/* 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 "../libcli/security/security.h" #include "../librpc/gen_ndr/ndr_security.h" #undef DBGC_CLASS #define DBGC_CLASS DBGC_ACLS /** * Security descriptor / NT Token level access check function. */ bool can_access_file_acl(struct connection_struct *conn, const struct smb_filename *smb_fname, uint32_t access_mask) { NTSTATUS status; uint32_t access_granted; struct security_descriptor *secdesc = NULL; bool ret; if (get_current_uid(conn) == (uid_t)0) { /* I'm sorry sir, I didn't know you were root... */ return true; } status = SMB_VFS_GET_NT_ACL(conn, smb_fname->base_name, (SECINFO_OWNER | SECINFO_GROUP | SECINFO_DACL), &secdesc); if (!NT_STATUS_IS_OK(status)) { DEBUG(5, ("Could not get acl: %s\n", nt_errstr(status))); ret = false; goto out; } status = se_access_check(secdesc, get_current_nttok(conn), access_mask, &access_granted); ret = NT_STATUS_IS_OK(status); if (DEBUGLEVEL >= 10) { DEBUG(10,("can_access_file_acl for file %s " "access_mask 0x%x, access_granted 0x%x " "access %s\n", smb_fname_str_dbg(smb_fname), (unsigned int)access_mask, (unsigned int)access_granted, ret ? "ALLOWED" : "DENIED" )); NDR_PRINT_DEBUG(security_descriptor, secdesc); } out: TALLOC_FREE(secdesc); return ret; } /**************************************************************************** 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 smb_filename *smb_fname) { TALLOC_CTX *ctx = talloc_tos(); char *dname = NULL; struct smb_filename *smb_fname_parent = NULL; NTSTATUS status; bool ret; if (!CAN_WRITE(conn)) { return False; } /* Get the parent directory permission mask and owners. */ if (!parent_dirname(ctx, smb_fname->base_name, &dname, NULL)) { return False; } status = create_synthetic_smb_fname(ctx, dname, NULL, NULL, &smb_fname_parent); if (!NT_STATUS_IS_OK(status)) { ret = false; goto out; } if(SMB_VFS_STAT(conn, smb_fname_parent) != 0) { ret = false; goto out; } /* fast paths first */ if (!S_ISDIR(smb_fname_parent->st.st_ex_mode)) { ret = false; goto out; } if (get_current_uid(conn) == (uid_t)0) { /* I'm sorry sir, I didn't know you were root... */ ret = true; 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(SMB_VFS_STAT(conn, smb_fname) != 0) { if (errno == ENOENT) { /* If the file doesn't already exist then * yes we'll be able to delete it. */ ret = true; goto out; } DEBUG(10,("can_delete_file_in_directory: can't " "stat file %s (%s)", smb_fname_str_dbg(smb_fname), strerror(errno) )); ret = false; 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 = can_access_file_acl(conn, smb_fname_parent, FILE_DELETE_CHILD); out: TALLOC_FREE(dname); TALLOC_FREE(smb_fname_parent); return ret; } /**************************************************************************** Actually emulate the in-kernel access checking for read/write access. We need this to successfully check for ability to write for dos filetimes. Note this doesn't take into account share write permissions. ****************************************************************************/ bool can_access_file_data(connection_struct *conn, const struct smb_filename *smb_fname, uint32 access_mask) { if (!(access_mask & (FILE_READ_DATA|FILE_WRITE_DATA))) { return False; } access_mask &= (FILE_READ_DATA|FILE_WRITE_DATA); /* some fast paths first */ DEBUG(10,("can_access_file_data: requesting 0x%x on file %s\n", (unsigned int)access_mask, smb_fname_str_dbg(smb_fname))); if (get_current_uid(conn) == (uid_t)0) { /* I'm sorry sir, I didn't know you were root... */ return True; } SMB_ASSERT(VALID_STAT(smb_fname->st)); /* Check primary owner access. */ if (get_current_uid(conn) == smb_fname->st.st_ex_uid) { switch (access_mask) { case FILE_READ_DATA: return (smb_fname->st.st_ex_mode & S_IRUSR) ? True : False; case FILE_WRITE_DATA: return (smb_fname->st.st_ex_mode & S_IWUSR) ? True : False; default: /* FILE_READ_DATA|FILE_WRITE_DATA */ if ((smb_fname->st.st_ex_mode & (S_IWUSR|S_IRUSR)) == (S_IWUSR|S_IRUSR)) { return True; } else { return False; } } } /* now for ACL checks */ return can_access_file_acl(conn, smb_fname, access_mask); } /**************************************************************************** Userspace check for write access. Note this doesn't take into account share write permissions. ****************************************************************************/ bool can_write_to_file(connection_struct *conn, const struct smb_filename *smb_fname) { return can_access_file_data(conn, smb_fname, FILE_WRITE_DATA); } /**************************************************************************** Check for an existing default Windows ACL on a directory. ****************************************************************************/ bool directory_has_default_acl(connection_struct *conn, const char *fname) { /* returns talloced off tos. */ struct security_descriptor *secdesc = NULL; unsigned int i; NTSTATUS status = SMB_VFS_GET_NT_ACL(conn, fname, SECINFO_DACL, &secdesc); if (!NT_STATUS_IS_OK(status) || secdesc == NULL) { 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; }