| 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
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| 2 | /* |
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| 3 | * Module version support |
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| 4 | * |
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| 5 | * Copyright (C) 2008 Rusty Russell |
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| 6 | */ |
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| 7 | |
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| 8 | #include <linux/module.h> |
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| 9 | #include <linux/string.h> |
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| 10 | #include <linux/printk.h> |
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| 11 | #include "internal.h" |
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| 12 | |
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| 13 | int check_version(const struct load_info *info, |
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| 14 | const char *symname, |
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| 15 | struct module *mod, |
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| 16 | const u32 *crc) |
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| 17 | { |
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| 18 | Elf_Shdr *sechdrs = info->sechdrs; |
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| 19 | unsigned int versindex = info->index.vers; |
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| 20 | unsigned int i, num_versions; |
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| 21 | struct modversion_info *versions; |
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| 22 | struct modversion_info_ext version_ext; |
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| 23 | |
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| 24 | /* Exporting module didn't supply crcs? OK, we're already tainted. */ |
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| 25 | if (!crc) |
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| 26 | return 1; |
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| 27 | |
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| 28 | /* If we have extended version info, rely on it */ |
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| 29 | if (info->index.vers_ext_crc) { |
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| 30 | for_each_modversion_info_ext(version_ext, info) { |
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| 31 | if (strcmp(version_ext.name, symname) != 0) |
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| 32 | continue; |
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| 33 | if (*version_ext.crc == *crc) |
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| 34 | return 1; |
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| 35 | pr_debug("Found checksum %X vs module %X\n" , |
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| 36 | *crc, *version_ext.crc); |
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| 37 | goto bad_version; |
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| 38 | } |
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| 39 | pr_warn_once("%s: no extended symbol version for %s\n" , |
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| 40 | info->name, symname); |
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| 41 | return 1; |
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| 42 | } |
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| 43 | |
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| 44 | /* No versions at all? modprobe --force does this. */ |
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| 45 | if (versindex == 0) |
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| 46 | return try_to_force_load(mod, reason: symname) == 0; |
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| 47 | |
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| 48 | versions = (void *)sechdrs[versindex].sh_addr; |
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| 49 | num_versions = sechdrs[versindex].sh_size |
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| 50 | / sizeof(struct modversion_info); |
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| 51 | |
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| 52 | for (i = 0; i < num_versions; i++) { |
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| 53 | u32 crcval; |
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| 54 | |
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| 55 | if (strcmp(versions[i].name, symname) != 0) |
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| 56 | continue; |
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| 57 | |
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| 58 | crcval = *crc; |
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| 59 | if (versions[i].crc == crcval) |
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| 60 | return 1; |
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| 61 | pr_debug("Found checksum %X vs module %lX\n" , |
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| 62 | crcval, versions[i].crc); |
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| 63 | goto bad_version; |
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| 64 | } |
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| 65 | |
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| 66 | /* Broken toolchain. Warn once, then let it go.. */ |
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| 67 | pr_warn_once("%s: no symbol version for %s\n" , info->name, symname); |
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| 68 | return 1; |
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| 69 | |
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| 70 | bad_version: |
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| 71 | pr_warn("%s: disagrees about version of symbol %s\n" , info->name, symname); |
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| 72 | return 0; |
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| 73 | } |
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| 74 | |
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| 75 | int check_modstruct_version(const struct load_info *info, |
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| 76 | struct module *mod) |
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| 77 | { |
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| 78 | struct find_symbol_arg fsa = { |
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| 79 | .name = "module_layout" , |
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| 80 | .gplok = true, |
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| 81 | }; |
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| 82 | bool have_symbol; |
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| 83 | |
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| 84 | /* |
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| 85 | * Since this should be found in kernel (which can't be removed), no |
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| 86 | * locking is necessary. Regardless use a RCU read section to keep |
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| 87 | * lockdep happy. |
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| 88 | */ |
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| 89 | scoped_guard(rcu) |
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| 90 | have_symbol = find_symbol(fsa: &fsa); |
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| 91 | BUG_ON(!have_symbol); |
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| 92 | |
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| 93 | return check_version(info, "module_layout" , mod, fsa.crc); |
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| 94 | } |
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| 95 | |
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| 96 | /* First part is kernel version, which we ignore if module has crcs. */ |
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| 97 | int same_magic(const char *amagic, const char *bmagic, |
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| 98 | bool has_crcs) |
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| 99 | { |
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| 100 | if (has_crcs) { |
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| 101 | amagic += strcspn(amagic, " " ); |
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| 102 | bmagic += strcspn(bmagic, " " ); |
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| 103 | } |
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| 104 | return strcmp(amagic, bmagic) == 0; |
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| 105 | } |
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| 106 | |
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| 107 | void modversion_ext_start(const struct load_info *info, |
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| 108 | struct modversion_info_ext *start) |
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| 109 | { |
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| 110 | unsigned int crc_idx = info->index.vers_ext_crc; |
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| 111 | unsigned int name_idx = info->index.vers_ext_name; |
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| 112 | Elf_Shdr *sechdrs = info->sechdrs; |
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| 113 | |
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| 114 | /* |
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| 115 | * Both of these fields are needed for this to be useful |
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| 116 | * Any future fields should be initialized to NULL if absent. |
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| 117 | */ |
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| 118 | if (crc_idx == 0 || name_idx == 0) { |
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| 119 | start->remaining = 0; |
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| 120 | return; |
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| 121 | } |
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| 122 | |
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| 123 | start->crc = (const u32 *)sechdrs[crc_idx].sh_addr; |
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| 124 | start->name = (const char *)sechdrs[name_idx].sh_addr; |
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| 125 | start->remaining = sechdrs[crc_idx].sh_size / sizeof(*start->crc); |
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| 126 | } |
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| 127 | |
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| 128 | void modversion_ext_advance(struct modversion_info_ext *vers) |
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| 129 | { |
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| 130 | vers->remaining--; |
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| 131 | vers->crc++; |
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| 132 | vers->name += strlen(vers->name) + 1; |
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| 133 | } |
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| 134 | |
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| 135 | /* |
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| 136 | * Generate the signature for all relevant module structures here. |
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| 137 | * If these change, we don't want to try to parse the module. |
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| 138 | */ |
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| 139 | void module_layout(struct module *mod, |
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| 140 | struct modversion_info *ver, |
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| 141 | struct kernel_param *kp, |
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| 142 | struct kernel_symbol *ks, |
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| 143 | struct tracepoint * const *tp) |
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| 144 | { |
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| 145 | } |
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| 146 | EXPORT_SYMBOL(module_layout); |
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| 147 | |
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