Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security

Pull keyring/nfs fixes from James Morris:
 "From David Howells:

  The first one fixes the handling of maximum buffer size for key
  descriptions, fixing the size at 4095 + NUL char rather than whatever
  PAGE_SIZE happens to be and permits you to read back the full
  description without it getting clipped because some extra information
  got prepended.

  The second and third fix a bug in NFS idmapper handling whereby a key
  representing a mapping between an id and a name expires and causing
  EKEYEXPIRED to be seen internally in NFS (which prevents the mapping
  from happening) rather than re-looking up the mapping"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
  KEYS: request_key() should reget expired keys rather than give EKEYEXPIRED
  KEYS: Simplify KEYRING_SEARCH_{NO,DO}_STATE_CHECK flags
  KEYS: Fix the size of the key description passed to/from userspace

5 files changed, 36 insertions, 34 deletions

diff --git a/security/keys/internal.h b/security/keys/internal.h
index b8960c4959a5..200e37867336 100644
--- a/security/keys/internal.h
+++ b/security/keys/internal.h
@@ -117,6 +117,7 @@ struct keyring_search_context {
 #define KEYRING_SEARCH_NO_UPDATE_TIME   0x0004  /* Don't update times */
 #define KEYRING_SEARCH_NO_CHECK_PERM    0x0008  /* Don't check permissions */
 #define KEYRING_SEARCH_DETECT_TOO_DEEP  0x0010  /* Give an error on excessive depth */
+#define KEYRING_SEARCH_SKIP_EXPIRED     0x0020  /* Ignore expired keys (intention to replace) */
 
         int (*iterator)(const void *object, void *iterator_data);
 
diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index eff88a5f5d40..4743d71e4aa6 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -26,6 +26,8 @@
 #include <asm/uaccess.h>
 #include "internal.h"
 
+#define KEY_MAX_DESC_SIZE 4096
+
 static int key_get_type_from_user(char *type,
                                   const char __user *_type,
                                   unsigned len)
@@ -78,7 +80,7 @@ SYSCALL_DEFINE5(add_key, const char __user *, _type,
 
         description = NULL;
         if (_description) {
-                description = strndup_user(_description, PAGE_SIZE);
+                description = strndup_user(_description, KEY_MAX_DESC_SIZE);
                 if (IS_ERR(description)) {
                         ret = PTR_ERR(description);
                         goto error;
@@ -177,7 +179,7 @@ SYSCALL_DEFINE4(request_key, const char __user *, _type,
                 goto error;
 
         /* pull the description into kernel space */
-        description = strndup_user(_description, PAGE_SIZE);
+        description = strndup_user(_description, KEY_MAX_DESC_SIZE);
         if (IS_ERR(description)) {
                 ret = PTR_ERR(description);
                 goto error;
@@ -287,7 +289,7 @@ long keyctl_join_session_keyring(const char __user *_name)
         /* fetch the name from userspace */
         name = NULL;
         if (_name) {
-                name = strndup_user(_name, PAGE_SIZE);
+                name = strndup_user(_name, KEY_MAX_DESC_SIZE);
                 if (IS_ERR(name)) {
                         ret = PTR_ERR(name);
                         goto error;
@@ -562,8 +564,9 @@ long keyctl_describe_key(key_serial_t keyid,
 {
         struct key *key, *instkey;
         key_ref_t key_ref;
-        char *tmpbuf;
+        char *infobuf;
         long ret;
+        int desclen, infolen;
 
         key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_NEED_VIEW);
         if (IS_ERR(key_ref)) {
@@ -586,38 +589,31 @@ long keyctl_describe_key(key_serial_t keyid,
         }
 
 okay:
-        /* calculate how much description we're going to return */
-        ret = -ENOMEM;
-        tmpbuf = kmalloc(PAGE_SIZE, GFP_KERNEL);
-        if (!tmpbuf)
-                goto error2;
-
         key = key_ref_to_ptr(key_ref);
+        desclen = strlen(key->description);
 
-        ret = snprintf(tmpbuf, PAGE_SIZE - 1,
-                       "%s;%d;%d;%08x;%s",
-                       key->type->name,
-                       from_kuid_munged(current_user_ns(), key->uid),
-                       from_kgid_munged(current_user_ns(), key->gid),
-                       key->perm,
-                       key->description ?: "");
-
-        /* include a NUL char at the end of the data */
-        if (ret > PAGE_SIZE - 1)
-                ret = PAGE_SIZE - 1;
-        tmpbuf[ret] = 0;
-        ret++;
+        /* calculate how much information we're going to return */
+        ret = -ENOMEM;
+        infobuf = kasprintf(GFP_KERNEL,
+                            "%s;%d;%d;%08x;",
+                            key->type->name,
+                            from_kuid_munged(current_user_ns(), key->uid),
+                            from_kgid_munged(current_user_ns(), key->gid),
+                            key->perm);
+        if (!infobuf)
+                goto error2;
+        infolen = strlen(infobuf);
+        ret = infolen + desclen + 1;
 
         /* consider returning the data */
-        if (buffer && buflen > 0) {
-                if (buflen > ret)
-                        buflen = ret;
-
-                if (copy_to_user(buffer, tmpbuf, buflen) != 0)
+        if (buffer && buflen >= ret) {
+                if (copy_to_user(buffer, infobuf, infolen) != 0 ||
+                    copy_to_user(buffer + infolen, key->description,
+                                 desclen + 1) != 0)
                         ret = -EFAULT;
         }
 
-        kfree(tmpbuf);
+        kfree(infobuf);
 error2:
         key_ref_put(key_ref);
 error:
@@ -649,7 +645,7 @@ long keyctl_keyring_search(key_serial_t ringid,
         if (ret < 0)
                 goto error;
 
-        description = strndup_user(_description, PAGE_SIZE);
+        description = strndup_user(_description, KEY_MAX_DESC_SIZE);
         if (IS_ERR(description)) {
                 ret = PTR_ERR(description);
                 goto error;
diff --git a/security/keys/keyring.c b/security/keys/keyring.c
index 8177010174f7..e72548b5897e 100644
--- a/security/keys/keyring.c
+++ b/security/keys/keyring.c
@@ -546,7 +546,8 @@ static int keyring_search_iterator(const void *object, void *iterator_data)
                 }
 
                 if (key->expiry && ctx->now.tv_sec >= key->expiry) {
-                        ctx->result = ERR_PTR(-EKEYEXPIRED);
+                        if (!(ctx->flags & KEYRING_SEARCH_SKIP_EXPIRED))
+                                ctx->result = ERR_PTR(-EKEYEXPIRED);
                         kleave(" = %d [expire]", ctx->skipped_ret);
                         goto skipped;
                 }
@@ -628,6 +629,10 @@ static bool search_nested_keyrings(struct key *keyring,
                ctx->index_key.type->name,
                ctx->index_key.description);
 
+#define STATE_CHECKS (KEYRING_SEARCH_NO_STATE_CHECK | KEYRING_SEARCH_DO_STATE_CHECK)
+        BUG_ON((ctx->flags & STATE_CHECKS) == 0 ||
+               (ctx->flags & STATE_CHECKS) == STATE_CHECKS);
+
         if (ctx->index_key.description)
                 ctx->index_key.desc_len = strlen(ctx->index_key.description);
 
@@ -637,7 +642,6 @@ static bool search_nested_keyrings(struct key *keyring,
         if (ctx->match_data.lookup_type == KEYRING_SEARCH_LOOKUP_ITERATE ||
             keyring_compare_object(keyring, &ctx->index_key)) {
                 ctx->skipped_ret = 2;
-                ctx->flags |= KEYRING_SEARCH_DO_STATE_CHECK;
                 switch (ctx->iterator(keyring_key_to_ptr(keyring), ctx)) {
                 case 1:
                         goto found;
@@ -649,8 +653,6 @@ static bool search_nested_keyrings(struct key *keyring,
         }
 
         ctx->skipped_ret = 0;
-        if (ctx->flags & KEYRING_SEARCH_NO_STATE_CHECK)
-                ctx->flags &= ~KEYRING_SEARCH_DO_STATE_CHECK;
 
         /* Start processing a new keyring */
 descend_to_keyring:
diff --git a/security/keys/request_key.c b/security/keys/request_key.c
index bb4337c7ae1b..0c7aea4dea54 100644
--- a/security/keys/request_key.c
+++ b/security/keys/request_key.c
@@ -516,6 +516,8 @@ struct key *request_key_and_link(struct key_type *type,
                 .match_data.cmp         = key_default_cmp,
                 .match_data.raw_data    = description,
                 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
+                .flags                  = (KEYRING_SEARCH_DO_STATE_CHECK |
+                                           KEYRING_SEARCH_SKIP_EXPIRED),
         };
         struct key *key;
         key_ref_t key_ref;
diff --git a/security/keys/request_key_auth.c b/security/keys/request_key_auth.c
index 6639e2cb8853..5d672f7580dd 100644
--- a/security/keys/request_key_auth.c
+++ b/security/keys/request_key_auth.c
@@ -249,6 +249,7 @@ struct key *key_get_instantiation_authkey(key_serial_t target_id)
                 .match_data.cmp         = key_default_cmp,
                 .match_data.raw_data    = description,
                 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
+                .flags                  = KEYRING_SEARCH_DO_STATE_CHECK,
         };
         struct key *authkey;
         key_ref_t authkey_ref;