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authorEric Paris <eparis@redhat.com>2010-10-13 16:24:48 -0400
committerJames Morris <jmorris@namei.org>2010-10-21 10:12:50 +1100
commitd5630b9d276bd389299ffea620b7c340ab19bcf5 (patch)
tree4e97cadf12518fb107f9e7140fa94343bd6643f5
parent2606fd1fa5710205b23ee859563502aa18362447 (diff)
downloadlinux-2.6.38-lt-ux500-d5630b9d276bd389299ffea620b7c340ab19bcf5.tar.gz
security: secid_to_secctx returns len when data is NULL
With the (long ago) interface change to have the secid_to_secctx functions do the string allocation instead of having the caller do the allocation we lost the ability to query the security server for the length of the upcoming string. The SECMARK code would like to allocate a netlink skb with enough length to hold the string but it is just too unclean to do the string allocation twice or to do the allocation the first time and hold onto the string and slen. This patch adds the ability to call security_secid_to_secctx() with a NULL data pointer and it will just set the slen pointer. Signed-off-by: Eric Paris <eparis@redhat.com> Reviewed-by: Paul Moore <paul.moore@hp.com> Signed-off-by: James Morris <jmorris@namei.org>
-rw-r--r--include/linux/security.h6
-rw-r--r--security/selinux/ss/services.c11
-rw-r--r--security/smack/smack_lsm.c3
3 files changed, 16 insertions, 4 deletions
diff --git a/include/linux/security.h b/include/linux/security.h
index d70adc394f6..b8246a8df7d 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -1285,9 +1285,13 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts)
* Return 0 if permission is granted.
*
* @secid_to_secctx:
- * Convert secid to security context.
+ * Convert secid to security context. If secdata is NULL the length of
+ * the result will be returned in seclen, but no secdata will be returned.
+ * This does mean that the length could change between calls to check the
+ * length and the next call which actually allocates and returns the secdata.
* @secid contains the security ID.
* @secdata contains the pointer that stores the converted security context.
+ * @seclen pointer which contains the length of the data
* @secctx_to_secid:
* Convert security context to secid.
* @secid contains the pointer to the generated security ID.
diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c
index 494ff527c17..60964d79e5e 100644
--- a/security/selinux/ss/services.c
+++ b/security/selinux/ss/services.c
@@ -991,7 +991,8 @@ static int context_struct_to_string(struct context *context, char **scontext, u3
{
char *scontextp;
- *scontext = NULL;
+ if (scontext)
+ *scontext = NULL;
*scontext_len = 0;
if (context->len) {
@@ -1008,6 +1009,9 @@ static int context_struct_to_string(struct context *context, char **scontext, u3
*scontext_len += strlen(policydb.p_type_val_to_name[context->type - 1]) + 1;
*scontext_len += mls_compute_context_len(context);
+ if (!scontext)
+ return 0;
+
/* Allocate space for the context; caller must free this space. */
scontextp = kmalloc(*scontext_len, GFP_ATOMIC);
if (!scontextp)
@@ -1047,7 +1051,8 @@ static int security_sid_to_context_core(u32 sid, char **scontext,
struct context *context;
int rc = 0;
- *scontext = NULL;
+ if (scontext)
+ *scontext = NULL;
*scontext_len = 0;
if (!ss_initialized) {
@@ -1055,6 +1060,8 @@ static int security_sid_to_context_core(u32 sid, char **scontext,
char *scontextp;
*scontext_len = strlen(initial_sid_to_string[sid]) + 1;
+ if (!scontext)
+ goto out;
scontextp = kmalloc(*scontext_len, GFP_ATOMIC);
if (!scontextp) {
rc = -ENOMEM;
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 174aec44bfa..bc39f4067af 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -3004,7 +3004,8 @@ static int smack_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)
{
char *sp = smack_from_secid(secid);
- *secdata = sp;
+ if (secdata)
+ *secdata = sp;
*seclen = strlen(sp);
return 0;
}