From: Christian Brauner <brauner@kernel.org>
To: Farid Zakaria <farid.m.zakaria@gmail.com>,
linux-fsdevel@vger.kernel.org
Cc: Daniel Borkmann <daniel@iogearbox.net>,
Alexei Starovoitov <ast@kernel.org>, Kees Cook <kees@kernel.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Jan Kara <jack@suse.cz>, Jonathan Corbet <corbet@lwn.net>,
linux-mm@kvack.org, bpf@vger.kernel.org, jannh@google.com,
mail@johnericson.me,
"Christian Brauner (Amutable)" <brauner@kernel.org>
Subject: [PATCH 05/21] binfmt_misc: split out entry_open_interpreter()
Date: Mon, 20 Jul 2026 11:33:28 +0200 [thread overview]
Message-ID: <20260720-work-bpf-binfmt_misc-ptinterp-v1-5-ddb76c9a508e@kernel.org> (raw)
In-Reply-To: <20260720-work-bpf-binfmt_misc-ptinterp-v1-0-ddb76c9a508e@kernel.org>
Opening the interpreter is a property of the matched entry: an 'F'
entry hands out a clone of the file it pre-opened at registration
time, any other entry opens the selected path. Give that its own
helper instead of an if/else in the middle of load_misc_binary(), and
let it fail early rather than carrying an ERR_PTR through the
successful branch.
No functional change.
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
---
fs/binfmt_misc.c | 44 +++++++++++++++++++++++++++++++-------------
1 file changed, 31 insertions(+), 13 deletions(-)
diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c
index 7a6bbeb8a58c..63c10066e3a6 100644
--- a/fs/binfmt_misc.c
+++ b/fs/binfmt_misc.c
@@ -352,6 +352,36 @@ static unsigned long entry_invocation_flags(const struct binfmt_misc_entry *e,
return flags;
}
+/**
+ * entry_open_interpreter - open the entry's interpreter for execution
+ * @e: matched binary type handler
+ * @interpreter: the interpreter selected for this exec
+ *
+ * An 'F' entry hands out a clone of the file it pre-opened at registration,
+ * any other entry opens the selected path.
+ *
+ * Return: the opened interpreter on success, an ERR_PTR on failure
+ */
+static struct file *entry_open_interpreter(const struct binfmt_misc_entry *e,
+ const char *interpreter)
+{
+ struct file *interp_file __free(fput) = NULL;
+ int retval;
+
+ if (!(e->flags & MISC_FMT_OPEN_FILE))
+ return open_exec(interpreter);
+
+ interp_file = file_clone_open(e->interp_file);
+ if (IS_ERR(interp_file))
+ return interp_file;
+
+ retval = exe_file_deny_write_access(interp_file);
+ if (retval)
+ return ERR_PTR(retval);
+
+ return no_free_ptr(interp_file);
+}
+
/*
* the loader itself
*/
@@ -426,19 +456,7 @@ static int load_misc_binary(struct linux_binprm *bprm)
if (retval < 0)
return retval;
- if (fmt->flags & MISC_FMT_OPEN_FILE) {
- interp_file = file_clone_open(fmt->interp_file);
- if (!IS_ERR(interp_file)) {
- int err = exe_file_deny_write_access(interp_file);
-
- if (err) {
- fput(interp_file);
- interp_file = ERR_PTR(err);
- }
- }
- } else {
- interp_file = open_exec(interpreter);
- }
+ interp_file = entry_open_interpreter(fmt, interpreter);
if (IS_ERR(interp_file))
return PTR_ERR(interp_file);
--
2.53.0
next prev parent reply other threads:[~2026-07-20 9:34 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-20 9:33 [PATCH 00/21] binfmt_misc: transparent interpreters and PT_INTERP loader substitution Christian Brauner
2026-07-20 9:33 ` [PATCH 01/21] exec: do not act on a stale execfd request without an executable Christian Brauner
2026-07-20 9:33 ` [PATCH 02/21] docs, binfmt_misc: keep general usage out of the handler sections Christian Brauner
2026-07-20 9:33 ` [PATCH 03/21] binfmt_misc: table-drive the register string flags Christian Brauner
2026-07-20 9:33 ` [PATCH 04/21] binfmt_misc: normalize the per-exec invocation flags Christian Brauner
2026-07-20 9:33 ` Christian Brauner [this message]
2026-07-20 9:33 ` [PATCH 06/21] binfmt_misc: split out build_interp_argv() Christian Brauner
2026-07-20 9:33 ` [PATCH 07/21] exec: release the replaced file with do_close_execat() Christian Brauner
2026-07-20 9:33 ` [PATCH 08/21] exec: add AT_FLAGS_TRANSPARENT_INTERP Christian Brauner
2026-07-20 9:33 ` [PATCH 09/21] exec: label mm->exe_file with the binary for a transparent dispatch Christian Brauner
2026-07-20 9:33 ` [PATCH 10/21] binfmt_misc: add transparent interpreter dispatch Christian Brauner
2026-07-20 9:33 ` [PATCH 11/21] binfmt_misc: add a static transparent flag 'T' Christian Brauner
2026-07-20 9:33 ` [PATCH 12/21] binfmt_misc: let a bpf handler run the interpreter transparently Christian Brauner
2026-07-20 9:33 ` [PATCH 13/21] selftests/exec: convert the binfmt_misc bpf test to the kselftest harness Christian Brauner
2026-07-20 9:33 ` [PATCH 14/21] selftests/exec: test the transparent binfmt_misc mode Christian Brauner
2026-07-20 9:33 ` [PATCH 15/21] binfmt_misc: document the transparent identity contract Christian Brauner
2026-07-20 9:33 ` [PATCH 16/21] exec: carry a PT_INTERP substitute in struct linux_binprm Christian Brauner
2026-07-20 9:33 ` [PATCH 17/21] binfmt_elf: consume a stashed PT_INTERP substitute Christian Brauner
2026-07-20 9:33 ` [PATCH 18/21] binfmt_misc: add the 'L' loader substitution flag Christian Brauner
2026-07-20 9:33 ` [PATCH 19/21] binfmt_misc: let a bpf handler request loader substitution Christian Brauner
2026-07-20 9:33 ` [PATCH 20/21] selftests/exec: test binfmt_misc " Christian Brauner
2026-07-20 9:33 ` [PATCH 21/21] binfmt_misc: document " Christian Brauner
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