[PATCH 1/2] libsepol/cil: support IPv4/IPv6 address embedding

[PATCH 1/2] libsepol/cil: support IPv4/IPv6 address embedding

[Christian Göttsche]

Accept IPv4 addresses embedded in IPv6, like `::ffff:127.0.0.1`.
This allows using those in nodecon statements leading to fine grained
access control:

    type=AVC msg=audit(11/29/21 20:27:44.437:419) : avc:  granted  { node_bind } for  pid=27500 comm=intercept saddr=::ffff:127.0.0.1 src=46293 scontext=xuser_u:xuser_r:xuser_t:s0 tcontext=system_u:object_r:lo_node_t:s0 tclass=tcp_socket

This does effect policies in the traditional language due to CIL usage
in semodule(8).

Also print on conversion failures the address in question.

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
---
 libsepol/cil/src/cil_build_ast.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/libsepol/cil/src/cil_build_ast.c b/libsepol/cil/src/cil_build_ast.c
index 9c34be23..eccb331b 100644
--- a/libsepol/cil/src/cil_build_ast.c
+++ b/libsepol/cil/src/cil_build_ast.c
@@ -5668,10 +5668,10 @@ int cil_fill_ipaddr(struct cil_tree_node *addr_node, struct cil_ipaddr *addr)
 		goto exit;
 	}
 
-	if (strchr(addr_node->data, '.') != NULL) {
-		addr->family = AF_INET;
-	} else {
+	if (strchr(addr_node->data, ':') != NULL) {
 		addr->family = AF_INET6;
+	} else {
+		addr->family = AF_INET;
 	}
 
 	rc = inet_pton(addr->family, addr_node->data, &addr->ip);
@@ -5683,7 +5683,7 @@ int cil_fill_ipaddr(struct cil_tree_node *addr_node, struct cil_ipaddr *addr)
 	return SEPOL_OK;
 
 exit:
-	cil_log(CIL_ERR, "Bad ip address or netmask\n"); 
+	cil_log(CIL_ERR, "Bad ip address or netmask: %s\n", (addr_node && addr_node->data) ? (const char *)addr_node->data : "n/a");
 	return rc;
 }
 
-- 
2.34.1

[PATCH 2/2] checkpolicy: warn on bogus IP address or netmask in nodecon statement

[Christian Göttsche]

Warn if the netmask is not contiguous or the address has host bits set,
e.g.:

    127.0.0.0 255.255.245.0
    127.0.0.1 255.255.255.0

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
---
 checkpolicy/policy_define.c | 50 +++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)

diff --git a/checkpolicy/policy_define.c b/checkpolicy/policy_define.c
index d3eb6111..b2ae3263 100644
--- a/checkpolicy/policy_define.c
+++ b/checkpolicy/policy_define.c
@@ -5290,6 +5290,14 @@ int define_ipv4_node_context()
 		goto out;
 	}
 
+	if (mask.s_addr != 0 && ((~mask.s_addr + 1) & ~mask.s_addr) != 0) {
+		yywarn("ipv4 mask is not contiguous");
+	}
+
+	if ((~mask.s_addr & addr.s_addr) != 0) {
+		yywarn("host bits in ipv4 address set");
+	}
+
 	newc = malloc(sizeof(ocontext_t));
 	if (!newc) {
 		yyerror("out of memory");
@@ -5325,6 +5333,40 @@ out:
 	return rc;
 }
 
+static int ipv6_is_mask_contiguous(const struct in6_addr *mask)
+{
+	int filled = 1;
+	unsigned i;
+
+	for (i = 0; i < 16; i++) {
+		if ((((~mask->s6_addr[i] & 0xFF) + 1) & (~mask->s6_addr[i] & 0xFF)) != 0) {
+			return 0;
+		}
+		if (!filled && mask->s6_addr[i] != 0) {
+			return 0;
+		}
+
+		if (filled && mask->s6_addr[i] != 0xFF) {
+			filled = 0;
+		}
+	}
+
+	return 1;
+}
+
+static int ipv6_has_host_bits_set(const struct in6_addr *addr, const struct in6_addr *mask)
+{
+	unsigned i;
+
+	for (i = 0; i < 16; i++) {
+		if ((addr->s6_addr[i] & ~mask->s6_addr[i]) != 0) {
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
 int define_ipv6_node_context(void)
 {
 	char *id;
@@ -5376,6 +5418,14 @@ int define_ipv6_node_context(void)
 		goto out;
 	}
 
+	if (!ipv6_is_mask_contiguous(&mask)) {
+		yywarn("ipv6 mask is not contiguous");
+	}
+
+	if (ipv6_has_host_bits_set(&addr, &mask)) {
+		yywarn("host bits in ipv6 address set");
+	}
+
 	newc = malloc(sizeof(ocontext_t));
 	if (!newc) {
 		yyerror("out of memory");
-- 
2.34.1

Re: [PATCH 1/2] libsepol/cil: support IPv4/IPv6 address embedding

[James Carter]

On Tue, Nov 30, 2021 at 4:51 PM Christian Göttsche
<cgzones@googlemail.com> wrote:
>
> Accept IPv4 addresses embedded in IPv6, like `::ffff:127.0.0.1`.
> This allows using those in nodecon statements leading to fine grained
> access control:
>
>     type=AVC msg=audit(11/29/21 20:27:44.437:419) : avc:  granted  { node_bind } for  pid=27500 comm=intercept saddr=::ffff:127.0.0.1 src=46293 scontext=xuser_u:xuser_r:xuser_t:s0 tcontext=system_u:object_r:lo_node_t:s0 tclass=tcp_socket
>
> This does effect policies in the traditional language due to CIL usage
> in semodule(8).
>
> Also print on conversion failures the address in question.
>
> Signed-off-by: Christian Göttsche <cgzones@googlemail.com>

Acked-by: James Carter <jwcart2@gmail.com>

> ---
>  libsepol/cil/src/cil_build_ast.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/libsepol/cil/src/cil_build_ast.c b/libsepol/cil/src/cil_build_ast.c
> index 9c34be23..eccb331b 100644
> --- a/libsepol/cil/src/cil_build_ast.c
> +++ b/libsepol/cil/src/cil_build_ast.c
> @@ -5668,10 +5668,10 @@ int cil_fill_ipaddr(struct cil_tree_node *addr_node, struct cil_ipaddr *addr)
>                 goto exit;
>         }
>
> -       if (strchr(addr_node->data, '.') != NULL) {
> -               addr->family = AF_INET;
> -       } else {
> +       if (strchr(addr_node->data, ':') != NULL) {
>                 addr->family = AF_INET6;
> +       } else {
> +               addr->family = AF_INET;
>         }
>
>         rc = inet_pton(addr->family, addr_node->data, &addr->ip);
> @@ -5683,7 +5683,7 @@ int cil_fill_ipaddr(struct cil_tree_node *addr_node, struct cil_ipaddr *addr)
>         return SEPOL_OK;
>
>  exit:
> -       cil_log(CIL_ERR, "Bad ip address or netmask\n");
> +       cil_log(CIL_ERR, "Bad ip address or netmask: %s\n", (addr_node && addr_node->data) ? (const char *)addr_node->data : "n/a");
>         return rc;
>  }
>
> --
> 2.34.1
>

Re: [PATCH 2/2] checkpolicy: warn on bogus IP address or netmask in nodecon statement

[James Carter]

On Tue, Nov 30, 2021 at 4:50 PM Christian Göttsche
<cgzones@googlemail.com> wrote:
>
> Warn if the netmask is not contiguous or the address has host bits set,
> e.g.:
>
>     127.0.0.0 255.255.245.0
>     127.0.0.1 255.255.255.0
>
> Signed-off-by: Christian Göttsche <cgzones@googlemail.com>

Acked-by: James Carter <jwcart2@gmail.com>

> ---
>  checkpolicy/policy_define.c | 50 +++++++++++++++++++++++++++++++++++++
>  1 file changed, 50 insertions(+)
>
> diff --git a/checkpolicy/policy_define.c b/checkpolicy/policy_define.c
> index d3eb6111..b2ae3263 100644
> --- a/checkpolicy/policy_define.c
> +++ b/checkpolicy/policy_define.c
> @@ -5290,6 +5290,14 @@ int define_ipv4_node_context()
>                 goto out;
>         }
>
> +       if (mask.s_addr != 0 && ((~mask.s_addr + 1) & ~mask.s_addr) != 0) {
> +               yywarn("ipv4 mask is not contiguous");
> +       }
> +
> +       if ((~mask.s_addr & addr.s_addr) != 0) {
> +               yywarn("host bits in ipv4 address set");
> +       }
> +
>         newc = malloc(sizeof(ocontext_t));
>         if (!newc) {
>                 yyerror("out of memory");
> @@ -5325,6 +5333,40 @@ out:
>         return rc;
>  }
>
> +static int ipv6_is_mask_contiguous(const struct in6_addr *mask)
> +{
> +       int filled = 1;
> +       unsigned i;
> +
> +       for (i = 0; i < 16; i++) {
> +               if ((((~mask->s6_addr[i] & 0xFF) + 1) & (~mask->s6_addr[i] & 0xFF)) != 0) {
> +                       return 0;
> +               }
> +               if (!filled && mask->s6_addr[i] != 0) {
> +                       return 0;
> +               }
> +
> +               if (filled && mask->s6_addr[i] != 0xFF) {
> +                       filled = 0;
> +               }
> +       }
> +
> +       return 1;
> +}
> +
> +static int ipv6_has_host_bits_set(const struct in6_addr *addr, const struct in6_addr *mask)
> +{
> +       unsigned i;
> +
> +       for (i = 0; i < 16; i++) {
> +               if ((addr->s6_addr[i] & ~mask->s6_addr[i]) != 0) {
> +                       return 1;
> +               }
> +       }
> +
> +       return 0;
> +}
> +
>  int define_ipv6_node_context(void)
>  {
>         char *id;
> @@ -5376,6 +5418,14 @@ int define_ipv6_node_context(void)
>                 goto out;
>         }
>
> +       if (!ipv6_is_mask_contiguous(&mask)) {
> +               yywarn("ipv6 mask is not contiguous");
> +       }
> +
> +       if (ipv6_has_host_bits_set(&addr, &mask)) {
> +               yywarn("host bits in ipv6 address set");
> +       }
> +
>         newc = malloc(sizeof(ocontext_t));
>         if (!newc) {
>                 yyerror("out of memory");
> --
> 2.34.1
>

Re: [PATCH 1/2] libsepol/cil: support IPv4/IPv6 address embedding

[James Carter]

On Thu, Dec 9, 2021 at 3:30 PM James Carter <jwcart2@gmail.com> wrote:
>
> On Tue, Nov 30, 2021 at 4:51 PM Christian Göttsche
> <cgzones@googlemail.com> wrote:
> >
> > Accept IPv4 addresses embedded in IPv6, like `::ffff:127.0.0.1`.
> > This allows using those in nodecon statements leading to fine grained
> > access control:
> >
> >     type=AVC msg=audit(11/29/21 20:27:44.437:419) : avc:  granted  { node_bind } for  pid=27500 comm=intercept saddr=::ffff:127.0.0.1 src=46293 scontext=xuser_u:xuser_r:xuser_t:s0 tcontext=system_u:object_r:lo_node_t:s0 tclass=tcp_socket
> >
> > This does effect policies in the traditional language due to CIL usage
> > in semodule(8).
> >
> > Also print on conversion failures the address in question.
> >
> > Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
>
> Acked-by: James Carter <jwcart2@gmail.com>
>
Both of these have been merged.
Thanks,
Jim

> > ---
> >  libsepol/cil/src/cil_build_ast.c | 8 ++++----
> >  1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/libsepol/cil/src/cil_build_ast.c b/libsepol/cil/src/cil_build_ast.c
> > index 9c34be23..eccb331b 100644
> > --- a/libsepol/cil/src/cil_build_ast.c
> > +++ b/libsepol/cil/src/cil_build_ast.c
> > @@ -5668,10 +5668,10 @@ int cil_fill_ipaddr(struct cil_tree_node *addr_node, struct cil_ipaddr *addr)
> >                 goto exit;
> >         }
> >
> > -       if (strchr(addr_node->data, '.') != NULL) {
> > -               addr->family = AF_INET;
> > -       } else {
> > +       if (strchr(addr_node->data, ':') != NULL) {
> >                 addr->family = AF_INET6;
> > +       } else {
> > +               addr->family = AF_INET;
> >         }
> >
> >         rc = inet_pton(addr->family, addr_node->data, &addr->ip);
> > @@ -5683,7 +5683,7 @@ int cil_fill_ipaddr(struct cil_tree_node *addr_node, struct cil_ipaddr *addr)
> >         return SEPOL_OK;
> >
> >  exit:
> > -       cil_log(CIL_ERR, "Bad ip address or netmask\n");
> > +       cil_log(CIL_ERR, "Bad ip address or netmask: %s\n", (addr_node && addr_node->data) ? (const char *)addr_node->data : "n/a");
> >         return rc;
> >  }
> >
> > --
> > 2.34.1
> >