NAME | SYNOPSIS | DESCRIPTION | OPTIONS | FILES | FILE FORMAT | File Contexts Format | Substitution File Format | NOTES | SEE ALSO | COLOPHON

selabel_file(5)           SELinux API documentation          selabel_file(5)

NAME         top

       selabel_file - userspace SELinux labeling interface and configuration
       file format for the file contexts backend

SYNOPSIS         top

       #include <selinux/label.h>

       int selabel_lookup(struct selabel_handle *hnd,
                          char **context,
                          const char *path, int mode);

       int selabel_lookup_raw(struct selabel_handle *hnd,
                          char **context,
                          const char *path, int mode);

DESCRIPTION         top

       The file contexts backend maps from pathname/mode combinations into
       security contexts. It is used to find the appropriate context for
       each file when relabeling a file system. The returned context must be
       freed using freecon(3).
       selabel_lookup(3) describes the function with its return and error
       codes, however the following errno is clarified further for the file
       contexts backend:

              ENOENT No context corresponding to the path and mode was found
                     - This will also be returned when the file contexts
                     series of files have a context of <<none>> against the
                     path (see the FILE FORMAT section).

       The path argument should be set to the full pathname of the file
       whose assigned context is being checked. The mode argument should be
       set to the mode bits of the file, as determined by lstat(2). mode may
       be zero, however full matching may not occur.

       Any messages generated by selabel_lookup(3) are sent to stderr by
       default, although this can be changed by selinux_set_callback(3).

       selabel_lookup_raw(3) behaves identically to selabel_lookup(3) but
       does not perform context translation.

       The FILES section details the configuration files used to determine a
       file context.

OPTIONS         top

       In addition to the global options described in selabel_open(3), this
       backend recognizes the following options:

              SELABEL_OPT_PATH
                     A non-null value for this option specifies a path to a
                     file that will be opened in lieu of the standard file
                     contexts file.  This value is also used as the base
                     name for determining the names of local customization
                     files.

              SELABEL_OPT_BASEONLY
                     A non-null value for this option indicates that any
                     local customizations to the file contexts mapping
                     should be ignored.

              SELABEL_OPT_SUBSET
                     A non-null value for this option is interpreted as a
                     path prefix, for example "/etc".  Only file context
                     specifications with starting with a first component
                     that prefix matches the given prefix are loaded.  This
                     may increase lookup performance, however any attempt to
                     look up a path not starting with the given prefix may
                     fail.  This optimization is no longer required due to
                     the use of file_contexts.bin files and is deprecated.

FILES         top

       The file context files used to retrieve the default context depends
       on the SELABEL_OPT_PATH parameter passed to selabel_open(3). If NULL,
       then the SELABEL_OPT_PATH value will default to the active policy
       file contexts location (as returned by selinux_file_context_path(3)),
       otherwise the actual SELABEL_OPT_PATH value specified is used.

       If SELABEL_OPT_BASEONLY is set, then the following files will be
       processed:

              1.  The mandatory file contexts file that is either the fully
                  qualified file name from SELABEL_OPT_PATH.value or if
                  NULL, then the path returned by
                  selinux_file_context_path(3).

              2.  The optional local and distribution substitution files
                  that perform path aliasing on the 'in memory' version of
                  the file contexts file.
                  These files have the same name as the mandatory file
                  contexts file with the extensions .subs and .subs_dist
                  added.

       If the SELABEL_OPT_BASEONLY is not set, then the following files will
       be processed:

              1.  The mandatory file contexts file that is either the fully
                  qualified file name from SELABEL_OPT_PATH.value or if
                  NULL, then the path returned by
                  selinux_file_context_path(3).

              2.  The optional local customizations file that has the same
                  name as the mandatory file contexts file with the
                  extension .local added.
                  selinux_file_context_local_path(3) will return the default
                  path to this file.

              3.  The optional user home directory customizations file that
                  has the same name as the mandatory file contexts file with
                  the extension .homedirs added.
                  selinux_file_context_homedir_path(3) will return the
                  default path to this file.

              4.  The optional local and distribution substitution files
                  that perform any path aliasing on the 'in memory' version
                  of the file contexts file (and the .local and/or .homedirs
                  if present). These files have the same name as the
                  mandatory file contexts file with the extensions .subs and
                  .subs_dist added.
                  selinux_file_context_subs_path(3) and
                  selinux_file_context_subs_dist_path(3) will return the
                  default paths to these files.

       The default file context series of files are:
              /etc/selinux/{SELINUXTYPE}/contexts/files/file_contexts
              /etc/selinux/{SELINUXTYPE}/contexts/files/file_contexts.local
              /etc/selinux/{SELINUXTYPE}/contexts/files/file_contexts.homedirs
              /etc/selinux/{SELINUXTYPE}/contexts/files/file_contexts.subs
              /etc/selinux/{SELINUXTYPE}/contexts/files/file_contexts.subs_dist

       Where {SELINUXTYPE} is the entry from the selinux configuration file
       config (see selinux_config(5)).

       Only the file_contexts file is mandatory, the remainder are optional.

       The entries within the file contexts series of files are shown in the
       FILE FORMAT section.

FILE FORMAT         top


File Contexts Format         top

       Each line within the file_contexts and the two customization files
       (.local and .homedirs) is as follows:

              pathname [file_type] context

       Where:
              pathname
                     An entry that defines the pathname that may be in the
                     form of a regular expression.
              file_type
                     An optional file type consisting of:
                            -b - Block Device      -c - Character Device
                            -d - Directory         -p - Named Pipe
                            -l - Symbolic Link     -s - Socket
                            -- - Ordinary file
              context
                     This entry can be either:

                            a.  The security context that will be assigned
                                to the file (i.e. returned as context).

                            b.  A value of <<none>> can be used to indicate
                                that the matching files should not be re-
                                labeled and causes selabel_lookup(3) to
                                return -1 with errno set to ENOENT.

       Example:
              # ./contexts/files/file_contexts
              # pathname file_type  context
              /.*                   system_u:object_r:default_t:s0
              /[^/]+        --      system_u:object_r:etc_runtime_t:s0
              /tmp/.*               <<none>>

Substitution File Format         top

       Each line within the substitution files (.subs and .subs_dist) has
       the form:
              subs_pathname pathname

       Where:
              pathname
                     A path that matches an entry in one or more of the file
                     contexts policy configuration file.
              subs_pathname
                     The path that will be aliased (considered equivalent)
                     with pathname by the look up process.

       Example:
              # ./contexts/files/file_contexts.subs
              # pathname  subs_pathname
              /myweb      /var/www
              /myspool    /var/spool/mail

              Using the above example, when selabel_lookup(3) is passed a
              path of /myweb/index.html the function will substitute the
              /myweb component with /var/www, therefore the path used is:

                     /var/www/index.html

NOTES         top

       1.  If contexts are to be validated, then the global option
           SELABEL_OPT_VALIDATE must be set before calling selabel_open(3).
           If this is not set, then it is possible for an invalid context to
           be returned.

       2.  If the size of file contexts series of files contain many
           entries, then selabel_open(3) may have a delay as it reads in the
           files, and if requested validates the entries.

       3.  Depending on the version of SELinux it is possible that a
           file_contexts.template file may also be present, however this is
           now deprecated.
           The template file has the same format as the file_contexts file
           and may also contain the keywords HOME_ROOT, HOME_DIR, ROLE and
           USER. This functionality has now been moved to the policy store
           and managed by semodule(8) and genhomedircon(8).

SEE ALSO         top

       selinux(8), selabel_open(3), selabel_lookup(3), selabel_stats(3),
       selabel_close(3), selinux_set_callback(3),
       selinux_file_context_path(3), freecon(3), selinux_config(5),
       lstat(2), selinux_file_context_subs_path(3),
       selinux_file_context_subs_dist_path(3),
       selinux_file_context_homedir_path(3),
       selinux_file_context_local_path(3), semodule(8), genhomedircon(8)

COLOPHON         top

       This page is part of the selinux (Security-Enhanced Linux user-space
       libraries and tools) project.  Information about the project can be
       found at ⟨https://github.com/SELinuxProject/selinux/wiki⟩.  If you
       have a bug report for this manual page, see
       ⟨https://github.com/SELinuxProject/selinux/wiki/Contributing⟩.  This
       page was obtained from the project's upstream Git repository
       ⟨https://github.com/SELinuxProject/selinux⟩ on 2017-11-25.  (At that
       time, the date of the most recent commit that was found in the repos‐
       itory was 2017-11-22.)  If you discover any rendering problems in
       this HTML version of the page, or you believe there is a better or
       more up-to-date source for the page, or you have corrections or
       improvements to the information in this COLOPHON (which is not part
       of the original manual page), send a mail to man-pages@man7.org

Security Enhanced Linux          01 Dec 2011                 selabel_file(5)

Pages that refer to this page: selabel_lookup_best_match(3)selabel_open(3)selabel_partial_match(3)selinux_restorecon_default_handle(3)restorecon_xattr(8)