Fix bug 5860: safe_strcpy gives a nasty error message for overlong strings

[Samba.git] / source / modules / vfs_acl_xattr.c

/*
 * Store Windows ACLs in xattrs.
 *
 * Copyright (C) Volker Lendecke, 2008
 * Copyright (C) Jeremy Allison, 2008
 *
 * 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/>.
 */

/* NOTE: This is an experimental module, not yet finished. JRA. */

#include "includes.h"
#include "librpc/gen_ndr/xattr.h"
#include "librpc/gen_ndr/ndr_xattr.h"

#undef DBGC_CLASS
#define DBGC_CLASS DBGC_VFS

static NTSTATUS parse_acl_blob(const DATA_BLOB *pblob,
                                const struct timespec cts,
                                uint32 security_info,
                                struct security_descriptor **ppdesc)
{
        TALLOC_CTX *ctx = talloc_tos();
        struct xattr_NTACL xacl;
        enum ndr_err_code ndr_err;
        size_t sd_size;

        ndr_err = ndr_pull_struct_blob(pblob, ctx, &xacl,
                        (ndr_pull_flags_fn_t)ndr_pull_xattr_NTACL);

        if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
                DEBUG(5, ("parse_acl_blob: ndr_pull_xattr_NTACL failed: %s\n",
                        ndr_errstr(ndr_err)));
                return ndr_map_error2ntstatus(ndr_err);;
        }

        if (xacl.version != 2) {
                return NT_STATUS_REVISION_MISMATCH;
        }

#if 0
        {
                struct timespec ts;
                /* Arg. This doesn't work. Too many activities
                 * change the ctime. May have to roll back to
                 * version 1.
                 */
                /*
                 * Check that the ctime timestamp is ealier
                 * than the stored timestamp.
                 */

                ts = nt_time_to_unix_timespec(&xacl.info.sd_ts->last_changed);

                if (timespec_compare(&cts, &ts) > 0) {
                        DEBUG(5, ("parse_acl_blob: stored ACL out of date "
                                "(%s > %s.\n",
                                timestring(ctx, cts.tv_sec),
                                timestring(ctx, ts.tv_sec)));
                        return NT_STATUS_EA_CORRUPT_ERROR;
                }
        }
#endif

        *ppdesc = make_sec_desc(ctx, SEC_DESC_REVISION, SEC_DESC_SELF_RELATIVE,
                        (security_info & OWNER_SECURITY_INFORMATION)
                        ? xacl.info.sd_ts->sd->owner_sid : NULL,
                        (security_info & GROUP_SECURITY_INFORMATION)
                        ? xacl.info.sd_ts->sd->group_sid : NULL,
                        (security_info & SACL_SECURITY_INFORMATION)
                        ? xacl.info.sd_ts->sd->sacl : NULL,
                        (security_info & DACL_SECURITY_INFORMATION)
                        ? xacl.info.sd_ts->sd->dacl : NULL,
                        &sd_size);

        TALLOC_FREE(xacl.info.sd);

        return (*ppdesc != NULL) ? NT_STATUS_OK : NT_STATUS_NO_MEMORY;
}

static NTSTATUS get_acl_blob(TALLOC_CTX *ctx,
                        vfs_handle_struct *handle,
                        files_struct *fsp,
                        const char *name,
                        DATA_BLOB *pblob)
{
        size_t size = 1024;
        uint8_t *val = NULL;
        uint8_t *tmp;
        ssize_t sizeret;
        int saved_errno = 0;

        ZERO_STRUCTP(pblob);

  again:

        tmp = TALLOC_REALLOC_ARRAY(ctx, val, uint8_t, size);
        if (tmp == NULL) {
                TALLOC_FREE(val);
                return NT_STATUS_NO_MEMORY;
        }
        val = tmp;

        become_root();
        if (fsp && fsp->fh->fd != -1) {
                sizeret = SMB_VFS_FGETXATTR(fsp, XATTR_NTACL_NAME, val, size);
        } else {
                sizeret = SMB_VFS_GETXATTR(handle->conn, name,
                                        XATTR_NTACL_NAME, val, size);
        }
        if (sizeret == -1) {
                saved_errno = errno;
        }
        unbecome_root();

        /* Max ACL size is 65536 bytes. */
        if (sizeret == -1) {
                errno = saved_errno;
                if ((errno == ERANGE) && (size != 65536)) {
                        /* Too small, try again. */
                        size = 65536;
                        goto again;
                }

                /* Real error - exit here. */
                TALLOC_FREE(val);
                return map_nt_error_from_unix(errno);
        }

        pblob->data = val;
        pblob->length = sizeret;
        return NT_STATUS_OK;
}

static NTSTATUS create_acl_blob(const struct security_descriptor *psd, DATA_BLOB *pblob)
{
        struct xattr_NTACL xacl;
        struct security_descriptor_timestamp sd_ts;
        enum ndr_err_code ndr_err;
        TALLOC_CTX *ctx = talloc_tos();
        struct timespec curr = timespec_current();

        ZERO_STRUCT(xacl);
        ZERO_STRUCT(sd_ts);

        /* Horrid hack as setting an xattr changes the ctime
         * on Linux. This gives a race of 1 second during
         * which we would not see a POSIX ACL set.
         */
        curr.tv_sec += 1;

        xacl.version = 2;
        xacl.info.sd_ts = &sd_ts;
        xacl.info.sd_ts->sd = CONST_DISCARD(struct security_descriptor *, psd);
        unix_timespec_to_nt_time(&xacl.info.sd_ts->last_changed, curr);

        DEBUG(10, ("create_acl_blob: timestamp stored as %s\n",
                timestring(ctx, curr.tv_sec) ));

        ndr_err = ndr_push_struct_blob(
                        pblob, ctx, &xacl,
                        (ndr_push_flags_fn_t)ndr_push_xattr_NTACL);

        if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
                DEBUG(5, ("create_acl_blob: ndr_push_xattr_NTACL failed: %s\n",
                        ndr_errstr(ndr_err)));
                return ndr_map_error2ntstatus(ndr_err);;
        }

        return NT_STATUS_OK;
}

static NTSTATUS store_acl_blob_fsp(files_struct *fsp,
                                DATA_BLOB *pblob)
{
        int ret;
        int saved_errno = 0;

        DEBUG(10,("store_acl_blob_fsp: storing blob length %u on file %s\n",
                        (unsigned int)pblob->length, fsp->fsp_name));

        become_root();
        if (fsp->fh->fd != -1) {
                ret = SMB_VFS_FSETXATTR(fsp, XATTR_NTACL_NAME,
                        pblob->data, pblob->length, 0);
        } else {
                ret = SMB_VFS_SETXATTR(fsp->conn, fsp->fsp_name,
                                XATTR_NTACL_NAME,
                                pblob->data, pblob->length, 0);
        }
        if (ret) {
                saved_errno = errno;
        }
        unbecome_root();
        if (ret) {
                errno = saved_errno;
                DEBUG(5, ("store_acl_blob_fsp: setting attr failed for file %s"
                        "with error %s\n",
                        fsp->fsp_name,
                        strerror(errno) ));
                return map_nt_error_from_unix(errno);
        }
        return NT_STATUS_OK;
}

static NTSTATUS store_acl_blob_pathname(connection_struct *conn,
                                        const char *fname,
                                        DATA_BLOB *pblob)
{
        int ret;
        int saved_errno = 0;

        DEBUG(10,("store_acl_blob_pathname: storing blob "
                        "length %u on file %s\n",
                        (unsigned int)pblob->length, fname));

        become_root();
        ret = SMB_VFS_SETXATTR(conn, fname,
                                XATTR_NTACL_NAME,
                                pblob->data, pblob->length, 0);
        if (ret) {
                saved_errno = errno;
        }
        unbecome_root();
        if (ret) {
                errno = saved_errno;
                DEBUG(5, ("store_acl_blob_pathname: setting attr failed "
                        "for file %s with error %s\n",
                        fname,
                        strerror(errno) ));
                return map_nt_error_from_unix(errno);
        }
        return NT_STATUS_OK;
}


static NTSTATUS get_nt_acl_xattr_internal(vfs_handle_struct *handle,
                                        files_struct *fsp,
                                        const char *name,
                                        uint32 security_info,
                                        struct security_descriptor **ppdesc)
{
        TALLOC_CTX *ctx = talloc_tos();
        DATA_BLOB blob;
        SMB_STRUCT_STAT sbuf;
        NTSTATUS status;

        if (fsp && name == NULL) {
                name = fsp->fsp_name;
        }

        DEBUG(10, ("get_nt_acl_xattr_internal: name=%s\n", name));

        status = get_acl_blob(ctx, handle, fsp, name, &blob);
        if (!NT_STATUS_IS_OK(status)) {
                DEBUG(10, ("get_acl_blob returned %s\n", nt_errstr(status)));
                return status;
        }

        if (fsp && fsp->fh->fd != -1) {
                if (SMB_VFS_FSTAT(fsp, &sbuf) == -1) {
                        return map_nt_error_from_unix(errno);
                }
        } else {
                if (SMB_VFS_STAT(handle->conn, name, &sbuf) == -1) {
                        return map_nt_error_from_unix(errno);
                }
        }

        status = parse_acl_blob(&blob, get_ctimespec(&sbuf),
                        security_info, ppdesc);
        if (!NT_STATUS_IS_OK(status)) {
                DEBUG(10, ("parse_acl_blob returned %s\n",
                                nt_errstr(status)));
                return status;
        }

        TALLOC_FREE(blob.data);
        return status;
}

/*********************************************************************
 Create a default security descriptor for a file in case no inheritance
 exists. All permissions to the owner and SYSTEM.
*********************************************************************/

static struct security_descriptor *default_file_sd(TALLOC_CTX *mem_ctx,
                                                SMB_STRUCT_STAT *psbuf)
{
        struct dom_sid owner_sid, group_sid;
        size_t sd_size;
        struct security_ace *pace = NULL;
        struct security_acl *pacl = NULL;

        uid_to_sid(&owner_sid, psbuf->st_uid);
        gid_to_sid(&group_sid, psbuf->st_gid);

        pace = TALLOC_ARRAY(mem_ctx, struct security_ace, 2);
        if (!pace) {
                return NULL;
        }

        init_sec_ace(&pace[0], &owner_sid, SEC_ACE_TYPE_ACCESS_ALLOWED,
                        SEC_RIGHTS_FILE_ALL, 0);
        init_sec_ace(&pace[1], &global_sid_System, SEC_ACE_TYPE_ACCESS_ALLOWED,
                        SEC_RIGHTS_FILE_ALL, 0);

        pacl = make_sec_acl(mem_ctx,
                                NT4_ACL_REVISION,
                                2,
                                pace);
        if (!pacl) {
                return NULL;
        }
        return make_sec_desc(mem_ctx,
                        SECURITY_DESCRIPTOR_REVISION_1,
                        SEC_DESC_SELF_RELATIVE|SEC_DESC_DACL_PRESENT|
                                SEC_DESC_DACL_DEFAULTED,
                        &owner_sid,
                        &group_sid,
                        NULL,
                        pacl,
                        &sd_size);
}

/*********************************************************************
*********************************************************************/

static NTSTATUS inherit_new_acl(vfs_handle_struct *handle,
                                        const char *fname,
                                        files_struct *fsp,
                                        bool container)
{
        TALLOC_CTX *ctx = talloc_tos();
        NTSTATUS status;
        struct security_descriptor *parent_desc = NULL;
        struct security_descriptor *psd = NULL;
        DATA_BLOB blob;
        size_t size;
        char *parent_name;

        if (!parent_dirname_talloc(ctx,
                                fname,
                                &parent_name,
                                NULL)) {
                return NT_STATUS_NO_MEMORY;
        }

        DEBUG(10,("inherit_new_acl: check directory %s\n",
                        parent_name));

        status = get_nt_acl_xattr_internal(handle,
                                        NULL,
                                        parent_name,
                                        DACL_SECURITY_INFORMATION,
                                        &parent_desc);
        if (!NT_STATUS_IS_OK(status)) {
                DEBUG(10,("inherit_new_acl: directory %s failed "
                        "to get acl %s\n",
                        parent_name,
                        nt_errstr(status) ));
                return status;
        }

        /* Create an inherited descriptor from the parent. */
        status = se_create_child_secdesc(ctx,
                                &psd,
                                &size,
                                parent_desc,
                                &handle->conn->server_info->ptok->user_sids[PRIMARY_USER_SID_INDEX],
                                &handle->conn->server_info->ptok->user_sids[PRIMARY_GROUP_SID_INDEX],
                                container);
        if (!NT_STATUS_IS_OK(status)) {
                return status;
        }
        if (psd->dacl == NULL) {
                SMB_STRUCT_STAT sbuf;
                int ret;

                TALLOC_FREE(psd);
                if (fsp && !fsp->is_directory && fsp->fh->fd != -1) {
                        ret = SMB_VFS_FSTAT(fsp, &sbuf);
                } else {
                        ret = SMB_VFS_STAT(fsp->conn,fsp->fsp_name, &sbuf);
                }
                if (ret == -1) {
                        return map_nt_error_from_unix(errno);
                }
                psd = default_file_sd(ctx, &sbuf);
                if (!psd) {
                        return NT_STATUS_NO_MEMORY;
                }
        }

        status = create_acl_blob(psd, &blob);
        if (!NT_STATUS_IS_OK(status)) {
                return status;
        }
        if (fsp) {
                return store_acl_blob_fsp(fsp, &blob);
        } else {
                return store_acl_blob_pathname(handle->conn, fname, &blob);
        }
}

/*********************************************************************
 Check ACL on open. For new files inherit from parent directory.
*********************************************************************/

static int open_acl_xattr(vfs_handle_struct *handle,
                                        const char *fname,
                                        files_struct *fsp,
                                        int flags,
                                        mode_t mode)
{
        uint32_t access_granted = 0;
        struct security_descriptor *pdesc = NULL;
        bool file_existed = true;
        NTSTATUS status = get_nt_acl_xattr_internal(handle,
                                        NULL,
                                        fname,
                                        (OWNER_SECURITY_INFORMATION |
                                         GROUP_SECURITY_INFORMATION |
                                         DACL_SECURITY_INFORMATION),
                                        &pdesc);
        if (NT_STATUS_IS_OK(status)) {
                /* See if we can access it. */
                status = se_access_check(pdesc,
                                        handle->conn->server_info->ptok,
                                        fsp->access_mask,
                                        &access_granted);
                if (!NT_STATUS_IS_OK(status)) {
                        errno = map_errno_from_nt_status(status);
                        return -1;
                }
        } else if (NT_STATUS_EQUAL(status,NT_STATUS_OBJECT_NAME_NOT_FOUND)) {
                file_existed = false;
        }

        DEBUG(10,("open_acl_xattr: get_nt_acl_attr_internal for "
                "file %s returned %s\n",
                fname,
                nt_errstr(status) ));

        fsp->fh->fd = SMB_VFS_NEXT_OPEN(handle, fname, fsp, flags, mode);

        if (!file_existed && fsp->fh->fd != -1) {
                /* File was created. Inherit from parent directory. */
                string_set(&fsp->fsp_name, fname);
                inherit_new_acl(handle, fname, fsp, false);
        }

        return fsp->fh->fd;
}

static int mkdir_acl_xattr(vfs_handle_struct *handle, const char *path, mode_t mode)
{
        int ret = SMB_VFS_NEXT_MKDIR(handle, path, mode);

        if (ret == -1) {
                return ret;
        }
        /* New directory - inherit from parent. */
        inherit_new_acl(handle, path, NULL, true);
        return ret;
}

static NTSTATUS fget_nt_acl_xattr(vfs_handle_struct *handle, files_struct *fsp,
        uint32 security_info, struct security_descriptor **ppdesc)
{
        NTSTATUS status = get_nt_acl_xattr_internal(handle, fsp,
                                NULL, security_info, ppdesc);
        if (NT_STATUS_IS_OK(status)) {
                if (DEBUGLEVEL >= 10) {
                        DEBUG(10,("fget_nt_acl_xattr: returning xattr sd for file %s\n",
                                fsp->fsp_name));
                        NDR_PRINT_DEBUG(security_descriptor, *ppdesc);
                }
                return NT_STATUS_OK;
        }
        return SMB_VFS_NEXT_FGET_NT_ACL(handle, fsp,
                        security_info, ppdesc);
}

static NTSTATUS get_nt_acl_xattr(vfs_handle_struct *handle,
        const char *name, uint32 security_info, struct security_descriptor **ppdesc)
{
        NTSTATUS status = get_nt_acl_xattr_internal(handle, NULL,
                                name, security_info, ppdesc);
        if (NT_STATUS_IS_OK(status)) {
                if (DEBUGLEVEL >= 10) {
                        DEBUG(10,("get_nt_acl_xattr: returning xattr sd for file %s\n",
                                name));
                        NDR_PRINT_DEBUG(security_descriptor, *ppdesc);
                }
                return NT_STATUS_OK;
        }
        return SMB_VFS_NEXT_GET_NT_ACL(handle, name,
                        security_info, ppdesc);
}

static NTSTATUS fset_nt_acl_xattr(vfs_handle_struct *handle, files_struct *fsp,
        uint32 security_info_sent, const struct security_descriptor *psd)
{
        NTSTATUS status;
        DATA_BLOB blob;

        if (DEBUGLEVEL >= 10) {
                DEBUG(10,("fset_nt_acl_xattr: incoming sd for file %s\n",
                        fsp->fsp_name));
                NDR_PRINT_DEBUG(security_descriptor,
                        CONST_DISCARD(struct security_descriptor *,psd));
        }

        status = SMB_VFS_NEXT_FSET_NT_ACL(handle, fsp, security_info_sent, psd);
        if (!NT_STATUS_IS_OK(status)) {
                return status;
        }

        /* Ensure owner and group are set. */
        if (!psd->owner_sid || !psd->group_sid) {
                int ret;
                SMB_STRUCT_STAT sbuf;
                DOM_SID owner_sid, group_sid;
                struct security_descriptor *nc_psd = dup_sec_desc(talloc_tos(), psd);

                if (!nc_psd) {
                        return NT_STATUS_OK;
                }
                if (fsp->is_directory || fsp->fh->fd == -1) {
                        ret = SMB_VFS_STAT(fsp->conn,fsp->fsp_name, &sbuf);
                } else {
                        ret = SMB_VFS_FSTAT(fsp, &sbuf);
                }
                if (ret == -1) {
                        /* Lower level acl set succeeded,
                         * so still return OK. */
                        return NT_STATUS_OK;
                }
                create_file_sids(&sbuf, &owner_sid, &group_sid);
                /* This is safe as nc_psd is discarded at fn exit. */
                nc_psd->owner_sid = &owner_sid;
                nc_psd->group_sid = &group_sid;
                security_info_sent |= (OWNER_SECURITY_INFORMATION|GROUP_SECURITY_INFORMATION);
                psd = nc_psd;
        }

        if ((security_info_sent & DACL_SECURITY_INFORMATION) &&
                        psd->dacl != NULL &&
                        (psd->type & (SE_DESC_DACL_AUTO_INHERITED|
                                SE_DESC_DACL_AUTO_INHERIT_REQ))==
                                (SE_DESC_DACL_AUTO_INHERITED|
                                SE_DESC_DACL_AUTO_INHERIT_REQ) ) {
                struct security_descriptor *new_psd = NULL;
                status = append_parent_acl(fsp, psd, &new_psd);
                if (!NT_STATUS_IS_OK(status)) {
                        /* Lower level acl set succeeded,
                         * so still return OK. */
                        return NT_STATUS_OK;
                }
                psd = new_psd;
        }

        if (DEBUGLEVEL >= 10) {
                DEBUG(10,("fset_nt_acl_xattr: storing xattr sd for file %s\n",
                        fsp->fsp_name));
                NDR_PRINT_DEBUG(security_descriptor,
                        CONST_DISCARD(struct security_descriptor *,psd));
        }
        create_acl_blob(psd, &blob);
        store_acl_blob_fsp(fsp, &blob);

        return NT_STATUS_OK;
}

/* VFS operations structure */

static vfs_op_tuple skel_op_tuples[] =
{
        {SMB_VFS_OP(mkdir_acl_xattr), SMB_VFS_OP_MKDIR, SMB_VFS_LAYER_TRANSPARENT},
        {SMB_VFS_OP(open_acl_xattr),  SMB_VFS_OP_OPEN,  SMB_VFS_LAYER_TRANSPARENT},

        /* NT File ACL operations */

        {SMB_VFS_OP(fget_nt_acl_xattr),SMB_VFS_OP_FGET_NT_ACL,SMB_VFS_LAYER_TRANSPARENT},
        {SMB_VFS_OP(get_nt_acl_xattr), SMB_VFS_OP_GET_NT_ACL, SMB_VFS_LAYER_TRANSPARENT},
        {SMB_VFS_OP(fset_nt_acl_xattr),SMB_VFS_OP_FSET_NT_ACL,SMB_VFS_LAYER_TRANSPARENT},

        {SMB_VFS_OP(NULL), SMB_VFS_OP_NOOP, SMB_VFS_LAYER_NOOP}
};

NTSTATUS vfs_acl_xattr_init(void)
{
        return smb_register_vfs(SMB_VFS_INTERFACE_VERSION, "acl_xattr", skel_op_tuples);
}