selinux/libselinux/man/man3/selabel_open.3
Richard Haines e40bbea95f libselinux: Add selabel_digest function
selabel_digest(3) if enabled by the SELABEL_OPT_DIGEST option during
selabel_open(3) will return an SHA1 digest of the spec files, plus
a list of the specfiles used to calculate the digest. There is a
test utility supplied that will demonstrate the functionality.

The use case for selabel_digest(3) is to implement an selinux_restorecon
function based on the Android version that writes a hash of the
file_contexts files to an extended attribute to enhance performance
(see external/libselinux/src/android.c selinux_android_restorecon()).

Signed-off-by: Richard Haines <richard_c_haines@btinternet.com>
2015-10-13 17:13:24 -04:00

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.\" Hey Emacs! This file is -*- nroff -*- source.
.\"
.\" Author: Eamon Walsh (ewalsh@tycho.nsa.gov) 2007
.TH "selabel_open" "3" "18 Jun 2007" "" "SELinux API documentation"
.SH "NAME"
selabel_open, selabel_close \- userspace SELinux labeling interface
.
.SH "SYNOPSIS"
.B #include <selinux/selinux.h>
.br
.B #include <selinux/label.h>
.sp
.BI "struct selabel_handle *selabel_open(int " backend ,
.in +\w'struct selabel_handle *selabel_open('u
.BI "const struct selinux_opt *" options ,
.br
.BI "unsigned " nopt ");"
.in
.sp
.BI "void selabel_close(struct selabel_handle *" hnd ");"
.
.SH "DESCRIPTION"
.BR selabel_open ()
is used to initialize a labeling handle to be used for lookup operations. The
.I backend
argument specifies which backend is to be opened; the list of current backends appears in
.B BACKENDS
below.
The
.I options
argument should be NULL or a pointer to an array of
.B selinux_opt
structures of length
.IR nopt :
.RS
.ta 4n 16n 24n
.nf
struct selinux_opt {
int type;
const char *value;
};
.fi
.ta
.RE
The available option types are described in
.B GLOBAL OPTIONS
below as well as in the documentation for each individual backend. The return value on success is a non-NULL value for use in subsequent label operations.
.BR selabel_close ()
terminates use of a handle, freeing any internal resources associated with it. After this call has been made, the handle must not be used again.
.
.SH "GLOBAL OPTIONS"
Global options which may be passed to
.BR selabel_open ()
include the following:
.
.TP
.B SELABEL_OPT_UNUSED
The option with a type code of zero is a no-op. Thus an array of options may be initizalized to zero and any untouched elements will not cause an error.
.TP
.B SELABEL_OPT_VALIDATE
A non-null value for this option enables context validation. By default,
.BR security_check_context (3)
is used; a custom validation function can be provided via
.BR selinux_set_callback (3).
Note that an invalid context may not be treated as an error unless it is actually encountered during a lookup operation.
.TP
.B SELABEL_OPT_DIGEST
A non-null value for this option enables the generation of an SHA1 digest of
the spec files loaded as described in
.BR selabel_digest (3)
.
.SH "BACKENDS"
.TP
.B SELABEL_CTX_FILE
File contexts backend, described in
.BR selabel_file (5).
.TP
.B SELABEL_CTX_MEDIA
Media contexts backend, described in
.BR selabel_media (5).
.TP
.B SELABEL_CTX_X
X Windows contexts backend, described in
.BR selabel_x (5).
.TP
.B SELABEL_CTX_DB
Database objects contexts backend, described in
.BR selabel_db (5).
.
.SH "RETURN VALUE"
A non-NULL handle value is returned on success. On error, NULL is returned and
.I errno
is set appropriately.
.
.SH "AUTHOR"
Eamon Walsh <ewalsh@tycho.nsa.gov>
.
.SH "SEE ALSO"
.ad l
.nh
.BR selabel_lookup (3),
.BR selabel_stats (3),
.BR selinux_set_callback (3),
.BR selinux (8)