From: Kees Cook <keescook@chromium.org>
To: "H . J . Lu" <hjl.tools@gmail.com>
Cc: Kees Cook <keescook@chromium.org>,
Chris Kennelly <ckennelly@google.com>,
Eric Biederman <ebiederm@xmission.com>,
Shuah Khan <shuah@kernel.org>,
Muhammad Usama Anjum <usama.anjum@collabora.com>,
John Hubbard <jhubbard@nvidia.com>,
Fangrui Song <maskray@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Yang Yingliang <yangyingliang@huawei.com>,
Mike Rapoport <rppt@kernel.org>,
Rui Salvaterra <rsalvaterra@gmail.com>,
Victor Stinner <vstinner@redhat.com>,
Jan Palus <jpalus@fastmail.com>,
Al Viro <viro@zeniv.linux.org.uk>,
Christian Brauner <brauner@kernel.org>, Jan Kara <jack@suse.cz>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux-kselftest@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-hardening@vger.kernel.org
Subject: [PATCH 2/3] binfmt_elf: Calculate total_size earlier
Date: Wed, 8 May 2024 10:31:47 -0700 [thread overview]
Message-ID: <20240508173149.677910-2-keescook@chromium.org> (raw)
In-Reply-To: <20240508172848.work.131-kees@kernel.org>
In preparation to support PT_LOAD with large p_align values on
non-PT_INTERP ET_DYN executables (i.e. "static pie"), we'll need to use
the total_size details earlier. Move this separately now to make the
next patch more readable. As total_size and load_bias are currently
calculated separately, this has no behavioral impact.
Signed-off-by: Kees Cook <keescook@chromium.org>
---
fs/binfmt_elf.c | 52 +++++++++++++++++++++++++------------------------
1 file changed, 27 insertions(+), 25 deletions(-)
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 5397b552fbeb..56432e019d4e 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1061,7 +1061,34 @@ static int load_elf_binary(struct linux_binprm *bprm)
* Header for ET_DYN binaries to calculate the
* randomization (load_bias) for all the LOAD
* Program Headers.
+ */
+
+ /*
+ * Calculate the entire size of the ELF mapping
+ * (total_size), used for the initial mapping,
+ * due to load_addr_set which is set to true later
+ * once the initial mapping is performed.
+ *
+ * Note that this is only sensible when the LOAD
+ * segments are contiguous (or overlapping). If
+ * used for LOADs that are far apart, this would
+ * cause the holes between LOADs to be mapped,
+ * running the risk of having the mapping fail,
+ * as it would be larger than the ELF file itself.
*
+ * As a result, only ET_DYN does this, since
+ * some ET_EXEC (e.g. ia64) may have large virtual
+ * memory holes between LOADs.
+ *
+ */
+ total_size = total_mapping_size(elf_phdata,
+ elf_ex->e_phnum);
+ if (!total_size) {
+ retval = -EINVAL;
+ goto out_free_dentry;
+ }
+
+ /*
* There are effectively two types of ET_DYN
* binaries: programs (i.e. PIE: ET_DYN with INTERP)
* and loaders (ET_DYN without INTERP, since they
@@ -1102,31 +1129,6 @@ static int load_elf_binary(struct linux_binprm *bprm)
* is then page aligned.
*/
load_bias = ELF_PAGESTART(load_bias - vaddr);
-
- /*
- * Calculate the entire size of the ELF mapping
- * (total_size), used for the initial mapping,
- * due to load_addr_set which is set to true later
- * once the initial mapping is performed.
- *
- * Note that this is only sensible when the LOAD
- * segments are contiguous (or overlapping). If
- * used for LOADs that are far apart, this would
- * cause the holes between LOADs to be mapped,
- * running the risk of having the mapping fail,
- * as it would be larger than the ELF file itself.
- *
- * As a result, only ET_DYN does this, since
- * some ET_EXEC (e.g. ia64) may have large virtual
- * memory holes between LOADs.
- *
- */
- total_size = total_mapping_size(elf_phdata,
- elf_ex->e_phnum);
- if (!total_size) {
- retval = -EINVAL;
- goto out_free_dentry;
- }
}
error = elf_load(bprm->file, load_bias + vaddr, elf_ppnt,
--
2.34.1
next prev parent reply other threads:[~2024-05-08 17:31 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-08 17:31 [PATCH 0/3] binfmt_elf: Honor PT_LOAD alignment for static PIE Kees Cook
2024-05-08 17:31 ` [PATCH 1/3] selftests/exec: Build both static and non-static load_address tests Kees Cook
2024-05-09 2:54 ` John Hubbard
2024-05-09 6:16 ` Kees Cook
2024-05-08 17:31 ` Kees Cook [this message]
2024-05-08 17:31 ` [PATCH 3/3] binfmt_elf: Honor PT_LOAD alignment for static PIE Kees Cook
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