linux(4): Implement xattr syscalls

Reviewed by:
Differential revision:	https://reviews.freebsd.org/D35544
MFC after:		1 month

4 files changed, 401 insertions, 21 deletions

diff --git a/sys/compat/linux/linux_dummy.c b/sys/compat/linux/linux_dummy.c
index 46596aa4a92a..861482b67d8f 100644
--- a/sys/compat/linux/linux_dummy.c
+++ b/sys/compat/linux/linux_dummy.c
@@ -146,24 +146,3 @@ DUMMY(pidfd_send_signal);
 DUMMY(io_uring_setup);
 DUMMY(io_uring_enter);
 DUMMY(io_uring_register);
-
-#define DUMMY_XATTR(s)						\
-int								\
-linux_ ## s ## xattr(						\
-    struct thread *td, struct linux_ ## s ## xattr_args *arg)	\
-{								\
-								\
-	return (EOPNOTSUPP);					\
-}
-DUMMY_XATTR(set);
-DUMMY_XATTR(lset);
-DUMMY_XATTR(fset);
-DUMMY_XATTR(get);
-DUMMY_XATTR(lget);
-DUMMY_XATTR(fget);
-DUMMY_XATTR(list);
-DUMMY_XATTR(llist);
-DUMMY_XATTR(flist);
-DUMMY_XATTR(remove);
-DUMMY_XATTR(lremove);
-DUMMY_XATTR(fremove);
diff --git a/sys/compat/linux/linux_xattr.c b/sys/compat/linux/linux_xattr.c
new file mode 100644
index 000000000000..60c4c8ddf4c9
--- /dev/null
+++ b/sys/compat/linux/linux_xattr.c
@@ -0,0 +1,399 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2023 Dmitry Chagin <dchagin@FreeBSD.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/extattr.h>
+#include <sys/fcntl.h>
+#include <sys/namei.h>
+#include <sys/proc.h>
+#include <sys/syscallsubr.h>
+
+#ifdef COMPAT_LINUX32
+#include <machine/../linux32/linux.h>
+#include <machine/../linux32/linux32_proto.h>
+#else
+#include <machine/../linux/linux.h>
+#include <machine/../linux/linux_proto.h>
+#endif
+
+#include <compat/linux/linux_util.h>
+
+#define	LINUX_XATTR_SIZE_MAX	65536
+#define	LINUX_XATTR_LIST_MAX	65536
+#define	LINUX_XATTR_NAME_MAX	255
+
+#define	LINUX_XATTR_CREATE	0x1
+#define	LINUX_XATTR_REPLACE	0x2
+#define	LINUX_XATTR_FLAGS	LINUX_XATTR_CREATE|LINUX_XATTR_REPLACE
+
+struct listxattr_args {
+	int		fd;
+	const char	*path;
+	char		*list;
+	l_size_t	size;
+	int		follow;
+};
+
+struct setxattr_args {
+	int		fd;
+	const char	*path;
+	const char	*name;
+	void 		*value;
+	l_size_t	size;
+	l_int		flags;
+	int		follow;
+};
+
+static char *extattr_namespace_names[] = EXTATTR_NAMESPACE_NAMES;
+
+
+static int
+xatrr_to_extattr(const char *uattrname, int *attrnamespace, char *attrname)
+{
+	char uname[LINUX_XATTR_NAME_MAX + 1], *dot;
+	size_t len, cplen;
+	int error;
+
+	error = copyinstr(uattrname, uname, sizeof(uname), &cplen);
+	if (error != 0)
+		return (error);
+	if (cplen == sizeof(uname))
+		return (ERANGE);
+	dot = strchr(uname, '.');
+	if (dot == NULL)
+		return (ENOTSUP);
+	*dot = '\0';
+	for (*attrnamespace = EXTATTR_NAMESPACE_USER;
+	    *attrnamespace < nitems(extattr_namespace_names);
+	    (*attrnamespace)++) {
+		if (bcmp(uname, extattr_namespace_names[*attrnamespace],
+		    dot - uname + 1) == 0) {
+			dot++;
+			len = strlen(dot) + 1;
+			bcopy(dot, attrname, len);
+			return (0);
+		}
+	}
+	return (ENOTSUP);
+}
+
+static int
+listxattr(struct thread *td, struct listxattr_args *args)
+{
+	char attrname[LINUX_XATTR_NAME_MAX + 1];
+	char *data, *prefix, *key;
+	struct uio auio;
+	struct iovec aiov;
+	unsigned char keylen;
+	size_t sz, cnt, rs, prefixlen, pairlen;
+	int attrnamespace, error;
+
+	if (args->size != 0)
+		sz = min(LINUX_XATTR_LIST_MAX, args->size);
+	else
+		sz = LINUX_XATTR_LIST_MAX;
+
+	data = malloc(sz, M_LINUX, M_WAITOK);
+	auio.uio_iov = &aiov;
+	auio.uio_iovcnt = 1;
+	auio.uio_rw = UIO_READ;
+	auio.uio_segflg = UIO_SYSSPACE;
+	auio.uio_td = td;
+	cnt = 0;
+	for (attrnamespace = EXTATTR_NAMESPACE_USER;
+	    attrnamespace < nitems(extattr_namespace_names);
+	    attrnamespace++) {
+		aiov.iov_base = data;
+		aiov.iov_len = sz;
+		auio.uio_resid = sz;
+		auio.uio_offset = 0;
+
+		if (args->path != NULL)
+			error = kern_extattr_list_path(td, args->path,
+			    attrnamespace, &auio, args->follow, UIO_USERSPACE);
+		else
+			error = kern_extattr_list_fd(td, args->fd,
+			    attrnamespace, &auio);
+		rs = sz - auio.uio_resid;
+		if (error != 0 || rs == 0)
+			continue;
+		prefix = extattr_namespace_names[attrnamespace];
+		prefixlen = strlen(prefix);
+		key = data;
+		while (rs > 0) {
+			keylen = (unsigned char)key[0];
+			pairlen = prefixlen + 1 + keylen + 1;
+			if (cnt + pairlen > LINUX_XATTR_LIST_MAX) {
+				error = E2BIG;
+				break;
+			}
+			if ((args->list != NULL && cnt > args->size) ||
+			    pairlen >= sizeof(attrname)) {
+				error = ERANGE;
+				break;
+			}
+			++key;
+			if (args->list != NULL) {
+				sprintf(attrname, "%s.%.*s", prefix, keylen, key);
+				error = copyout(attrname, args->list, pairlen);
+				if (error != 0)
+					break;
+				args->list += pairlen;
+			}
+			cnt += pairlen;
+			key += keylen;
+			rs -= (keylen + 1);
+		}
+	}
+	if (error == 0)
+		td->td_retval[0] = cnt;
+	free(data, M_LINUX);
+	return (error);
+}
+
+int
+linux_listxattr(struct thread *td, struct linux_listxattr_args *args)
+{
+	struct listxattr_args eargs = {
+		.fd = -1,
+		.path = args->path,
+		.list = args->list,
+		.size = args->size,
+		.follow = FOLLOW,
+	};
+
+	return (listxattr(td, &eargs));
+}
+
+int
+linux_llistxattr(struct thread *td, struct linux_llistxattr_args *args)
+{
+	struct listxattr_args eargs = {
+		.fd = -1,
+		.path = args->path,
+		.list = args->list,
+		.size = args->size,
+		.follow = NOFOLLOW,
+	};
+
+	return (listxattr(td, &eargs));
+}
+
+int
+linux_flistxattr(struct thread *td, struct linux_flistxattr_args *args)
+{
+	struct listxattr_args eargs = {
+		.fd = args->fd,
+		.path = NULL,
+		.list = args->list,
+		.size = args->size,
+		.follow = 0,
+	};
+
+	return (listxattr(td, &eargs));
+}
+
+static int
+linux_path_removexattr(struct thread *td, const char *upath, const char *uname,
+    int follow)
+{
+	char attrname[LINUX_XATTR_NAME_MAX + 1];
+	int attrnamespace, error;
+
+	error = xatrr_to_extattr(uname, &attrnamespace, attrname);
+	if (error != 0)
+		return (error);
+
+	return (kern_extattr_delete_path(td, upath, attrnamespace,
+	    attrname, follow, UIO_USERSPACE));
+}
+
+int
+linux_removexattr(struct thread *td, struct linux_removexattr_args *args)
+{
+
+	return (linux_path_removexattr(td, args->path, args->name,
+	    FOLLOW));
+}
+
+int
+linux_lremovexattr(struct thread *td, struct linux_lremovexattr_args *args)
+{
+
+	return (linux_path_removexattr(td, args->path, args->name,
+	    NOFOLLOW));
+}
+
+int
+linux_fremovexattr(struct thread *td, struct linux_fremovexattr_args *args)
+{
+	char attrname[LINUX_XATTR_NAME_MAX + 1];
+	int attrnamespace, error;
+
+	error = xatrr_to_extattr(args->name, &attrnamespace, attrname);
+	if (error != 0)
+		return (error);
+	return (kern_extattr_delete_fd(td, args->fd, attrnamespace,
+	    attrname));
+}
+
+static int
+linux_path_getxattr(struct thread *td, const char *upath, const char *uname,
+    void *value, l_size_t size, int follow)
+{
+	char attrname[LINUX_XATTR_NAME_MAX + 1];
+	int attrnamespace, error;
+
+	error = xatrr_to_extattr(uname, &attrnamespace, attrname);
+	if (error != 0)
+		return (error);
+
+	return (kern_extattr_get_path(td, upath, attrnamespace,
+	    attrname, value, size, follow, UIO_USERSPACE));
+}
+
+int
+linux_getxattr(struct thread *td, struct linux_getxattr_args *args)
+{
+
+	return (linux_path_getxattr(td, args->path, args->name,
+	    args->value, args->size, FOLLOW));
+}
+
+int
+linux_lgetxattr(struct thread *td, struct linux_lgetxattr_args *args)
+{
+
+	return (linux_path_getxattr(td, args->path, args->name,
+	    args->value, args->size, NOFOLLOW));
+}
+
+int
+linux_fgetxattr(struct thread *td, struct linux_fgetxattr_args *args)
+{
+	char attrname[LINUX_XATTR_NAME_MAX + 1];
+	int attrnamespace, error;
+
+	error = xatrr_to_extattr(args->name, &attrnamespace, attrname);
+	if (error != 0)
+		return (error);
+	return (kern_extattr_get_fd(td, args->fd, attrnamespace,
+	    attrname, args->value, args->size));
+}
+
+static int
+setxattr(struct thread *td, struct setxattr_args *args)
+{
+	char attrname[LINUX_XATTR_NAME_MAX + 1];
+	int attrnamespace, error;
+
+	if ((args->flags & ~(LINUX_XATTR_FLAGS)) != 0 ||
+	    args->flags == (LINUX_XATTR_FLAGS))
+		return (EINVAL);
+	error = xatrr_to_extattr(args->name, &attrnamespace, attrname);
+	if (error != 0)
+		return (error);
+
+	if ((args->flags & (LINUX_XATTR_FLAGS)) != 0 ) {
+		if (args->path != NULL)
+			error = kern_extattr_get_path(td, args->path,
+			    attrnamespace, attrname, NULL, args->size,
+			    args->follow, UIO_USERSPACE);
+		else
+			error = kern_extattr_get_fd(td, args->fd,
+			    attrnamespace, attrname, NULL, args->size);
+		if ((args->flags & LINUX_XATTR_CREATE) != 0) {
+			if (error == 0)
+				error = EEXIST;
+			else if (error == ENOATTR)
+				error = 0;
+		}
+		if (error != 0)
+			goto out;
+	}
+	if (args->path != NULL)
+		error = kern_extattr_set_path(td, args->path, attrnamespace,
+		    attrname, args->value, args->size, args->follow,
+		    UIO_USERSPACE);
+	else
+		error = kern_extattr_set_fd(td, args->fd, attrnamespace,
+		    attrname, args->value, args->size);
+out:
+	td->td_retval[0] = 0;
+	return (error);
+}
+
+int
+linux_setxattr(struct thread *td, struct linux_setxattr_args *args)
+{
+	struct setxattr_args eargs = {
+		.fd = -1,
+		.path = args->path,
+		.name = args->name,
+		.value = args->value,
+		.size = args->size,
+		.flags = args->flags,
+		.follow = FOLLOW,
+	};
+
+	return (setxattr(td, &eargs));
+}
+
+int
+linux_lsetxattr(struct thread *td, struct linux_lsetxattr_args *args)
+{
+	struct setxattr_args eargs = {
+		.fd = -1,
+		.path = args->path,
+		.name = args->name,
+		.value = args->value,
+		.size = args->size,
+		.flags = args->flags,
+		.follow = NOFOLLOW,
+	};
+
+	return (setxattr(td, &eargs));
+}
+
+int
+linux_fsetxattr(struct thread *td, struct linux_fsetxattr_args *args)
+{
+	struct setxattr_args eargs = {
+		.fd = args->fd,
+		.path = NULL,
+		.name = args->name,
+		.value = args->value,
+		.size = args->size,
+		.flags = args->flags,
+		.follow = 0,
+	};
+
+	return (setxattr(td, &eargs));
+}
diff --git a/sys/modules/linux/Makefile b/sys/modules/linux/Makefile
index 294a7d595cc6..42ce6607dfc2 100644
--- a/sys/modules/linux/Makefile
+++ b/sys/modules/linux/Makefile
@@ -34,6 +34,7 @@ SRCS=	linux${SFX}_dummy_machdep.c \
 	linux_timer.c \
 	linux_uid16.c \
 	linux_vdso.c \
+	linux_xattr.c \
 	opt_inet6.h \
 	opt_ktrace.h \
 	opt_posix.h \
diff --git a/sys/modules/linux64/Makefile b/sys/modules/linux64/Makefile
index 4fe9ccd576c1..0a133e6e79b4 100644
--- a/sys/modules/linux64/Makefile
+++ b/sys/modules/linux64/Makefile
@@ -29,6 +29,7 @@ SRCS=	linux_dummy_machdep.c \
 	linux_time.c \
 	linux_vdso.c \
 	linux_timer.c \
+	linux_xattr.c \
 	opt_ktrace.h \
 	opt_inet6.h \
 	opt_posix.h \