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Get the entitlements of a given Mach-O image existing in memory
#import <Foundation/Foundation.h>
#import <mach-o/loader.h>
#if __has_include(<Kernel/kern/cs_blobs.h>)
# import <Kernel/kern/cs_blobs.h>
#else
/* some Darwin distributions don't provide the cs_blobs header
* copy it from the macOS SDK if available, otherwise one of
* https://opensource.apple.com/source/xnu/xnu-4903.221.2/osfmk/kern/cs_blobs.h.auto.html
* https://github.com/apple/darwin-xnu/blob/a449c6a3b8014d9406c2ddbdc81795da24aa7443/osfmk/kern/cs_blobs.h
* (these should be API and ABI stable, so any version of xnu should be fine)
*/
# import "cs_blobs.h"
#endif
/**
* @function entitlementsForImage
* @param mh A pointer to the mach_header of the image to search. The entire image must be loaded into readable memory. The header may be either @c mach_header or @c mach_header_64
* @param error An error to be filled out in the event of one of the following:
* (1) The type of mach_header provided can not be identified
* (2) The signature blob of the image could not be found
* (3) The signature blob has an invalid magic
* (4) The entitlement blob could not be found
* (*) The entitlemnt blob was not able to be converted to a dictionary
* @return The embedded entitlements of a given image
* @discussion Based on @c Security/codesign_wrapper/check_entitlements.c . This routine does not check the validity of the code signature
*/
NSDictionary *_Nullable entitlementsForImage(const struct mach_header *_Nonnull const mh, NSError *_Nullable *_Nullable error) {
const struct load_command *lc = NULL;
if (mh->magic == MH_MAGIC_64) {
lc = (void *)mh + sizeof(struct mach_header_64);
} else if (mh->magic == MH_MAGIC) {
lc = (void *)mh + sizeof(struct mach_header);
} else {
if (error) {
*error = [NSError errorWithDomain:@"null.leptos.entitlementsForImage" code:1 userInfo:@{
NSLocalizedDescriptionKey : @"mach_header has an unknown magic"
}];
}
return nil;
}
const CS_SuperBlob *superBlob = NULL;
for (uint32_t cmd = 0; cmd < mh->ncmds; cmd++) {
if (lc->cmd == LC_CODE_SIGNATURE) {
const struct linkedit_data_command *sb = (void *)lc;
superBlob = (void *)mh + sb->dataoff;
break;
}
lc = (void *)lc + lc->cmdsize;
}
if (!superBlob) {
if (error) {
*error = [NSError errorWithDomain:@"null.leptos.entitlementsForImage" code:2 userInfo:@{
NSLocalizedDescriptionKey : @"Could not find signature blob"
}];
}
return nil;
}
if (ntohl(superBlob->magic) != CSMAGIC_EMBEDDED_SIGNATURE) {
if (error) {
*error = [NSError errorWithDomain:@"null.leptos.entitlementsForImage" code:3 userInfo:@{
NSLocalizedDescriptionKey : @"Signature blob has an unknown magic"
}];
}
return nil;
}
NSData *blobData = NULL;
const uint32_t blobCount = ntohl(superBlob->count);
for (uint32_t i = 0; i < blobCount; i++) {
const CS_GenericBlob *blob = (void *)superBlob + ntohl(superBlob->index[i].offset);
if (ntohl(blob->magic) != CSMAGIC_EMBEDDED_ENTITLEMENTS) {
continue;
}
blobData = [NSData dataWithBytesNoCopy:(void *)blob->data length:ntohl(blob->length) - offsetof(CS_GenericBlob, data) freeWhenDone:NO];
break;
}
if (!blobData) {
if (error) {
*error = [NSError errorWithDomain:@"null.leptos.entitlementsForImage" code:4 userInfo:@{
NSLocalizedDescriptionKey : @"Could not find entitlements blob"
}];
}
return nil;
}
return [NSPropertyListSerialization propertyListWithData:blobData options:NSPropertyListImmutable format:NULL error:error];
}
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