[lustre-devel] [PATCH 06/24] lustre: llite: make foreign symlinks aware of mount namespaces

[James Simmons]

Currently the foreign symlink code test if mount namespace is the
same namespace related to the sysfs tree. This doesn't cover all
cases. Linux supports limiting which mounts are visible to a
process with mount namespaces. Lets add this support as well.

WC-bug-id: https://jira.whamcloud.com/browse/LU-10824
Lustre-commit: 942b4e118677af587 ("LU-10824 llite: make foreign symlinks aware of mount namespaces")
Signed-off-by: James Simmons <jsimmons at infradead.org>
Reviewed-on: https://review.whamcloud.com/45609
Reviewed-by: Andreas Dilger <adilger at whamcloud.com>
Reviewed-by: Faccini Bruno <bruno.faccini at intel.com>
Reviewed-by: Oleg Drokin <green at whamcloud.com>
---
 fs/lustre/llite/llite_foreign_symlink.c | 8 ++++----
 fs/lustre/llite/llite_internal.h        | 1 +
 fs/lustre/llite/llite_lib.c             | 1 +
 3 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/fs/lustre/llite/llite_foreign_symlink.c b/fs/lustre/llite/llite_foreign_symlink.c
index bfade93..64bc5db 100644
--- a/fs/lustre/llite/llite_foreign_symlink.c
+++ b/fs/lustre/llite/llite_foreign_symlink.c
@@ -367,15 +367,15 @@ static struct dentry *ll_foreign_dir_lookup(struct inode *parent,
 
 static bool has_same_mount_namespace(struct ll_sb_info *sbi)
 {
-	int rc;
+	bool same;
 
-	rc = (sbi->ll_mnt.mnt == current->fs->root.mnt);
-	if (!rc)
+	same = (sbi->ll_mnt_ns == current->nsproxy->mnt_ns);
+	if (!same)
 		LCONSOLE_WARN("%s: client mount %s and '%s.%d' not in same mnt-namespace\n",
 			      sbi->ll_fsname, sbi->ll_kset.kobj.name,
 			      current->comm, current->pid);
 
-	return rc;
+	return same;
 }
 
 ssize_t foreign_symlink_enable_show(struct kobject *kobj,
diff --git a/fs/lustre/llite/llite_internal.h b/fs/lustre/llite/llite_internal.h
index 54fd8d4..a2abec6 100644
--- a/fs/lustre/llite/llite_internal.h
+++ b/fs/lustre/llite/llite_internal.h
@@ -672,6 +672,7 @@ struct ll_sb_info {
 	struct obd_device	*ll_dt_obd;
 	struct dentry		*ll_debugfs_entry;
 	struct lu_fid		ll_root_fid; /* root object fid */
+	struct mnt_namespace	*ll_mnt_ns;
 
 	DECLARE_BITMAP(ll_flags, LL_SBI_NUM_FLAGS); /* enum ll_sbi_flags */
 	unsigned int		ll_xattr_cache_enabled:1,
diff --git a/fs/lustre/llite/llite_lib.c b/fs/lustre/llite/llite_lib.c
index 87cdc36..f8ecdcba 100644
--- a/fs/lustre/llite/llite_lib.c
+++ b/fs/lustre/llite/llite_lib.c
@@ -445,6 +445,7 @@ static int client_common_fill_super(struct super_block *sb, char *md, char *dt)
 	sb->s_maxbytes = MAX_LFS_FILESIZE;
 	sbi->ll_namelen = osfs->os_namelen;
 	sbi->ll_mnt.mnt = current->fs->root.mnt;
+	sbi->ll_mnt_ns = current->nsproxy->mnt_ns;
 
 	if (test_bit(LL_SBI_USER_XATTR, sbi->ll_flags) &&
 	    !(data->ocd_connect_flags & OBD_CONNECT_XATTR)) {
-- 
1.8.3.1