fs/proc/bootconfig.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * /proc/bootconfig - Extra boot configuration
   4  */
   5 #include <linux/fs.h>
   6 #include <linux/init.h>
   7 #include <linux/printk.h>
   8 #include <linux/proc_fs.h>
   9 #include <linux/seq_file.h>
  10 #include <linux/bootconfig.h>
  11 #include <linux/slab.h>
  12
  13 static char *saved_boot_config;
  14
  15 static int boot_config_proc_show(struct seq_file *m, void *v)
  16 {
  17         if (saved_boot_config)
  18                 seq_puts(m, saved_boot_config);
  19         return 0;
  20 }
  21
  22 /* Rest size of buffer */
  23 #define rest(dst, end) ((end) > (dst) ? (end) - (dst) : 0)
  24
  25 /* Return the needed total length if @size is 0 */
  26 static int __init copy_xbc_key_value_list(char *dst, size_t size)
  27 {
  28         struct xbc_node *leaf, *vnode;
  29         char *key, *end = dst + size;
  30         const char *val;
  31         char q;
  32         int ret = 0;
  33
  34         key = kzalloc(XBC_KEYLEN_MAX, GFP_KERNEL);
  35
  36         xbc_for_each_key_value(leaf, val) {
  37                 ret = xbc_node_compose_key(leaf, key, XBC_KEYLEN_MAX);
  38                 if (ret < 0)
  39                         break;
  40                 ret = snprintf(dst, rest(dst, end), "%s = ", key);
  41                 if (ret < 0)
  42                         break;
  43                 dst += ret;
  44                 vnode = xbc_node_get_child(leaf);
  45                 if (vnode) {
  46                         xbc_array_for_each_value(vnode, val) {
  47                                 if (strchr(val, '"'))
  48                                         q = '\'';
  49                                 else
  50                                         q = '"';
  51                                 ret = snprintf(dst, rest(dst, end), "%c%s%c%s",
  52                                         q, val, q, vnode->next ? ", " : "\n");
  53                                 if (ret < 0)
  54                                         goto out;
  55                                 dst += ret;
  56                         }
  57                 } else {
  58                         ret = snprintf(dst, rest(dst, end), "\"\"\n");
  59                         if (ret < 0)
  60                                 break;
  61                         dst += ret;
  62                 }
  63         }
  64 out:
  65         kfree(key);
  66
  67         return ret < 0 ? ret : dst - (end - size);
  68 }
  69
  70 static int __init proc_boot_config_init(void)
  71 {
  72         int len;
  73
  74         len = copy_xbc_key_value_list(NULL, 0);
  75         if (len < 0)
  76                 return len;
  77
  78         if (len > 0) {
  79                 saved_boot_config = kzalloc(len + 1, GFP_KERNEL);
  80                 if (!saved_boot_config)
  81                         return -ENOMEM;
  82
  83                 len = copy_xbc_key_value_list(saved_boot_config, len + 1);
  84                 if (len < 0) {
  85                         kfree(saved_boot_config);
  86                         return len;
  87                 }
  88         }
  89
  90         proc_create_single("bootconfig", 0, NULL, boot_config_proc_show);
  91
  92         return 0;
  93 }
  94 fs_initcall(proc_boot_config_init);