KEYS: Add an iovec version of KEYCTL_INSTANTIATE

Add a keyctl op (KEYCTL_INSTANTIATE_IOV) that is like KEYCTL_INSTANTIATE, but
takes an iovec array and concatenates the data in-kernel into one buffer.
Since the KEYCTL_INSTANTIATE copies the data anyway, this isn't too much of a
problem.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>

6 files changed, 167 insertions, 11 deletions

diff --git a/Documentation/keys.txt b/Documentation/keys.txt
index a6a97fdfaddd..6523a9e6f293 100644
--- a/Documentation/keys.txt
+++ b/Documentation/keys.txt
@@ -637,6 +637,9 @@ The keyctl syscall functions are:
         long keyctl(KEYCTL_INSTANTIATE, key_serial_t key,
                     const void *payload, size_t plen,
                     key_serial_t keyring);
+        long keyctl(KEYCTL_INSTANTIATE_IOV, key_serial_t key,
+                    const struct iovec *payload_iov, unsigned ioc,
+                    key_serial_t keyring);
 
      If the kernel calls back to userspace to complete the instantiation of a
      key, userspace should use this call to supply data for the key before the
@@ -652,6 +655,9 @@ The keyctl syscall functions are:
 
      The payload and plen arguments describe the payload data as for add_key().
 
+     The payload_iov and ioc arguments describe the payload data in an iovec
+     array instead of a single buffer.
+
 
  (*) Negatively instantiate a partially constructed key.
 
@@ -1244,10 +1250,11 @@ hand the request off to (perhaps a path held in placed in another key by, for
 example, the KDE desktop manager).
 
 The program (or whatever it calls) should finish construction of the key by
-calling KEYCTL_INSTANTIATE, which also permits it to cache the key in one of
-the keyrings (probably the session ring) before returning. Alternatively, the
-key can be marked as negative with KEYCTL_NEGATE or KEYCTL_REJECT; this also
-permits the key to be cached in one of the keyrings.
+calling KEYCTL_INSTANTIATE or KEYCTL_INSTANTIATE_IOV, which also permits it to
+cache the key in one of the keyrings (probably the session ring) before
+returning.  Alternatively, the key can be marked as negative with KEYCTL_NEGATE
+or KEYCTL_REJECT; this also permits the key to be cached in one of the
+keyrings.
 
 If it returns with the key remaining in the unconstructed state, the key will
 be marked as being negative, it will be added to the session keyring, and an
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index d5ed94d30aad..b46b75bef496 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2138,6 +2138,11 @@ config SYSVIPC_COMPAT
         def_bool y
         depends on COMPAT && SYSVIPC
 
+config KEYS_COMPAT
+        bool
+        depends on COMPAT && KEYS
+        default y
+
 endmenu
 
 
diff --git a/include/linux/keyctl.h b/include/linux/keyctl.h
index 7022974def0c..9b0b865ce622 100644
--- a/include/linux/keyctl.h
+++ b/include/linux/keyctl.h
@@ -54,5 +54,6 @@
 #define KEYCTL_GET_SECURITY             17      /* get key security label */
 #define KEYCTL_SESSION_TO_PARENT        18      /* apply session keyring to parent process */
 #define KEYCTL_REJECT                   19      /* reject a partially constructed key */
+#define KEYCTL_INSTANTIATE_IOV          20      /* instantiate a partially constructed key */
 
 #endif /*  _LINUX_KEYCTL_H */
diff --git a/security/keys/compat.c b/security/keys/compat.c
index 17c99d0149ec..338b510e9027 100644
--- a/security/keys/compat.c
+++ b/security/keys/compat.c
@@ -12,9 +12,52 @@
 #include <linux/syscalls.h>
 #include <linux/keyctl.h>
 #include <linux/compat.h>
+#include <linux/slab.h>
 #include "internal.h"
 
 /*
+ * Instantiate a key with the specified compatibility multipart payload and
+ * link the key into the destination keyring if one is given.
+ *
+ * The caller must have the appropriate instantiation permit set for this to
+ * work (see keyctl_assume_authority).  No other permissions are required.
+ *
+ * If successful, 0 will be returned.
+ */
+long compat_keyctl_instantiate_key_iov(
+        key_serial_t id,
+        const struct compat_iovec __user *_payload_iov,
+        unsigned ioc,
+        key_serial_t ringid)
+{
+        struct iovec iovstack[UIO_FASTIOV], *iov = iovstack;
+        long ret;
+
+        if (_payload_iov == 0 || ioc == 0)
+                goto no_payload;
+
+        ret = compat_rw_copy_check_uvector(WRITE, _payload_iov, ioc,
+                                           ARRAY_SIZE(iovstack),
+                                           iovstack, &iov);
+        if (ret < 0)
+                return ret;
+        if (ret == 0)
+                goto no_payload_free;
+
+        ret = keyctl_instantiate_key_common(id, iov, ioc, ret, ringid);
+
+        if (iov != iovstack)
+                kfree(iov);
+        return ret;
+
+no_payload_free:
+        if (iov != iovstack)
+                kfree(iov);
+no_payload:
+        return keyctl_instantiate_key_common(id, NULL, 0, 0, ringid);
+}
+
+/*
  * The key control system call, 32-bit compatibility version for 64-bit archs
  *
  * This should only be called if the 64-bit arch uses weird pointers in 32-bit
@@ -88,6 +131,10 @@ asmlinkage long compat_sys_keyctl(u32 option,
         case KEYCTL_REJECT:
                 return keyctl_reject_key(arg2, arg3, arg4, arg5);
 
+        case KEYCTL_INSTANTIATE_IOV:
+                return compat_keyctl_instantiate_key_iov(
+                        arg2, compat_ptr(arg3), arg4, arg5);
+
         default:
                 return -EOPNOTSUPP;
         }
diff --git a/security/keys/internal.h b/security/keys/internal.h
index 286c0959ee51..07a025f81902 100644
--- a/security/keys/internal.h
+++ b/security/keys/internal.h
@@ -215,6 +215,13 @@ extern long keyctl_get_security(key_serial_t keyid, char __user *buffer,
                                 size_t buflen);
 extern long keyctl_session_to_parent(void);
 extern long keyctl_reject_key(key_serial_t, unsigned, unsigned, key_serial_t);
+extern long keyctl_instantiate_key_iov(key_serial_t,
+                                       const struct iovec __user *,
+                                       unsigned, key_serial_t);
+
+extern long keyctl_instantiate_key_common(key_serial_t,
+                                          const struct iovec __user *,
+                                          unsigned, size_t, key_serial_t);
 
 /*
  * Debugging key validation
diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index 0d7b1946ff94..427fddcaeb19 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -913,6 +913,21 @@ static int keyctl_change_reqkey_auth(struct key *key)
 }
 
 /*
+ * Copy the iovec data from userspace
+ */
+static long copy_from_user_iovec(void *buffer, const struct iovec *iov,
+                                 unsigned ioc)
+{
+        for (; ioc > 0; ioc--) {
+                if (copy_from_user(buffer, iov->iov_base, iov->iov_len) != 0)
+                        return -EFAULT;
+                buffer += iov->iov_len;
+                iov++;
+        }
+        return 0;
+}
+
+/*
  * Instantiate a key with the specified payload and link the key into the
  * destination keyring if one is given.
  *
@@ -921,10 +936,11 @@ static int keyctl_change_reqkey_auth(struct key *key)
  *
  * If successful, 0 will be returned.
  */
-long keyctl_instantiate_key(key_serial_t id,
-                            const void __user *_payload,
-                            size_t plen,
-                            key_serial_t ringid)
+long keyctl_instantiate_key_common(key_serial_t id,
+                                   const struct iovec *payload_iov,
+                                   unsigned ioc,
+                                   size_t plen,
+                                   key_serial_t ringid)
 {
         const struct cred *cred = current_cred();
         struct request_key_auth *rka;
@@ -953,7 +969,7 @@ long keyctl_instantiate_key(key_serial_t id,
         /* pull the payload in if one was supplied */
         payload = NULL;
 
-        if (_payload) {
+        if (payload_iov) {
                 ret = -ENOMEM;
                 payload = kmalloc(plen, GFP_KERNEL);
                 if (!payload) {
@@ -965,8 +981,8 @@ long keyctl_instantiate_key(key_serial_t id,
                                 goto error;
                 }
 
-                ret = -EFAULT;
-                if (copy_from_user(payload, _payload, plen) != 0)
+                ret = copy_from_user_iovec(payload, payload_iov, ioc);
+                if (ret < 0)
                         goto error2;
         }
 
@@ -997,6 +1013,72 @@ error:
 }
 
 /*
+ * Instantiate a key with the specified payload and link the key into the
+ * destination keyring if one is given.
+ *
+ * The caller must have the appropriate instantiation permit set for this to
+ * work (see keyctl_assume_authority).  No other permissions are required.
+ *
+ * If successful, 0 will be returned.
+ */
+long keyctl_instantiate_key(key_serial_t id,
+                            const void __user *_payload,
+                            size_t plen,
+                            key_serial_t ringid)
+{
+        if (_payload && plen) {
+                struct iovec iov[1] = {
+                        [0].iov_base = (void __user *)_payload,
+                        [0].iov_len  = plen
+                };
+
+                return keyctl_instantiate_key_common(id, iov, 1, plen, ringid);
+        }
+
+        return keyctl_instantiate_key_common(id, NULL, 0, 0, ringid);
+}
+
+/*
+ * Instantiate a key with the specified multipart payload and link the key into
+ * the destination keyring if one is given.
+ *
+ * The caller must have the appropriate instantiation permit set for this to
+ * work (see keyctl_assume_authority).  No other permissions are required.
+ *
+ * If successful, 0 will be returned.
+ */
+long keyctl_instantiate_key_iov(key_serial_t id,
+                                const struct iovec __user *_payload_iov,
+                                unsigned ioc,
+                                key_serial_t ringid)
+{
+        struct iovec iovstack[UIO_FASTIOV], *iov = iovstack;
+        long ret;
+
+        if (_payload_iov == 0 || ioc == 0)
+                goto no_payload;
+
+        ret = rw_copy_check_uvector(WRITE, _payload_iov, ioc,
+                                    ARRAY_SIZE(iovstack), iovstack, &iov);
+        if (ret < 0)
+                return ret;
+        if (ret == 0)
+                goto no_payload_free;
+
+        ret = keyctl_instantiate_key_common(id, iov, ioc, ret, ringid);
+
+        if (iov != iovstack)
+                kfree(iov);
+        return ret;
+
+no_payload_free:
+        if (iov != iovstack)
+                kfree(iov);
+no_payload:
+        return keyctl_instantiate_key_common(id, NULL, 0, 0, ringid);
+}
+
+/*
  * Negatively instantiate the key with the given timeout (in seconds) and link
  * the key into the destination keyring if one is given.
  *
@@ -1528,6 +1610,13 @@ SYSCALL_DEFINE5(keyctl, int, option, unsigned long, arg2, unsigned long, arg3,
                                          (unsigned) arg4,
                                          (key_serial_t) arg5);
 
+        case KEYCTL_INSTANTIATE_IOV:
+                return keyctl_instantiate_key_iov(
+                        (key_serial_t) arg2,
+                        (const struct iovec __user *) arg3,
+                        (unsigned) arg4,
+                        (key_serial_t) arg5);
+
         default:
                 return -EOPNOTSUPP;
         }