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This needs a fixed toolchain, and a userspace rebuild to work.
For these reasons, it's had difficulty getting upstream.
ie, Fedora has a new enough toolchain, and has been rebuilt, so we don't need
the ifdefs. Other distros don't/haven't, and this patch would break them
if pushed upstream.
Subject: [Fwd: Re: [PATCH] Disable execmem for sparc]
From: Stephen Smalley <sds@tycho.nsa.gov>
To: Dave Jones <davej@redhat.com>
Date: Wed, 28 Apr 2010 16:04:56 -0400
Message-Id: <1272485096.6013.326.camel@moss-pluto.epoch.ncsc.mil>
-------- Forwarded Message --------
From: Stephen Smalley <sds@tycho.nsa.gov>
To: David Miller <davem@davemloft.net>
Cc: tcallawa@redhat.com, dennis@ausil.us, sparclinux@vger.kernel.org, dgilmore@redhat.com, jmorris@namei.org, eparis@parisplace.org
Subject: Re: [PATCH] Disable execmem for sparc
Date: Wed, 28 Apr 2010 15:57:57 -0400
On Tue, 2010-04-27 at 11:47 -0700, David Miller wrote:
> From: "Tom \"spot\" Callaway" <tcallawa@redhat.com>
> Date: Tue, 27 Apr 2010 14:20:21 -0400
>
> > [root@apollo ~]$ cat /proc/2174/maps
> > 00010000-00014000 r-xp 00000000 fd:00 15466577
> > /sbin/mingetty
> > 00022000-00024000 rwxp 00002000 fd:00 15466577
> > /sbin/mingetty
> > 00024000-00046000 rwxp 00000000 00:00 0
> > [heap]
>
> SELINUX probably barfs on the executable heap, the PLT is in the HEAP
> just like powerpc32 and that's why VM_DATA_DEFAULT_FLAGS has to set
> both executable and writable.
>
> You also can't remove the CONFIG_PPC32 ifdefs in selinux, since
> because of the VM_DATA_DEFAULT_FLAGS setting used still in that arch,
> the heap will always have executable permission, just like sparc does.
> You have to support those binaries forever, whether you like it or not.
>
> Let's just replace the CONFIG_PPC32 ifdef in SELINUX with CONFIG_PPC32
> || CONFIG_SPARC as in Tom's original patch and let's be done with
> this.
>
> In fact I would go through all the arch/ header files and check the
> VM_DATA_DEFAULT_FLAGS settings and add the necessary new ifdefs to the
> SELINUX code so that other platforms don't have the pain of having to
> go through this process too.
To avoid maintaining per-arch ifdefs, it seems that we could just
directly use (VM_DATA_DEFAULT_FLAGS & VM_EXEC) as the basis for deciding
whether to enable or disable these checks. VM_DATA_DEFAULT_FLAGS isn't
constant on some architectures but instead depends on
current->personality, but we want this applied uniformly. So we'll just
use the initial task state to determine whether or not to enable these
checks.
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index ebee467..a03fd74 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2999,13 +2999,15 @@ static int selinux_file_ioctl(struct file *file, unsigned int cmd,
return file_has_perm(cred, file, av);
}
+static int default_noexec;
+
static int file_map_prot_check(struct file *file, unsigned long prot, int shared)
{
const struct cred *cred = current_cred();
int rc = 0;
-#ifndef CONFIG_PPC32
- if ((prot & PROT_EXEC) && (!file || (!shared && (prot & PROT_WRITE)))) {
+ if (default_noexec &&
+ (prot & PROT_EXEC) && (!file || (!shared && (prot & PROT_WRITE)))) {
/*
* We are making executable an anonymous mapping or a
* private file mapping that will also be writable.
@@ -3015,7 +3017,6 @@ static int file_map_prot_check(struct file *file, unsigned long prot, int shared
if (rc)
goto error;
}
-#endif
if (file) {
/* read access is always possible with a mapping */
@@ -3076,8 +3077,8 @@ static int selinux_file_mprotect(struct vm_area_struct *vma,
if (selinux_checkreqprot)
prot = reqprot;
-#ifndef CONFIG_PPC32
- if ((prot & PROT_EXEC) && !(vma->vm_flags & VM_EXEC)) {
+ if (default_noexec &&
+ (prot & PROT_EXEC) && !(vma->vm_flags & VM_EXEC)) {
int rc = 0;
if (vma->vm_start >= vma->vm_mm->start_brk &&
vma->vm_end <= vma->vm_mm->brk) {
@@ -3099,7 +3100,6 @@ static int selinux_file_mprotect(struct vm_area_struct *vma,
if (rc)
return rc;
}
-#endif
return file_map_prot_check(vma->vm_file, prot, vma->vm_flags&VM_SHARED);
}
@@ -5662,6 +5662,8 @@ static __init int selinux_init(void)
/* Set the security state for the initial task. */
cred_init_security();
+ default_noexec = !(VM_DATA_DEFAULT_FLAGS & VM_EXEC);
+
sel_inode_cache = kmem_cache_create("selinux_inode_security",
sizeof(struct inode_security_struct),
0, SLAB_PANIC, NULL);
--
Stephen Smalley
National Security Agency
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