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security_compute_create_name(3)



I noticed the security_compute_create_name(3) is not merged yet,
although its corresponding kernel feature got merged.

So, let me remind the patch I sent to the list several months ago.

I'd like to use this interface to implement special case handling
for the default labeling behavior on temporary database objects.

Thanks,

 Signed-off-by: KaiGai Kohei <kohei.kaigai@xxxxxxxxxxxx>
---
 libselinux/include/selinux/selinux.h               |   10 ++
 libselinux/man/man3/security_compute_av.3          |   17 ++++-
 libselinux/man/man3/security_compute_create_name.3 |    1 +
 libselinux/src/compute_create.c                    |   88 +++++++++++++++++---
 libselinux/src/selinux_internal.h                  |    2 +
 5 files changed, 105 insertions(+), 13 deletions(-)

diff --git a/libselinux/include/selinux/selinux.h
b/libselinux/include/selinux/selinux.h
index 0725b57..d0ddb78 100644
--- a/libselinux/include/selinux/selinux.h
+++ b/libselinux/include/selinux/selinux.h
@@ -211,6 +211,16 @@ extern int security_compute_create_raw(const
security_context_t scon,
 				       const security_context_t tcon,
 				       security_class_t tclass,
 				       security_context_t * newcon);
+extern int security_compute_create_name(const security_context_t scon,
+					const security_context_t tcon,
+					security_class_t tclass,
+					const char *objname,
+					security_context_t * newcon);
+extern int security_compute_create_name_raw(const security_context_t scon,
+					    const security_context_t tcon,
+					    security_class_t tclass,
+					    const char *objname,
+					    security_context_t * newcon);

 /* Compute a relabeling decision and set *newcon to refer to it.
    Caller must free via freecon. */
diff --git a/libselinux/man/man3/security_compute_av.3
b/libselinux/man/man3/security_compute_av.3
index f2d9f30..8e821cf 100644
--- a/libselinux/man/man3/security_compute_av.3
+++ b/libselinux/man/man3/security_compute_av.3
@@ -1,6 +1,6 @@
 .TH "security_compute_av" "3" "1 January 2004" "russell@xxxxxxxxxxxx"
"SELinux API documentation"
 .SH "NAME"
-security_compute_av, security_compute_av_flags,
security_compute_create, security_compute_relabel,
+security_compute_av, security_compute_av_flags,
security_compute_create, security_compute_create_name,
security_compute_relabel,
 security_compute_member, security_compute_user,
security_get_initial_context \- query
 the SELinux policy database in the kernel.

@@ -15,6 +15,8 @@ the SELinux policy database in the kernel.
 .sp
 .BI "int security_compute_create(security_context_t "scon ",
security_context_t "tcon ", security_class_t "tclass ",
security_context_t *" newcon );
 .sp
+.BI "int security_compute_create_name(security_context_t "scon ",
security_context_t "tcon ", security_class_t "tclass ", const char
*"objname ", security_context_t *" newcon );
+.sp
 .BI "int security_compute_relabel(security_context_t "scon ",
security_context_t "tcon ", security_class_t "tclass ",
security_context_t *" newcon );
 .sp
 .BI "int security_compute_member(security_context_t "scon ",
security_context_t "tcon ", security_class_t "tclass ",
security_context_t *" newcon );
@@ -56,6 +58,19 @@ which indicates the decision is computed on a
permissive domain.
 is used to compute a context to use for labeling a new object in a particular
 class based on a SID pair.

+.B security_compute_create_name
+is identical to
+.B security_compute_create
+but also takes name of the new object in creation as an argument.
+When
+.BR TYPE_TRANSITION
+rule on the given class and a SID pair has object name extension,
+we shall be able to obtain a correct
+.BR newcon
+according to the security policy. Note that this interface is only
+supported on the linux 2.6.40 or later.
+In the older kernel, the object name will be simply ignored.
+
 .B security_compute_relabel
 is used to compute the new context to use when relabeling an object, it is used
 in the pam_selinux.so source and the newrole source to determine the correct
diff --git a/libselinux/man/man3/security_compute_create_name.3
b/libselinux/man/man3/security_compute_create_name.3
new file mode 100644
index 0000000..a60bca4
--- /dev/null
+++ b/libselinux/man/man3/security_compute_create_name.3
@@ -0,0 +1 @@
+.so man3/security_compute_av.3
diff --git a/libselinux/src/compute_create.c b/libselinux/src/compute_create.c
index 0bbeeed..3c05be3 100644
--- a/libselinux/src/compute_create.c
+++ b/libselinux/src/compute_create.c
@@ -6,19 +6,58 @@
 #include <errno.h>
 #include <string.h>
 #include <limits.h>
+#include <ctype.h>
 #include "selinux_internal.h"
 #include "policy.h"
 #include "mapping.h"

-int security_compute_create_raw(const security_context_t scon,
-				const security_context_t tcon,
-				security_class_t tclass,
-				security_context_t * newcon)
+static int object_name_encode(const char *objname, char *buffer, size_t buflen)
+{
+	int	code;
+	size_t	offset = 0;
+
+	if (buflen - offset < 1)
+		return -1;
+	buffer[offset++] = ' ';
+
+	do {
+		code = *objname++;
+
+		if (isalnum(code) || code == '\0' || code == '-' ||
+		    code == '.' || code == '_' || code == '~') {
+			if (buflen - offset < 1)
+				return -1;
+			buffer[offset++] = code;
+		} else if (code == ' ') {
+			if (buflen - offset < 1)
+				return -1;
+			buffer[offset++] = '+';
+		} else {
+			static const char *table = "0123456789ABCDEF";
+			int	l = (code & 0x0f);
+			int	h = (code & 0xf0) >> 4;
+
+			if (buflen - offset < 3)
+				return -1;
+			buffer[offset++] = '%';
+			buffer[offset++] = table[h];
+			buffer[offset++] = table[l];
+		}
+	} while (code != '\0');
+
+	return 0;
+}
+
+int security_compute_create_name_raw(const security_context_t scon,
+				     const security_context_t tcon,
+				     security_class_t tclass,
+				     const char *objname,
+				     security_context_t * newcon)
 {
 	char path[PATH_MAX];
 	char *buf;
 	size_t size;
-	int fd, ret;
+	int fd, ret, len;

 	if (!selinux_mnt) {
 		errno = ENOENT;
@@ -36,7 +75,14 @@ int security_compute_create_raw(const
security_context_t scon,
 		ret = -1;
 		goto out;
 	}
-	snprintf(buf, size, "%s %s %hu", scon, tcon, unmap_class(tclass));
+	len = snprintf(buf, size, "%s %s %hu",
+		       scon, tcon, unmap_class(tclass));
+	if (objname &&
+	    object_name_encode(objname, buf + len, size - len) < 0) {
+		errno = ENAMETOOLONG;
+		ret = -1;
+		goto out2;
+	}

 	ret = write(fd, buf, strlen(buf));
 	if (ret < 0)
@@ -59,13 +105,23 @@ int security_compute_create_raw(const
security_context_t scon,
 	close(fd);
 	return ret;
 }
+hidden_def(security_compute_create_name_raw)

+int security_compute_create_raw(const security_context_t scon,
+				const security_context_t tcon,
+				security_class_t tclass,
+				security_context_t * newcon)
+{
+	return security_compute_create_name_raw(scon, tcon, tclass,
+						NULL, newcon);
+}
 hidden_def(security_compute_create_raw)

-int security_compute_create(const security_context_t scon,
-			    const security_context_t tcon,
-			    security_class_t tclass,
-			    security_context_t * newcon)
+int security_compute_create_name(const security_context_t scon,
+				 const security_context_t tcon,
+				 security_class_t tclass,
+				 const char *objname,
+				 security_context_t * newcon)
 {
 	int ret;
 	security_context_t rscon;
@@ -79,8 +135,8 @@ int security_compute_create(const security_context_t scon,
 		return -1;
 	}

-	ret = security_compute_create_raw(rscon, rtcon, tclass, &rnewcon);
-
+	ret = security_compute_create_name_raw(rscon, rtcon, tclass,
+					       objname, &rnewcon);
 	freecon(rscon);
 	freecon(rtcon);
 	if (!ret) {
@@ -90,5 +146,13 @@ int security_compute_create(const security_context_t scon,

 	return ret;
 }
+hidden_def(security_compute_create_name)

+int security_compute_create(const security_context_t scon,
+			    const security_context_t tcon,
+			    security_class_t tclass,
+			    security_context_t * newcon)
+{
+	return security_compute_create_name(scon, tcon, tclass, NULL, newcon);
+}
 hidden_def(security_compute_create)
diff --git a/libselinux/src/selinux_internal.h
b/libselinux/src/selinux_internal.h
index fdddfaf..3f14955 100644
--- a/libselinux/src/selinux_internal.h
+++ b/libselinux/src/selinux_internal.h
@@ -23,6 +23,8 @@ hidden_proto(selinux_mkload_policy)
     hidden_proto(security_compute_user_raw)
     hidden_proto(security_compute_create)
     hidden_proto(security_compute_create_raw)
+    hidden_proto(security_compute_create_name)
+    hidden_proto(security_compute_create_name_raw)
     hidden_proto(security_compute_member_raw)
     hidden_proto(security_compute_relabel_raw)
     hidden_proto(is_selinux_enabled)

-- 
KaiGai Kohei <kaigai@xxxxxxxxxxxx>

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