From: Shaun A. Johnson <shaun@linuxmagic.com>
Date: Mon, 13 Aug 2018 23:43:04 +0000 (-0700)
Subject: lib: Changed chown to chmod for Linux NFS Flush
X-Git-Tag: 2.3.9~414
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7d4375dd8f7c67f630d7be272dc0873ba4857612;p=thirdparty%2Fdovecot%2Fcore.git

lib: Changed chown to chmod for Linux NFS Flush

This change switches the chown call to a chmod call in the function
nfs_flush_chown_uid because the chown call was resulting in certain
permission bits being dropped when the nfs attributes were flushed.

Functionality for FreeBSD/Solaris was left unchanged.
---

diff --git a/src/lib/nfs-workarounds.c b/src/lib/nfs-workarounds.c
index bcbfcd7579..4bbea8aa6e 100644
--- a/src/lib/nfs-workarounds.c
+++ b/src/lib/nfs-workarounds.c
@@ -146,10 +146,9 @@ int nfs_safe_link(const char *oldpath, const char *newpath, bool links1)
 
 static void nfs_flush_chown_uid(const char *path)
 {
-	uid_t uid;
 
 #ifdef ATTRCACHE_FLUSH_CHOWN_UID_1
-	uid = (uid_t)-1;
+	uid_t uid = (uid_t)-1;
 	if (chown(path, uid, (gid_t)-1) < 0) {
 		if (errno == ESTALE || errno == EPERM || errno == ENOENT) {
 			/* attr cache is flushed */
@@ -164,9 +163,9 @@ static void nfs_flush_chown_uid(const char *path)
 #else
 	struct stat st;
 
-	if (stat(path, &st) == 0)
-		uid = st.st_uid;
-	else {
+	if (stat(path, &st) == 0) {
+		/* do nothing */
+	} else {
 		if (errno == ESTALE) {
 			/* ESTALE causes the OS to flush the attr cache */
 			return;
@@ -178,8 +177,10 @@ static void nfs_flush_chown_uid(const char *path)
 		i_error("nfs_flush_chown_uid: stat(%s) failed: %m", path);
 		return;
 	}
-	if (chown(path, uid, (gid_t)-1) < 0) {
-		if (errno == ESTALE || errno == EPERM || errno == ENOENT) {
+	/* we use chmod for this operation since chown has been seen to drop S_UID
+	   and S_GID bits from directory inodes in certain conditions */
+	if (chmod(path, st.st_mode & 07777) < 0) {
+		if (errno == EPERM) {
 			/* attr cache is flushed */
 			return;
 		}
@@ -187,7 +188,8 @@ static void nfs_flush_chown_uid(const char *path)
 			nfs_flush_file_handle_cache_parent_dir(path);
 			return;
 		}
-		i_error("nfs_flush_chown_uid: chown(%s) failed: %m", path);
+		i_error("nfs_flush_chown_uid: chmod(%s, %04o) failed: %m",
+				path, st.st_mode & 07777);
 	}
 #endif
 }