X-Git-Url: https://git.saurik.com/apple/security.git/blobdiff_plain/80e2389990082500d76eb566d4946be3e786c3ef..d8f41ccd20de16f8ebe2ccc84d47bf1cb2b26bbb:/codesign_wrapper/check_entitlements.c

diff --git a/codesign_wrapper/check_entitlements.c b/codesign_wrapper/check_entitlements.c
new file mode 100644
index 00000000..0ab4da76
--- /dev/null
+++ b/codesign_wrapper/check_entitlements.c
@@ -0,0 +1,400 @@
+/*
+ *  check_entitlements.c
+ *
+ *
+ *  Created by Conrad Sauerwald on 7/9/08.
+ *  Copyright 2008 __MyCompanyName__. All rights reserved.
+ *
+ */
+
+#include <paths.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+#include <stdlib.h>
+#include <assert.h>
+#include <signal.h>
+#include <sys/stat.h>
+#include <sys/socket.h>
+#include <getopt.h>
+#include <stdbool.h>
+#include <limits.h>
+
+#define DEBUG_ASSERT_PRODUCTION_CODE 0
+#include <AssertMacros.h>
+
+#include <CoreFoundation/CoreFoundation.h>
+
+#define log(format, args...)    \
+    fprintf(stderr, "codesign_wrapper " format "\n", ##args);
+#define cflog(format, args...) do { \
+CFStringRef logstr = CFStringCreateWithFormat(NULL, NULL, CFSTR(format), ##args); \
+if (logstr) { CFShow(logstr); CFRelease(logstr); } \
+} while(0); \
+
+enum { CSMAGIC_EMBEDDED_ENTITLEMENTS = 0xfade7171 };
+
+typedef struct {
+    uint32_t type;
+    uint32_t offset;
+} cs_blob_index;
+
+CFDataRef
+extract_entitlements_blob(const uint8_t *data, size_t length)
+{
+    CFDataRef entitlements = NULL;
+    cs_blob_index *csbi = (cs_blob_index *)data;
+
+    require(data && length, out);
+    require(csbi->type == ntohl(CSMAGIC_EMBEDDED_ENTITLEMENTS), out);
+    require(length == ntohl(csbi->offset), out);
+    entitlements = CFDataCreate(kCFAllocatorDefault,
+        (uint8_t*)(data + sizeof(cs_blob_index)),
+        (CFIndex)(length - sizeof(cs_blob_index)));
+out:
+    return entitlements;
+}
+
+typedef struct {
+    bool valid_application_identifier;
+    bool valid_keychain_access_group;
+    bool illegal_entitlement;
+} filter_whitelist_ctx;
+
+void
+filter_entitlement(const void *key, const void *value,
+        filter_whitelist_ctx *ctx)
+{
+    if (CFEqual(key, CFSTR("application-identifier"))) {
+        // value isn't string
+        if (CFGetTypeID(value) != CFStringGetTypeID()) {
+            cflog("ERR: Illegal entitlement value %@ for key %@", value, key);
+            return;
+        }
+
+        // log it for posterity
+        cflog("NOTICE: application-identifier := '%@'", value);
+
+        // - put in an application-identifier that is messed up: <char-string>.<char-string-repeat>.
+        // split ident by periods and make sure the first two are not the same
+        // - put in an application-identifier they're not allowed to have: but we have no way to tell, although "apple" is illegal
+        // is apple, superseded by doesn't have at least 2 components split by a period
+
+        CFArrayRef identifier_pieces = CFStringCreateArrayBySeparatingStrings(kCFAllocatorDefault, value, CFSTR("."));	/* No separators in the string returns array with that string; string == sep returns two empty strings */
+        if (!identifier_pieces || (CFArrayGetCount(identifier_pieces) < 2)) {
+            cflog("ERR: Malformed identifier %@ := %@", key, value);
+            return;
+        }
+
+        // doubled-up identifier
+        if (CFEqual(CFArrayGetValueAtIndex(identifier_pieces, 0),
+            CFArrayGetValueAtIndex(identifier_pieces, 1))) {
+                cflog("ERR: Malformed identifier %@ := %@", key, value);
+                return;
+        }
+
+        // incomplete identifier: "blabla."
+        if (CFEqual(CFArrayGetValueAtIndex(identifier_pieces, 1), CFSTR(""))) {
+            cflog("ERR: Malformed identifier %@ := %@", key, value);
+            return;
+        }
+
+        ctx->valid_application_identifier = true;
+        return;
+    }
+
+    if (CFEqual(key, CFSTR("keychain-access-groups"))) {
+        // if there is one, false until proven correct
+        ctx->valid_keychain_access_group = false;
+
+        // log it for posterity - we're not expecting people to use it yet
+        cflog("NOTICE: keychain-access-groups := %@", value);
+
+        // - put in keychain-access-groups containing "apple"
+        if (CFGetTypeID(value) == CFStringGetTypeID()) {
+            if (CFEqual(CFSTR("apple"), value) ||
+                (CFStringFind(value, CFSTR("*"), 0).location != kCFNotFound)) {
+                cflog("ERR: Illegal keychain access group value %@ for key %@", value, key);
+                return;
+            }
+        } else if (CFGetTypeID(value) == CFArrayGetTypeID()) {
+            CFIndex i, count = CFArrayGetCount(value);
+            for (i=0; i<count; i++) {
+                CFStringRef val = (CFStringRef)CFArrayGetValueAtIndex(value, i);
+                if (CFGetTypeID(val) != CFStringGetTypeID()) {
+                    cflog("ERR: Illegal value in keychain access groups array %@", val);
+                    return;
+                }
+                if (CFEqual(CFSTR("apple"), val) ||
+                    (CFStringFind(val, CFSTR("*"), 0).location != kCFNotFound)) {
+                    cflog("ERR: Illegal keychain access group value %@ for key %@", value, key);
+                    return;
+                }
+            }
+        } else {
+            cflog("ERR: Illegal entitlement value %@ for key %@", value, key);
+            return;
+        }
+
+        ctx->valid_keychain_access_group = true;
+        return;
+    }
+
+    // - double check there's no "get-task-allow"
+    // - nothing else should be allowed
+    cflog("ERR: Illegal entitlement key '%@' := '%@'", key, value);
+    ctx->illegal_entitlement = true;
+}
+
+bool
+filter_entitlements(CFDictionaryRef entitlements)
+{
+    if (!entitlements)
+        return true;
+
+    // did not put in an application-identifier: that keeps us from identifying the app securely
+    filter_whitelist_ctx ctx = { /* valid_application_identifier */ false,
+                                 /* valid_keychain_access_group */ true,
+                                 /* illegal_entitlement */ false };
+    CFDictionaryApplyFunction(entitlements,
+            (CFDictionaryApplierFunction)filter_entitlement, &ctx);
+    return (ctx.valid_application_identifier && ctx.valid_keychain_access_group &&
+        !ctx.illegal_entitlement);
+}
+
+static pid_t kill_child = -1;
+void child_timeout(int sig)
+{
+    if (kill_child != -1) {
+        kill(kill_child, sig);
+        kill_child = -1;
+    }
+}
+
+pid_t fork_child(void (*pre_exec)(void *arg), void *pre_exec_arg,
+        const char * const argv[])
+{
+    unsigned delay = 1, maxDelay = 60;
+    for (;;) {
+        pid_t pid;
+        switch (pid = fork()) {
+            case -1: /* fork failed */
+                switch (errno) {
+                    case EINTR:
+                        continue; /* no problem */
+                    case EAGAIN:
+                        if (delay < maxDelay) {
+                            sleep(delay);
+                            delay *= 2;
+                            continue;
+                        }
+                        /* fall through */
+                    default:
+                        perror("fork");
+                        return -1;
+                }
+                assert(-1); /* unreached */
+
+            case 0: /* child */
+                if (pre_exec)
+                    pre_exec(pre_exec_arg);
+                execv(argv[0], (char * const *)argv);
+                perror("execv");
+                _exit(1);
+
+            default: /* parent */
+                return pid;
+                break;
+        }
+        break;
+    }
+    return -1;
+}
+
+
+int fork_child_timeout(void (*pre_exec)(), char *pre_exec_arg,
+        const char * const argv[], int timeout)
+{
+    int exit_status = -1;
+    pid_t child_pid = fork_child(pre_exec, pre_exec_arg, argv);
+    if (timeout) {
+        kill_child = child_pid;
+        alarm(timeout);
+    }
+    while (1) {
+        int err = wait4(child_pid, &exit_status, 0, NULL);
+        if (err == -1) {
+            perror("wait4");
+            if (errno == EINTR)
+                continue;
+        }
+        if (err == child_pid) {
+            if (WIFSIGNALED(exit_status)) {
+                log("child %d received signal %d", child_pid, WTERMSIG(exit_status));
+                kill(child_pid, SIGHUP);
+                return -2;
+            }
+            if (WIFEXITED(exit_status))
+                return WEXITSTATUS(exit_status);
+            return -1;
+        }
+    }
+}
+
+
+void dup_io(int arg[])
+{
+    dup2(arg[0], arg[1]);
+    close(arg[0]);
+}
+
+
+int fork_child_timeout_output(int child_fd, int *parent_fd, const char * const argv[], int timeout)
+{
+    int output[2];
+    if (socketpair(AF_UNIX, SOCK_STREAM, 0, output))
+        return -1;
+    fcntl(output[1], F_SETFD, 1); /* close in child */
+    int redirect_child[] = { output[0], child_fd };
+    int err = fork_child_timeout(dup_io, (void*)redirect_child, argv, timeout);
+    if (!err) {
+        close(output[0]); /* close the child side in the parent */
+        *parent_fd = output[1];
+    }
+    return err;
+}
+
+ssize_t read_fd(int fd, void **buffer)
+{
+    int err = -1;
+    size_t capacity = 1024;
+    char * data = malloc(capacity);
+    size_t size = 0;
+    while (1) {
+        int bytes_left = capacity - size;
+        int bytes_read = read(fd, data + size, bytes_left);
+        if (bytes_read >= 0) {
+            size += bytes_read;
+            if (capacity == size) {
+                capacity *= 2;
+                data = realloc(data, capacity);
+                if (!data) {
+                    err = -1;
+                    break;
+                }
+                continue;
+            }
+            err = 0;
+        } else
+            err = -1;
+        break;
+    }
+    if (0 == size) {
+        if (data)
+            free(data);
+        return err;
+    }
+
+    *buffer = data;
+    return size;
+}
+
+static char * codesign_binary = "/usr/bin/codesign";
+
+int
+main(int argc, char *argv[])
+{
+#if 0
+    if (argc == 1) {
+        CFArrayRef empty_array = CFArrayCreate(NULL, NULL, 0, NULL);
+        CFMutableDictionaryRef dict = CFDictionaryCreateMutable(kCFAllocatorDefault,
+            0, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);
+
+        // empty
+        require(!filter_entitlements(dict), fail_test);
+
+        CFDictionarySetValue(dict, CFSTR("get-task-allow"), kCFBooleanTrue);
+
+        // no get-task-allow allowed
+        require(!filter_entitlements(dict), fail_test);
+        CFDictionaryRemoveValue(dict, CFSTR("get-task-allow"));
+
+        CFDictionarySetValue(dict, CFSTR("application-identifier"), empty_array);
+        require(!filter_entitlements(dict), fail_test);
+
+        CFDictionarySetValue(dict, CFSTR("application-identifier"), CFSTR("apple"));
+        require(!filter_entitlements(dict), fail_test);
+        CFDictionarySetValue(dict, CFSTR("application-identifier"), CFSTR("AJ$K#GK$.AJ$K#GK$.hoi"));
+        require(!filter_entitlements(dict), fail_test);
+        CFDictionarySetValue(dict, CFSTR("application-identifier"), CFSTR("AJ$K#GK$."));
+        require(!filter_entitlements(dict), fail_test);
+        CFDictionarySetValue(dict, CFSTR("application-identifier"), CFSTR("AJ$K#GK$.hoi"));
+        require(filter_entitlements(dict), fail_test);
+
+        CFDictionarySetValue(dict, CFSTR("keychain-access-groups"), CFSTR("apple"));
+        require(!filter_entitlements(dict), fail_test);
+        const void *ary[] = { CFSTR("test"), CFSTR("apple") };
+        CFArrayRef ka_array = CFArrayCreate(NULL, ary, sizeof(ary)/sizeof(*ary), NULL);
+        CFDictionarySetValue(dict, CFSTR("keychain-access-groups"), ka_array);
+        require(!filter_entitlements(dict), fail_test);
+        CFDictionarySetValue(dict, CFSTR("keychain-access-groups"), CFSTR("AJ$K#GK$.joh"));
+        require(filter_entitlements(dict), fail_test);
+        CFDictionarySetValue(dict, CFSTR("this-should-not"), CFSTR("be-there"));
+        require(!filter_entitlements(dict), fail_test);
+
+        exit(0);
+fail_test:
+        fprintf(stderr, "failed internal test\n");
+        exit(1);
+    }
+#endif
+
+    if (argc != 2) {
+        fprintf(stderr, "usage: %s <file>\n", argv[0]);
+        exit(1);
+    }
+
+    do {
+
+        fprintf(stderr, "NOTICE: check_entitlements on %s", argv[1]);
+
+        int exit_status;
+        const char * const extract_entitlements[] =
+        { codesign_binary, "--display", "--entitlements", "-", argv[1], NULL };
+        int entitlements_fd;
+        if ((exit_status = fork_child_timeout_output(STDOUT_FILENO, &entitlements_fd,
+                        extract_entitlements, 0))) {
+            fprintf(stderr, "ERR: failed to extract entitlements: %d\n", exit_status);
+            break;
+        }
+
+        void *entitlements = NULL;
+        size_t entitlements_size = read_fd(entitlements_fd, &entitlements);
+        if (entitlements_size == -1)
+            break;
+        close(entitlements_fd);
+
+        if (entitlements && entitlements_size) {
+            CFDataRef ent = extract_entitlements_blob(entitlements, entitlements_size);
+            free(entitlements);
+            require(ent, out);
+            CFPropertyListRef entitlements_dict =
+                CFPropertyListCreateFromXMLData(kCFAllocatorDefault,
+                ent, kCFPropertyListImmutable, NULL);
+            CFRelease(ent);
+            require(entitlements_dict, out);
+            if (!filter_entitlements(entitlements_dict)) {
+                fprintf(stderr, "ERR: bad entitlements\n");
+                exit(1);
+            }
+            exit(0);
+        } else {
+            fprintf(stderr, "ERR: no entitlements!\n");
+        }
+    } while (0);
+out:
+    return 1;
+}
\ No newline at end of file