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[PATCH 2/7] libselinux: labeling support (try 4)
From: Eamon Walsh <ewalsh_at_nospam>Date: Fri Jun 15 2007 - 23:35:21 GMT
To: SE Linux <selinux@tycho.nsa.gov>
This patch includes the interface and generic handle code. Tested
with some sample input values, worked OK.
Signed-off-by: Eamon Walsh <ewalsh@tycho.nsa.gov>
---
include/selinux/label.h | 124 ++++++++++++++++++++++++++++++++++++++++++
src/label.c | 140 ++++++++++++++++++++++++++++++++++++++++++++++++
src/label_internal.h | 74 +++++++++++++++++++++++++
3 files changed, 338 insertions(+)
Index: libselinux/include/selinux/label.h
===================================================================
--- libselinux/include/selinux/label.h (revision 0)
+++ libselinux/include/selinux/label.h (revision 0)
@@ -0,0 +1,124 @@
+/*
+ * Labeling interface for userspace object managers and others.
+ *
+ * Author : Eamon Walsh <ewalsh@tycho.nsa.gov>
+ */
+#ifndef _SELABEL_H_
+#define _SELABEL_H_
+
+#include <sys/types.h>
+#include <selinux/selinux.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+ * Opaque type used for all label handles.
+ */
+
+struct selabel_handle;
+
+/*
+ * Available backends.
+ */
+
+/* file contexts */
+#define SELABEL_CTX_FILE 0
+/* media contexts */
+#define SELABEL_CTX_MEDIA 1
+/* x contexts */
+#define SELABEL_CTX_X 2
+
+/*
+ * Available options
+ */
+
+/* no-op option, useful for unused slots in an array of options */
+#define SELABEL_OPT_UNUSED 0
+/* validate contexts before returning them (boolean value) */
+#define SELABEL_OPT_VALIDATE 1
+/* don't use local customizations to backend data (boolean value) */
+#define SELABEL_OPT_BASEONLY 2
+/* specify an alternate path to use when loading backend data */
+#define SELABEL_OPT_PATH 3
+/* select a subset of the search space as an optimization (file backend) */
+#define SELABEL_OPT_SUBSET 4
+/* total number of options */
+#define SELABEL_NOPT 6
+
+struct selabel_opt {
+ int type;
+ const char *value;
+};
+
+/*
+ * Label operations
+ */
+
+/**
+ * selabel_open - Create a labeling handle.
+ * @backend: one of the constants specifying a supported labeling backend.
+ * @opts: array of selabel_opt structures specifying label options or NULL.
+ * @nopts: number of elements in opts array or zero for no options.
+ *
+ * Open a labeling backend for use. The available backend identifiers are
+ * listed above. Options may be provided via the opts parameter; available
+ * options are listed above. Not all options may be supported by every
+ * backend. Return value is the created handle on success or NULL with
+ * @errno set on failure.
+ */
+struct selabel_handle *selabel_open(unsigned int backend,
+ struct selabel_opt *opts, size_t nopts);
+
+/**
+ * selabel_close - Close a labeling handle.
+ * @handle: specifies handle to close
+ *
+ * Destroy the specified handle, closing files, freeing allocated memory,
+ * etc. The handle may not be further used after it has been closed.
+ */
+void selabel_close(struct selabel_handle *handle);
+
+/**
+ * selabel_lookup - Perform labeling lookup operation.
+ * @handle: specifies backend instance to query
+ * @con: returns the appropriate context with which to label the object
+ * @key: string input to lookup operation
+ * @type: numeric input to the lookup operation
+ *
+ * Perform a labeling lookup operation. Return %0 on success, -%1 with
+ * @errno set on failure. The key and type arguments are the inputs to the
+ * lookup operation; appropriate values are dictated by the backend in use.
+ * The result is returned in the memory pointed to by @con and must be freed
+ * by the user with freecon().
+ */
+int selabel_lookup(struct selabel_handle *handle, security_context_t *con,
+ const char *key, int type);
+int selabel_lookup_raw(struct selabel_handle *handle, security_context_t *con,
+ const char *key, int type);
+
+/**
+ * selabel_stats - log labeling operation statistics.
+ * @handle: specifies backend instance to query
+ *
+ * Log a message with information about the number of queries performed,
+ * number of unused matching entries, or other operational statistics.
+ * Message is backend-specific, some backends may not output a message.
+ */
+void selabel_stats(struct selabel_handle *handle);
+
+/*
+ * Type codes used by specific backends
+ */
+
+/* X backend */
+#define SELABEL_X_PROP 1
+#define SELABEL_X_EXT 2
+#define SELABEL_X_CLIENT 3
+
+
+#ifdef __cplusplus
+}
+#endif
+#endif /* _SELABEL_H_ */
Index: libselinux/src/label_internal.h
===================================================================
--- libselinux/src/label_internal.h (revision 0)
+++ libselinux/src/label_internal.h (revision 0)
@@ -0,0 +1,74 @@
+/*
+ * This file describes the internal interface used by the labeler
+ * for calling the user-supplied memory allocation, validation,
+ * and locking routine.
+ *
+ * Author : Eamon Walsh <ewalsh@epoch.ncsc.mil>
+ */
+#ifndef _SELABEL_INTERNAL_H_
+#define _SELABEL_INTERNAL_H_
+
+#include <stdlib.h>
+#include <stdarg.h>
+#include <selinux/selinux.h>
+#include <selinux/label.h>
+#include "dso.h"
+
+/*
+ * Installed backends
+ */
+int selabel_file_init(struct selabel_handle *rec, struct selabel_opt *opts,
+ size_t nopts) hidden;
+int selabel_media_init(struct selabel_handle *rec, struct selabel_opt *opts,
+ size_t nopts) hidden;
+int selabel_x_init(struct selabel_handle *rec, struct selabel_opt *opts,
+ size_t nopts) hidden;
+
+/*
+ * Labeling internal structures
+ */
+struct selabel_lookup_rec {
+ security_context_t ctx_raw;
+ security_context_t ctx_trans;
+ int validated;
+};
+
+struct selabel_handle {
+ /* arguments that were passed to selabel_open */
+ unsigned int backend;
+ int validating;
+
+ /* labeling operations */
+ struct selabel_lookup_rec *(*func_lookup) (struct selabel_handle *h,
+ const char *key, int type);
+ void (*func_close) (struct selabel_handle *h);
+ void (*func_stats) (struct selabel_handle *h);
+
+ /* supports backend-specific state information */
+ void *data;
+};
+
+/*
+ * Validation function
+ */
+extern int
+selabel_validate(struct selabel_handle *rec,
+ struct selabel_lookup_rec *contexts) hidden;
+
+/*
+ * Compatibility support
+ */
+extern void __attribute__ ((format(printf, 1, 2)))
+(*myprintf) (const char *fmt,...);
+
+#define COMPAT_LOG(type, fmt...) if (myprintf) \
+ myprintf(fmt); \
+ else \
+ selinux_log(type, fmt);
+
+extern int
+compat_validate(struct selabel_handle *rec,
+ struct selabel_lookup_rec *contexts,
+ const char *path, unsigned lineno) hidden;
+
+#endif /* _SELABEL_INTERNAL_H_ */
Index: libselinux/src/label.c
===================================================================
--- libselinux/src/label.c (revision 0)
+++ libselinux/src/label.c (revision 0)
@@ -0,0 +1,140 @@
+/*
+ * Generalized labeling frontend for userspace object managers.
+ *
+ * Author : Eamon Walsh <ewalsh@epoch.ncsc.mil>
+ */
+
+#include <sys/types.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "callbacks.h"
+#include "label_internal.h"
+
+#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
+
+typedef int (*selabel_initfunc)(struct selabel_handle *rec,
+ struct selabel_opt *opts, size_t nopts);
+
+static selabel_initfunc initfuncs[] = {
+ &selabel_file_init,
+ &selabel_media_init,
+ &selabel_x_init
+};
+
+/*
+ * Validation functions
+ */
+
+static inline int selabel_is_validate_set(struct selabel_opt *opts, size_t n)
+{
+ while (n--)
+ if (opts[n].type == SELABEL_OPT_VALIDATE)
+ return !!opts[n].value;
+
+ return 0;
+}
+
+int selabel_validate(struct selabel_handle *rec,
+ struct selabel_lookup_rec *contexts)
+{
+ int rc = 0;
+
+ if (!rec->validating || contexts->validated)
+ goto out;
+
+ rc = selinux_validate(&contexts->ctx_raw);
+ if (rc < 0)
+ goto out;
+
+ contexts->validated = 1;
+out:
+ return rc;
+}
+
+/*
+ * Public API
+ */
+
+struct selabel_handle *selabel_open(unsigned int backend,
+ struct selabel_opt *opts, size_t nopts)
+{
+ struct selabel_handle *rec = NULL;
+
+ if (backend >= ARRAY_SIZE(initfuncs)) {
+ errno = EINVAL;
+ goto out;
+ }
+
+ rec = (struct selabel_handle *)malloc(sizeof(*rec));
+ if (!rec)
+ goto out;
+
+ memset(rec, 0, sizeof(*rec));
+ rec->backend = backend;
+ rec->validating = selabel_is_validate_set(opts, nopts);
+
+ if ((*initfuncs[backend])(rec, opts, nopts)) {
+ free(rec);
+ rec = NULL;
+ }
+
+out:
+ return rec;
+}
+
+static struct selabel_lookup_rec *
+selabel_lookup_common(struct selabel_handle *rec, int translating,
+ const char *key, int type)
+{
+ struct selabel_lookup_rec *lr = rec->func_lookup(rec, key, type);
+ if (!lr)
+ return NULL;
+
+ if (compat_validate(rec, lr, "file_contexts", 0))
+ return NULL;
+
+ if (translating &&
+ selinux_raw_to_trans_context(lr->ctx_raw, &lr->ctx_trans))
+ return NULL;
+
+ return lr;
+}
+
+int selabel_lookup(struct selabel_handle *rec, security_context_t *con,
+ const char *key, int type)
+{
+ struct selabel_lookup_rec *lr;
+
+ lr = selabel_lookup_common(rec, 1, key, type);
+ if (!lr)
+ return -1;
+
+ *con = strdup(lr->ctx_trans);
+ return *con ? 0 : -1;
+}
+
+int selabel_lookup_raw(struct selabel_handle *rec, security_context_t *con,
+ const char *key, int type)
+{
+ struct selabel_lookup_rec *lr;
+
+ lr = selabel_lookup_common(rec, 0, key, type);
+ if (!lr)
+ return -1;
+
+ *con = strdup(lr->ctx_raw);
+ return *con ? 0 : -1;
+}
+
+void selabel_close(struct selabel_handle *rec)
+{
+ rec->func_close(rec);
+ free(rec);
+}
+
+void selabel_stats(struct selabel_handle *rec)
+{
+ rec->func_stats(rec);
+}
--
Eamon Walsh <ewalsh@tycho.nsa.gov>
National Security Agency
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