bpf: mark a NULL kfunc argument precisegrafted

check_kfunc_arg() allows bpf_register_is_null() for nullable arguments
w/o marking the underlying scalar register precise. Hence a checkpoint
created on such a path would prune against arbitrary scalar value.

Fixes: 3bda08b63670 ("bpf: Allow NULL buffers in bpf_dynptr_slice(_rw)")
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260904-register-is-null-precise-fixes-v1-5-0f5a360ff15d@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 142 insertions, 0 deletions

diff --git a/fs/smb/client/reparse.h b/fs/smb/client/reparse.h
new file mode 100644
index 000000000..0164dc47b
--- /dev/null
+++ b/fs/smb/client/reparse.h
@@ -0,0 +1,142 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2024 Paulo Alcantara <pc@manguebit.com>
+ */
+
+#ifndef _CIFS_REPARSE_H
+#define _CIFS_REPARSE_H
+
+#include <linux/fs.h>
+#include <linux/stat.h>
+#include <linux/uidgid.h>
+#include "fs_context.h"
+#include "cifsglob.h"
+#include "../common/smbfsctl.h"
+
+#define REPARSE_SYM_PATH_MAX 4060
+
+/*
+ * Used only by cifs.ko to ignore reparse points from files when client or
+ * server doesn't support FSCTL_GET_REPARSE_POINT.
+ */
+#define IO_REPARSE_TAG_INTERNAL ((__u32)~0U)
+
+static inline dev_t reparse_mkdev(void *ptr)
+{
+	u64 v = le64_to_cpu(*(__le64 *)ptr);
+
+	return MKDEV(v & 0xffffffff, v >> 32);
+}
+
+static inline kuid_t wsl_make_kuid(struct cifs_sb_info *cifs_sb,
+				   void *ptr)
+{
+	u32 uid = le32_to_cpu(*(__le32 *)ptr);
+
+	if (cifs_sb_flags(cifs_sb) & CIFS_MOUNT_OVERR_UID)
+		return cifs_sb->ctx->linux_uid;
+	return make_kuid(current_user_ns(), uid);
+}
+
+static inline kgid_t wsl_make_kgid(struct cifs_sb_info *cifs_sb,
+				   void *ptr)
+{
+	u32 gid = le32_to_cpu(*(__le32 *)ptr);
+
+	if (cifs_sb_flags(cifs_sb) & CIFS_MOUNT_OVERR_GID)
+		return cifs_sb->ctx->linux_gid;
+	return make_kgid(current_user_ns(), gid);
+}
+
+static inline u64 reparse_mode_nfs_type(mode_t mode)
+{
+	switch (mode & S_IFMT) {
+	case S_IFLNK: return NFS_SPECFILE_LNK;
+	case S_IFBLK: return NFS_SPECFILE_BLK;
+	case S_IFCHR: return NFS_SPECFILE_CHR;
+	case S_IFIFO: return NFS_SPECFILE_FIFO;
+	case S_IFSOCK: return NFS_SPECFILE_SOCK;
+	}
+	return 0;
+}
+
+static inline u32 reparse_mode_wsl_tag(mode_t mode)
+{
+	switch (mode & S_IFMT) {
+	case S_IFLNK: return IO_REPARSE_TAG_LX_SYMLINK;
+	case S_IFBLK: return IO_REPARSE_TAG_LX_BLK;
+	case S_IFCHR: return IO_REPARSE_TAG_LX_CHR;
+	case S_IFIFO: return IO_REPARSE_TAG_LX_FIFO;
+	case S_IFSOCK: return IO_REPARSE_TAG_AF_UNIX;
+	}
+	return 0;
+}
+
+/*
+ * Match a reparse point inode if reparse tag and ctime haven't changed.
+ *
+ * Windows Server updates ctime of reparse points when their data have changed.
+ * The server doesn't allow changing reparse tags from existing reparse points,
+ * though it's worth checking.
+ */
+static inline bool reparse_inode_match(struct inode *inode,
+				       struct cifs_fattr *fattr)
+{
+	struct cifsInodeInfo *cinode = CIFS_I(inode);
+	struct timespec64 ctime = inode_get_ctime(inode);
+
+	/*
+	 * Do not match reparse tags when client or server doesn't support
+	 * FSCTL_GET_REPARSE_POINT.  @fattr->cf_cifstag should contain correct
+	 * reparse tag from query dir response but the client won't be able to
+	 * read the reparse point data anyway.  This spares us a revalidation.
+	 */
+	if (cinode->reparse_tag != IO_REPARSE_TAG_INTERNAL &&
+	    cinode->reparse_tag != fattr->cf_cifstag)
+		return false;
+	return (cinode->cifsAttrs & ATTR_REPARSE_POINT) &&
+		timespec64_equal(&ctime, &fattr->cf_ctime);
+}
+
+static inline bool cifs_open_data_reparse(struct cifs_open_info_data *data)
+{
+	u32 attrs;
+	bool ret;
+
+	if (data->contains_posix_file_info) {
+		struct smb311_posix_qinfo *fi = &data->posix_fi;
+
+		attrs = le32_to_cpu(fi->DosAttributes);
+		if (data->reparse_point) {
+			attrs |= ATTR_REPARSE_POINT;
+			fi->DosAttributes = cpu_to_le32(attrs);
+		}
+
+	} else {
+		struct smb2_file_all_info *fi = &data->fi;
+
+		attrs = le32_to_cpu(fi->Attributes);
+		if (data->reparse_point) {
+			attrs |= ATTR_REPARSE_POINT;
+			fi->Attributes = cpu_to_le32(attrs);
+		}
+	}
+
+	ret = attrs & ATTR_REPARSE_POINT;
+
+	return ret;
+}
+
+bool cifs_reparse_point_to_fattr(struct cifs_sb_info *cifs_sb,
+				 struct cifs_fattr *fattr,
+				 struct cifs_open_info_data *data);
+int create_reparse_symlink(const unsigned int xid, struct inode *inode,
+			   struct dentry *dentry, struct cifs_tcon *tcon,
+			   const char *full_path, const char *symname);
+int mknod_reparse(unsigned int xid, struct inode *inode, struct dentry *dentry,
+		  struct cifs_tcon *tcon, const char *full_path, umode_t mode,
+		  dev_t dev);
+struct reparse_data_buffer *smb2_get_reparse_point_buffer(const struct kvec *rsp_iov,
+							  u32 *plen);
+
+#endif /* _CIFS_REPARSE_H */