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authorDavid Howells <dhowells@redhat.com>2008-04-29 01:01:26 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-04-29 08:06:16 -0700
commit70a5bb72b55e82fbfbf1e22cae6975fac58a1e2d (patch)
tree8e6dcaf5630388d81b23845f293789f2d6a3596b /security/keys/keyctl.c
parent4a38e122e2cc6294779021ff4ccc784a3997059e (diff)
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keys: add keyctl function to get a security label
Add a keyctl() function to get the security label of a key. The following is added to Documentation/keys.txt: (*) Get the LSM security context attached to a key. long keyctl(KEYCTL_GET_SECURITY, key_serial_t key, char *buffer, size_t buflen) This function returns a string that represents the LSM security context attached to a key in the buffer provided. Unless there's an error, it always returns the amount of data it could produce, even if that's too big for the buffer, but it won't copy more than requested to userspace. If the buffer pointer is NULL then no copy will take place. A NUL character is included at the end of the string if the buffer is sufficiently big. This is included in the returned count. If no LSM is in force then an empty string will be returned. A process must have view permission on the key for this function to be successful. [akpm@linux-foundation.org: declare keyctl_get_security()] Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Stephen Smalley <sds@tycho.nsa.gov> Cc: Paul Moore <paul.moore@hp.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: James Morris <jmorris@namei.org> Cc: Kevin Coffman <kwc@citi.umich.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'security/keys/keyctl.c')
-rw-r--r--security/keys/keyctl.c66
1 files changed, 66 insertions, 0 deletions
diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index 1698bf90ee8..56e963b700b 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -20,6 +20,7 @@
#include <linux/string.h>
#include <linux/err.h>
#include <linux/vmalloc.h>
+#include <linux/security.h>
#include <asm/uaccess.h>
#include "internal.h"
@@ -1080,6 +1081,66 @@ error:
} /* end keyctl_assume_authority() */
+/*
+ * get the security label of a key
+ * - the key must grant us view permission
+ * - if there's a buffer, we place up to buflen bytes of data into it
+ * - unless there's an error, we return the amount of information available,
+ * irrespective of how much we may have copied (including the terminal NUL)
+ * - implements keyctl(KEYCTL_GET_SECURITY)
+ */
+long keyctl_get_security(key_serial_t keyid,
+ char __user *buffer,
+ size_t buflen)
+{
+ struct key *key, *instkey;
+ key_ref_t key_ref;
+ char *context;
+ long ret;
+
+ key_ref = lookup_user_key(NULL, keyid, 0, 1, KEY_VIEW);
+ if (IS_ERR(key_ref)) {
+ if (PTR_ERR(key_ref) != -EACCES)
+ return PTR_ERR(key_ref);
+
+ /* viewing a key under construction is also permitted if we
+ * have the authorisation token handy */
+ instkey = key_get_instantiation_authkey(keyid);
+ if (IS_ERR(instkey))
+ return PTR_ERR(key_ref);
+ key_put(instkey);
+
+ key_ref = lookup_user_key(NULL, keyid, 0, 1, 0);
+ if (IS_ERR(key_ref))
+ return PTR_ERR(key_ref);
+ }
+
+ key = key_ref_to_ptr(key_ref);
+ ret = security_key_getsecurity(key, &context);
+ if (ret == 0) {
+ /* if no information was returned, give userspace an empty
+ * string */
+ ret = 1;
+ if (buffer && buflen > 0 &&
+ copy_to_user(buffer, "", 1) != 0)
+ ret = -EFAULT;
+ } else if (ret > 0) {
+ /* return as much data as there's room for */
+ if (buffer && buflen > 0) {
+ if (buflen > ret)
+ buflen = ret;
+
+ if (copy_to_user(buffer, context, buflen) != 0)
+ ret = -EFAULT;
+ }
+
+ kfree(context);
+ }
+
+ key_ref_put(key_ref);
+ return ret;
+}
+
/*****************************************************************************/
/*
* the key control system call
@@ -1160,6 +1221,11 @@ asmlinkage long sys_keyctl(int option, unsigned long arg2, unsigned long arg3,
case KEYCTL_ASSUME_AUTHORITY:
return keyctl_assume_authority((key_serial_t) arg2);
+ case KEYCTL_GET_SECURITY:
+ return keyctl_get_security((key_serial_t) arg2,
+ (char *) arg3,
+ (size_t) arg4);
+
default:
return -EOPNOTSUPP;
}