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From: =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= <u.kleine-koenig@pengutronix.de>
Date: Tue, 18 Feb 2020 15:23:52 +0100
Subject: [PATCH] attr: make use of O_PATH to set attributes of symlinks and
devices
This fixes setting atime/mtime for symlinks which before this patch changed
the timestamps for the symlink's target (and resulted in an error if the
symlink is dangling).
---
attr.c | 24 ++++++++++++++++++++++--
1 file changed, 22 insertions(+), 2 deletions(-)
diff --git a/attr.c b/attr.c
index 08c9d24cb446..ae2a759e9c86 100644
--- a/attr.c
+++ b/attr.c
@@ -304,6 +304,7 @@ static nfsstat3 set_time(int fd, sattr3 new)
return NFS3_OK;
}
+#ifndef O_PATH
/*
* setting of time, races with local filesystem
*
@@ -399,6 +400,7 @@ static nfsstat3 set_attr_unsafe(const char *path, nfs_fh3 nfh, sattr3 new)
return set_time_path(path, buf, new);
}
+#endif /* #ifndef O_PATH */
/*
* set attributes of an object
@@ -410,13 +412,29 @@ nfsstat3 set_attr(const char *path, nfs_fh3 nfh, sattr3 new)
uid_t new_uid;
gid_t new_gid;
backend_statstruct buf;
+#ifdef O_PATH
+ int flags = O_PATH | O_NOFOLLOW;
+#endif
res = backend_lstat(path, &buf);
if (res != 0)
return NFS3ERR_STALE;
+#ifdef O_PATH
+
+ if (new.size.set_it == TRUE) {
+ if (!S_ISREG(buf.st_mode))
+ return NFS3ERR_NOTSUPP;
+ flags = O_WRONLY | O_NONBLOCK;
+ }
+
+ fd = backend_open(path, flags);
+ if (fd < 0)
+ return NFS3ERR_STALE;
+
+#else
/*
- * don't open(2) device nodes, it could trigger
+ * don't open(2) device nodes without O_PATH, it could trigger
* module loading on the server
*/
if (S_ISBLK(buf.st_mode) || S_ISCHR(buf.st_mode))
@@ -424,7 +442,7 @@ nfsstat3 set_attr(const char *path, nfs_fh3 nfh, sattr3 new)
#ifdef S_ISLNK
/*
- * opening a symlink would open the underlying file,
+ * opening a symlink without O_PATH would open the underlying file,
* don't try to do that
*/
if (S_ISLNK(buf.st_mode))
@@ -441,6 +459,8 @@ nfsstat3 set_attr(const char *path, nfs_fh3 nfh, sattr3 new)
if (fd == -1)
return set_attr_unsafe(path, nfh, new);
+#endif /* #ifdef O_PATH / else */
+
res = backend_fstat(fd, &buf);
if (res == -1) {
backend_close(fd);
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