selinux: introduce security_context_str_to_sid

There seems to be a little confusion as to whether the scontext_len
parameter of security_context_to_sid() includes the nul-byte or
not. Reading security_context_to_sid_core(), it seems that the
expectation is that it does not (both the string copying and the test
for scontext_len being zero hint at that).

Introduce the helper security_context_str_to_sid() to do the strlen()
call and fix all callers.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <pmoore@redhat.com>

1 files changed, 9 insertions, 17 deletions

diff --git a/security/selinux/selinuxfs.c b/security/selinux/selinuxfs.c
index 5bed7716f8ab..c02da25d7b63 100644
--- a/security/selinux/selinuxfs.c
+++ b/security/selinux/selinuxfs.c
@@ -731,13 +731,11 @@ static ssize_t sel_write_access(struct file *file, char *buf, size_t size)
         if (sscanf(buf, "%s %s %hu", scon, tcon, &tclass) != 3)
                 goto out;
 
-        length = security_context_to_sid(scon, strlen(scon) + 1, &ssid,
-                                         GFP_KERNEL);
+        length = security_context_str_to_sid(scon, &ssid, GFP_KERNEL);
         if (length)
                 goto out;
 
-        length = security_context_to_sid(tcon, strlen(tcon) + 1, &tsid,
-                                         GFP_KERNEL);
+        length = security_context_str_to_sid(tcon, &tsid, GFP_KERNEL);
         if (length)
                 goto out;
 
@@ -819,13 +817,11 @@ static ssize_t sel_write_create(struct file *file, char *buf, size_t size)
                 objname = namebuf;
         }
 
-        length = security_context_to_sid(scon, strlen(scon) + 1, &ssid,
-                                         GFP_KERNEL);
+        length = security_context_str_to_sid(scon, &ssid, GFP_KERNEL);
         if (length)
                 goto out;
 
-        length = security_context_to_sid(tcon, strlen(tcon) + 1, &tsid,
-                                         GFP_KERNEL);
+        length = security_context_str_to_sid(tcon, &tsid, GFP_KERNEL);
         if (length)
                 goto out;
 
@@ -882,13 +878,11 @@ static ssize_t sel_write_relabel(struct file *file, char *buf, size_t size)
         if (sscanf(buf, "%s %s %hu", scon, tcon, &tclass) != 3)
                 goto out;
 
-        length = security_context_to_sid(scon, strlen(scon) + 1, &ssid,
-                                         GFP_KERNEL);
+        length = security_context_str_to_sid(scon, &ssid, GFP_KERNEL);
         if (length)
                 goto out;
 
-        length = security_context_to_sid(tcon, strlen(tcon) + 1, &tsid,
-                                         GFP_KERNEL);
+        length = security_context_str_to_sid(tcon, &tsid, GFP_KERNEL);
         if (length)
                 goto out;
 
@@ -940,7 +934,7 @@ static ssize_t sel_write_user(struct file *file, char *buf, size_t size)
         if (sscanf(buf, "%s %s", con, user) != 2)
                 goto out;
 
-        length = security_context_to_sid(con, strlen(con) + 1, &sid, GFP_KERNEL);
+        length = security_context_str_to_sid(con, &sid, GFP_KERNEL);
         if (length)
                 goto out;
 
@@ -1000,13 +994,11 @@ static ssize_t sel_write_member(struct file *file, char *buf, size_t size)
         if (sscanf(buf, "%s %s %hu", scon, tcon, &tclass) != 3)
                 goto out;
 
-        length = security_context_to_sid(scon, strlen(scon) + 1, &ssid,
-                                         GFP_KERNEL);
+        length = security_context_str_to_sid(scon, &ssid, GFP_KERNEL);
         if (length)
                 goto out;
 
-        length = security_context_to_sid(tcon, strlen(tcon) + 1, &tsid,
-                                         GFP_KERNEL);
+        length = security_context_str_to_sid(tcon, &tsid, GFP_KERNEL);
         if (length)
                 goto out;