfs3_proc_setacls(inode, acl, S_ISDIR(inode->i_mode) ?
-						      dfacl : NULL);
+
 	posix_acl_release(acl);
-out_release_dfacl:
-	posix_acl_release(dfacl);
-	return error;
+
+	*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;
 }