tools/testing/selftests/lsm/common.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Linux Security Module infrastructure tests
   4  *
   5  * Copyright © 2023 Casey Schaufler <casey@schaufler-ca.com>
   6  */
   7
   8 #define _GNU_SOURCE
   9 #include <linux/lsm.h>
  10 #include <fcntl.h>
  11 #include <string.h>
  12 #include <stdio.h>
  13 #include <stdlib.h>
  14 #include <unistd.h>
  15 #include <sys/types.h>
  16 #include "common.h"
  17
  18 #define PROCATTR "/proc/self/attr/"
  19
  20 int read_proc_attr(const char *attr, char *value, size_t size)
  21 {
  22         int fd;
  23         int len;
  24         char *path;
  25
  26         len = strlen(PROCATTR) + strlen(attr) + 1;
  27         path = calloc(len, 1);
  28         if (path == NULL)
  29                 return -1;
  30         sprintf(path, "%s%s", PROCATTR, attr);
  31
  32         fd = open(path, O_RDONLY);
  33         free(path);
  34
  35         if (fd < 0)
  36                 return -1;
  37         len = read(fd, value, size);
  38
  39         close(fd);
  40
  41         /* Ensure value is terminated */
  42         if (len <= 0 || len == size)
  43                 return -1;
  44         value[len] = '\0';
  45
  46         path = strchr(value, '\n');
  47         if (path)
  48                 *path = '\0';
  49
  50         return 0;
  51 }
  52
  53 int read_sysfs_lsms(char *lsms, size_t size)
  54 {
  55         FILE *fp;
  56         size_t red;
  57
  58         fp = fopen("/sys/kernel/security/lsm", "r");
  59         if (fp == NULL)
  60                 return -1;
  61         red = fread(lsms, 1, size, fp);
  62         fclose(fp);
  63
  64         if (red <= 0 || red == size)
  65                 return -1;
  66         lsms[red] = '\0';
  67         return 0;
  68 }
  69
  70 int attr_lsm_count(void)
  71 {
  72         char *names = calloc(sysconf(_SC_PAGESIZE), 1);
  73         int count = 0;
  74
  75         if (!names)
  76                 return 0;
  77
  78         if (read_sysfs_lsms(names, sysconf(_SC_PAGESIZE)))
  79                 return 0;
  80
  81         if (strstr(names, "selinux"))
  82                 count++;
  83         if (strstr(names, "smack"))
  84                 count++;
  85         if (strstr(names, "apparmor"))
  86                 count++;
  87
  88         return count;
  89 }