Re: [PATCH v4] selinux: policydb - fix byte order and alignment issues

[William Roberts]

On Fri, Oct 19, 2018 at 7:28 AM Stephen Smalley  wrote:
>
> On 10/18/2018 03:47 AM, Ondrej Mosnacek wrote:
> > Do the LE conversions before doing the Infiniband-related range checks.
> > The incorrect checks are otherwise causing a failure to load any policy
> > with an ibendportcon rule on BE systems. This can be reproduced by
> > running (on e.g. ppc64):
> >
> > cat >my_module.cil < > (type test_ibendport_t)
> > (roletype object_r test_ibendport_t)
> > (ibendportcon mlx4_0 1 (system_u object_r test_ibendport_t ((s0) (s0
> > EOF
> > semodule -i my_module.cil
> >
> > Also, fix loading/storing the 64-bit subnet prefix for OCON_IBPKEY to
> > use a correctly aligned buffer.
> >
> > Finally, do not use the 'nodebuf' (u32) buffer where 'buf' (__le32)
> > should be used instead.
> >
> > Tested internally on a ppc64 machine with a RHEL 7 kernel with this
> > patch applied.
> >
> > Cc: Daniel Jurgens 
> > Cc: Eli Cohen 
> > Cc: James Morris 
> > Cc: Doug Ledford 
> > Cc:  # 4.13+
> > Fixes: a806f7a1616f ("selinux: Create policydb version for Infiniband 
> > support")
> > Signed-off-by: Ondrej Mosnacek 
> > ---
> >   security/selinux/ss/policydb.c | 46 +++---
> >   1 file changed, 32 insertions(+), 14 deletions(-)
> >
> > Changes in v4:
> >   - defer assignment to 16-bit struct fields to after the range check
> >
> > Changes in v3:
> >   - use separate buffer for the 64-bit subnet_prefix
> >   - add comments on the byte ordering of subnet_prefix
> >   - deduplicate the le32_to_cpu() calls from checks
> >
> > Changes in v2:
> >   - add reproducer to commit message
> >   - update e-mail address of James Morris
> >   - better Cc also the old SELinux ML
> >
> > diff --git a/security/selinux/ss/policydb.c b/security/selinux/ss/policydb.c
> > index f4eadd3f7350..d50668006a52 100644
> > --- a/security/selinux/ss/policydb.c
> > +++ b/security/selinux/ss/policydb.c
> > @@ -2108,6 +2108,7 @@ static int ocontext_read(struct policydb *p, struct 
> > policydb_compat_info *info,
> >   {
> >   int i, j, rc;
> >   u32 nel, len;
> > + __be64 prefixbuf[1];
> >   __le32 buf[3];
> >   struct ocontext *l, *c;
> >   u32 nodebuf[8];
> > @@ -2217,21 +2218,30 @@ static int ocontext_read(struct policydb *p, struct 
> > policydb_compat_info *info,
> >   goto out;
> >   break;
> >   }
> > - case OCON_IBPKEY:
> > - rc = next_entry(nodebuf, fp, sizeof(u32) * 4);
> > + case OCON_IBPKEY: {
> > + u32 pkey_lo, pkey_hi;
> > +
> > + rc = next_entry(prefixbuf, fp, sizeof(u64));
> > + if (rc)
> > + goto out;
> > +
> > + /* we need to have subnet_prefix in CPU order 
> > */
> > + c->u.ibpkey.subnet_prefix = 
> > be64_to_cpu(prefixbuf[0]);
> > +
> > + rc = next_entry(buf, fp, sizeof(u32) * 2);
> >   if (rc)
> >   goto out;
> >
> > - c->u.ibpkey.subnet_prefix = 
> > be64_to_cpu(*((__be64 *)nodebuf));
> > + pkey_lo = le32_to_cpu(buf[0]);
> > + pkey_hi = le32_to_cpu(buf[1]);
> >
> > - if (nodebuf[2] > 0x ||
> > - nodebuf[3] > 0x) {
> > + if (pkey_lo > U16_MAX || pkey_hi > U16_MAX) {
> >   rc = -EINVAL;
> >   goto out;
> >   }
> >
> > - c->u.ibpkey.low_pkey = 
> > le32_to_cpu(nodebuf[2]);
> > - c->u.ibpkey.high_pkey = 
> > le32_to_cpu(nodebuf[3]);
> > + c->u.ibpkey.low_pkey  = pkey_lo;
> > + c->u.ibpkey.high_pkey = pkey_hi;
> >
> >   rc = context_read_and_validate(>context[0],
> >  p,
> > @@ -2239,6 +2249,7 @@ static int ocontext_read(struct policydb *p, struct 
> > policydb_compat_info *info,
> >   if (rc)
> >   goto out;
> >   break;
> > + }
> >   case OCON_IBENDPORT:
> >   rc = next_entry(buf, fp, sizeof(u32) * 2);
> >   if (rc)
> > @@ -2249,13 +2260,14 @@ static int ocontext_read(struct policydb *p, struct 
> > policydb_compat_info *info,
> >   if (rc)
> >   goto out;
> >
> > - if (buf[1] > 0xff || buf[1] == 0) {
> > +

Re: [PATCH v4] selinux: policydb - fix byte order and alignment issues

[Stephen Smalley]

On 10/18/2018 03:47 AM, Ondrej Mosnacek wrote:

Do the LE conversions before doing the Infiniband-related range checks.
The incorrect checks are otherwise causing a failure to load any policy
with an ibendportcon rule on BE systems. This can be reproduced by
running (on e.g. ppc64):

cat >my_module.cil <
Cc: Eli Cohen 
Cc: James Morris 
Cc: Doug Ledford 
Cc:  # 4.13+
Fixes: a806f7a1616f ("selinux: Create policydb version for Infiniband support")
Signed-off-by: Ondrej Mosnacek 
---
  security/selinux/ss/policydb.c | 46 +++---
  1 file changed, 32 insertions(+), 14 deletions(-)

Changes in v4:
  - defer assignment to 16-bit struct fields to after the range check

Changes in v3:
  - use separate buffer for the 64-bit subnet_prefix
  - add comments on the byte ordering of subnet_prefix
  - deduplicate the le32_to_cpu() calls from checks

Changes in v2:
  - add reproducer to commit message
  - update e-mail address of James Morris
  - better Cc also the old SELinux ML

diff --git a/security/selinux/ss/policydb.c b/security/selinux/ss/policydb.c
index f4eadd3f7350..d50668006a52 100644
--- a/security/selinux/ss/policydb.c
+++ b/security/selinux/ss/policydb.c
@@ -2108,6 +2108,7 @@ static int ocontext_read(struct policydb *p, struct 
policydb_compat_info *info,
  {
int i, j, rc;
u32 nel, len;
+   __be64 prefixbuf[1];
__le32 buf[3];
struct ocontext *l, *c;
u32 nodebuf[8];
@@ -2217,21 +2218,30 @@ static int ocontext_read(struct policydb *p, struct 
policydb_compat_info *info,
goto out;
break;
}
-   case OCON_IBPKEY:
-   rc = next_entry(nodebuf, fp, sizeof(u32) * 4);
+   case OCON_IBPKEY: {
+   u32 pkey_lo, pkey_hi;
+
+   rc = next_entry(prefixbuf, fp, sizeof(u64));
+   if (rc)
+   goto out;
+
+   /* we need to have subnet_prefix in CPU order */
+   c->u.ibpkey.subnet_prefix = 
be64_to_cpu(prefixbuf[0]);
+
+   rc = next_entry(buf, fp, sizeof(u32) * 2);
if (rc)
goto out;
  
-c->u.ibpkey.subnet_prefix = be64_to_cpu(*((__be64 *)nodebuf));

+   pkey_lo = le32_to_cpu(buf[0]);
+   pkey_hi = le32_to_cpu(buf[1]);
  
-if (nodebuf[2] > 0x ||

-   nodebuf[3] > 0x) {
+   if (pkey_lo > U16_MAX || pkey_hi > U16_MAX) {
rc = -EINVAL;
goto out;
}
  
-c->u.ibpkey.low_pkey = le32_to_cpu(nodebuf[2]);

-   c->u.ibpkey.high_pkey = le32_to_cpu(nodebuf[3]);
+   c->u.ibpkey.low_pkey  = pkey_lo;
+   c->u.ibpkey.high_pkey = pkey_hi;
  
  rc = context_read_and_validate(>context[0],

   p,
@@ -2239,6 +2249,7 @@ static int ocontext_read(struct policydb *p, struct 
policydb_compat_info *info,
if (rc)
goto out;
break;
+   }
case OCON_IBENDPORT:
rc = next_entry(buf, fp, sizeof(u32) * 2);
if (rc)
@@ -2249,13 +2260,14 @@ static int ocontext_read(struct policydb *p, struct 
policydb_compat_info *info,
if (rc)
goto out;
  
-if (buf[1] > 0xff || buf[1] == 0) {

+   c->u.ibendport.port = le32_to_cpu(buf[1]);


ibendport.port is a u8 here, same issue.


+
+   if (c->u.ibendport.port > 0xff ||
+   c->u.ibendport.port == 0) {
rc = -EINVAL;
goto out;
}
  
-c->u.ibendport.port = le32_to_cpu(buf[1]);

-
rc = context_read_and_validate(>context[0],
   p,
   fp);
@@ -3105,6 +3117,7 @@ static int ocontext_write(struct policydb *p, struct 
policydb_compat_info *info,
  {
unsigned int i, j, rc;
size_t nel, len;
+   __be64 prefixbuf[1];
__le32 buf[3];
u32 nodebuf[8];
struct ocontext *c;
@@ -3192,12 +3205,17 @@ static int ocontext_write(struct policydb *p, struct 
policydb_compat_info *info,