libselinux: New Android property labeling backend

This is already in the android repo.  This is here to prevent potential
conflicts of the selabel indices, and possibly with an eye toward an eventual
reunification of the two libselinuxes down the road.

Reviewed-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Dan Walsh <dwalsh@redhat.com>

3 files changed, 299 insertions, 0 deletions

diff --git a/libselinux/src/label.c b/libselinux/src/label.c
index 89e28f19..11f6e967 100644
--- a/libselinux/src/label.c
+++ b/libselinux/src/label.c
@@ -24,6 +24,7 @@ static selabel_initfunc initfuncs[] = {
 	&selabel_media_init,
 	&selabel_x_init,
 	&selabel_db_init,
+	&selabel_property_init,
 };
 
 static void selabel_subs_fini(struct selabel_sub *ptr)
diff --git a/libselinux/src/label_android_property.c b/libselinux/src/label_android_property.c
new file mode 100644
index 00000000..2a4c3b09
--- /dev/null
+++ b/libselinux/src/label_android_property.c
@@ -0,0 +1,296 @@
+/*
+ * Property Service contexts backend for labeling Android 
+ * property keys
+ */
+
+#include <stdarg.h>
+#include <string.h>
+#include <ctype.h>
+#include <errno.h>
+#include <limits.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include "callbacks.h"
+#include "label_internal.h"
+
+/* A property security context specification. */
+typedef struct spec {
+	struct selabel_lookup_rec lr;    /* holds contexts for lookup result */
+	char *property_key;              /* property key string */
+} spec_t;
+
+/* Our stored configuration */
+struct saved_data {
+	/*
+	 * The array of specifications is sorted for longest
+	 * prefix match
+	 */
+	spec_t *spec_arr;
+	unsigned int nspec; /* total number of specifications */
+};
+
+static int cmp(const void *A, const void *B)
+{
+	const struct spec *sp1 = A, *sp2 = B;
+
+	if (strncmp(sp1->property_key,"*",1) == 0)
+		return 1;
+	if (strncmp(sp2->property_key,"*",1) == 0)
+		return -1;
+
+	size_t L1 = strlen(sp1->property_key);
+	size_t L2 = strlen(sp2->property_key);
+
+	return (L1 < L2) - (L1 > L2);
+}
+
+/*
+ * Warn about duplicate specifications.
+ */
+static int nodups_specs(struct saved_data *data, const char *path)
+{
+	int rc = 0;
+	unsigned int ii, jj;
+	struct spec *curr_spec, *spec_arr = data->spec_arr;
+
+	for (ii = 0; ii < data->nspec; ii++) {
+		curr_spec = &spec_arr[ii];
+		for (jj = ii + 1; jj < data->nspec; jj++) {
+			if ((!strcmp(spec_arr[jj].property_key, curr_spec->property_key))) {
+				rc = -1;
+				errno = EINVAL;
+				if (strcmp
+				    (spec_arr[jj].lr.ctx_raw,
+				     curr_spec->lr.ctx_raw)) {
+					selinux_log
+						(SELINUX_ERROR,
+						 "%s: Multiple different specifications for %s  (%s and %s).\n",
+						 path, curr_spec->property_key,
+						 spec_arr[jj].lr.ctx_raw,
+						 curr_spec->lr.ctx_raw);
+				} else {
+					selinux_log
+						(SELINUX_ERROR,
+						 "%s: Multiple same specifications for %s.\n",
+						 path, curr_spec->property_key);
+				}
+			}
+		}
+	}
+	return rc;
+}
+
+static int process_line(struct selabel_handle *rec,
+			const char *path, char *line_buf, 
+			int pass, unsigned lineno)
+{
+	int items, len;
+	char buf1[BUFSIZ], buf2[BUFSIZ];
+	char *buf_p, *prop = buf1, *context = buf2;
+	struct saved_data *data = (struct saved_data *)rec->data;
+	spec_t *spec_arr = data->spec_arr;
+	unsigned int nspec = data->nspec;
+
+	len = strlen(line_buf);
+	if (line_buf[len - 1] == '\n')
+		line_buf[len - 1] = 0;
+	buf_p = line_buf;
+	while (isspace(*buf_p))
+		buf_p++;
+	/* Skip comment lines and empty lines. */
+	if (*buf_p == '#' || *buf_p == 0)
+		return 0;
+	items = sscanf(line_buf, "%255s %255s", prop, context);
+	if (items != 2) {
+		selinux_log(SELINUX_WARNING,
+			    "%s:  line %d is missing fields, skipping\n", path,
+			    lineno);
+		return 0;
+	}
+
+	if (pass == 1) {
+		/* On the second pass, process and store the specification in spec. */
+		spec_arr[nspec].property_key = strdup(prop);
+		if (!spec_arr[nspec].property_key) {
+			selinux_log(SELINUX_WARNING,
+				    "%s:  out of memory at line %d on prop %s\n",
+				    path, lineno, prop);
+		return -1;
+	    
+		}
+
+		spec_arr[nspec].lr.ctx_raw = strdup(context);
+		if (!spec_arr[nspec].lr.ctx_raw) {
+			selinux_log(SELINUX_WARNING,
+				    "%s:  out of memory at line %d on context %s\n",
+				    path, lineno, context);
+		return -1;
+		}
+     	}
+
+	data->nspec = ++nspec;
+	return 0;
+}
+
+static int init(struct selabel_handle *rec, struct selinux_opt *opts,
+		unsigned n)
+{
+	struct saved_data *data = (struct saved_data *)rec->data;
+	const char *path = NULL;
+	FILE *fp;
+	char line_buf[BUFSIZ];
+	unsigned int lineno = 0, maxnspec, pass;
+	int status = -1;
+	struct stat sb;
+
+	/* Process arguments */
+	while (n--)
+		switch (opts[n].type) {
+		case SELABEL_OPT_PATH:
+			path = opts[n].value;
+			break;
+		default:
+			selinux_log(SELINUX_WARNING,
+				    "Argument type (%d) not recognized. Skipping\n", opts[n].type);
+			break;
+		}
+
+	/* Open the specification file. */
+	if ((fp = fopen(path, "r")) == NULL)
+		return -1;
+
+	if (fstat(fileno(fp), &sb) < 0)
+		return -1;
+	if (!S_ISREG(sb.st_mode)) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	/*
+	 * Two passes of the specification file. First is to get the size.
+	 * After the first pass, the spec array is malloced to the appropriate 
+	 * size. Second pass is to populate the spec array and check for 
+	 * dups.
+	 */
+	maxnspec = UINT_MAX / sizeof(spec_t);
+	for (pass = 0; pass < 2; pass++) {
+		data->nspec = 0;
+
+		while (fgets(line_buf, sizeof line_buf - 1, fp)
+		       && data->nspec < maxnspec) {
+			if (process_line(rec, path, line_buf, pass, ++lineno) != 0) {
+				goto finish;
+			}
+		}
+
+		if (pass == 1) {
+			status = nodups_specs(data, path);
+	    
+			if (status)
+				goto finish;
+		}
+
+		if (pass == 0) {
+
+			if (data->nspec == 0) {
+				status = 0;
+				goto finish;
+			}
+
+			if (NULL == (data->spec_arr =
+				     malloc(sizeof(spec_t) * data->nspec)))
+				goto finish;
+
+			memset(data->spec_arr, 0, sizeof(spec_t)*data->nspec);
+			maxnspec = data->nspec;
+			rewind(fp);
+		}
+	}
+
+	qsort(data->spec_arr, data->nspec, sizeof(struct spec), cmp);
+
+	status = 0;
+finish:
+	fclose(fp);
+	return status;
+}
+
+/*
+ * Backend interface routines
+ */
+static void closef(struct selabel_handle *rec)
+{
+	struct saved_data *data = (struct saved_data *)rec->data;
+	struct spec *spec;
+	unsigned int i;
+
+	for (i = 0; i < data->nspec; i++) {
+		spec = &data->spec_arr[i];
+		free(spec->property_key);
+		free(spec->lr.ctx_raw);
+		free(spec->lr.ctx_trans);
+	}
+
+	if (data->spec_arr)
+		free(data->spec_arr);
+	
+	free(data);
+}
+
+static struct selabel_lookup_rec *lookup(struct selabel_handle *rec, 
+					 const char *key, 
+					 int __attribute__((unused)) type)
+{
+	struct saved_data *data = (struct saved_data *)rec->data;
+	spec_t *spec_arr = data->spec_arr;
+	unsigned int i;
+	struct selabel_lookup_rec *ret = NULL;
+
+	if (!data->nspec) {
+		errno = ENOENT;
+		goto finish;
+	}
+
+	for (i = 0; i < data->nspec; i++) {
+		if (strncmp(spec_arr[i].property_key, key, 
+		    strlen(spec_arr[i].property_key)) == 0) {
+			break;
+		}
+		if (strncmp(spec_arr[i].property_key, "*", 1) == 0)
+			break;
+	}
+
+	if (i >= data->nspec) {
+		/* No matching specification. */
+		errno = ENOENT;
+		goto finish;
+	}
+
+	ret = &spec_arr[i].lr;
+
+finish:
+	return ret;
+}
+
+static void stats(struct selabel_handle __attribute__((unused)) *rec)
+{
+	selinux_log(SELINUX_WARNING, "'stats' functionality not implemented.\n");
+}
+
+int selabel_property_init(struct selabel_handle *rec, struct selinux_opt *opts,
+		      unsigned nopts)
+{
+	struct saved_data *data;
+
+	data = (struct saved_data *)malloc(sizeof(*data));
+	if (!data)
+		return -1;
+	memset(data, 0, sizeof(*data));
+
+	rec->data = data;
+	rec->func_close = &closef;
+	rec->func_stats = &stats;
+	rec->func_lookup = &lookup;
+
+	return init(rec, opts, nopts);
+}
diff --git a/libselinux/src/label_internal.h b/libselinux/src/label_internal.h
index 79d54952..435ecf2f 100644
--- a/libselinux/src/label_internal.h
+++ b/libselinux/src/label_internal.h
@@ -25,6 +25,8 @@ int selabel_x_init(struct selabel_handle *rec, struct selinux_opt *opts,
 		   unsigned nopts) hidden;
 int selabel_db_init(struct selabel_handle *rec,
 		    struct selinux_opt *opts, unsigned nopts) hidden;
+int selabel_property_init(struct selabel_handle *rec,
+			  struct selinux_opt *opts, unsigned nopts) hidden;
 
 /*
  * Labeling internal structures