Merge branch 'compat.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull compat mount cleanups from Al Viro:
 "The last remnants of mount(2) compat buried by Christoph.

  Buried into NFS, that is.

  Generally I'm less enthusiastic about "let's use in_compat_syscall()
  deep in call chain" kind of approach than Christoph seems to be, but
  in this case it's warranted - that had been an NFS-specific wart,
  hopefully not to be repeated in any other filesystems (read: any new
  filesystem introducing non-text mount options will get NAKed even if
  it doesn't mess the layout up).

  IOW, not worth trying to grow an infrastructure that would avoid that
  use of in_compat_syscall()..."

* 'compat.mount' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  fs: remove compat_sys_mount
  fs,nfs: lift compat nfs4 mount data handling into the nfs code
  nfs: simplify nfs4_parse_monolithic

5 files changed, 126 insertions, 209 deletions

diff --git a/fs/Makefile b/fs/Makefile
index 1c7b0e3f6daa..d72ee2ce7af0 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -37,7 +37,6 @@ obj-$(CONFIG_FS_DAX)		+= dax.o
 obj-$(CONFIG_FS_ENCRYPTION)	+= crypto/
 obj-$(CONFIG_FS_VERITY)		+= verity/
 obj-$(CONFIG_FILE_LOCKING)      += locks.o
-obj-$(CONFIG_COMPAT)		+= compat.o
 obj-$(CONFIG_BINFMT_AOUT)	+= binfmt_aout.o
 obj-$(CONFIG_BINFMT_EM86)	+= binfmt_em86.o
 obj-$(CONFIG_BINFMT_MISC)	+= binfmt_misc.o
diff --git a/fs/compat.c b/fs/compat.c
deleted file mode 100644
index 436d228cf71c..000000000000
--- a/fs/compat.c
+++ /dev/null
@@ -1,132 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-only
-/*
- *  linux/fs/compat.c
- *
- *  Kernel compatibililty routines for e.g. 32 bit syscall support
- *  on 64 bit kernels.
- *
- *  Copyright (C) 2002       Stephen Rothwell, IBM Corporation
- *  Copyright (C) 1997-2000  Jakub Jelinek  (jakub@redhat.com)
- *  Copyright (C) 1998       Eddie C. Dost  (ecd@skynet.be)
- *  Copyright (C) 2001,2002  Andi Kleen, SuSE Labs 
- *  Copyright (C) 2003       Pavel Machek (pavel@ucw.cz)
- */
-
-#include <linux/compat.h>
-#include <linux/nfs4_mount.h>
-#include <linux/syscalls.h>
-#include <linux/slab.h>
-#include <linux/uaccess.h>
-#include "internal.h"
-
-struct compat_nfs_string {
-	compat_uint_t len;
-	compat_uptr_t data;
-};
-
-static inline void compat_nfs_string(struct nfs_string *dst,
-				     struct compat_nfs_string *src)
-{
-	dst->data = compat_ptr(src->data);
-	dst->len = src->len;
-}
-
-struct compat_nfs4_mount_data_v1 {
-	compat_int_t version;
-	compat_int_t flags;
-	compat_int_t rsize;
-	compat_int_t wsize;
-	compat_int_t timeo;
-	compat_int_t retrans;
-	compat_int_t acregmin;
-	compat_int_t acregmax;
-	compat_int_t acdirmin;
-	compat_int_t acdirmax;
-	struct compat_nfs_string client_addr;
-	struct compat_nfs_string mnt_path;
-	struct compat_nfs_string hostname;
-	compat_uint_t host_addrlen;
-	compat_uptr_t host_addr;
-	compat_int_t proto;
-	compat_int_t auth_flavourlen;
-	compat_uptr_t auth_flavours;
-};
-
-static int do_nfs4_super_data_conv(void *raw_data)
-{
-	int version = *(compat_uint_t *) raw_data;
-
-	if (version == 1) {
-		struct compat_nfs4_mount_data_v1 *raw = raw_data;
-		struct nfs4_mount_data *real = raw_data;
-
-		/* copy the fields backwards */
-		real->auth_flavours = compat_ptr(raw->auth_flavours);
-		real->auth_flavourlen = raw->auth_flavourlen;
-		real->proto = raw->proto;
-		real->host_addr = compat_ptr(raw->host_addr);
-		real->host_addrlen = raw->host_addrlen;
-		compat_nfs_string(&real->hostname, &raw->hostname);
-		compat_nfs_string(&real->mnt_path, &raw->mnt_path);
-		compat_nfs_string(&real->client_addr, &raw->client_addr);
-		real->acdirmax = raw->acdirmax;
-		real->acdirmin = raw->acdirmin;
-		real->acregmax = raw->acregmax;
-		real->acregmin = raw->acregmin;
-		real->retrans = raw->retrans;
-		real->timeo = raw->timeo;
-		real->wsize = raw->wsize;
-		real->rsize = raw->rsize;
-		real->flags = raw->flags;
-		real->version = raw->version;
-	}
-
-	return 0;
-}
-
-#define NFS4_NAME	"nfs4"
-
-COMPAT_SYSCALL_DEFINE5(mount, const char __user *, dev_name,
-		       const char __user *, dir_name,
-		       const char __user *, type, compat_ulong_t, flags,
-		       const void __user *, data)
-{
-	char *kernel_type;
-	void *options;
-	char *kernel_dev;
-	int retval;
-
-	kernel_type = copy_mount_string(type);
-	retval = PTR_ERR(kernel_type);
-	if (IS_ERR(kernel_type))
-		goto out;
-
-	kernel_dev = copy_mount_string(dev_name);
-	retval = PTR_ERR(kernel_dev);
-	if (IS_ERR(kernel_dev))
-		goto out1;
-
-	options = copy_mount_options(data);
-	retval = PTR_ERR(options);
-	if (IS_ERR(options))
-		goto out2;
-
-	if (kernel_type && options) {
-		if (!strcmp(kernel_type, NFS4_NAME)) {
-			retval = -EINVAL;
-			if (do_nfs4_super_data_conv(options))
-				goto out3;
-		}
-	}
-
-	retval = do_mount(kernel_dev, dir_name, kernel_type, flags, options);
-
- out3:
-	kfree(options);
- out2:
-	kfree(kernel_dev);
- out1:
-	kfree(kernel_type);
- out:
-	return retval;
-}
diff --git a/fs/internal.h b/fs/internal.h
index 10517ece4516..a7cd0f64faa4 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -82,9 +82,6 @@ int may_linkat(struct path *link);
 /*
  * namespace.c
  */
-extern void *copy_mount_options(const void __user *);
-extern char *copy_mount_string(const void __user *);
-
 extern struct vfsmount *lookup_mnt(const struct path *);
 extern int finish_automount(struct vfsmount *, struct path *);
 
diff --git a/fs/namespace.c b/fs/namespace.c
index 32a0b9146757..294e05a13d17 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -3072,7 +3072,7 @@ static void shrink_submounts(struct mount *mnt)
 	}
 }
 
-void *copy_mount_options(const void __user * data)
+static void *copy_mount_options(const void __user * data)
 {
 	char *copy;
 	unsigned left, offset;
@@ -3108,7 +3108,7 @@ void *copy_mount_options(const void __user * data)
 	return copy;
 }
 
-char *copy_mount_string(const void __user *data)
+static char *copy_mount_string(const void __user *data)
 {
 	return data ? strndup_user(data, PATH_MAX) : NULL;
 }
diff --git a/fs/nfs/fs_context.c b/fs/nfs/fs_context.c
index 524812984e2d..222afba70bc0 100644
--- a/fs/nfs/fs_context.c
+++ b/fs/nfs/fs_context.c
@@ -1039,6 +1039,65 @@ out_invalid_fh:
 }
 
 #if IS_ENABLED(CONFIG_NFS_V4)
+struct compat_nfs_string {
+	compat_uint_t len;
+	compat_uptr_t data;
+};
+
+static inline void compat_nfs_string(struct nfs_string *dst,
+				     struct compat_nfs_string *src)
+{
+	dst->data = compat_ptr(src->data);
+	dst->len = src->len;
+}
+
+struct compat_nfs4_mount_data_v1 {
+	compat_int_t version;
+	compat_int_t flags;
+	compat_int_t rsize;
+	compat_int_t wsize;
+	compat_int_t timeo;
+	compat_int_t retrans;
+	compat_int_t acregmin;
+	compat_int_t acregmax;
+	compat_int_t acdirmin;
+	compat_int_t acdirmax;
+	struct compat_nfs_string client_addr;
+	struct compat_nfs_string mnt_path;
+	struct compat_nfs_string hostname;
+	compat_uint_t host_addrlen;
+	compat_uptr_t host_addr;
+	compat_int_t proto;
+	compat_int_t auth_flavourlen;
+	compat_uptr_t auth_flavours;
+};
+
+static void nfs4_compat_mount_data_conv(struct nfs4_mount_data *data)
+{
+	struct compat_nfs4_mount_data_v1 *compat =
+			(struct compat_nfs4_mount_data_v1 *)data;
+
+	/* copy the fields backwards */
+	data->auth_flavours = compat_ptr(compat->auth_flavours);
+	data->auth_flavourlen = compat->auth_flavourlen;
+	data->proto = compat->proto;
+	data->host_addr = compat_ptr(compat->host_addr);
+	data->host_addrlen = compat->host_addrlen;
+	compat_nfs_string(&data->hostname, &compat->hostname);
+	compat_nfs_string(&data->mnt_path, &compat->mnt_path);
+	compat_nfs_string(&data->client_addr, &compat->client_addr);
+	data->acdirmax = compat->acdirmax;
+	data->acdirmin = compat->acdirmin;
+	data->acregmax = compat->acregmax;
+	data->acregmin = compat->acregmin;
+	data->retrans = compat->retrans;
+	data->timeo = compat->timeo;
+	data->wsize = compat->wsize;
+	data->rsize = compat->rsize;
+	data->flags = compat->flags;
+	data->version = compat->version;
+}
+
 /*
  * Validate NFSv4 mount options
  */
@@ -1049,89 +1108,83 @@ static int nfs4_parse_monolithic(struct fs_context *fc,
 	struct sockaddr *sap = (struct sockaddr *)&ctx->nfs_server.address;
 	char *c;
 
-	if (data == NULL)
-		goto out_no_data;
+	if (!data) {
+		if (is_remount_fc(fc))
+			goto done;
+		return nfs_invalf(fc,
+			"NFS4: mount program didn't pass any mount data");
+	}
 
 	ctx->version = 4;
 
-	switch (data->version) {
-	case 1:
-		if (data->host_addrlen > sizeof(ctx->nfs_server.address))
-			goto out_no_address;
-		if (data->host_addrlen == 0)
-			goto out_no_address;
-		ctx->nfs_server.addrlen = data->host_addrlen;
-		if (copy_from_user(sap, data->host_addr, data->host_addrlen))
-			return -EFAULT;
-		if (!nfs_verify_server_address(sap))
-			goto out_no_address;
-		ctx->nfs_server.port = ntohs(((struct sockaddr_in *)sap)->sin_port);
-
-		if (data->auth_flavourlen) {
-			rpc_authflavor_t pseudoflavor;
-			if (data->auth_flavourlen > 1)
-				goto out_inval_auth;
-			if (copy_from_user(&pseudoflavor,
-					   data->auth_flavours,
-					   sizeof(pseudoflavor)))
-				return -EFAULT;
-			ctx->selected_flavor = pseudoflavor;
-		} else
-			ctx->selected_flavor = RPC_AUTH_UNIX;
-
-		c = strndup_user(data->hostname.data, NFS4_MAXNAMLEN);
-		if (IS_ERR(c))
-			return PTR_ERR(c);
-		ctx->nfs_server.hostname = c;
+	if (data->version != 1)
+		return generic_parse_monolithic(fc, data);
 
-		c = strndup_user(data->mnt_path.data, NFS4_MAXPATHLEN);
-		if (IS_ERR(c))
-			return PTR_ERR(c);
-		ctx->nfs_server.export_path = c;
-		dfprintk(MOUNT, "NFS: MNTPATH: '%s'\n", c);
+	if (in_compat_syscall())
+		nfs4_compat_mount_data_conv(data);
 
-		c = strndup_user(data->client_addr.data, 16);
-		if (IS_ERR(c))
-			return PTR_ERR(c);
-		ctx->client_address = c;
-
-		/*
-		 * Translate to nfs_fs_context, which nfs_fill_super
-		 * can deal with.
-		 */
+	if (data->host_addrlen > sizeof(ctx->nfs_server.address))
+		goto out_no_address;
+	if (data->host_addrlen == 0)
+		goto out_no_address;
+	ctx->nfs_server.addrlen = data->host_addrlen;
+	if (copy_from_user(sap, data->host_addr, data->host_addrlen))
+		return -EFAULT;
+	if (!nfs_verify_server_address(sap))
+		goto out_no_address;
+	ctx->nfs_server.port = ntohs(((struct sockaddr_in *)sap)->sin_port);
 
-		ctx->flags	= data->flags & NFS4_MOUNT_FLAGMASK;
-		ctx->rsize	= data->rsize;
-		ctx->wsize	= data->wsize;
-		ctx->timeo	= data->timeo;
-		ctx->retrans	= data->retrans;
-		ctx->acregmin	= data->acregmin;
-		ctx->acregmax	= data->acregmax;
-		ctx->acdirmin	= data->acdirmin;
-		ctx->acdirmax	= data->acdirmax;
-		ctx->nfs_server.protocol = data->proto;
-		nfs_validate_transport_protocol(ctx);
-		if (ctx->nfs_server.protocol == XPRT_TRANSPORT_UDP)
-			goto out_invalid_transport_udp;
+	if (data->auth_flavourlen) {
+		rpc_authflavor_t pseudoflavor;
 
-		break;
-	default:
-		goto generic;
+		if (data->auth_flavourlen > 1)
+			goto out_inval_auth;
+		if (copy_from_user(&pseudoflavor, data->auth_flavours,
+				   sizeof(pseudoflavor)))
+			return -EFAULT;
+		ctx->selected_flavor = pseudoflavor;
+	} else {
+		ctx->selected_flavor = RPC_AUTH_UNIX;
 	}
 
+	c = strndup_user(data->hostname.data, NFS4_MAXNAMLEN);
+	if (IS_ERR(c))
+		return PTR_ERR(c);
+	ctx->nfs_server.hostname = c;
+
+	c = strndup_user(data->mnt_path.data, NFS4_MAXPATHLEN);
+	if (IS_ERR(c))
+		return PTR_ERR(c);
+	ctx->nfs_server.export_path = c;
+	dfprintk(MOUNT, "NFS: MNTPATH: '%s'\n", c);
+
+	c = strndup_user(data->client_addr.data, 16);
+	if (IS_ERR(c))
+		return PTR_ERR(c);
+	ctx->client_address = c;
+
+	/*
+	 * Translate to nfs_fs_context, which nfs_fill_super
+	 * can deal with.
+	 */
+
+	ctx->flags	= data->flags & NFS4_MOUNT_FLAGMASK;
+	ctx->rsize	= data->rsize;
+	ctx->wsize	= data->wsize;
+	ctx->timeo	= data->timeo;
+	ctx->retrans	= data->retrans;
+	ctx->acregmin	= data->acregmin;
+	ctx->acregmax	= data->acregmax;
+	ctx->acdirmin	= data->acdirmin;
+	ctx->acdirmax	= data->acdirmax;
+	ctx->nfs_server.protocol = data->proto;
+	nfs_validate_transport_protocol(ctx);
+	if (ctx->nfs_server.protocol == XPRT_TRANSPORT_UDP)
+		goto out_invalid_transport_udp;
+done:
 	ctx->skip_reconfig_option_check = true;
 	return 0;
 
-generic:
-	return generic_parse_monolithic(fc, data);
-
-out_no_data:
-	if (is_remount_fc(fc)) {
-		ctx->skip_reconfig_option_check = true;
-		return 0;
-	}
-	return nfs_invalf(fc, "NFS4: mount program didn't pass any mount data");
-
 out_inval_auth:
 	return nfs_invalf(fc, "NFS4: Invalid number of RPC auth flavours %d",
 		      data->auth_flavourlen);