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70 lines
2.7 KiB
70 lines
2.7 KiB
1 year ago
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commit cdbef4e97a1cbc68cbaf16ba57d71858d2c69973
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Author: Jeff Layton <jlayton@kernel.org>
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Date: Tue Jan 10 09:37:25 2023 -0500
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nfs-utils: Don't allow junction tests to trigger automounts
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JianHong reported some strange behavior with automounts on an nfs server
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without an explicit pseudoroot. When clients issued a readdir in the
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pseudoroot, automounted directories that were not yet mounted would show
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up even if they weren't exported, though the clients wouldn't be able to
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do anything with them.
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The issue was that triggering the automount on a directory would cause
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the mountd upcall to time out, which would cause nfsd to include the
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automounted dentry in the readdir response. Eventually, the automount
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would work and report that it wasn't exported and subsequent attempts to
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access the dentry would (properly) fail.
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We never want mountd to trigger an automount. The kernel should do that
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if it wants to use it. Change the junction checks to do an O_PATH open
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and use fstatat with AT_NO_AUTOMOUNT.
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Cc: Chuck Lever <chuck.lever@oracle.com>
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Link: https://bugzilla.redhat.com/show_bug.cgi?id=2148353
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Link: https://bugzilla.kernel.org/show_bug.cgi?id=216777
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Reported-by: JianHong Yin <jiyin@redhat.com>
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Signed-off-by: Jeff Layton <jlayton@kernel.org>
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Signed-off-by: Steve Dickson <steved@redhat.com>
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diff --git a/support/junction/junction.c b/support/junction/junction.c
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index 41cce26..0628bb0 100644
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--- a/support/junction/junction.c
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+++ b/support/junction/junction.c
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@@ -93,7 +93,7 @@ junction_is_directory(int fd, const char *path)
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{
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struct stat stb;
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- if (fstat(fd, &stb) == -1) {
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+ if (fstatat(fd, "", &stb, AT_NO_AUTOMOUNT|AT_EMPTY_PATH) == -1) {
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xlog(D_GENERAL, "%s: failed to stat %s: %m",
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__func__, path);
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return FEDFS_ERR_ACCESS;
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@@ -121,7 +121,7 @@ junction_is_sticky_bit_set(int fd, const char *path)
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{
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struct stat stb;
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- if (fstat(fd, &stb) == -1) {
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+ if (fstatat(fd, "", &stb, AT_NO_AUTOMOUNT|AT_EMPTY_PATH) == -1) {
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xlog(D_GENERAL, "%s: failed to stat %s: %m",
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__func__, path);
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return FEDFS_ERR_ACCESS;
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@@ -155,7 +155,7 @@ junction_set_sticky_bit(int fd, const char *path)
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{
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struct stat stb;
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- if (fstat(fd, &stb) == -1) {
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+ if (fstatat(fd, "", &stb, AT_NO_AUTOMOUNT|AT_EMPTY_PATH) == -1) {
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xlog(D_GENERAL, "%s: failed to stat %s: %m",
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__func__, path);
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return FEDFS_ERR_ACCESS;
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@@ -393,7 +393,7 @@ junction_get_mode(const char *pathname, mode_t *mode)
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if (retval != FEDFS_OK)
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return retval;
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- if (fstat(fd, &stb) == -1) {
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+ if (fstatat(fd, "", &stb, AT_NO_AUTOMOUNT|AT_EMPTY_PATH) == -1) {
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xlog(D_GENERAL, "%s: failed to stat %s: %m",
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__func__, pathname);
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(void)close(fd);
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