/src/samba/source3/modules/vfs_acl_common.c

Source
/*
 * Store Windows ACLs in data store - common functions.
 * #included into modules/vfs_acl_xattr.c and modules/vfs_acl_tdb.c
 *
 * Copyright (C) Volker Lendecke, 2008
 * Copyright (C) Jeremy Allison, 2009
 * Copyright (C) Ralph Böhme, 2016
 *
 * 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 "vfs_acl_common.h"
#include "smbd/smbd.h"
#include "system/filesys.h"
#include "librpc/gen_ndr/ndr_xattr.h"
#include "../libcli/security/security.h"
#include "../librpc/gen_ndr/ndr_security.h"
#include "../lib/util/bitmap.h"
#include "passdb/lookup_sid.h"

#include <gnutls/gnutls.h>
#include <gnutls/crypto.h>

static NTSTATUS create_acl_blob(const struct security_descriptor *psd,
      DATA_BLOB *pblob,
      uint16_t hash_type,
      uint8_t hash[XATTR_SD_HASH_SIZE]);

#define HASH_SECURITY_INFO (SECINFO_OWNER | \
        SECINFO_GROUP | \
        SECINFO_DACL | \
        SECINFO_SACL)

bool init_acl_common_config(vfs_handle_struct *handle,
          const char *module_name)
{
  struct acl_common_config *config = NULL;
  const struct enum_list *default_acl_style_list = NULL;

  default_acl_style_list = get_default_acl_style_list();

  config = talloc_zero(handle->conn, struct acl_common_config);
  if (config == NULL) {
    DBG_ERR("talloc_zero() failed\n");
    errno = ENOMEM;
    return false;
  }

  config->ignore_system_acls = lp_parm_bool(SNUM(handle->conn),
              module_name,
              "ignore system acls",
              false);
  config->default_acl_style = lp_parm_enum(SNUM(handle->conn),
             module_name,
             "default acl style",
             default_acl_style_list,
             DEFAULT_ACL_POSIX);

  SMB_VFS_HANDLE_SET_DATA(handle, config, NULL,
        struct acl_common_config,
        return false);

  return true;
}


/*******************************************************************
 Hash a security descriptor.
*******************************************************************/

static NTSTATUS hash_blob_sha256(DATA_BLOB blob,
         uint8_t *hash)
{
  int rc;

  ZERO_ARRAY_LEN(hash, XATTR_SD_HASH_SIZE);

  rc = gnutls_hash_fast(GNUTLS_DIG_SHA256,
            blob.data,
            blob.length,
            hash);
  if (rc < 0) {
    return NT_STATUS_INTERNAL_ERROR;
  }

  return NT_STATUS_OK;
}

/*******************************************************************
 Hash a security descriptor.
*******************************************************************/

static NTSTATUS hash_sd_sha256(struct security_descriptor *psd,
      uint8_t *hash)
{
  DATA_BLOB blob;
  NTSTATUS status;

  memset(hash, '\0', XATTR_SD_HASH_SIZE);
  status = create_acl_blob(psd, &blob, XATTR_SD_HASH_TYPE_SHA256, hash);
  if (!NT_STATUS_IS_OK(status)) {
    return status;
  }
  return hash_blob_sha256(blob, hash);
}

/*******************************************************************
 Parse out a struct security_descriptor from a DATA_BLOB.
*******************************************************************/

static NTSTATUS parse_acl_blob(const DATA_BLOB *pblob,
             TALLOC_CTX *mem_ctx,
             struct security_descriptor **ppdesc,
             uint16_t *p_hash_type,
             uint16_t *p_version,
             uint8_t hash[XATTR_SD_HASH_SIZE],
             uint8_t sys_acl_hash[XATTR_SD_HASH_SIZE])
{
  struct xattr_NTACL xacl;
  enum ndr_err_code ndr_err;
  size_t sd_size;
  TALLOC_CTX *frame = talloc_stackframe();

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

  if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
    DBG_INFO("ndr_pull_xattr_NTACL failed: %s\n",
       ndr_errstr(ndr_err));
    TALLOC_FREE(frame);
    return ndr_map_error2ntstatus(ndr_err);
  }

  *p_version = xacl.version;

  switch (xacl.version) {
    case 1:
      *ppdesc = make_sec_desc(mem_ctx, SD_REVISION,
          xacl.info.sd->type | SEC_DESC_SELF_RELATIVE,
          xacl.info.sd->owner_sid,
          xacl.info.sd->group_sid,
          xacl.info.sd->sacl,
          xacl.info.sd->dacl,
          &sd_size);
      /* No hash - null out. */
      *p_hash_type = XATTR_SD_HASH_TYPE_NONE;
      memset(hash, '\0', XATTR_SD_HASH_SIZE);
      break;
    case 2:
      *ppdesc = make_sec_desc(mem_ctx, SD_REVISION,
          xacl.info.sd_hs2->sd->type | SEC_DESC_SELF_RELATIVE,
          xacl.info.sd_hs2->sd->owner_sid,
          xacl.info.sd_hs2->sd->group_sid,
          xacl.info.sd_hs2->sd->sacl,
          xacl.info.sd_hs2->sd->dacl,
          &sd_size);
      /* No hash - null out. */
      *p_hash_type = XATTR_SD_HASH_TYPE_NONE;
      memset(hash, '\0', XATTR_SD_HASH_SIZE);
      break;
    case 3:
      *ppdesc = make_sec_desc(mem_ctx, SD_REVISION,
          xacl.info.sd_hs3->sd->type | SEC_DESC_SELF_RELATIVE,
          xacl.info.sd_hs3->sd->owner_sid,
          xacl.info.sd_hs3->sd->group_sid,
          xacl.info.sd_hs3->sd->sacl,
          xacl.info.sd_hs3->sd->dacl,
          &sd_size);
      *p_hash_type = xacl.info.sd_hs3->hash_type;
      /* Current version 3 (if no sys acl hash available). */
      memcpy(hash, xacl.info.sd_hs3->hash, XATTR_SD_HASH_SIZE);
      break;
    case 4:
      *ppdesc = make_sec_desc(mem_ctx, SD_REVISION,
          xacl.info.sd_hs4->sd->type | SEC_DESC_SELF_RELATIVE,
          xacl.info.sd_hs4->sd->owner_sid,
          xacl.info.sd_hs4->sd->group_sid,
          xacl.info.sd_hs4->sd->sacl,
          xacl.info.sd_hs4->sd->dacl,
          &sd_size);
      *p_hash_type = xacl.info.sd_hs4->hash_type;
      /* Current version 4. */
      memcpy(hash, xacl.info.sd_hs4->hash, XATTR_SD_HASH_SIZE);
      memcpy(sys_acl_hash, xacl.info.sd_hs4->sys_acl_hash, XATTR_SD_HASH_SIZE);
      break;
    default:
      TALLOC_FREE(frame);
      return NT_STATUS_REVISION_MISMATCH;
  }

  TALLOC_FREE(frame);

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

/*******************************************************************
 Create a DATA_BLOB from a hash of the security descriptor storead at
 the system layer and the NT ACL we wish to preserve
*******************************************************************/

static NTSTATUS create_acl_blob(const struct security_descriptor *psd,
      DATA_BLOB *pblob,
      uint16_t hash_type,
      uint8_t hash[XATTR_SD_HASH_SIZE])
{
  struct xattr_NTACL xacl;
  struct security_descriptor_hash_v3 sd_hs3;
  enum ndr_err_code ndr_err;
  TALLOC_CTX *ctx = talloc_tos();

  ZERO_STRUCT(xacl);
  ZERO_STRUCT(sd_hs3);

  xacl.version = 3;
  xacl.info.sd_hs3 = &sd_hs3;
  xacl.info.sd_hs3->sd = discard_const_p(struct security_descriptor, psd);
  xacl.info.sd_hs3->hash_type = hash_type;
  memcpy(&xacl.info.sd_hs3->hash[0], hash, XATTR_SD_HASH_SIZE);

  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)) {
    DBG_INFO("ndr_push_xattr_NTACL failed: %s\n",
       ndr_errstr(ndr_err));
    return ndr_map_error2ntstatus(ndr_err);
  }

  return NT_STATUS_OK;
}

/*******************************************************************
 Create a DATA_BLOB from a hash of the security descriptors 
 (system and NT) stored at the system layer and the NT ACL we wish 
 to preserve.
*******************************************************************/

static NTSTATUS create_sys_acl_blob(const struct security_descriptor *psd,
            DATA_BLOB *pblob,
            uint16_t hash_type,
            uint8_t hash[XATTR_SD_HASH_SIZE],
            const char *description,
            uint8_t sys_acl_hash[XATTR_SD_HASH_SIZE])
{
  struct xattr_NTACL xacl;
  struct security_descriptor_hash_v4 sd_hs4;
  enum ndr_err_code ndr_err;
  TALLOC_CTX *ctx = talloc_tos();

  ZERO_STRUCT(xacl);
  ZERO_STRUCT(sd_hs4);

  xacl.version = 4;
  xacl.info.sd_hs4 = &sd_hs4;
  xacl.info.sd_hs4->sd = discard_const_p(struct security_descriptor, psd);
  xacl.info.sd_hs4->hash_type = hash_type;
  memcpy(&xacl.info.sd_hs4->hash[0], hash, XATTR_SD_HASH_SIZE);
  xacl.info.sd_hs4->description = description;
  memcpy(&xacl.info.sd_hs4->sys_acl_hash[0], sys_acl_hash, XATTR_SD_HASH_SIZE);

  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)) {
    DBG_INFO("ndr_push_xattr_NTACL failed: %s\n",
       ndr_errstr(ndr_err));
    return ndr_map_error2ntstatus(ndr_err);
  }

  return NT_STATUS_OK;
}

/*******************************************************************
 Add in 3 inheritable components for a non-inheritable directory ACL.
 CREATOR_OWNER/CREATOR_GROUP/WORLD.
*******************************************************************/

static NTSTATUS add_directory_inheritable_components(vfs_handle_struct *handle,
                                const char *name,
        SMB_STRUCT_STAT *psbuf,
        struct security_descriptor *psd)
{
  struct connection_struct *conn = handle->conn;
  int num_aces = (psd->dacl ? psd->dacl->num_aces : 0);
  struct smb_filename smb_fname;
  enum security_ace_type acltype;
  uint32_t access_mask;
  mode_t dir_mode;
  mode_t file_mode;
  mode_t mode;
  struct security_ace *new_ace_list;

  if (psd->dacl) {
    new_ace_list = talloc_zero_array(psd->dacl,
             struct security_ace,
             num_aces + 3);
  } else {
    /*
     * make_sec_acl() at the bottom of this function
     * duplicates new_ace_list
     */
    new_ace_list = talloc_zero_array(talloc_tos(),
             struct security_ace,
             num_aces + 3);
  }

  if (new_ace_list == NULL) {
    return NT_STATUS_NO_MEMORY;
  }

  /* Fake a quick smb_filename. */
  ZERO_STRUCT(smb_fname);
  smb_fname.st = *psbuf;
  smb_fname.base_name = discard_const_p(char, name);

  dir_mode = unix_mode(conn,
      FILE_ATTRIBUTE_DIRECTORY, &smb_fname, NULL);
  file_mode = unix_mode(conn,
      FILE_ATTRIBUTE_ARCHIVE, &smb_fname, NULL);

  mode = dir_mode | file_mode;

  DBG_DEBUG("directory %s, mode = 0%o\n", name, (unsigned int)mode);

  if (num_aces) {
    memcpy(new_ace_list, psd->dacl->aces,
      num_aces * sizeof(struct security_ace));
  }
  access_mask = map_canon_ace_perms(SNUM(conn), &acltype,
        mode & 0700, false);

  init_sec_ace(&new_ace_list[num_aces],
      &global_sid_Creator_Owner,
      acltype,
      access_mask,
      SEC_ACE_FLAG_CONTAINER_INHERIT|
        SEC_ACE_FLAG_OBJECT_INHERIT|
        SEC_ACE_FLAG_INHERIT_ONLY);
  access_mask = map_canon_ace_perms(SNUM(conn), &acltype,
        (mode << 3) & 0700, false);
  init_sec_ace(&new_ace_list[num_aces+1],
      &global_sid_Creator_Group,
      acltype,
      access_mask,
      SEC_ACE_FLAG_CONTAINER_INHERIT|
        SEC_ACE_FLAG_OBJECT_INHERIT|
        SEC_ACE_FLAG_INHERIT_ONLY);
  access_mask = map_canon_ace_perms(SNUM(conn), &acltype,
        (mode << 6) & 0700, false);
  init_sec_ace(&new_ace_list[num_aces+2],
      &global_sid_World,
      acltype,
      access_mask,
      SEC_ACE_FLAG_CONTAINER_INHERIT|
        SEC_ACE_FLAG_OBJECT_INHERIT|
        SEC_ACE_FLAG_INHERIT_ONLY);
  if (psd->dacl) {
    psd->dacl->aces = new_ace_list;
    psd->dacl->num_aces += 3;
    psd->dacl->size += new_ace_list[num_aces].size +
      new_ace_list[num_aces+1].size +
      new_ace_list[num_aces+2].size;
  } else {
    psd->dacl = make_sec_acl(psd,
        NT4_ACL_REVISION,
        3,
        new_ace_list);
    if (psd->dacl == NULL) {
      return NT_STATUS_NO_MEMORY;
    }
  }
  return NT_STATUS_OK;
}

/**
 * Validate an ACL blob
 *
 * This validates an ACL blob against the underlying filesystem ACL. If this
 * function returns NT_STATUS_OK ppsd can be
 *
 * 1. the ACL from the blob (psd_from_fs=false), or
 * 2. the ACL from the fs (psd_from_fs=true), or
 * 3. NULL (!)
 *
 * If the return value is anything else then NT_STATUS_OK, ppsd is set to NULL
 * and psd_from_fs set to false.
 *
 * Returning the underlying filesystem ACL in case no. 2 is really just an
 * optimisation, because some validations have to fetch the filesystem ACL as
 * part of the validation, so we already have it available and callers might
 * need it as well.
 **/
static NTSTATUS validate_nt_acl_blob(TALLOC_CTX *mem_ctx,
        vfs_handle_struct *handle,
        struct files_struct *fsp,
        const struct smb_filename *smb_fname,
        const DATA_BLOB *blob,
        struct security_descriptor **ppsd,
        bool *psd_is_from_fs)
{
  NTSTATUS status;
  uint16_t hash_type = XATTR_SD_HASH_TYPE_NONE;
  uint16_t xattr_version = 0;
  uint8_t hash[XATTR_SD_HASH_SIZE];
  uint8_t sys_acl_hash[XATTR_SD_HASH_SIZE];
  uint8_t hash_tmp[XATTR_SD_HASH_SIZE];
  uint8_t sys_acl_hash_tmp[XATTR_SD_HASH_SIZE];
  struct security_descriptor *psd = NULL;
  struct security_descriptor *psd_blob = NULL;
  struct security_descriptor *psd_fs = NULL;
  char *sys_acl_blob_description = NULL;
  DATA_BLOB sys_acl_blob = { 0 };
  struct acl_common_config *config = NULL;

  *ppsd = NULL;
  *psd_is_from_fs = false;

  SMB_VFS_HANDLE_GET_DATA(handle, config,
        struct acl_common_config,
        return NT_STATUS_UNSUCCESSFUL);

  status = parse_acl_blob(blob,
        mem_ctx,
        &psd_blob,
        &hash_type,
        &xattr_version,
        &hash[0],
        &sys_acl_hash[0]);
  if (!NT_STATUS_IS_OK(status)) {
    DBG_DEBUG("parse_acl_blob returned %s\n", nt_errstr(status));
    goto fail;
  }

  /* determine which type of xattr we got */
  switch (xattr_version) {
  case 1:
  case 2:
    /* These xattr types are unilateral, they do not
     * require confirmation of the hash.  In particular,
     * the NTVFS file server uses version 1, but
     * 'samba-tool ntacl' can set these as well */
    *ppsd = psd_blob;
    return NT_STATUS_OK;
  case 3:
  case 4:
    if (config->ignore_system_acls) {
      *ppsd = psd_blob;
      return NT_STATUS_OK;
    }

    break;
  default:
    DBG_DEBUG("ACL blob revision mismatch (%u) for file %s\n",
        (unsigned int)hash_type, smb_fname->base_name);
    TALLOC_FREE(psd_blob);
    return NT_STATUS_OK;
  }

  /* determine which type of xattr we got */
  if (hash_type != XATTR_SD_HASH_TYPE_SHA256) {
    DBG_DEBUG("ACL blob hash type (%u) unexpected for file %s\n",
        (unsigned int)hash_type, smb_fname->base_name);
    TALLOC_FREE(psd_blob);
    return NT_STATUS_OK;
  }

  /* determine which type of xattr we got */
  switch (xattr_version) {
  case 4:
  {
    int ret;
    /* Get the full underlying sd, then hash. */
    ret = SMB_VFS_NEXT_SYS_ACL_BLOB_GET_FD(handle,
                   fsp,
                   mem_ctx,
                   &sys_acl_blob_description,
                   &sys_acl_blob);
    /* If we fail to get the ACL blob (for some reason) then this
     * is not fatal, we just work based on the NT ACL only */
    if (ret == 0) {
      status = hash_blob_sha256(sys_acl_blob, sys_acl_hash_tmp);
      if (!NT_STATUS_IS_OK(status)) {
        goto fail;
      }

      TALLOC_FREE(sys_acl_blob_description);
      TALLOC_FREE(sys_acl_blob.data);

      if (memcmp(&sys_acl_hash[0], &sys_acl_hash_tmp[0], 
           XATTR_SD_HASH_SIZE) == 0) {
        /* Hash matches, return blob sd. */
        DBG_DEBUG("blob hash matches for file %s\n",
            smb_fname->base_name);
        *ppsd = psd_blob;
        return NT_STATUS_OK;
      }
    }

    /* Otherwise, fall though and see if the NT ACL hash matches */
    FALL_THROUGH;
  }
  case 3:
    /* Get the full underlying sd for the hash
       or to return as backup. */
    status = SMB_VFS_NEXT_FGET_NT_ACL(handle,
              fsp,
              HASH_SECURITY_INFO,
              mem_ctx,
              &psd_fs);
    if (!NT_STATUS_IS_OK(status)) {
      DBG_DEBUG("get_next_acl for file %s returned %s\n",
          smb_fname->base_name, nt_errstr(status));
      goto fail;
    }

    status = hash_sd_sha256(psd_fs, hash_tmp);
    if (!NT_STATUS_IS_OK(status)) {
      TALLOC_FREE(psd_blob);
      *ppsd = psd_fs;
      *psd_is_from_fs = true;
      return NT_STATUS_OK;
    }

    if (memcmp(&hash[0], &hash_tmp[0], XATTR_SD_HASH_SIZE) == 0) {
      /* Hash matches, return blob sd. */
      DBG_DEBUG("blob hash matches for file %s\n",
          smb_fname->base_name);
      *ppsd = psd_blob;
      return NT_STATUS_OK;
    }

    /* Hash doesn't match, return underlying sd. */
    DBG_DEBUG("blob hash does not match for file %s - returning "
        "file system SD mapping.\n",
        smb_fname->base_name);

    if (DEBUGLEVEL >= 10) {
      DBG_DEBUG("acl for blob hash for %s is:\n",
          smb_fname->base_name);
      NDR_PRINT_DEBUG(security_descriptor, psd_fs);
    }

    TALLOC_FREE(psd_blob);
    *ppsd = psd_fs;
    *psd_is_from_fs = true;
  }

  return NT_STATUS_OK;

fail:
  TALLOC_FREE(psd);
  TALLOC_FREE(psd_blob);
  TALLOC_FREE(psd_fs);
  TALLOC_FREE(sys_acl_blob_description);
  TALLOC_FREE(sys_acl_blob.data);
  return status;
}

/*******************************************************************
 Pull a DATA_BLOB from an xattr given an fsp.
 If the hash doesn't match, or doesn't exist - return the underlying
 filesystem sd.
*******************************************************************/

NTSTATUS fget_nt_acl_common(
  NTSTATUS (*fget_acl_blob_fn)(TALLOC_CTX *ctx,
            vfs_handle_struct *handle,
            files_struct *fsp,
            DATA_BLOB *pblob),
  vfs_handle_struct *handle,
  files_struct *fsp,
  uint32_t security_info,
  TALLOC_CTX *mem_ctx,
  struct security_descriptor **ppdesc)
{
  DATA_BLOB blob = data_blob_null;
  NTSTATUS status;
  struct security_descriptor *psd = NULL;
  const struct smb_filename *smb_fname = fsp->fsp_name;
  bool psd_is_from_fs = false;
  struct acl_common_config *config = NULL;

  SMB_VFS_HANDLE_GET_DATA(handle, config,
        struct acl_common_config,
        return NT_STATUS_UNSUCCESSFUL);

  DBG_DEBUG("name=%s\n", smb_fname->base_name);

  status = fget_acl_blob_fn(mem_ctx, handle, fsp, &blob);
  if (NT_STATUS_IS_OK(status)) {
    status = validate_nt_acl_blob(mem_ctx,
          handle,
          fsp,
          smb_fname,
          &blob,
          &psd,
          &psd_is_from_fs);
    TALLOC_FREE(blob.data);
    if (!NT_STATUS_IS_OK(status)) {
      DBG_DEBUG("ACL validation for [%s] failed\n",
          smb_fname->base_name);
      goto fail;
    }
  }

  if (psd == NULL) {
    /* Get the full underlying sd, as we failed to get the
     * blob for the hash, or the revision/hash type wasn't
     * known */

    if (config->ignore_system_acls) {
      status = vfs_stat_fsp(fsp);
      if (!NT_STATUS_IS_OK(status)) {
        goto fail;
      }

      status = make_default_filesystem_acl(
        mem_ctx,
        config->default_acl_style,
        smb_fname->base_name,
        &fsp->fsp_name->st,
        &psd);
      if (!NT_STATUS_IS_OK(status)) {
        goto fail;
      }
    } else {
      status = SMB_VFS_NEXT_FGET_NT_ACL(handle,
                fsp,
                security_info,
                mem_ctx,
                &psd);

      if (!NT_STATUS_IS_OK(status)) {
        DBG_DEBUG("get_next_acl for file %s "
            "returned %s\n",
            smb_fname->base_name,
            nt_errstr(status));
        goto fail;
      }

      psd_is_from_fs = true;
    }
  }

  if (psd_is_from_fs) {
    status = vfs_stat_fsp(fsp);
    if (!NT_STATUS_IS_OK(status)) {
      goto fail;
    }

    /*
     * We're returning the underlying ACL from the
     * filesystem. If it's a directory, and has no
     * inheritable ACE entries we have to fake them.
     */

    if (fsp->fsp_flags.is_directory &&
        !sd_has_inheritable_components(psd, true)) {
      status = add_directory_inheritable_components(
        handle,
        smb_fname->base_name,
        &fsp->fsp_name->st,
        psd);
      if (!NT_STATUS_IS_OK(status)) {
        goto fail;
      }
    }

    /*
     * The underlying POSIX module always sets the
     * ~SEC_DESC_DACL_PROTECTED bit, as ACLs can't be inherited in
     * this way under POSIX. Remove it for Windows-style ACLs.
     */
    psd->type &= ~SEC_DESC_DACL_PROTECTED;
  }

  if (!(security_info & SECINFO_OWNER)) {
    psd->owner_sid = NULL;
  }
  if (!(security_info & SECINFO_GROUP)) {
    psd->group_sid = NULL;
  }
  if (!(security_info & SECINFO_DACL)) {
    psd->type &= ~SEC_DESC_DACL_PRESENT;
    psd->dacl = NULL;
  }
  if (!(security_info & SECINFO_SACL)) {
    psd->type &= ~SEC_DESC_SACL_PRESENT;
    psd->sacl = NULL;
  }

  if (DEBUGLEVEL >= 10) {
    DBG_DEBUG("returning acl for %s is:\n",
        smb_fname->base_name);
    NDR_PRINT_DEBUG(security_descriptor, psd);
  }

  *ppdesc = psd;

  return NT_STATUS_OK;

fail:
  TALLOC_FREE(psd);
  return status;
}

/*********************************************************************
 Set the underlying ACL (e.g. POSIX ACLS, POSIX owner, etc)
*********************************************************************/
static NTSTATUS set_underlying_acl(vfs_handle_struct *handle, files_struct *fsp,
           struct security_descriptor *psd,
           uint32_t security_info_sent,
           bool chown_needed)
{
  NTSTATUS status;
  const struct security_token *token = NULL;
  struct dom_sid_buf buf;

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

  /* We got access denied here. If we're already root,
     or we didn't need to do a chown, or the fsp isn't
     open with WRITE_OWNER access, just return. */
  if (get_current_uid(handle->conn) == 0 || !chown_needed) {
    return NT_STATUS_ACCESS_DENIED;
  }
  status = check_any_access_fsp(fsp, SEC_STD_WRITE_OWNER);
  if (!NT_STATUS_IS_OK(status)) {
    return status;
  }

  /*
   * Only allow take-ownership, not give-ownership. That's the way Windows
   * implements SEC_STD_WRITE_OWNER. MS-FSA 2.1.5.16 just states: If
   * InputBuffer.OwnerSid is not a valid owner SID for a file in the
   * objectstore, as determined in an implementation specific manner, the
   * object store MUST return STATUS_INVALID_OWNER.
   */
  token = get_current_nttok(fsp->conn);
  if (!security_token_is_sid(token, psd->owner_sid)) {
    return NT_STATUS_INVALID_OWNER;
  }

  DBG_DEBUG("overriding chown on file %s for sid %s\n",
      fsp_str_dbg(fsp),
      dom_sid_str_buf(psd->owner_sid, &buf));

  /* Ok, we failed to chown and we have
     SEC_STD_WRITE_OWNER access - override. */
  become_root();
  status = SMB_VFS_NEXT_FSET_NT_ACL(handle, fsp, security_info_sent, psd);
  unbecome_root();

  return status;
}

/*********************************************************************
 Store a v3 security descriptor
*********************************************************************/
static NTSTATUS store_v3_blob(
  NTSTATUS (*store_acl_blob_fsp_fn)(vfs_handle_struct *handle,
            files_struct *fsp,
            DATA_BLOB *pblob),
  vfs_handle_struct *handle, files_struct *fsp,
  struct security_descriptor *psd,
  struct security_descriptor *pdesc_next,
  uint8_t hash[XATTR_SD_HASH_SIZE])
{
  NTSTATUS status;
  DATA_BLOB blob;

  if (DEBUGLEVEL >= 10) {
    DBG_DEBUG("storing xattr sd for file %s\n",
        fsp_str_dbg(fsp));
    NDR_PRINT_DEBUG(
        security_descriptor,
        discard_const_p(struct security_descriptor, psd));

    if (pdesc_next != NULL) {
      DBG_DEBUG("storing xattr sd based on \n");
      NDR_PRINT_DEBUG(
          security_descriptor,
          discard_const_p(struct security_descriptor,
              pdesc_next));
    } else {
      DBG_DEBUG("ignoring underlying sd\n");
    }
  }
  status = create_acl_blob(psd, &blob, XATTR_SD_HASH_TYPE_SHA256, hash);
  if (!NT_STATUS_IS_OK(status)) {
    DBG_DEBUG("create_acl_blob failed\n");
    return status;
  }

  status = store_acl_blob_fsp_fn(handle, fsp, &blob);
  return status;
}

/*********************************************************************
 Store a security descriptor given an fsp.
*********************************************************************/

NTSTATUS fset_nt_acl_common(
  NTSTATUS (*fget_acl_blob_fn)(TALLOC_CTX *ctx,
            vfs_handle_struct *handle,
            files_struct *fsp,
            DATA_BLOB *pblob),
  NTSTATUS (*store_acl_blob_fsp_fn)(vfs_handle_struct *handle,
            files_struct *fsp,
            DATA_BLOB *pblob),
  const char *module_name,
  vfs_handle_struct *handle, files_struct *fsp,
  uint32_t security_info_sent,
  const struct security_descriptor *orig_psd)
{
  NTSTATUS status;
  int ret;
  DATA_BLOB blob, sys_acl_blob;
  struct security_descriptor *pdesc_next = NULL;
  struct security_descriptor *psd = NULL;
  uint8_t hash[XATTR_SD_HASH_SIZE];
  uint8_t sys_acl_hash[XATTR_SD_HASH_SIZE];
  bool chown_needed = false;
  char *sys_acl_description;
  TALLOC_CTX *frame = talloc_stackframe();
  bool ignore_file_system_acl = lp_parm_bool(
      SNUM(handle->conn), module_name, "ignore system acls", false);
  struct acl_common_fsp_ext *ext = NULL;

  if (DEBUGLEVEL >= 10) {
    DBG_DEBUG("incoming sd for file %s\n", fsp_str_dbg(fsp));
    NDR_PRINT_DEBUG(security_descriptor,
      discard_const_p(struct security_descriptor, orig_psd));
  }

  status = fget_nt_acl_common(fget_acl_blob_fn, handle, fsp,
      SECINFO_OWNER|SECINFO_GROUP|SECINFO_DACL|SECINFO_SACL,
             frame,
      &psd);

  if (!NT_STATUS_IS_OK(status)) {
    TALLOC_FREE(frame);
    return status;
  }

  psd->revision = orig_psd->revision;
  if (security_info_sent & SECINFO_DACL) {
    psd->type = orig_psd->type;
    /* All our SD's are self relative. */
    psd->type |= SEC_DESC_SELF_RELATIVE;
  }

  if ((security_info_sent & SECINFO_OWNER) && (orig_psd->owner_sid != NULL)) {
    if (!dom_sid_equal(orig_psd->owner_sid, psd->owner_sid)) {
      /* We're changing the owner. */
      chown_needed = true;
    }
    psd->owner_sid = orig_psd->owner_sid;
  }
  if ((security_info_sent & SECINFO_GROUP) && (orig_psd->group_sid != NULL)) {
    if (!dom_sid_equal(orig_psd->group_sid, psd->group_sid)) {
      /* We're changing the group. */
      chown_needed = true;
    }
    psd->group_sid = orig_psd->group_sid;
  }
  if (security_info_sent & SECINFO_DACL) {
    if (security_descriptor_with_ms_nfs(orig_psd)) {
      /*
       * If the sd contains a MS NFS SID, do
       * nothing, it's a chmod() request from OS X
       * with AAPL context.
       */
      TALLOC_FREE(frame);
      return NT_STATUS_OK;
    }
    psd->dacl = orig_psd->dacl;
    psd->type |= SEC_DESC_DACL_PRESENT;
  }
  if (security_info_sent & SECINFO_SACL) {
    psd->sacl = orig_psd->sacl;
    psd->type |= SEC_DESC_SACL_PRESENT;
  }

  ext = VFS_ADD_FSP_EXTENSION(handle,
            fsp,
            struct acl_common_fsp_ext,
            NULL);
  ext->setting_nt_acl = true;

  if (ignore_file_system_acl) {
    if (chown_needed) {
      /* send only ownership stuff to lower layer */
      security_info_sent &= (SECINFO_OWNER | SECINFO_GROUP);
      status = set_underlying_acl(handle, fsp, psd,
                security_info_sent, true);
      if (!NT_STATUS_IS_OK(status)) {
        goto done;
      }
    }
    ZERO_ARRAY(hash);
    status = store_v3_blob(store_acl_blob_fsp_fn, handle, fsp, psd,
               NULL, hash);
    goto done;
  }

  status = set_underlying_acl(handle, fsp, psd, security_info_sent,
            chown_needed);
  if (!NT_STATUS_IS_OK(status)) {
    goto done;
  }

  /* Get the full underlying sd, then hash. */
  status = SMB_VFS_NEXT_FGET_NT_ACL(handle,
            fsp,
            HASH_SECURITY_INFO,
            frame,
            &pdesc_next);

  if (!NT_STATUS_IS_OK(status)) {
    goto done;
  }

  status = hash_sd_sha256(pdesc_next, hash);
  if (!NT_STATUS_IS_OK(status)) {
    goto done;
  }

  /* Get the full underlying sd, then hash. */
  ret = SMB_VFS_NEXT_SYS_ACL_BLOB_GET_FD(handle,
                 fsp,
                 frame,
                 &sys_acl_description,
                 &sys_acl_blob);

  /* If we fail to get the ACL blob (for some reason) then this
   * is not fatal, we just work based on the NT ACL only */
  if (ret != 0) {
    status = store_v3_blob(store_acl_blob_fsp_fn, handle, fsp, psd,
               pdesc_next, hash);

    goto done;
  }

  status = hash_blob_sha256(sys_acl_blob, sys_acl_hash);
  if (!NT_STATUS_IS_OK(status)) {
    goto done;
  }

  if (DEBUGLEVEL >= 10) {
    DBG_DEBUG("storing xattr sd for file %s based on system ACL\n",
        fsp_str_dbg(fsp));
    NDR_PRINT_DEBUG(security_descriptor,
        discard_const_p(struct security_descriptor, psd));

    DBG_DEBUG("storing hash in xattr sd based on system ACL and:\n");
    NDR_PRINT_DEBUG(security_descriptor,
        discard_const_p(struct security_descriptor, pdesc_next));
  }

  /* We store hashes of both the sys ACL blob and the NT
   * security descriptor mapped from that ACL so as to improve
   * our chances against some inadvertent change breaking the
   * hash used */
  status = create_sys_acl_blob(psd, &blob, XATTR_SD_HASH_TYPE_SHA256, hash, 
             sys_acl_description, sys_acl_hash);
  if (!NT_STATUS_IS_OK(status)) {
    DBG_DEBUG("create_sys_acl_blob failed\n");
    goto done;
  }

  status = store_acl_blob_fsp_fn(handle, fsp, &blob);

done:
  VFS_REMOVE_FSP_EXTENSION(handle, fsp);
  TALLOC_FREE(frame);
  return status;
}

static int acl_common_remove_object(vfs_handle_struct *handle,
          struct files_struct *dirfsp,
          const struct smb_filename *smb_fname,
          bool is_directory)
{
  connection_struct *conn = handle->conn;
  struct stat_ex st;
  struct file_id id;
  files_struct *fsp = NULL;
  int ret = 0;

  SMB_ASSERT(strchr_m(smb_fname->base_name, '/') == NULL);

  ret = SMB_VFS_FSTATAT(
    conn, dirfsp, smb_fname, &st, AT_SYMLINK_NOFOLLOW);
  if (ret == -1) {
    return ret;
  }

  DBG_DEBUG("removing %s %s/%s\n",
      is_directory ? "directory" : "file",
      fsp_str_dbg(dirfsp),
      smb_fname_str_dbg(smb_fname));

  /* Ensure we have this file open with DELETE access. */
  id = vfs_file_id_from_sbuf(conn, &st);
  for (fsp = file_find_di_first(conn->sconn, id, true); fsp;
         fsp = file_find_di_next(fsp, true)) {
    if (fsp->access_mask & DELETE_ACCESS &&
        fsp->fsp_flags.delete_on_close)
    {
      /* We did open this for delete,
       * allow the delete as root.
       */
      break;
    }
  }

  if (!fsp) {
    DBG_DEBUG("%s %s/%s not an open file\n",
        is_directory ? "directory" : "file",
        fsp_str_dbg(dirfsp),
        smb_fname_str_dbg(smb_fname));
    return EACCES;
  }

  become_root();
  ret = SMB_VFS_NEXT_UNLINKAT(handle,
            dirfsp,
            smb_fname,
            is_directory ? AT_REMOVEDIR : 0);
  unbecome_root();

  return ret;
}

int rmdir_acl_common(struct vfs_handle_struct *handle,
    struct files_struct *dirfsp,
    const struct smb_filename *smb_fname)
{
  int ret;

  /* Try the normal rmdir first. */
  ret = SMB_VFS_NEXT_UNLINKAT(handle,
      dirfsp,
      smb_fname,
      AT_REMOVEDIR);
  if (ret == 0) {
    return 0;
  }
  if (errno == EACCES || errno == EPERM) {
    /* Failed due to access denied,
       see if we need to root override. */
    return acl_common_remove_object(handle,
            dirfsp,
            smb_fname,
            true);
  }

  DBG_DEBUG("unlink of %s failed %s\n",
      smb_fname->base_name,
      strerror(errno));
  return -1;
}

int unlink_acl_common(struct vfs_handle_struct *handle,
      struct files_struct *dirfsp,
      const struct smb_filename *smb_fname,
      int flags)
{
  int ret;

  /* Try the normal unlink first. */
  ret = SMB_VFS_NEXT_UNLINKAT(handle,
        dirfsp,
        smb_fname,
        flags);
  if (ret == 0) {
    return 0;
  }
  if (errno == EACCES || errno == EPERM) {
    /* Failed due to access denied,
       see if we need to root override. */

    /* Don't do anything fancy for streams. */
    if (is_ntfs_stream_smb_fname(smb_fname)) {
      return -1;
    }
    return acl_common_remove_object(handle,
          dirfsp,
          smb_fname,
          false);
  }

  DBG_DEBUG("unlink of %s failed %s\n",
      smb_fname->base_name,
      strerror(errno));
  return -1;
}

int fchmod_acl_module_common(struct vfs_handle_struct *handle,
           struct files_struct *fsp, mode_t mode)
{
  if (fsp->fsp_flags.posix_open
      || fsp->fsp_name->flags & SMB_FILENAME_POSIX_PATH) {
    /* Only allow this on POSIX opens. */
    return SMB_VFS_NEXT_FCHMOD(handle, fsp, mode);
  }
  return 0;
}

Coverage Report

Created: 2026-07-25 07:00