chcat: don't crash if access to binary policy is prohibited
diff mbox series

Message ID d204aaea-ca46-49c2-f7cd-6f20889cecbf@gmail.com
State New
Headers show
Series
  • chcat: don't crash if access to binary policy is prohibited
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Commit Message

bauen1 May 9, 2020, 2:06 p.m. UTC
sobject will crash if access to the binary policy is prohibited by
selinux, e.g. refpolicy
this also breaks file operations that don't require seobject.

Signed-off-by: bauen1 <j2468h@gmail.com>
---
 python/chcat/chcat | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

Comments

Nicolas Iooss May 10, 2020, 5:25 p.m. UTC | #1
On Sat, May 9, 2020 at 4:06 PM bauen1 <j2468h@googlemail.com> wrote:
>
> sobject will crash if access to the binary policy is prohibited by
> selinux, e.g. refpolicy
> this also breaks file operations that don't require seobject.
>
> Signed-off-by: bauen1 <j2468h@gmail.com>

Hello,
This patch looks very hackish. In fact, an underlying issue that
exists with seobject is that "import seobject" raises an exception
when it is used from an environment that is not allowed to read the
policy:

>>> import seobject
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python3.8/site-packages/seobject.py", line 33, in <module>
    import sepolicy
  File "/usr/lib/python3.8/site-packages/sepolicy/__init__.py", line
186, in <module>
    raise e
  File "/usr/lib/python3.8/site-packages/sepolicy/__init__.py", line
182, in <module>
    policy_file = get_installed_policy()
  File "/usr/lib/python3.8/site-packages/sepolicy/__init__.py", line
137, in get_installed_policy
    raise ValueError(_("No SELinux Policy installed"))
ValueError: No SELinux Policy installed

Is this the issue you encountered when you write "seobject will crash"?

In my humble opinion, trying to hide such an issue by moving "import
seobject" makes maintaining the project more difficult. I would prefer
seeing a way to allow using "import seobject" without raising
exceptions, but working on this is unfortunately quite time-consuming
(I have not seen a straightforward way to deal with this, and there
exist several ways to solve this in not-very-direct ways, for example
with lazy loading of the policy when needed or with replacing some API
with stub functions if the policy cannot be loaded).

Therefore I will not ack this patch, but I will not block ("Nack") it
if another maintainer wants to include it.

Thanks,
Nicolas

> ---
>  python/chcat/chcat | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/python/chcat/chcat b/python/chcat/chcat
> index fdd2e46e..55408577 100755
> --- a/python/chcat/chcat
> +++ b/python/chcat/chcat
> @@ -28,7 +28,6 @@ import os
>  import pwd
>  import getopt
>  import selinux
> -import seobject
>
>  PROGNAME = "policycoreutils"
>  try:
> @@ -65,6 +64,7 @@ def verify_users(users):
>
>
>  def chcat_user_add(newcat, users):
> +    import seobject
>      errors = 0
>      logins = seobject.loginRecords()
>      seusers = logins.get_all()
> @@ -144,6 +144,7 @@ def chcat_add(orig, newcat, objects, login_ind):
>
>
>  def chcat_user_remove(newcat, users):
> +    import seobject
>      errors = 0
>      logins = seobject.loginRecords()
>      seusers = logins.get_all()
> @@ -233,6 +234,7 @@ def chcat_remove(orig, newcat, objects, login_ind):
>
>
>  def chcat_user_replace(newcat, users):
> +    import seobject
>      errors = 0
>      logins = seobject.loginRecords()
>      seusers = logins.get_all()
> @@ -376,6 +378,7 @@ def listcats():
>
>
>  def listusercats(users):
> +    import seobject
>      if len(users) == 0:
>          try:
>              users.append(os.getlogin())
> --
> 2.26.2
>
Stephen Smalley May 29, 2020, 1:16 p.m. UTC | #2
On Sun, May 10, 2020 at 1:26 PM Nicolas Iooss <nicolas.iooss@m4x.org> wrote:
>
> On Sat, May 9, 2020 at 4:06 PM bauen1 <j2468h@googlemail.com> wrote:
> >
> > sobject will crash if access to the binary policy is prohibited by
> > selinux, e.g. refpolicy
> > this also breaks file operations that don't require seobject.
> >
> > Signed-off-by: bauen1 <j2468h@gmail.com>
>
> Hello,
> This patch looks very hackish. In fact, an underlying issue that
> exists with seobject is that "import seobject" raises an exception
> when it is used from an environment that is not allowed to read the
> policy:
>
> >>> import seobject
> Traceback (most recent call last):
>   File "<stdin>", line 1, in <module>
>   File "/usr/lib/python3.8/site-packages/seobject.py", line 33, in <module>
>     import sepolicy
>   File "/usr/lib/python3.8/site-packages/sepolicy/__init__.py", line
> 186, in <module>
>     raise e
>   File "/usr/lib/python3.8/site-packages/sepolicy/__init__.py", line
> 182, in <module>
>     policy_file = get_installed_policy()
>   File "/usr/lib/python3.8/site-packages/sepolicy/__init__.py", line
> 137, in get_installed_policy
>     raise ValueError(_("No SELinux Policy installed"))
> ValueError: No SELinux Policy installed
>
> Is this the issue you encountered when you write "seobject will crash"?
>
> In my humble opinion, trying to hide such an issue by moving "import
> seobject" makes maintaining the project more difficult. I would prefer
> seeing a way to allow using "import seobject" without raising
> exceptions, but working on this is unfortunately quite time-consuming
> (I have not seen a straightforward way to deal with this, and there
> exist several ways to solve this in not-very-direct ways, for example
> with lazy loading of the policy when needed or with replacing some API
> with stub functions if the policy cannot be loaded).
>
> Therefore I will not ack this patch, but I will not block ("Nack") it
> if another maintainer wants to include it.

I'm not opposed to the patch itself (I assume the current code breaks
usage of chcat under MLS policy by regular users who lack access to
the policy file), but your Signed-off-by line ought to be revised to
contain your real name. Otherwise, it doesn't really serve its
purpose.  See  the discussion of Signed-off-by in
https://www.kernel.org/doc/html/latest/process/submitting-patches.html.

Patch
diff mbox series

diff --git a/python/chcat/chcat b/python/chcat/chcat
index fdd2e46e..55408577 100755
--- a/python/chcat/chcat
+++ b/python/chcat/chcat
@@ -28,7 +28,6 @@  import os
 import pwd
 import getopt
 import selinux
-import seobject
 
 PROGNAME = "policycoreutils"
 try:
@@ -65,6 +64,7 @@  def verify_users(users):
 
 
 def chcat_user_add(newcat, users):
+    import seobject
     errors = 0
     logins = seobject.loginRecords()
     seusers = logins.get_all()
@@ -144,6 +144,7 @@  def chcat_add(orig, newcat, objects, login_ind):
 
 
 def chcat_user_remove(newcat, users):
+    import seobject
     errors = 0
     logins = seobject.loginRecords()
     seusers = logins.get_all()
@@ -233,6 +234,7 @@  def chcat_remove(orig, newcat, objects, login_ind):
 
 
 def chcat_user_replace(newcat, users):
+    import seobject
     errors = 0
     logins = seobject.loginRecords()
     seusers = logins.get_all()
@@ -376,6 +378,7 @@  def listcats():
 
 
 def listusercats(users):
+    import seobject
     if len(users) == 0:
         try:
             users.append(os.getlogin())