selinux_restorecon

Section: SELinux API documentation (3)
Updated: 20 Oct 2015
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NAME

selinux_restorecon - restore file(s) default SELinux security contexts

SYNOPSIS

#include <selinux/restorecon.h>

int selinux_restorecon(const char *pathname,
unsigned int restorecon_flags);

DESCRIPTION

selinux_restorecon() restores file default security contexts on filesystems that support extended attributes (see xattr(7)), based on:

pathname containing a directory or file to be relabeled.
If this is a directory and the restorecon_flags SELINUX_RESTORECON_RECURSE has been set (for descending through directories), then selinux_restorecon() will write an SHA1 digest of specfile entries calculated by selabel_get_digests_all_partial_matches(3) to an extended attribute of security.sehash once the relabeling has been completed successfully (see the NOTES section for details).
These digests will be checked should selinux_restorecon() be rerun with the restorecon_flags SELINUX_RESTORECON_RECURSE flag set. If any of the specfile entries had been updated, the digest will also be updated. However if the digest is the same, no relabeling checks will take place.
The restorecon_flags that can be used to manage the usage of the SHA1 digest are:

: SELINUX_RESTORECON_SKIP_DIGEST
SELINUX_RESTORECON_IGNORE_DIGEST

restorecon_flags contains the labeling option/rules as follows:

SELINUX_RESTORECON_SKIP_DIGEST Do not check or update any extended attribute security.sehash entries.

SELINUX_RESTORECON_IGNORE_DIGEST force the checking of labels even if the stored SHA1 digest matches the specfile entries SHA1 digest. The specfile entries digest will be written to the security.sehash extended attribute once relabeling has been completed successfully provided the SELINUX_RESTORECON_NOCHANGE flag has not been set.

SELINUX_RESTORECON_NOCHANGE don't change any file labels (passive check) or update the digest in the security.sehash extended attribute.

SELINUX_RESTORECON_SET_SPECFILE_CTX If set, reset the files label to match the default specfile context. If not set only reset the files "type" component of the context to match the default specfile context.

SELINUX_RESTORECON_RECURSE change file and directory labels recursively (descend directories) and if successful write an SHA1 digest of the specfile entries to an extended attribute as described in the NOTES section.

SELINUX_RESTORECON_VERBOSE log file label changes.

: Note that if SELINUX_RESTORECON_VERBOSE and SELINUX_RESTORECON_PROGRESS flags are set, then SELINUX_RESTORECON_PROGRESS will take precedence.

SELINUX_RESTORECON_PROGRESS show progress by outputting the number of files in 1k blocks processed to stdout. If the SELINUX_RESTORECON_MASS_RELABEL flag is also set then the approximate percentage complete will be shown.

SELINUX_RESTORECON_MASS_RELABEL generally set when relabeling the entire OS, that will then show the approximate percentage complete. The SELINUX_RESTORECON_PROGRESS flag must also be set.

SELINUX_RESTORECON_REALPATH convert passed-in pathname to the canonical pathname using realpath(3).

SELINUX_RESTORECON_XDEV prevent descending into directories that have a different device number than the pathname entry from which the descent began.

SELINUX_RESTORECON_ADD_ASSOC attempt to add an association between an inode and a specification. If there is already an association for the inode and it conflicts with the specification, then use the last matching specification.

SELINUX_RESTORECON_ABORT_ON_ERROR abort on errors during the file tree walk.

SELINUX_RESTORECON_SYSLOG_CHANGES log any label changes to syslog(3).

SELINUX_RESTORECON_LOG_MATCHES log what specfile context matched each file.

SELINUX_RESTORECON_IGNORE_NOENTRY ignore files that do not exist.

SELINUX_RESTORECON_IGNORE_MOUNTS do not read /proc/mounts to obtain a list of non-seclabel mounts to be excluded from relabeling checks.
Setting SELINUX_RESTORECON_IGNORE_MOUNTS is useful where there is a non-seclabel fs mounted with a seclabel fs mounted on a directory below this.

SELINUX_RESTORECON_CONFLICT_ERROR to treat conflicting specifications, such as where two hardlinks for the same inode have different contexts, as errors.

The behavior regarding the checking and updating of the SHA1 digest described above is the default behavior. It is possible to change this by first calling selabel_open(3) and not enabling the SELABEL_OPT_DIGEST option, then calling selinux_restorecon_set_sehandle(3) to set the handle to be used by selinux_restorecon(3).

If the pathname is a directory path, then it is possible to set directories to be excluded from the path by calling selinux_restorecon_set_exclude_list(3) with a NULL terminated list before calling selinux_restorecon(3).

By default selinux_restorecon(3) reads /proc/mounts to obtain a list of non-seclabel mounts to be excluded from relabeling checks unless the SELINUX_RESTORECON_IGNORE_MOUNTS flag has been set.

RETURN VALUE

On success, zero is returned. On error, -1 is returned and errno is set appropriately.

NOTES

1.

To improve performance when relabeling file systems recursively (e.g. the restorecon_flags SELINUX_RESTORECON_RECURSE flag is set) selinux_restorecon() will write a calculated SHA1 digest of the specfile entries returned by selabel_get_digests_all_partial_matches(3) to an extended attribute named security.sehash for each directory in the pathname path.

2.

To check the extended attribute entry use getfattr(1), for example:

: getfattr -e hex -n security.sehash /

3.

Should any of the specfile entries have changed, then when selinux_restorecon() is run again with the SELINUX_RESTORECON_RECURSE flag set, new SHA1 digests will be calculated and all files automatically relabeled depending on the settings of the SELINUX_RESTORECON_SET_SPECFILE_CTX flag (provided SELINUX_RESTORECON_NOCHANGE is not set).

4.

/sys and in-memory filesystems do not support the security.sehash extended attribute and are automatically excluded from any relabeling checks.

5.

By default stderr is used to log output messages and errors. This may be changed by calling selinux_set_callback(3) with the SELINUX_CB_LOG type option.