Centralize .modinfo detection and property validation.
Signed-off-by: Matthew Maurer <mmau...@google.com>
---
kernel/module/main.c | 82 ++++++++++++++++++++++++++++++++++++--------
1 file changed, 68 insertions(+), 14 deletions(-)
diff --git a/kernel/module/main.c b/kernel/module/main.c
index 6a9159afca02..511d645ac577 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -195,6 +195,38 @@ static unsigned int find_sec(const struct load_info *info,
const char *name)
return 0;
}
+/**
+ * find_any_unique_sec() - Find a unique section index by name
+ * @info: Load info for the module to scan
+ * @name: Name of the section we're looking for
+ *
+ * Locates a unique section by name. Ignores SHF_ALLOC.
+ *
+ * Return: Section index if found uniquely, zero if absent, negative count
+ * of total instances if multiple were found.
+ */
+static int find_any_unique_sec(const struct load_info *info, const char *name)
+{
+ unsigned int idx;
+ unsigned int count = 0;
+ int i;
+
+ for (i = 1; i < info->hdr->e_shnum; i++) {
+ if (strcmp(info->secstrings + info->sechdrs[i].sh_name,
+ name) == 0) {
+ count++;
+ idx = i;
+ }
+ }
+ if (count == 1) {
+ return idx;
+ } else if (count == 0) {
+ return 0;
+ } else {
+ return -count;
+ }
+}
+
/* Find a module section, or NULL. */
static void *section_addr(const struct load_info *info, const char *name)
{
@@ -1854,6 +1886,39 @@ static int elf_validity_cache_secstrings(struct
load_info *info)
return 0;
}
+/**
+ * elf_validity_cache_index_info() - Validate and cache modinfo section
+ * @info: Load info to populate the modinfo index on.
+ * Must have &load_info->sechdrs and &load_info->secstrings populated
+ *
+ * Checks that if there is a .modinfo section, it is unique.
+ * Then, it caches its index in &load_info->index.info.
+ * Finally, it tries to populate the name to improve error messages.
+ *
+ * Return: %0 if valid, %-ENOEXEC if multiple modinfo sections were found.
+ */
+static int elf_validity_cache_index_info(struct load_info *info)
+{
+ int info_idx;
+
+ info_idx = find_any_unique_sec(info, ".modinfo");
+
+ if (info_idx == 0)
+ /* Early return, no .modinfo */
+ return 0;
+
+ if (info_idx < 0) {
+ pr_err("Only one .modinfo section must exist.\n");
+ return -ENOEXEC;
+ }
+
+ info->index.info = info_idx;
+ /* Try to find a name early so we can log errors with a module name */
+ info->name = get_modinfo(info, "name");
+
+ return 0;
+}
+
/*
* Check userspace passed ELF module against our expectations, and cache
* useful variables for further processing as we go.
@@ -1880,13 +1945,15 @@ static int elf_validity_cache_copy(struct load_info
*info, int flags)
Elf_Shdr *shdr;
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;
err = elf_validity_cache_sechdrs(info);
if (err < 0)
return err;
err = elf_validity_cache_secstrings(info);
+ if (err < 0)
+ return err;
+ err = elf_validity_cache_index_info(info);
if (err < 0)
return err;
@@ -1912,24 +1979,11 @@ static int elf_validity_cache_copy(struct load_info
*info, int flags)
".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;
}
break;
}
}
- 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)");
--
2.46.1.824.gd892dcdcdd-goog
