[PATCH] ima: cleanup the match_token policy code

[PATCH] ima: cleanup the match_token policy code

[Mimi Zohar]

Start the policy_tokens and the associated enumeration from zero,
simplifying the pt macro.

Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
---
 security/integrity/ima/ima_policy.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index d17a23b5c91d..e89af72b98ed 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -665,9 +665,9 @@ void ima_update_policy(void)
 	ima_update_policy_flag();
 }
 
+/* Keep the enumeration in sync with the policy_tokens! */
 enum {
-	Opt_err = -1,
-	Opt_measure = 1, Opt_dont_measure,
+	Opt_measure, Opt_dont_measure,
 	Opt_appraise, Opt_dont_appraise,
 	Opt_audit, Opt_hash, Opt_dont_hash,
 	Opt_obj_user, Opt_obj_role, Opt_obj_type,
@@ -677,10 +677,10 @@ enum {
 	Opt_uid_gt, Opt_euid_gt, Opt_fowner_gt,
 	Opt_uid_lt, Opt_euid_lt, Opt_fowner_lt,
 	Opt_appraise_type, Opt_permit_directio,
-	Opt_pcr
+	Opt_pcr, Opt_err
 };
 
-static match_table_t policy_tokens = {
+static const match_table_t policy_tokens = {
 	{Opt_measure, "measure"},
 	{Opt_dont_measure, "dont_measure"},
 	{Opt_appraise, "appraise"},
@@ -1188,7 +1188,7 @@ void ima_policy_stop(struct seq_file *m, void *v)
 {
 }
 
-#define pt(token)	policy_tokens[token + Opt_err].pattern
+#define pt(token)	policy_tokens[token].pattern
 #define mt(token)	mask_tokens[token]
 
 /*
-- 
2.7.5

Re: [PATCH] ima: cleanup the match_token policy code

[Linus Torvalds]

On Mon, Dec 17, 2018 at 4:14 PM Mimi Zohar <zohar@linux.ibm.com> wrote:
>
> Start the policy_tokens and the associated enumeration from zero,
> simplifying the pt macro.

I applied this directly, since I decided to just commit my own "don't
use negative Opt_err" patch for the test_and_set_bit() cases, and they
kind of go together.

There's still a -1 in security/keys/encrypted-keys/encrypted.c, and
there are also three cases of "Opt_error = -1" in the security layer.

All of which look pointless and wrong, but not actively buggy, so I'll
leave them alone.

                 Linus

Re: [PATCH] ima: cleanup the match_token policy code

[Al Viro]

On Mon, Dec 17, 2018 at 04:36:54PM -0800, Linus Torvalds wrote:
> On Mon, Dec 17, 2018 at 4:14 PM Mimi Zohar <zohar@linux.ibm.com> wrote:
> >
> > Start the policy_tokens and the associated enumeration from zero,
> > simplifying the pt macro.
> 
> I applied this directly, since I decided to just commit my own "don't
> use negative Opt_err" patch for the test_and_set_bit() cases, and they
> kind of go together.
> 
> There's still a -1 in security/keys/encrypted-keys/encrypted.c, and
> there are also three cases of "Opt_error = -1" in the security layer.
> 
> All of which look pointless and wrong, but not actively buggy, so I'll
> leave them alone.

FWIW, that part of LSM shite is getting taken out and shot - LSM-related
preps in the beginning of mount API series are, at the moment, at
 fs/btrfs/ctree.h           |   4 -
 fs/btrfs/super.c           |  82 ++-------
 fs/namespace.c             |   9 +-
 fs/nfs/internal.h          |   2 +-
 fs/nfs/super.c             |  34 ++--
 fs/super.c                 |  23 +--
 include/linux/lsm_hooks.h  |  17 +-
 include/linux/security.h   |  82 ++-------
 security/security.c        |  39 +++--
 security/selinux/hooks.c   | 798 ++++++++++++++++++++++++++++++++------------------------------------------------------
 security/smack/smack_lsm.c | 359 +++++++++++++++------------------------
 11 files changed, 523 insertions(+), 926 deletions(-)
and unlike the original variant there's not much touched in security/*
further in the series...

No match_token() uses left in there after this part.

Re: [PATCH] ima: cleanup the match_token policy code

[Al Viro]

On Tue, Dec 18, 2018 at 01:33:48AM +0000, Al Viro wrote:
> On Mon, Dec 17, 2018 at 04:36:54PM -0800, Linus Torvalds wrote:
> > On Mon, Dec 17, 2018 at 4:14 PM Mimi Zohar <zohar@linux.ibm.com> wrote:
> > >
> > > Start the policy_tokens and the associated enumeration from zero,
> > > simplifying the pt macro.
> > 
> > I applied this directly, since I decided to just commit my own "don't
> > use negative Opt_err" patch for the test_and_set_bit() cases, and they
> > kind of go together.
> > 
> > There's still a -1 in security/keys/encrypted-keys/encrypted.c, and
> > there are also three cases of "Opt_error = -1" in the security layer.
> > 
> > All of which look pointless and wrong, but not actively buggy, so I'll
> > leave them alone.
> 
> FWIW, that part of LSM shite is getting taken out and shot - LSM-related
> preps in the beginning of mount API series are, at the moment, at
>  fs/btrfs/ctree.h           |   4 -
>  fs/btrfs/super.c           |  82 ++-------
>  fs/namespace.c             |   9 +-
>  fs/nfs/internal.h          |   2 +-
>  fs/nfs/super.c             |  34 ++--
>  fs/super.c                 |  23 +--
>  include/linux/lsm_hooks.h  |  17 +-
>  include/linux/security.h   |  82 ++-------
>  security/security.c        |  39 +++--
>  security/selinux/hooks.c   | 798 ++++++++++++++++++++++++++++++++------------------------------------------------------
>  security/smack/smack_lsm.c | 359 +++++++++++++++------------------------
>  11 files changed, 523 insertions(+), 926 deletions(-)
> and unlike the original variant there's not much touched in security/*
> further in the series...
> 
> No match_token() uses left in there after this part.

In LSM, that is...

Re: [PATCH] ima: cleanup the match_token policy code

[Mimi Zohar]

On Tue, 2018-12-18 at 01:33 +0000, Al Viro wrote:
> On Mon, Dec 17, 2018 at 04:36:54PM -0800, Linus Torvalds wrote:
> > On Mon, Dec 17, 2018 at 4:14 PM Mimi Zohar <zohar@linux.ibm.com> wrote:
> > >
> > > Start the policy_tokens and the associated enumeration from zero,
> > > simplifying the pt macro.
> > 
> > I applied this directly, since I decided to just commit my own "don't
> > use negative Opt_err" patch for the test_and_set_bit() cases, and they
> > kind of go together.
> > 
> > There's still a -1 in security/keys/encrypted-keys/encrypted.c, and
> > there are also three cases of "Opt_error = -1" in the security layer.
> > 
> > All of which look pointless and wrong, but not actively buggy, so I'll
> > leave them alone.
> 
> FWIW, that part of LSM shite is getting taken out and shot - LSM-related
> preps in the beginning of mount API series are, at the moment, at
>  fs/btrfs/ctree.h           |   4 -
>  fs/btrfs/super.c           |  82 ++-------
>  fs/namespace.c             |   9 +-
>  fs/nfs/internal.h          |   2 +-
>  fs/nfs/super.c             |  34 ++--
>  fs/super.c                 |  23 +--
>  include/linux/lsm_hooks.h  |  17 +-
>  include/linux/security.h   |  82 ++-------
>  security/security.c        |  39 +++--
>  security/selinux/hooks.c   | 798 ++++++++++++++++++++++++++++++++------------------------------------------------------
>  security/smack/smack_lsm.c | 359 +++++++++++++++------------------------
>  11 files changed, 523 insertions(+), 926 deletions(-)
> and unlike the original variant there's not much touched in security/*
> further in the series...
> 
> No match_token() uses left in there after this part.

Could you expand on commit 5b2ea6199614 ("selinux: switch away from
match_token()") patch description.  All that it says is "It's not a
good fit, unfortunately, and the next step will make it even less so.
Open-code what we need here."  And there's even less for the
equivalent Smack patch, which just says "same issue as with
selinux...".

Mimi

Re: [PATCH] ima: cleanup the match_token policy code

[Al Viro]

On Mon, Dec 17, 2018 at 10:00:07PM -0500, Mimi Zohar wrote:

> Could you expand on commit 5b2ea6199614 ("selinux: switch away from
> match_token()") patch description.  All that it says is "It's not a
> good fit, unfortunately, and the next step will make it even less so.
> Open-code what we need here."  And there's even less for the
> equivalent Smack patch, which just says "same issue as with
> selinux...".

match_token() would require messing around with strsep() or something
equivalent.  It's not a regex; foo=%s has no idea that comma is in any
way special, etc.

As for the next commit...  Killing the Cthulhu-awful mess in
selinux_sb_eat_lsm_opts() (allocating two temproraries, concatenating
(comma-separated) non-LSM options into one, concatenating (pipe-separated)
dequoted LSM options into another, then splitting that another by '|'
instances and figuring out which option each piece is, etc.)
is a Good Thing(tm).  And having to dance around the needs of
match_token() adds extra headache, for no good reason.

Re: [PATCH] ima: cleanup the match_token policy code

[Mimi Zohar]

On Tue, 2018-12-18 at 04:06 +0000, Al Viro wrote:
> On Mon, Dec 17, 2018 at 10:00:07PM -0500, Mimi Zohar wrote:
> 
> > Could you expand on commit 5b2ea6199614 ("selinux: switch away from
> > match_token()") patch description.  All that it says is "It's not a
> > good fit, unfortunately, and the next step will make it even less so.
> > Open-code what we need here."  And there's even less for the
> > equivalent Smack patch, which just says "same issue as with
> > selinux...".
> 
> match_token() would require messing around with strsep() or something
> equivalent.  It's not a regex; foo=%s has no idea that comma is in any
> way special, etc.
> 
> As for the next commit...  Killing the Cthulhu-awful mess in
> selinux_sb_eat_lsm_opts() (allocating two temproraries, concatenating
> (comma-separated) non-LSM options into one, concatenating (pipe-separated)
> dequoted LSM options into another, then splitting that another by '|'
> instances and figuring out which option each piece is, etc.)
> is a Good Thing(tm).  And having to dance around the needs of
> match_token() adds extra headache, for no good reason.

Ok, so it is this particular combination of things, not the general
usage of strsep or match_token that you're objecting to.  So fixing
the other match_token non-LSM instances is fine.

To prevent the enumeration and the match_table from going out of sync,
I was thinking about defining a macro to create the match_table_t:

#define __policy_tokens_match(ENUM, str) {Opt_ ## ENUM, #str},

static const match_table_t policy_tokens = {
        __policy_tokens_id(__policy_tokens_match)
};

and the enumeration:

enum policy_tokens_id {
        __policy_tokens_id(__policy_tokens_enumify)
};

Mimi