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/*
* Media contexts backend for labeling system
*
* Author : Eamon Walsh <ewalsh@tycho.nsa.gov>
*/
#include <sys/stat.h>
#include <string.h>
#include <stdio.h>
#include <stdio_ext.h>
#include <ctype.h>
#include <errno.h>
#include <limits.h>
#include "callbacks.h"
#include "label_internal.h"
/*
* Internals
*/
/* A context specification. */
typedef struct spec {
struct selabel_lookup_rec lr; /* holds contexts for lookup result */
char *key; /* key string */
int matches; /* number of matches made during operation */
} spec_t;
struct saved_data {
unsigned int nspec;
spec_t *spec_arr;
};
static int process_line(const char *path, char *line_buf, int pass,
unsigned lineno, struct selabel_handle *rec)
{
struct saved_data *data = (struct saved_data *)rec->data;
int items;
char *buf_p;
char *key, *context;
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, "%as %as ", &key, &context);
if (items < 2) {
selinux_log(SELINUX_WARNING,
"%s: line %d is missing fields, skipping\n", path,
lineno);
if (items == 1)
free(key);
return 0;
}
if (pass == 1) {
data->spec_arr[data->nspec].key = key;
data->spec_arr[data->nspec].lr.ctx_raw = context;
}
data->nspec++;
if (pass == 0) {
free(key);
free(context);
}
return 0;
}
static int init(struct selabel_handle *rec, struct selinux_opt *opts,
unsigned n)
{
FILE *fp;
struct saved_data *data = (struct saved_data *)rec->data;
const char *path = NULL;
char *line_buf = NULL;
size_t line_len = 0;
int status = -1;
unsigned int lineno, pass, maxnspec;
struct stat sb;
/* Process arguments */
while (n--)
switch(opts[n].type) {
case SELABEL_OPT_PATH:
path = opts[n].value;
break;
}
/* Open the specification file. */
if (!path)
path = selinux_media_context_path();
if ((fp = fopen(path, "r")) == NULL)
return -1;
__fsetlocking(fp, FSETLOCKING_BYCALLER);
if (fstat(fileno(fp), &sb) < 0)
return -1;
if (!S_ISREG(sb.st_mode)) {
errno = EINVAL;
return -1;
}
rec->spec_file = strdup(path);
/*
* Perform two passes over the specification file.
* The first pass counts the number of specifications and
* performs simple validation of the input. At the end
* of the first pass, the spec array is allocated.
* The second pass performs detailed validation of the input
* and fills in the spec array.
*/
maxnspec = UINT_MAX / sizeof(spec_t);
for (pass = 0; pass < 2; pass++) {
lineno = 0;
data->nspec = 0;
while (getline(&line_buf, &line_len, fp) > 0 &&
data->nspec < maxnspec) {
if (process_line(path, line_buf, pass, ++lineno, rec))
goto finish;
}
lineno = 0;
if (pass == 0) {
if (data->nspec == 0) {
status = 0;
goto finish;
}
data->spec_arr = malloc(sizeof(spec_t)*data->nspec);
if (data->spec_arr == NULL)
goto finish;
memset(data->spec_arr, 0, sizeof(spec_t)*data->nspec);
maxnspec = data->nspec;
rewind(fp);
}
}
free(line_buf);
status = 0;
finish:
fclose(fp);
return status;
}
/*
* Backend interface routines
*/
static void close(struct selabel_handle *rec)
{
struct saved_data *data = (struct saved_data *)rec->data;
struct spec *spec, *spec_arr = data->spec_arr;
unsigned int i;
for (i = 0; i < data->nspec; i++) {
spec = &spec_arr[i];
free(spec->key);
free(spec->lr.ctx_raw);
free(spec->lr.ctx_trans);
}
if (spec_arr)
free(spec_arr);
memset(data, 0, sizeof(*data));
}
static struct selabel_lookup_rec *lookup(struct selabel_handle *rec,
const char *key,
int type __attribute__((unused)))
{
struct saved_data *data = (struct saved_data *)rec->data;
spec_t *spec_arr = data->spec_arr;
unsigned int i;
for (i = 0; i < data->nspec; i++) {
if (!strncmp(spec_arr[i].key, key, strlen(key) + 1))
break;
if (!strncmp(spec_arr[i].key, "*", 2))
break;
}
if (i >= data->nspec) {
/* No matching specification. */
errno = ENOENT;
return NULL;
}
spec_arr[i].matches++;
return &spec_arr[i].lr;
}
static void stats(struct selabel_handle *rec)
{
struct saved_data *data = (struct saved_data *)rec->data;
unsigned int i, total = 0;
for (i = 0; i < data->nspec; i++)
total += data->spec_arr[i].matches;
selinux_log(SELINUX_INFO, "%u entries, %u matches made\n",
data->nspec, total);
}
int selabel_media_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 = &close;
rec->func_lookup = &lookup;
rec->func_stats = &stats;
return init(rec, opts, nopts);
}
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