[PATCH v3 0/3] smb: fix xfstests generic/035

[PATCH v3 0/3] smb: fix xfstests generic/035

[ChenXiaoSong]

From: ChenXiaoSong <chenxiaosong@kylinos.cn>

v2->v3:
  - Patch #02: iterate over `global_ft.idr`.

v2: https://lore.kernel.org/linux-cifs/20260804123301.285434-1-chenxiaosong@chenxiaosong.com/

ChenXiaoSong (3):
  smb/server: rename to ksmbd_has_nonposix_open_child()
  smb/server: deny overwriting targets with non-POSIX opens
  smb/client: fix nlink of an overwritten open file

 fs/smb/client/inode.c     | 11 ++++++-----
 fs/smb/server/vfs.c       | 15 ++++++++++++++-
 fs/smb/server/vfs_cache.c | 29 ++++++++++++++++++++++++++++-
 fs/smb/server/vfs_cache.h |  3 ++-
 4 files changed, 50 insertions(+), 8 deletions(-)

-- 
2.54.0

[PATCH v3 3/3] smb/client: fix nlink of an overwritten open file

[ChenXiaoSong]

From: ChenXiaoSong <chenxiaosong@kylinos.cn>

Reproducer:

  1. server: systemctl start ksmbd
  2. client: mount with `posix` option
     mount -t cifs -o posix //${server_ip}/export /mnt
  3. client: touch /mnt/file1 /mnt/file2
  4. client: C program: int fd = open("/mnt/file2", O_RDONLY);
  5. client: C program: rename("/mnt/file1", "/mnt/file2");
  6. client: C program: struct stat stbuf; fstat(fd, &stbuf);
                        stbuf.st_nlink is 1, should be 0

This patch fixes xfstests generic/035 when mounted with `posix` option.

Signed-off-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
---
 fs/smb/client/inode.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/fs/smb/client/inode.c b/fs/smb/client/inode.c
index 0afff761aab9..0b6273ce01a8 100644
--- a/fs/smb/client/inode.c
+++ b/fs/smb/client/inode.c
@@ -2648,11 +2648,8 @@ cifs_rename2(struct mnt_idmap *idmap, struct inode *source_dir,
 	if (d_really_is_positive(target_dentry)) {
 		if (!rc) {
 			struct inode *inode = d_inode(target_dentry);
-			/*
-			 * Samba and ksmbd servers allow renaming a target
-			 * directory that is open, so make sure to update
-			 * ->i_nlink and then mark it as delete pending.
-			 */
+
+			/* Update the target link count after rename. */
 			if (S_ISDIR(inode->i_mode)) {
 				drop_cached_dir_by_name(xid, tcon, to_name, cifs_sb);
 				spin_lock(&inode->i_lock);
@@ -2663,6 +2660,10 @@ cifs_rename2(struct mnt_idmap *idmap, struct inode *source_dir,
 				CIFS_I(inode)->time = 0; /* force reval */
 				inode_set_ctime_current(inode);
 				inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode));
+			} else {
+				cifs_mark_open_handles_for_deleted_file(inode, to_name);
+				cifs_drop_nlink(inode);
+				inode_set_ctime_current(inode);
 			}
 		} else if (rc == -EACCES || rc == -EEXIST) {
 			/*
-- 
2.54.0

[PATCH v3 1/3] smb/server: rename to ksmbd_has_nonposix_open_child()

[ChenXiaoSong]

From: ChenXiaoSong <chenxiaosong@kylinos.cn>

The original function name `ksmbd_has_open_files()` could be confused with
the function name introduced in the next patch, and it does not accurately
describe what this function does.

Signed-off-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
---
 fs/smb/server/vfs.c       | 2 +-
 fs/smb/server/vfs_cache.c | 2 +-
 fs/smb/server/vfs_cache.h | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/smb/server/vfs.c b/fs/smb/server/vfs.c
index 28940c7b5f83..16ef8d051b18 100644
--- a/fs/smb/server/vfs.c
+++ b/fs/smb/server/vfs.c
@@ -721,7 +721,7 @@ int ksmbd_vfs_rename(struct ksmbd_work *work, struct ksmbd_file *old_fp,
 	if (err)
 		goto out_drop_write;
 
-	if (d_is_dir(old_child) && ksmbd_has_open_files(old_fp)) {
+	if (d_is_dir(old_child) && ksmbd_has_nonposix_open_child(old_fp)) {
 		err = -EACCES;
 		goto out3;
 	}
diff --git a/fs/smb/server/vfs_cache.c b/fs/smb/server/vfs_cache.c
index eac9886eb6e3..028bc1b0f652 100644
--- a/fs/smb/server/vfs_cache.c
+++ b/fs/smb/server/vfs_cache.c
@@ -1137,7 +1137,7 @@ struct ksmbd_file *ksmbd_lookup_fd_inode(struct dentry *dentry)
 	return NULL;
 }
 
-bool ksmbd_has_open_files(struct ksmbd_file *old_fp)
+bool ksmbd_has_nonposix_open_child(struct ksmbd_file *old_fp)
 {
 	struct dentry *dentry = old_fp->filp->f_path.dentry;
 	struct ksmbd_file *fp;
diff --git a/fs/smb/server/vfs_cache.h b/fs/smb/server/vfs_cache.h
index 127ea4987e3f..9dca617bc429 100644
--- a/fs/smb/server/vfs_cache.h
+++ b/fs/smb/server/vfs_cache.h
@@ -212,7 +212,7 @@ bool ksmbd_has_stream_without_delete_share(struct ksmbd_file *fp);
 int ksmbd_close_fd_app_instance_id(char *app_instance_id);
 struct ksmbd_file *ksmbd_lookup_fd_cguid(char *cguid);
 struct ksmbd_file *ksmbd_lookup_fd_inode(struct dentry *dentry);
-bool ksmbd_has_open_files(struct ksmbd_file *old_fp);
+bool ksmbd_has_nonposix_open_child(struct ksmbd_file *old_fp);
 unsigned int ksmbd_open_durable_fd(struct ksmbd_file *fp);
 struct ksmbd_file *ksmbd_open_fd(struct ksmbd_work *work, struct file *filp);
 void ksmbd_launch_ksmbd_durable_scavenger(void);
-- 
2.54.0

[PATCH v3 2/3] smb/server: deny overwriting targets with non-POSIX opens

[ChenXiaoSong]

From: ChenXiaoSong <chenxiaosong@kylinos.cn>

Reproducer:

  1. server: systemctl start ksmbd
  2. client: mount without `posix` option
     mount -t cifs //${server_ip}/export /mnt
  3. client: touch /mnt/file1 /mnt/file2
  4. client: C program: int fd = open("/mnt/file2", O_RDONLY);
  5. client: C program: rename("/mnt/file1", "/mnt/file2");
  6. client: C program: struct stat stbuf; fstat(fd, &stbuf);
                        stbuf.st_nlink is 1, should be 0

This patch fixes xfstests generic/035 when mounted without `posix` option.

Suggested-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
---
 fs/smb/server/vfs.c       | 13 +++++++++++++
 fs/smb/server/vfs_cache.c | 27 +++++++++++++++++++++++++++
 fs/smb/server/vfs_cache.h |  1 +
 3 files changed, 41 insertions(+)

diff --git a/fs/smb/server/vfs.c b/fs/smb/server/vfs.c
index 16ef8d051b18..9102ab47a3aa 100644
--- a/fs/smb/server/vfs.c
+++ b/fs/smb/server/vfs.c
@@ -726,6 +726,19 @@ int ksmbd_vfs_rename(struct ksmbd_work *work, struct ksmbd_file *old_fp,
 		goto out3;
 	}
 
+	/*
+	 * See MS-FSA 2.1.5.15.12.
+	 * An overwrite rename must fail with STATUS_ACCESS_DENIED if the
+	 * existing target still has a non-POSIX open.
+	 */
+	if (!(flags & (RENAME_NOREPLACE | RENAME_EXCHANGE)) &&
+	    d_inode(rd.new_dentry) &&
+	    d_inode(rd.new_dentry) != d_inode(old_child) &&
+	    ksmbd_has_other_nonposix_open(rd.new_dentry)) {
+		err = -EACCES;
+		goto out3;
+	}
+
 	err = ksmbd_vfs_check_rename_share(work, old_path);
 	if (err)
 		goto out3;
diff --git a/fs/smb/server/vfs_cache.c b/fs/smb/server/vfs_cache.c
index 028bc1b0f652..90348a409162 100644
--- a/fs/smb/server/vfs_cache.c
+++ b/fs/smb/server/vfs_cache.c
@@ -1137,6 +1137,33 @@ struct ksmbd_file *ksmbd_lookup_fd_inode(struct dentry *dentry)
 	return NULL;
 }
 
+bool ksmbd_has_other_nonposix_open(struct dentry *dentry)
+{
+	struct ksmbd_file *fp;
+	struct inode *inode = d_inode(dentry);
+	unsigned int id;
+	bool ret = false;
+
+	if (!inode)
+		return false;
+
+	read_lock(&global_ft.lock);
+	idr_for_each_entry(global_ft.idr, fp, id) {
+		if (READ_ONCE(fp->f_state) != FP_INITED)
+			continue;
+		if (inode != file_inode(fp->filp))
+			continue;
+		if (fp->is_posix_ctxt)
+			continue;
+
+		ret = true;
+		break;
+	}
+	read_unlock(&global_ft.lock);
+
+	return ret;
+}
+
 bool ksmbd_has_nonposix_open_child(struct ksmbd_file *old_fp)
 {
 	struct dentry *dentry = old_fp->filp->f_path.dentry;
diff --git a/fs/smb/server/vfs_cache.h b/fs/smb/server/vfs_cache.h
index 9dca617bc429..5cac022b540b 100644
--- a/fs/smb/server/vfs_cache.h
+++ b/fs/smb/server/vfs_cache.h
@@ -212,6 +212,7 @@ bool ksmbd_has_stream_without_delete_share(struct ksmbd_file *fp);
 int ksmbd_close_fd_app_instance_id(char *app_instance_id);
 struct ksmbd_file *ksmbd_lookup_fd_cguid(char *cguid);
 struct ksmbd_file *ksmbd_lookup_fd_inode(struct dentry *dentry);
+bool ksmbd_has_other_nonposix_open(struct dentry *dentry);
 bool ksmbd_has_nonposix_open_child(struct ksmbd_file *old_fp);
 unsigned int ksmbd_open_durable_fd(struct ksmbd_file *fp);
 struct ksmbd_file *ksmbd_open_fd(struct ksmbd_work *work, struct file *filp);
-- 
2.54.0