orangefs: cleanup uses of strncpy

strncpy() is deprecated for use on NUL-terminated destination strings
[1] and as such we should prefer more robust and less ambiguous string
interfaces.

There is some care taken to ensure these destination buffers are
NUL-terminated by bounding the strncpy()'s by ORANGEFS_NAME_MAX - 1 or
ORANGEFS_MAX_SERVER_ADDR_LEN - 1. Instead, we can use the new 2-argument
version of strscpy() to guarantee NUL-termination on the destination
buffers while simplifying the code.

Based on usage with printf-likes, we can see these buffers are expected
to be NUL-terminated:
|	gossip_debug(GOSSIP_NAME_DEBUG,
|			"%s: doing lookup on %s under %pU,%d\n",
|			__func__,
|			new_op->upcall.req.lookup.d_name,
|			&new_op->upcall.req.lookup.parent_refn.khandle,
|			new_op->upcall.req.lookup.parent_refn.fs_id);
...
|	gossip_debug(GOSSIP_SUPER_DEBUG,
|			"Attempting ORANGEFS Remount via host %s\n",
|			new_op->upcall.req.fs_mount.orangefs_config_server);

NUL-padding isn't required for any of these destination buffers as
they've all been zero-allocated with op_alloc() or kzalloc().

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>
Link: https://lore.kernel.org/r/20240322-strncpy-fs-orangefs-dcache-c-v1-1-15d12debbf38@google.com
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>

3 files changed, 15 insertions, 32 deletions

diff --git a/fs/orangefs/dcache.c b/fs/orangefs/dcache.c
index 8bbe9486e3a6..395a00ed8ac7 100644
--- a/fs/orangefs/dcache.c
+++ b/fs/orangefs/dcache.c
@@ -33,9 +33,7 @@ static int orangefs_revalidate_lookup(struct dentry *dentry)
 
 	new_op->upcall.req.lookup.sym_follow = ORANGEFS_LOOKUP_LINK_NO_FOLLOW;
 	new_op->upcall.req.lookup.parent_refn = parent->refn;
-	strncpy(new_op->upcall.req.lookup.d_name,
-		dentry->d_name.name,
-		ORANGEFS_NAME_MAX - 1);
+	strscpy(new_op->upcall.req.lookup.d_name, dentry->d_name.name);
 
 	gossip_debug(GOSSIP_DCACHE_DEBUG,
 		     "%s:%s:%d interrupt flag [%d]\n",
diff --git a/fs/orangefs/namei.c b/fs/orangefs/namei.c
index c9dfd5c6a097..200558ec72f0 100644
--- a/fs/orangefs/namei.c
+++ b/fs/orangefs/namei.c
@@ -41,8 +41,7 @@ static int orangefs_create(struct mnt_idmap *idmap,
 	fill_default_sys_attrs(new_op->upcall.req.create.attributes,
 			       ORANGEFS_TYPE_METAFILE, mode);
 
-	strncpy(new_op->upcall.req.create.d_name,
-		dentry->d_name.name, ORANGEFS_NAME_MAX - 1);
+	strscpy(new_op->upcall.req.create.d_name, dentry->d_name.name);
 
 	ret = service_operation(new_op, __func__, get_interruptible_flag(dir));
 
@@ -137,8 +136,7 @@ static struct dentry *orangefs_lookup(struct inode *dir, struct dentry *dentry,
 		     &parent->refn.khandle);
 	new_op->upcall.req.lookup.parent_refn = parent->refn;
 
-	strncpy(new_op->upcall.req.lookup.d_name, dentry->d_name.name,
-		ORANGEFS_NAME_MAX - 1);
+	strscpy(new_op->upcall.req.lookup.d_name, dentry->d_name.name);
 
 	gossip_debug(GOSSIP_NAME_DEBUG,
 		     "%s: doing lookup on %s under %pU,%d\n",
@@ -192,8 +190,7 @@ static int orangefs_unlink(struct inode *dir, struct dentry *dentry)
 		return -ENOMEM;
 
 	new_op->upcall.req.remove.parent_refn = parent->refn;
-	strncpy(new_op->upcall.req.remove.d_name, dentry->d_name.name,
-		ORANGEFS_NAME_MAX - 1);
+	strscpy(new_op->upcall.req.remove.d_name, dentry->d_name.name);
 
 	ret = service_operation(new_op, "orangefs_unlink",
 				get_interruptible_flag(inode));
@@ -247,10 +244,8 @@ static int orangefs_symlink(struct mnt_idmap *idmap,
 			       ORANGEFS_TYPE_SYMLINK,
 			       mode);
 
-	strncpy(new_op->upcall.req.sym.entry_name,
-		dentry->d_name.name,
-		ORANGEFS_NAME_MAX - 1);
-	strncpy(new_op->upcall.req.sym.target, symname, ORANGEFS_NAME_MAX - 1);
+	strscpy(new_op->upcall.req.sym.entry_name, dentry->d_name.name);
+	strscpy(new_op->upcall.req.sym.target, symname);
 
 	ret = service_operation(new_op, __func__, get_interruptible_flag(dir));
 
@@ -324,8 +319,7 @@ static int orangefs_mkdir(struct mnt_idmap *idmap, struct inode *dir,
 	fill_default_sys_attrs(new_op->upcall.req.mkdir.attributes,
 			      ORANGEFS_TYPE_DIRECTORY, mode);
 
-	strncpy(new_op->upcall.req.mkdir.d_name,
-		dentry->d_name.name, ORANGEFS_NAME_MAX - 1);
+	strscpy(new_op->upcall.req.mkdir.d_name, dentry->d_name.name);
 
 	ret = service_operation(new_op, __func__, get_interruptible_flag(dir));
 
@@ -405,12 +399,8 @@ static int orangefs_rename(struct mnt_idmap *idmap,
 	new_op->upcall.req.rename.old_parent_refn = ORANGEFS_I(old_dir)->refn;
 	new_op->upcall.req.rename.new_parent_refn = ORANGEFS_I(new_dir)->refn;
 
-	strncpy(new_op->upcall.req.rename.d_old_name,
-		old_dentry->d_name.name,
-		ORANGEFS_NAME_MAX - 1);
-	strncpy(new_op->upcall.req.rename.d_new_name,
-		new_dentry->d_name.name,
-		ORANGEFS_NAME_MAX - 1);
+	strscpy(new_op->upcall.req.rename.d_old_name, old_dentry->d_name.name);
+	strscpy(new_op->upcall.req.rename.d_new_name, new_dentry->d_name.name);
 
 	ret = service_operation(new_op,
 				"orangefs_rename",
diff --git a/fs/orangefs/super.c b/fs/orangefs/super.c
index 34849b4a3243..fb4d09c2f531 100644
--- a/fs/orangefs/super.c
+++ b/fs/orangefs/super.c
@@ -253,9 +253,8 @@ int orangefs_remount(struct orangefs_sb_info_s *orangefs_sb)
 	new_op = op_alloc(ORANGEFS_VFS_OP_FS_MOUNT);
 	if (!new_op)
 		return -ENOMEM;
-	strncpy(new_op->upcall.req.fs_mount.orangefs_config_server,
-		orangefs_sb->devname,
-		ORANGEFS_MAX_SERVER_ADDR_LEN);
+	strscpy(new_op->upcall.req.fs_mount.orangefs_config_server,
+		orangefs_sb->devname);
 
 	gossip_debug(GOSSIP_SUPER_DEBUG,
 		     "Attempting ORANGEFS Remount via host %s\n",
@@ -400,8 +399,7 @@ static int orangefs_unmount(int id, __s32 fs_id, const char *devname)
 		return -ENOMEM;
 	op->upcall.req.fs_umount.id = id;
 	op->upcall.req.fs_umount.fs_id = fs_id;
-	strncpy(op->upcall.req.fs_umount.orangefs_config_server,
-	    devname, ORANGEFS_MAX_SERVER_ADDR_LEN - 1);
+	strscpy(op->upcall.req.fs_umount.orangefs_config_server, devname);
 	r = service_operation(op, "orangefs_fs_umount", 0);
 	/* Not much to do about an error here. */
 	if (r)
@@ -494,9 +492,7 @@ struct dentry *orangefs_mount(struct file_system_type *fst,
 	if (!new_op)
 		return ERR_PTR(-ENOMEM);
 
-	strncpy(new_op->upcall.req.fs_mount.orangefs_config_server,
-		devname,
-		ORANGEFS_MAX_SERVER_ADDR_LEN - 1);
+	strscpy(new_op->upcall.req.fs_mount.orangefs_config_server, devname);
 
 	gossip_debug(GOSSIP_SUPER_DEBUG,
 		     "Attempting ORANGEFS Mount via host %s\n",
@@ -543,9 +539,8 @@ struct dentry *orangefs_mount(struct file_system_type *fst,
 	 * on successful mount, store the devname and data
 	 * used
 	 */
-	strncpy(ORANGEFS_SB(sb)->devname,
-		devname,
-		ORANGEFS_MAX_SERVER_ADDR_LEN - 1);
+	strscpy(ORANGEFS_SB(sb)->devname, devname);
+
 
 	/* mount_pending must be cleared */
 	ORANGEFS_SB(sb)->mount_pending = 0;