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         if (!key)
  36                 return -ENOMEM;
  37
  38         xbc_for_each_key_value(leaf, val) {
  39                 ret = xbc_node_compose_key(leaf, key, XBC_KEYLEN_MAX);
  40                 if (ret < 0)
  41                         break;
  42                 ret = snprintf(dst, rest(dst, end), "%s = ", key);
  43                 if (ret < 0)
  44                         break;
  45                 dst += ret;
  46                 vnode = xbc_node_get_child(leaf);
  47                 if (vnode) {
  48                         xbc_array_for_each_value(vnode, val) {
  49                                 if (strchr(val, '"'))
  50                                         q = '\'';
  51                                 else
  52                                         q = '"';
  53                                 ret = snprintf(dst, rest(dst, end), "%c%s%c%s",
  54                                         q, val, q, xbc_node_is_array(vnode) ? ", " : "\n");
  55                                 if (ret < 0)
  56                                         goto out;
  57                                 dst += ret;
  58                         }
  59                 } else {
  60                         ret = snprintf(dst, rest(dst, end), "\"\"\n");
  61                         if (ret < 0)
  62                                 break;
  63                         dst += ret;
  64                 }
  65                 if (ret >= 0 && boot_command_line[0]) {
  66                         ret = snprintf(dst, rest(dst, end), "# Parameters from bootloader:\n# %s\n",
  67                                        boot_command_line);
  68                         if (ret > 0)
  69                                 dst += ret;
  70                 }
  71         }
  72 out:
  73         kfree(key);
  74
  75         return ret < 0 ? ret : dst - (end - size);
  76 }
  77
  78 static int __init proc_boot_config_init(void)
  79 {
  80         int len;
  81
  82         len = copy_xbc_key_value_list(NULL, 0);
  83         if (len < 0)
  84                 return len;
  85
  86         if (len > 0) {
  87                 saved_boot_config = kzalloc(len + 1, GFP_KERNEL);
  88                 if (!saved_boot_config)
  89                         return -ENOMEM;
  90
  91                 len = copy_xbc_key_value_list(saved_boot_config, len + 1);
  92                 if (len < 0) {
  93                         kfree(saved_boot_config);
  94                         return len;
  95                 }
  96         }
  97
  98         proc_create_single("bootconfig", 0, NULL, boot_config_proc_show);
  99
 100         return 0;
 101 }
 102 fs_initcall(proc_boot_config_init);