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module: setup load info before module_sig_check()

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We want to be able to log the module name in early error messages, such as
when module signature verification fails.  Previously, the module name is
set in layout_and_allocate(), meaning that any error messages that happen
before (such as those in module_sig_check()) won't be logged with a module
name, which isn't terribly helpful.

In order to do this, reshuffle the order in load_module() and set up
load info earlier so that we can log the module name along with these
error messages. This requires splitting rewrite_section_headers() out of
setup_load_info().

While we're at it, clean up and split up the operations done in
layout_and_allocate(), setup_load_info(), and rewrite_section_headers()
more cleanly so these functions only perform what their names suggest.

Signed-off-by: Jessica Yu <jeyu@kernel.org>
This commit is contained in:
Jessica Yu 2018-06-22 14:00:01 +02:00
parent 81a0abd9f2
commit 5fdc7db644
1 changed files with 43 additions and 34 deletions
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77
kernel/module.c
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@ -2488,7 +2488,11 @@ static char *get_modinfo(struct load_info *info, const char *tag)
Elf_Shdr *infosec = &info->sechdrs[info->index.info];
unsigned long size = infosec->sh_size;
for (p = (char *)infosec->sh_addr; p; p = next_string(p, &size)) {
/*
* get_modinfo() calls made before rewrite_section_headers()
* must use sh_offset, as sh_addr isn't set!
*/
for (p = (char *)info->hdr + infosec->sh_offset; p; p = next_string(p, &size)) {
if (strncmp(p, tag, taglen) == 0 && p[taglen] == '=')
return p + taglen + 1;
}
@ -2928,17 +2932,7 @@ static int rewrite_section_headers(struct load_info *info, int flags)
}
/* Track but don't keep modinfo and version sections. */
if (flags & MODULE_INIT_IGNORE_MODVERSIONS)
info->index.vers = 0; /* Pretend no __versions section! */
else
info->index.vers = find_sec(info, "__versions");
info->sechdrs[info->index.vers].sh_flags &= ~(unsigned long)SHF_ALLOC;
info->index.info = find_sec(info, ".modinfo");
if (!info->index.info)
info->name = "(missing .modinfo section)";
else
info->name = get_modinfo(info, "name");
info->sechdrs[info->index.info].sh_flags &= ~(unsigned long)SHF_ALLOC;
return 0;
@ -2955,16 +2949,18 @@ 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;
int err;
/* Set up the convenience variables */
info->sechdrs = (void *)info->hdr + info->hdr->e_shoff;
info->secstrings = (void *)info->hdr
+ info->sechdrs[info->hdr->e_shstrndx].sh_offset;
err = rewrite_section_headers(info, flags);
if (err)
return err;
/* 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 = "(missing .modinfo section)";
else
info->name = get_modinfo(info, "name");
/* Find internal symbols and strings. */
for (i = 1; i < info->hdr->e_shnum; i++) {
@ -2977,6 +2973,11 @@ static int setup_load_info(struct load_info *info, int flags)
}
}
if (info->index.sym == 0) {
pr_warn("%s: module has no symbols (stripped?)\n", info->name);
return -ENOEXEC;
}
info->index.mod = find_sec(info, ".gnu.linkonce.this_module");
if (!info->index.mod) {
pr_warn("%s: No module found in object\n",
@ -2984,26 +2985,22 @@ static int setup_load_info(struct load_info *info, int flags)
return -ENOEXEC;
}
/* This is temporary: point mod into copy of data. */
info->mod = (void *)info->sechdrs[info->index.mod].sh_addr;
info->mod = (void *)info->hdr + info->sechdrs[info->index.mod].sh_offset;
/*
* If we didn't load the .modinfo 'name' field, fall back to
* 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 (info->index.sym == 0) {
pr_warn("%s: module has no symbols (stripped?)\n", info->name);
return -ENOEXEC;
}
if (flags & MODULE_INIT_IGNORE_MODVERSIONS)
info->index.vers = 0; /* Pretend no __versions section! */
else
info->index.vers = find_sec(info, "__versions");
info->index.pcpu = find_pcpusec(info);
/* Check module struct version now, before we try to use module. */
if (!check_modstruct_version(info, info->mod))
return -ENOEXEC;
return 0;
}
@ -3303,13 +3300,6 @@ static struct module *layout_and_allocate(struct load_info *info, int flags)
unsigned int ndx;
int err;
err = setup_load_info(info, flags);
if (err)
return ERR_PTR(err);
if (blacklisted(info->name))
return ERR_PTR(-EPERM);
err = check_modinfo(info->mod, info, flags);
if (err)
return ERR_PTR(err);
@ -3657,17 +3647,36 @@ static int load_module(struct load_info *info, const char __user *uargs,
int flags)
{
struct module *mod;
long err;
long err = 0;
char *after_dashes;
err = elf_header_check(info);
if (err)
goto free_copy;
err = setup_load_info(info, flags);
if (err)
goto free_copy;
if (blacklisted(info->name)) {
err = -EPERM;
goto free_copy;
}
err = module_sig_check(info, flags);
if (err)
goto free_copy;
err = elf_header_check(info);
err = rewrite_section_headers(info, flags);
if (err)
goto free_copy;
/* Check module struct version now, before we try to use module. */
if (!check_modstruct_version(info, info->mod)) {
err = -ENOEXEC;
goto free_copy;
}
/* Figure out module layout, and allocate all the memory. */
mod = layout_and_allocate(info, flags);
if (IS_ERR(mod)) {