lkml.org 
[lkml]   [2020]   [Jul]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Date
Subject[PATCH 6/7] exec: Factor bprm_stack_limits out of prepare_arg_pages

In preparation for implementiong kernel_execve (which will take kernel
pointers not userspace pointers) factor out bprm_stack_limits out of
prepare_arg_pages. This separates the counting which depends upon the
getting data from userspace from the calculations of the stack limits
which is usable in kernel_execve.

The remove prepare_args_pages and compute bprm->argc and bprm->envc
directly in do_execveat_common, before bprm_stack_limits is called.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
fs/exec.c | 23 ++++++++++++-----------
1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/fs/exec.c b/fs/exec.c
index 50508892fa71..f8135dc149b3 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -448,19 +448,10 @@ static int count(struct user_arg_ptr argv, int max)
return i;
}

-static int prepare_arg_pages(struct linux_binprm *bprm,
- struct user_arg_ptr argv, struct user_arg_ptr envp)
+static int bprm_stack_limits(struct linux_binprm *bprm)
{
unsigned long limit, ptr_size;

- bprm->argc = count(argv, MAX_ARG_STRINGS);
- if (bprm->argc < 0)
- return bprm->argc;
-
- bprm->envc = count(envp, MAX_ARG_STRINGS);
- if (bprm->envc < 0)
- return bprm->envc;
-
/*
* Limit to 1/4 of the max stack size or 3/4 of _STK_LIM
* (whichever is smaller) for the argv+env strings.
@@ -1964,7 +1955,17 @@ static int do_execveat_common(int fd, struct filename *filename,
goto out_ret;
}

- retval = prepare_arg_pages(bprm, argv, envp);
+ retval = count(argv, MAX_ARG_STRINGS);
+ if (retval < 0)
+ goto out_free;
+ bprm->argc = retval;
+
+ retval = count(envp, MAX_ARG_STRINGS);
+ if (retval < 0)
+ goto out_free;
+ bprm->envc = retval;
+
+ retval = bprm_stack_limits(bprm);
if (retval < 0)
goto out_free;

--
2.25.0
\
 
 \ /
  Last update: 2020-07-14 15:35    [W:0.113 / U:4.028 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site