linux-kernel - [PATCH v4 10/16] module: Factor out elf_validity_cache

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Message-ID: <20240924212024.540574-11-mmaurer@google.com>
Date: Tue, 24 Sep 2024 21:19:52 +0000
From: Matthew Maurer <mmaurer@...gle.com>
To: masahiroy@...nel.org, ndesaulniers@...gle.com, ojeda@...nel.org, 
	gary@...yguo.net, mcgrof@...nel.org, Alex Gaynor <alex.gaynor@...il.com>
Cc: rust-for-linux@...r.kernel.org, linux-kbuild@...r.kernel.org, 
	linux-kernel@...r.kernel.org, neal@...pa.dev, marcan@...can.st, j@...nau.net, 
	asahi@...ts.linux.dev, Matthew Maurer <mmaurer@...gle.com>, 
	Petr Pavlu <petr.pavlu@...e.com>, Sami Tolvanen <samitolvanen@...gle.com>, 
	Daniel Gomez <da.gomez@...sung.com>, Boqun Feng <boqun.feng@...il.com>, 
	"Björn Roy Baron" <bjorn3_gh@...tonmail.com>, Benno Lossin <benno.lossin@...ton.me>, 
	Andreas Hindborg <a.hindborg@...nel.org>, Alice Ryhl <aliceryhl@...gle.com>, 
	Trevor Gross <tmgross@...ch.edu>, linux-modules@...r.kernel.org
Subject: [PATCH v4 10/16] module: Factor out elf_validity_cache_strtab

This patch only moves the existing strtab population to a function.
Validation comes in a following patch, this is split out to make the new
validation checks more clearly separated.

Signed-off-by: Matthew Maurer <mmaurer@...gle.com>
---
 kernel/module/main.c | 23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

diff --git a/kernel/module/main.c b/kernel/module/main.c
index e04a228c694a..c082d5d41a8d 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -2089,6 +2089,23 @@ static int elf_validity_cache_index(struct load_info *info, int flags)
 	return 0;
 }
 
+/**
+ * elf_validity_cache_strtab() - Cache symbol string table
+ * @info: Load info to read from and update.
+ *        Must have &load_info->sechdrs and &load_info->secstrings populated.
+ *        Must have &load_info->index populated.
+ *
+ * Return: 0 on success, negative error code if a check failed.
+ */
+static int elf_validity_cache_strtab(struct load_info *info)
+{
+	Elf_Shdr *str_shdr = &info->sechdrs[info->index.str];
+	char *strtab = (char *)info->hdr + str_shdr->sh_offset;
+
+	info->strtab = strtab;
+	return 0;
+}
+
 /*
  * Check userspace passed ELF module against our expectations, and cache
  * useful variables for further processing as we go.
@@ -2122,9 +2139,9 @@ static int elf_validity_cache_copy(struct load_info *info, int flags)
 	err = elf_validity_cache_index(info, flags);
 	if (err < 0)
 		return err;
-
-	/* Sets internal strings. */
-	info->strtab = (char *)info->hdr + info->sechdrs[info->index.str].sh_offset;
+	err = elf_validity_cache_strtab(info);
+	if (err < 0)
+		return err;
 
 	/* This is temporary: point mod into copy of data. */
 	info->mod = (void *)info->hdr + info->sechdrs[info->index.mod].sh_offset;
-- 
2.46.1.824.gd892dcdcdd-goog