ima: extend "mask" policy matching support

The current "mask" policy option matches files opened as MAY_READ,
MAY_WRITE, MAY_APPEND or MAY_EXEC.  This patch extends the "mask"
option to match files opened containing one of these modes.  For
example, "mask=^MAY_READ" would match files opened read-write.

Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Dr. Greg Wettstein <gw@idfusion.org>
Cc: stable@vger.kernel.org

diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy
index 4a571fa10f9690f1089a7a53ae34583ed3b7b0f4..0a378a88217a48a00b012435cba2ba2bdccd3fa6 100644 (file)
--- a/Documentation/ABI/testing/ima_policy
+++ b/Documentation/ABI/testing/ima_policy
@@ -27,7 +27,8 @@ Description:
 
                base:   func:= [BPRM_CHECK][MMAP_CHECK][FILE_CHECK][MODULE_CHECK]
                                [FIRMWARE_CHECK]
-                       mask:= [MAY_READ] [MAY_WRITE] [MAY_APPEND] [MAY_EXEC]
+                       mask:= [[^]MAY_READ] [[^]MAY_WRITE] [[^]MAY_APPEND]
+                              [[^]MAY_EXEC]
                        fsmagic:= hex value
                        fsuuid:= file system UUID (e.g 8bcbe394-4f13-4144-be8e-5aa9ea2ce2f6)
                        uid:= decimal value

diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 525301cf7d90f8a184ed4ef2030a581924b7257e..b3a2038ed4243ba5da5e887d4a26d1818c138589 100644 (file)
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -27,6 +27,7 @@
 #define IMA_UID                0x0008
 #define IMA_FOWNER     0x0010
 #define IMA_FSUUID     0x0020
+#define IMA_INMASK     0x0040
 #define IMA_EUID       0x0080
 
 #define UNKNOWN                0
@@ -187,6 +188,9 @@ static bool ima_match_rules(struct ima_rule_entry *rule,
        if ((rule->flags & IMA_MASK) &&
            (rule->mask != mask && func != POST_SETATTR))
                return false;
+       if ((rule->flags & IMA_INMASK) &&
+           (!(rule->mask & mask) && func != POST_SETATTR))
+               return false;
        if ((rule->flags & IMA_FSMAGIC)
            && rule->fsmagic != inode->i_sb->s_magic)
                return false;
@@ -448,6 +452,7 @@ static void ima_log_string(struct audit_buffer *ab, char *key, char *value)
 static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
 {
        struct audit_buffer *ab;
+       char *from;
        char *p;
        int result = 0;
 
@@ -538,18 +543,23 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
                        if (entry->mask)
                                result = -EINVAL;
 
-                       if ((strcmp(args[0].from, "MAY_EXEC")) == 0)
+                       from = args[0].from;
+                       if (*from == '^')
+                               from++;
+
+                       if ((strcmp(from, "MAY_EXEC")) == 0)
                                entry->mask = MAY_EXEC;
-                       else if (strcmp(args[0].from, "MAY_WRITE") == 0)
+                       else if (strcmp(from, "MAY_WRITE") == 0)
                                entry->mask = MAY_WRITE;
-                       else if (strcmp(args[0].from, "MAY_READ") == 0)
+                       else if (strcmp(from, "MAY_READ") == 0)
                                entry->mask = MAY_READ;
-                       else if (strcmp(args[0].from, "MAY_APPEND") == 0)
+                       else if (strcmp(from, "MAY_APPEND") == 0)
                                entry->mask = MAY_APPEND;
                        else
                                result = -EINVAL;
                        if (!result)
-                               entry->flags |= IMA_MASK;
+                               entry->flags |= (*args[0].from == '^')
+                                    ? IMA_INMASK : IMA_MASK;
                        break;
                case Opt_fsmagic:
                        ima_log_string(ab, "fsmagic", args[0].from);