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module: move more elf validity checks to elf_validity_check() 

The symbol and strings section validation currently happen in
setup_load_info() but since they are also doing validity checks
move this to elf_validity_check().

Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
This commit is contained in:
Luis Chamberlain 2023-03-19 14:35:40 -07:00
parent c7ee8aebf6
commit 1bb49db991
1 changed files with 44 additions and 35 deletions
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79
kernel/module/main.c
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@ -1658,6 +1658,8 @@ static int elf_validity_check(struct load_info *info)
Elf_Shdr *shdr, *strhdr;
int err;
unsigned int num_mod_secs = 0, mod_idx;
unsigned int num_info_secs = 0, info_idx;
unsigned int num_sym_secs = 0, sym_idx;
if (info->len < sizeof(*(info->hdr))) {
pr_err("Invalid ELF header len %lu\n", info->len);
@ -1761,6 +1763,8 @@ static int elf_validity_check(struct load_info *info)
info->hdr->e_shnum);
goto no_exec;
}
num_sym_secs++;
sym_idx = i;
fallthrough;
default:
err = validate_section_offset(info, shdr);
@ -1773,6 +1777,10 @@ static int elf_validity_check(struct load_info *info)
".gnu.linkonce.this_module") == 0) {
num_mod_secs++;
mod_idx = i;
} else if (strcmp(info->secstrings + shdr->sh_name,
".modinfo") == 0) {
num_info_secs++;
info_idx = i;
}
if (shdr->sh_flags & SHF_ALLOC) {
@ -1786,6 +1794,27 @@ static int elf_validity_check(struct load_info *info)
}
}
if (num_info_secs > 1) {
pr_err("Only one .modinfo section must exist.\n");
goto no_exec;
} else if (num_info_secs == 1) {
/* Try to find a name early so we can log errors with a module name */
info->index.info = info_idx;
info->name = get_modinfo(info, "name");
}
if (num_sym_secs != 1) {
pr_warn("%s: module has no symbols (stripped?)\n",
info->name ?: "(missing .modinfo section or name field)");
goto no_exec;
}
/* Sets internal symbols and strings. */
info->index.sym = sym_idx;
shdr = &info->sechdrs[sym_idx];
info->index.str = shdr->sh_link;
info->strtab = (char *)info->hdr + info->sechdrs[info->index.str].sh_offset;
/*
* The ".gnu.linkonce.this_module" ELF section is special. It is
* what modpost uses to refer to __this_module and let's use rely
@ -1802,7 +1831,8 @@ static int elf_validity_check(struct load_info *info)
* size
*/
if (num_mod_secs != 1) {
pr_err("Only one .gnu.linkonce.this_module section must exist.\n");
pr_err("module %s: Only one .gnu.linkonce.this_module section must exist.\n",
info->name ?: "(missing .modinfo section or name field)");
goto no_exec;
}
@ -1813,17 +1843,20 @@ static int elf_validity_check(struct load_info *info)
* pedantic about it.
*/
if (shdr->sh_type == SHT_NOBITS) {
pr_err(".gnu.linkonce.this_module section must have a size set\n");
pr_err("module %s: .gnu.linkonce.this_module section must have a size set\n",
info->name ?: "(missing .modinfo section or name field)");
goto no_exec;
}
if (!(shdr->sh_flags & SHF_ALLOC)) {
pr_err(".gnu.linkonce.this_module must occupy memory during process execution\n");
pr_err("module %s: .gnu.linkonce.this_module must occupy memory during process execution\n",
info->name ?: "(missing .modinfo section or name field)");
goto no_exec;
}
if (shdr->sh_size != sizeof(struct module)) {
pr_err(".gnu.linkonce.this_module section size must match the kernel's built struct module size at run time\n");
pr_err("module %s: .gnu.linkonce.this_module section size must match the kernel's built struct module size at run time\n",
info->name ?: "(missing .modinfo section or name field)");
goto no_exec;
}
@ -1832,6 +1865,13 @@ static int elf_validity_check(struct load_info *info)
/* This is temporary: point mod into copy of data. */
info->mod = (void *)info->hdr + shdr->sh_offset;
/*
* If we didn't load the .modinfo 'name' field earlier, fall back to
* on-disk struct mod 'name' field.
*/
if (!info->name)
info->name = info->mod->name;
return 0;
no_exec:
@ -1954,37 +1994,6 @@ static int rewrite_section_headers(struct load_info *info, int flags)
*/
static int setup_load_info(struct load_info *info, int flags)
{
unsigned int i;
/* Try to find a name early so we can log errors with a module name */
info->index.info = find_sec(info, ".modinfo");
if (info->index.info)
info->name = get_modinfo(info, "name");
/* Find internal symbols and strings. */
for (i = 1; i < info->hdr->e_shnum; i++) {
if (info->sechdrs[i].sh_type == SHT_SYMTAB) {
info->index.sym = i;
info->index.str = info->sechdrs[i].sh_link;
info->strtab = (char *)info->hdr
+ info->sechdrs[info->index.str].sh_offset;
break;
}
}
if (info->index.sym == 0) {
pr_warn("%s: module has no symbols (stripped?)\n",
info->name ?: "(missing .modinfo section or name field)");
return -ENOEXEC;
}
/*
* If we didn't load the .modinfo 'name' field earlier, fall back to
* on-disk struct mod 'name' field.
*/
if (!info->name)
info->name = info->mod->name;
if (flags & MODULE_INIT_IGNORE_MODVERSIONS)
info->index.vers = 0; /* Pretend no __versions section! */
else