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Date:      Mon, 6 May 2019 20:46:58 +0000 (UTC)
From:      Alan Somers <asomers@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-projects@freebsd.org
Subject:   svn commit: r347209 - in projects/fuse2: sys/fs/fuse tests/sys/fs/fusefs
Message-ID:  <201905062046.x46KkwFJ052149@repo.freebsd.org>
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Author: asomers
Date: Mon May  6 20:46:58 2019
New Revision: 347209
URL: https://svnweb.freebsd.org/changeset/base/347209

Log:
  fusefs: allow ftruncate on files without write permission
  
  ftruncate should succeed as long as the file descriptor is writable, even if
  the file doesn't have write permission.  This is important when combined
  with O_CREAT.
  
  Reported by:	pjdfstest
  Sponsored by:	The FreeBSD Foundation

Modified:
  projects/fuse2/sys/fs/fuse/fuse_internal.c
  projects/fuse2/sys/fs/fuse/fuse_vnops.c
  projects/fuse2/tests/sys/fs/fusefs/default_permissions.cc

Modified: projects/fuse2/sys/fs/fuse/fuse_internal.c
==============================================================================
--- projects/fuse2/sys/fs/fuse/fuse_internal.c	Mon May  6 20:41:56 2019	(r347208)
+++ projects/fuse2/sys/fs/fuse/fuse_internal.c	Mon May  6 20:46:58 2019	(r347209)
@@ -128,6 +128,9 @@ fuse_internal_access(struct vnode *vp,
 	data = fuse_get_mpdata(mp);
 	dataflags = data->dataflags;
 
+	if (mode == 0)
+		return 0;
+
 	if (mode & VMODIFY_PERMS && vfs_isrdonly(mp)) {
 		switch (vp->v_type) {
 		case VDIR:

Modified: projects/fuse2/sys/fs/fuse/fuse_vnops.c
==============================================================================
--- projects/fuse2/sys/fs/fuse/fuse_vnops.c	Mon May  6 20:41:56 2019	(r347208)
+++ projects/fuse2/sys/fs/fuse/fuse_vnops.c	Mon May  6 20:46:58 2019	(r347209)
@@ -1574,7 +1574,7 @@ fuse_vnop_setattr(struct vop_setattr_args *ap)
 			 */
 			return (0);
 		}
-		accmode |= VWRITE;
+		/* Don't set accmode.  Permission to trunc is checked upstack */
 	}
 	/*
 	 * TODO: for atime and mtime, only require VWRITE if UTIMENS_NULL is

Modified: projects/fuse2/tests/sys/fs/fusefs/default_permissions.cc
==============================================================================
--- projects/fuse2/tests/sys/fs/fusefs/default_permissions.cc	Mon May  6 20:41:56 2019	(r347208)
+++ projects/fuse2/tests/sys/fs/fusefs/default_permissions.cc	Mon May  6 20:46:58 2019	(r347209)
@@ -86,6 +86,25 @@ void expect_chmod(uint64_t ino, mode_t mode)
 	})));
 }
 
+void expect_create(const char *relpath, uint64_t ino)
+{
+	EXPECT_CALL(*m_mock, process(
+		ResultOf([=](auto in) {
+			const char *name = (const char*)in->body.bytes +
+				sizeof(fuse_open_in);
+			return (in->header.opcode == FUSE_CREATE &&
+				(0 == strcmp(relpath, name)));
+		}, Eq(true)),
+		_)
+	).WillOnce(Invoke(ReturnImmediate([=](auto in __unused, auto out) {
+		SET_OUT_HEADER_LEN(out, create);
+		out->body.create.entry.attr.mode = S_IFREG | 0644;
+		out->body.create.entry.nodeid = ino;
+		out->body.create.entry.entry_valid = UINT64_MAX;
+		out->body.create.entry.attr_valid = UINT64_MAX;
+	})));
+}
+
 void expect_getattr(uint64_t ino, mode_t mode, uint64_t attr_valid, int times,
 	uid_t uid = 0, gid_t gid = 0)
 {
@@ -129,30 +148,8 @@ class Write: public DefaultPermissions {};
  * rename vops (they all share a common path for permission checks in
  * VOP_LOOKUP)
  */
-class Create: public DefaultPermissions {
-public:
+class Create: public DefaultPermissions {};
 
-void expect_create(const char *relpath, uint64_t ino)
-{
-	EXPECT_CALL(*m_mock, process(
-		ResultOf([=](auto in) {
-			const char *name = (const char*)in->body.bytes +
-				sizeof(fuse_open_in);
-			return (in->header.opcode == FUSE_CREATE &&
-				(0 == strcmp(relpath, name)));
-		}, Eq(true)),
-		_)
-	).WillOnce(Invoke(ReturnImmediate([=](auto in __unused, auto out) {
-		SET_OUT_HEADER_LEN(out, create);
-		out->body.create.entry.attr.mode = S_IFREG | 0644;
-		out->body.create.entry.nodeid = ino;
-		out->body.create.entry.entry_valid = UINT64_MAX;
-		out->body.create.entry.attr_valid = UINT64_MAX;
-	})));
-}
-
-};
-
 class Deleteextattr: public DefaultPermissions {
 public:
 void expect_removexattr()
@@ -795,6 +792,42 @@ TEST_F(Setattr, eacces)
 
 	EXPECT_NE(0, chmod(FULLPATH, newmode));
 	EXPECT_EQ(EPERM, errno);
+}
+
+/*
+ * ftruncate() of a file without writable permissions should succeed as long as
+ * the file descriptor is writable.  This is important when combined with
+ * O_CREAT
+ */
+TEST_F(Setattr, ftruncate_of_newly_created_file)
+{
+	const char FULLPATH[] = "mountpoint/some_file.txt";
+	const char RELPATH[] = "some_file.txt";
+	const uint64_t ino = 42;
+	const mode_t mode = 0000;
+	int fd;
+
+	expect_getattr(1, S_IFDIR | 0777, UINT64_MAX, 1);
+	EXPECT_LOOKUP(1, RELPATH).WillOnce(Invoke(ReturnErrno(ENOENT)));
+	expect_create(RELPATH, ino);
+	EXPECT_CALL(*m_mock, process(
+		ResultOf([](auto in) {
+			return (in->header.opcode == FUSE_SETATTR &&
+				in->header.nodeid == ino &&
+				(in->body.setattr.valid & FATTR_SIZE));
+		}, Eq(true)),
+		_)
+	).WillOnce(Invoke(ReturnImmediate([=](auto in __unused, auto out) {
+		SET_OUT_HEADER_LEN(out, attr);
+		out->body.attr.attr.ino = ino;
+		out->body.attr.attr.mode = S_IFREG | mode;
+		out->body.attr.attr_valid = UINT64_MAX;
+	})));
+
+	fd = open(FULLPATH, O_CREAT | O_RDWR, 0);
+	ASSERT_LE(0, fd) << strerror(errno);
+	ASSERT_EQ(0, ftruncate(fd, 100)) << strerror(errno);
+	/* Deliberately leak fd */
 }
 
 /*

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