From eb27f9b7bf9c1dc902d9545eecf805831bd4e46c Mon Sep 17 00:00:00 2001 From: Jeremy Allison Date: Tue, 5 Jan 2016 11:18:12 -0800 Subject: [PATCH 1/8] CVE-2015-7560: s3: smbd: Add refuse_symlink() function that can be used to prevent operations on a symlink. BUG: https://bugzilla.samba.org/show_bug.cgi?id=11648 Signed-off-by: Jeremy Allison Reviewed-by: Michael Adam --- source3/smbd/trans2.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) --- a/source3/smbd/trans2.c +++ b/source3/smbd/trans2.c @@ -51,6 +51,34 @@ static char *store_file_unix_basic_info2 files_struct *fsp, const SMB_STRUCT_STAT *psbuf); +/**************************************************************************** + Check if an open file handle or pathname is a symlink. +****************************************************************************/ + +static NTSTATUS refuse_symlink(connection_struct *conn, + const files_struct *fsp, + const char *name) +{ + SMB_STRUCT_STAT sbuf; + const SMB_STRUCT_STAT *pst = NULL; + + if (fsp) { + pst = &fsp->fsp_name->st; + } else { + int ret = vfs_stat_smb_fname(conn, + name, + &sbuf); + if (ret == -1) { + return map_nt_error_from_unix(errno); + } + pst = &sbuf; + } + if (S_ISLNK(pst->st_ex_mode)) { + return NT_STATUS_ACCESS_DENIED; + } + return NT_STATUS_OK; +} + /******************************************************************** Roundup a value to the nearest allocation roundup size boundary. Only do this for Windows clients. @@ -181,12 +209,22 @@ NTSTATUS get_ea_names_from_file(TALLOC_C char **names, **tmp; size_t num_names; ssize_t sizeret = -1; + NTSTATUS status; + + if (pnames) { + *pnames = NULL; + } + *pnum_names = 0; if (!lp_ea_support(SNUM(conn))) { - if (pnames) { - *pnames = NULL; - } - *pnum_names = 0; + return NT_STATUS_OK; + } + + status = refuse_symlink(conn, fsp, fname); + if (!NT_STATUS_IS_OK(status)) { + /* + * Just return no EA's on a symlink. + */ return NT_STATUS_OK; } @@ -236,10 +274,6 @@ NTSTATUS get_ea_names_from_file(TALLOC_C if (sizeret == 0) { TALLOC_FREE(names); - if (pnames) { - *pnames = NULL; - } - *pnum_names = 0; return NT_STATUS_OK; } @@ -550,6 +584,7 @@ NTSTATUS set_ea(connection_struct *conn, const struct smb_filename *smb_fname, struct ea_list *ea_list) { char *fname = NULL; + NTSTATUS status; if (!lp_ea_support(SNUM(conn))) { return NT_STATUS_EAS_NOT_SUPPORTED; @@ -559,6 +594,12 @@ NTSTATUS set_ea(connection_struct *conn, return NT_STATUS_ACCESS_DENIED; } + status = refuse_symlink(conn, fsp, smb_fname->base_name); + if (!NT_STATUS_IS_OK(status)) { + return status; + } + + /* For now setting EAs on streams isn't supported. */ fname = smb_fname->base_name; @@ -4931,6 +4972,13 @@ NTSTATUS smbd_do_qfilepathinfo(connectio uint16 num_file_acls = 0; uint16 num_def_acls = 0; + status = refuse_symlink(conn, + fsp, + smb_fname->base_name); + if (!NT_STATUS_IS_OK(status)) { + return status; + } + if (fsp && fsp->fh->fd != -1) { file_acl = SMB_VFS_SYS_ACL_GET_FD(fsp); } else { @@ -6452,6 +6500,7 @@ static NTSTATUS smb_set_posix_acl(connec uint16 num_def_acls; bool valid_file_acls = True; bool valid_def_acls = True; + NTSTATUS status; if (total_data < SMB_POSIX_ACL_HEADER_SIZE) { return NT_STATUS_INVALID_PARAMETER; @@ -6479,6 +6528,11 @@ static NTSTATUS smb_set_posix_acl(connec return NT_STATUS_INVALID_PARAMETER; } + status = refuse_symlink(conn, fsp, smb_fname->base_name); + if (!NT_STATUS_IS_OK(status)) { + return status; + } + DEBUG(10,("smb_set_posix_acl: file %s num_file_acls = %u, num_def_acls = %u\n", smb_fname ? smb_fname_str_dbg(smb_fname) : fsp_str_dbg(fsp), (unsigned int)num_file_acls, --- a/source3/smbd/nttrans.c +++ b/source3/smbd/nttrans.c @@ -877,6 +877,12 @@ NTSTATUS set_sd(files_struct *fsp, struc return NT_STATUS_OK; } + if (S_ISLNK(fsp->fsp_name->st.st_ex_mode)) { + DEBUG(10, ("ACL set on symlink %s denied.\n", + fsp_str_dbg(fsp))); + return NT_STATUS_ACCESS_DENIED; + } + if (psd->owner_sid == NULL) { security_info_sent &= ~SECINFO_OWNER; } @@ -1925,6 +1931,12 @@ NTSTATUS smbd_do_query_security_desc(con return NT_STATUS_ACCESS_DENIED; } + if (S_ISLNK(fsp->fsp_name->st.st_ex_mode)) { + DEBUG(10, ("ACL get on symlink %s denied.\n", + fsp_str_dbg(fsp))); + return NT_STATUS_ACCESS_DENIED; + } + if (security_info_wanted & (SECINFO_DACL|SECINFO_OWNER| SECINFO_GROUP|SECINFO_SACL)) { /* Don't return SECINFO_LABEL if anything else was