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Diffstat (limited to 'source3/smbd/file_access.c')
| -rw-r--r-- | source3/smbd/file_access.c | 244 |
1 files changed, 244 insertions, 0 deletions
diff --git a/source3/smbd/file_access.c b/source3/smbd/file_access.c new file mode 100644 index 0000000..476aead --- /dev/null +++ b/source3/smbd/file_access.c @@ -0,0 +1,244 @@ +/* + Unix SMB/CIFS implementation. + Check access to files based on security descriptors. + Copyright (C) Jeremy Allison 2005-2006. + Copyright (C) Michael Adam 2007. + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see <http://www.gnu.org/licenses/>. +*/ + +#include "includes.h" +#include "system/filesys.h" +#include "../libcli/security/security.h" +#include "../librpc/gen_ndr/ndr_security.h" +#include "smbd/smbd.h" + +#undef DBGC_CLASS +#define DBGC_CLASS DBGC_ACLS + +/**************************************************************************** + Actually emulate the in-kernel access checking for delete access. We need + this to successfully return ACCESS_DENIED on a file open for delete access. +****************************************************************************/ + +bool can_delete_file_in_directory(connection_struct *conn, + struct files_struct *dirfsp, + const struct smb_filename *smb_fname) +{ + struct smb_filename *smb_fname_parent = NULL; + bool ret; + NTSTATUS status; + + if (!CAN_WRITE(conn)) { + return False; + } + + if (!lp_acl_check_permissions(SNUM(conn))) { + /* This option means don't check. */ + return true; + } + + if (get_current_uid(conn) == (uid_t)0) { + /* I'm sorry sir, I didn't know you were root... */ + return true; + } + + if (dirfsp != conn->cwd_fsp) { + smb_fname_parent = dirfsp->fsp_name; + } else { + struct smb_filename *atname = NULL; + /* + * Get a pathref on the parent. + */ + status = parent_pathref(talloc_tos(), + conn->cwd_fsp, + smb_fname, + &smb_fname_parent, + &atname); + if (!NT_STATUS_IS_OK(status)) { + return false; + } + } + + SMB_ASSERT(VALID_STAT(smb_fname_parent->st)); + + /* fast paths first */ + + if (!S_ISDIR(smb_fname_parent->st.st_ex_mode)) { + ret = false; + goto out; + } + +#ifdef S_ISVTX + /* sticky bit means delete only by owner of file or by root or + * by owner of directory. */ + if (smb_fname_parent->st.st_ex_mode & S_ISVTX) { + if (!VALID_STAT(smb_fname->st)) { + /* If the file doesn't already exist then + * yes we'll be able to delete it. */ + ret = true; + goto out; + } + + /* + * Patch from SATOH Fumiyasu <fumiyas@miraclelinux.com> + * for bug #3348. Don't assume owning sticky bit + * directory means write access allowed. + * Fail to delete if we're not the owner of the file, + * or the owner of the directory as we have no possible + * chance of deleting. Otherwise, go on and check the ACL. + */ + if ((get_current_uid(conn) != + smb_fname_parent->st.st_ex_uid) && + (get_current_uid(conn) != smb_fname->st.st_ex_uid)) { + DEBUG(10,("can_delete_file_in_directory: not " + "owner of file %s or directory %s", + smb_fname_str_dbg(smb_fname), + smb_fname_str_dbg(smb_fname_parent))); + ret = false; + goto out; + } + } +#endif + + /* now for ACL checks */ + + /* + * There's two ways to get the permission to delete a file: First by + * having the DELETE bit on the file itself and second if that does + * not help, by the DELETE_CHILD bit on the containing directory. + * + * Here we only check the directory permissions, we will + * check the file DELETE permission separately. + */ + + ret = NT_STATUS_IS_OK(smbd_check_access_rights_fsp( + conn->cwd_fsp, + smb_fname_parent->fsp, + false, + FILE_DELETE_CHILD)); + out: + if (smb_fname_parent != dirfsp->fsp_name) { + TALLOC_FREE(smb_fname_parent); + } + return ret; +} + +/**************************************************************************** + Userspace check for write access to fsp. +****************************************************************************/ + +bool can_write_to_fsp(struct files_struct *fsp) +{ + return NT_STATUS_IS_OK(smbd_check_access_rights_fsp( + fsp->conn->cwd_fsp, + fsp, + false, + FILE_WRITE_DATA)); +} + +/**************************************************************************** + Check for an existing default Windows ACL on a directory fsp. +****************************************************************************/ + +bool directory_has_default_acl_fsp(struct files_struct *fsp) +{ + struct security_descriptor *secdesc = NULL; + unsigned int i; + NTSTATUS status; + + status = SMB_VFS_FGET_NT_ACL(metadata_fsp(fsp), + SECINFO_DACL, + talloc_tos(), + &secdesc); + + if (!NT_STATUS_IS_OK(status) || + secdesc == NULL || + secdesc->dacl == NULL) + { + TALLOC_FREE(secdesc); + return false; + } + + for (i = 0; i < secdesc->dacl->num_aces; i++) { + struct security_ace *psa = &secdesc->dacl->aces[i]; + + if (psa->flags & (SEC_ACE_FLAG_OBJECT_INHERIT| + SEC_ACE_FLAG_CONTAINER_INHERIT)) + { + TALLOC_FREE(secdesc); + return true; + } + } + TALLOC_FREE(secdesc); + return false; +} + +/**************************************************************************** + Check if setting delete on close is allowed on this fsp. +****************************************************************************/ + +NTSTATUS can_set_delete_on_close(files_struct *fsp, uint32_t dosmode) +{ + /* + * Only allow delete on close for writable files. + */ + + if ((dosmode & FILE_ATTRIBUTE_READONLY) && + !lp_delete_readonly(SNUM(fsp->conn))) { + DEBUG(10,("can_set_delete_on_close: file %s delete on close " + "flag set but file attribute is readonly.\n", + fsp_str_dbg(fsp))); + return NT_STATUS_CANNOT_DELETE; + } + + /* + * Only allow delete on close for writable shares. + */ + + if (!CAN_WRITE(fsp->conn)) { + DEBUG(10,("can_set_delete_on_close: file %s delete on " + "close flag set but write access denied on share.\n", + fsp_str_dbg(fsp))); + return NT_STATUS_ACCESS_DENIED; + } + + /* + * Only allow delete on close for files/directories opened with delete + * intent. + */ + + if (!(fsp->access_mask & DELETE_ACCESS)) { + DEBUG(10,("can_set_delete_on_close: file %s delete on " + "close flag set but delete access denied.\n", + fsp_str_dbg(fsp))); + return NT_STATUS_ACCESS_DENIED; + } + + /* Don't allow delete on close for non-empty directories. */ + if (fsp->fsp_flags.is_directory) { + SMB_ASSERT(!fsp_is_alternate_stream(fsp)); + + /* Or the root of a share. */ + if (ISDOT(fsp->fsp_name->base_name)) { + DEBUG(10,("can_set_delete_on_close: can't set delete on " + "close for the root of a share.\n")); + return NT_STATUS_ACCESS_DENIED; + } + + return can_delete_directory_fsp(fsp); + } + + return NT_STATUS_OK; +} |