cifs: fix crash querying symlinks stored as reparse-points
We never parsed/returned any data from .get_link() when the object is a windows reparse-point containing a symlink. This results in the VFS layer oopsing accessing an uninitialized buffer: ... [ 171.407172] Call Trace: [ 171.408039] readlink_copy+0x29/0x70 [ 171.408872] vfs_readlink+0xc1/0x1f0 [ 171.409709] ? readlink_copy+0x70/0x70 [ 171.410565] ? simple_attr_release+0x30/0x30 [ 171.411446] ? getname_flags+0x105/0x2a0 [ 171.412231] do_readlinkat+0x1b7/0x1e0 [ 171.412938] ? __ia32_compat_sys_newfstat+0x30/0x30 ... Fix this by adding code to handle these buffers and make sure we do return a valid buffer to .get_link() CC: Stable <stable@vger.kernel.org> Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Steve French <stfrench@microsoft.com>
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4b972a01a7
Коммит
5de254dca8
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@ -2372,6 +2372,41 @@ smb2_get_dfs_refer(const unsigned int xid, struct cifs_ses *ses,
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kfree(dfs_rsp);
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return rc;
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}
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static int
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parse_reparse_symlink(struct reparse_symlink_data_buffer *symlink_buf,
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u32 plen, char **target_path,
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struct cifs_sb_info *cifs_sb)
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{
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unsigned int sub_len;
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unsigned int sub_offset;
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/* We only handle Symbolic Link : MS-FSCC 2.1.2.4 */
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if (le32_to_cpu(symlink_buf->ReparseTag) != IO_REPARSE_TAG_SYMLINK) {
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cifs_dbg(VFS, "srv returned invalid symlink buffer\n");
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return -EIO;
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}
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sub_offset = le16_to_cpu(symlink_buf->SubstituteNameOffset);
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sub_len = le16_to_cpu(symlink_buf->SubstituteNameLength);
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if (sub_offset + 20 > plen ||
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sub_offset + sub_len + 20 > plen) {
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cifs_dbg(VFS, "srv returned malformed symlink buffer\n");
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return -EIO;
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}
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*target_path = cifs_strndup_from_utf16(
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symlink_buf->PathBuffer + sub_offset,
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sub_len, true, cifs_sb->local_nls);
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if (!(*target_path))
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return -ENOMEM;
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convert_delimiter(*target_path, '/');
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cifs_dbg(FYI, "%s: target path: %s\n", __func__, *target_path);
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return 0;
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}
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#define SMB2_SYMLINK_STRUCT_SIZE \
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(sizeof(struct smb2_err_rsp) - 1 + sizeof(struct smb2_symlink_err_rsp))
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@ -2401,11 +2436,13 @@ smb2_query_symlink(const unsigned int xid, struct cifs_tcon *tcon,
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struct kvec close_iov[1];
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struct smb2_create_rsp *create_rsp;
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struct smb2_ioctl_rsp *ioctl_rsp;
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char *ioctl_buf;
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struct reparse_data_buffer *reparse_buf;
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u32 plen;
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cifs_dbg(FYI, "%s: path: %s\n", __func__, full_path);
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*target_path = NULL;
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if (smb3_encryption_required(tcon))
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flags |= CIFS_TRANSFORM_REQ;
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@ -2483,17 +2520,36 @@ smb2_query_symlink(const unsigned int xid, struct cifs_tcon *tcon,
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if ((rc == 0) && (is_reparse_point)) {
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/* See MS-FSCC 2.3.23 */
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ioctl_buf = (char *)ioctl_rsp + le32_to_cpu(ioctl_rsp->OutputOffset);
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reparse_buf = (struct reparse_data_buffer *)
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((char *)ioctl_rsp +
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le32_to_cpu(ioctl_rsp->OutputOffset));
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plen = le32_to_cpu(ioctl_rsp->OutputCount);
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if (plen + le32_to_cpu(ioctl_rsp->OutputOffset) >
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rsp_iov[1].iov_len) {
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cifs_dbg(VFS, "srv returned invalid ioctl length: %d\n", plen);
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cifs_dbg(VFS, "srv returned invalid ioctl len: %d\n",
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plen);
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rc = -EIO;
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goto querty_exit;
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}
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/* Do stuff with ioctl_buf/plen */
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if (plen < 8) {
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cifs_dbg(VFS, "reparse buffer is too small. Must be "
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"at least 8 bytes but was %d\n", plen);
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rc = -EIO;
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goto querty_exit;
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}
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if (plen < le16_to_cpu(reparse_buf->ReparseDataLength) + 8) {
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cifs_dbg(VFS, "srv returned invalid reparse buf "
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"length: %d\n", plen);
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rc = -EIO;
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goto querty_exit;
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}
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rc = parse_reparse_symlink(
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(struct reparse_symlink_data_buffer *)reparse_buf,
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plen, target_path, cifs_sb);
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goto querty_exit;
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}
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@ -914,7 +914,19 @@ struct reparse_mount_point_data_buffer {
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__u8 PathBuffer[0]; /* Variable Length */
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} __packed;
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/* See MS-FSCC 2.1.2.4 and cifspdu.h for struct reparse_symlink_data */
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#define SYMLINK_FLAG_RELATIVE 0x00000001
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struct reparse_symlink_data_buffer {
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__le32 ReparseTag;
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__le16 ReparseDataLength;
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__u16 Reserved;
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__le16 SubstituteNameOffset;
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__le16 SubstituteNameLength;
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__le16 PrintNameOffset;
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__le16 PrintNameLength;
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__le32 Flags;
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__u8 PathBuffer[0]; /* Variable Length */
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} __packed;
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/* See MS-FSCC 2.1.2.6 and cifspdu.h for struct reparse_posix_data */
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