From e7f7785449a1f459a4a3ca92f82f56fb054dd2b9 Mon Sep 17 00:00:00 2001
From: "Eric W. Biederman" <ebiederm@xmission.com>
Date: Thu, 12 Mar 2020 10:17:17 -0500
Subject: [PATCH] binfmt: Move install_exec_creds after setup_new_exec to match
binfmt_elf
In 2016 Linus moved install_exec_creds immediately after
setup_new_exec, in binfmt_elf as a cleanup and as part of closing a
potential information leak.
Perform the same cleanup for the other binary formats.
Different binary formats doing the same things the same way makes exec
easier to reason about and easier to maintain.
Greg Ungerer reports:
> I tested the the whole series on non-MMU m68k and non-MMU arm
> (exercising binfmt_flat) and it all tested out with no problems,
> so for the binfmt_flat changes:
Tested-by: Greg Ungerer <gerg@linux-m68k.org>
Ref: 9f834ec18def ("binfmt_elf: switch to new creds when switching to new mm")
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Greg Ungerer <gerg@linux-m68k.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
arch/x86/ia32/ia32_aout.c | 3 +--
fs/binfmt_aout.c | 2 +-
fs/binfmt_elf_fdpic.c | 2 +-
fs/binfmt_flat.c | 3 +--
4 files changed, 4 insertions(+), 6 deletions(-)
diff --git a/arch/x86/ia32/ia32_aout.c b/arch/x86/ia32/ia32_aout.c
index 9bb71abd66bd3..37b36a8ce5fa7 100644
--- a/arch/x86/ia32/ia32_aout.c
+++ b/arch/x86/ia32/ia32_aout.c
@@ -140,6 +140,7 @@ static int load_aout_binary(struct linux_binprm *bprm)
set_personality_ia32(false);
setup_new_exec(bprm);
+ install_exec_creds(bprm);
regs->cs = __USER32_CS;
regs->r8 = regs->r9 = regs->r10 = regs->r11 = regs->r12 =
@@ -156,8 +157,6 @@ static int load_aout_binary(struct linux_binprm *bprm)
if (retval < 0)
return retval;
- install_exec_creds(bprm);
-
if (N_MAGIC(ex) == OMAGIC) {
unsigned long text_addr, map_size;
diff --git a/fs/binfmt_aout.c b/fs/binfmt_aout.c
index 8e8346a81723c..ace587b66904c 100644
--- a/fs/binfmt_aout.c
+++ b/fs/binfmt_aout.c
@@ -162,6 +162,7 @@ static int load_aout_binary(struct linux_binprm * bprm)
set_personality(PER_LINUX);
#endif
setup_new_exec(bprm);
+ install_exec_creds(bprm);
current->mm->end_code = ex.a_text +
(current->mm->start_code = N_TXTADDR(ex));
@@ -174,7 +175,6 @@ static int load_aout_binary(struct linux_binprm * bprm)
if (retval < 0)
return retval;
- install_exec_creds(bprm);
if (N_MAGIC(ex) == OMAGIC) {
unsigned long text_addr, map_size;
diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index 240f666635437..6c94c6d53d971 100644
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -353,6 +353,7 @@ static int load_elf_fdpic_binary(struct linux_binprm *bprm)
current->personality |= READ_IMPLIES_EXEC;
setup_new_exec(bprm);
+ install_exec_creds(bprm);
set_binfmt(&elf_fdpic_format);
@@ -434,7 +435,6 @@ static int load_elf_fdpic_binary(struct linux_binprm *bprm)
current->mm->start_stack = current->mm->start_brk + stack_size;
#endif
- install_exec_creds(bprm);
if (create_elf_fdpic_tables(bprm, current->mm,
&exec_params, &interp_params) < 0)
goto error;
diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index 831a2b25ba79f..1a1d1fcb893f1 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -541,6 +541,7 @@ static int load_flat_file(struct linux_binprm *bprm,
/* OK, This is the point of no return */
set_personality(PER_LINUX_32BIT);
setup_new_exec(bprm);
+ install_exec_creds(bprm);
}
/*
@@ -963,8 +964,6 @@ static int load_flat_binary(struct linux_binprm *bprm)
}
}
- install_exec_creds(bprm);
-
set_binfmt(&flat_format);
#ifdef CONFIG_MMU
--
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