On Apache
Under GNU General Public License
2024-04-24 14:17 @18.191.211.66 CrawledBy Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; ClaudeBot/1.0; +claudebot@anthropic.com)
selabel_file(5) SELinux API documentation selabel_file(5)
NAME
selabel_file - userspace SELinux labeling interface and configuration file format for the
file contexts backend
SYNOPSIS
#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
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 fol-
lowing 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 con-
text translation.
The FILES section details the configuration files used to determine a file context.
OPTIONS
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 exam-
ple "/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
The file context files used to retrieve the default context depends on the SELA-
BEL_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_con-
text_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 alias-
ing 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
File Contexts Format
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
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 con-
figuration 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
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 sela-
bel_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
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)
Security Enhanced Linux 01 Dec 2011 selabel_file(5)
Generated by $Id: phpMan.php,v 4.55 2007/09/05 04:42:51 chedong Exp $ Author: Che Dong
On Apache
Under GNU General Public License
2024-04-24 14:17 @18.191.211.66 CrawledBy Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; ClaudeBot/1.0; +claudebot@anthropic.com)