This adds userspace access to Diffie-Hellman computations through a new keyctl() syscall command to calculate shared secrets or public keys using input parameters stored in the keyring. Input key ids are provided in a struct due to the current 5-arg limit for the keyctl syscall. Only user keys are supported in order to avoid exposing the content of logon or encrypted keys. The output is written to the provided buffer, based on the assumption that the values are only needed in userspace. Future support for other types of key derivation would involve a new command, like KEYCTL_ECDH_COMPUTE. Once Diffie-Hellman support is included in the crypto API, this code can be converted to use the crypto API to take advantage of possible hardware acceleration and reduce redundant code.
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| @@ -12,6 +12,8 @@ · 11 unmodified lines | ||
| 12 | 12 | #ifndef _LINUX_KEYCTL_H |
| 13 | 13 | #define _LINUX_KEYCTL_H |
| 14 | 14 | |
| 15 | +#include <linux/types.h> | |
| 16 | + | |
| 15 | 17 | /* special process keyring shortcut IDs */ |
| 16 | 18 | #define KEY_SPEC_THREAD_KEYRING -1 /* - key ID for thread-specific keyring */ |
| 17 | 19 | #define KEY_SPEC_PROCESS_KEYRING -2 /* - key ID for process-specific keyring */ |
| @@ -57,5 +59,13 @@ · 39 unmodified lines | ||
| 57 | 59 | #define KEYCTL_INSTANTIATE_IOV 20 /* instantiate a partially constructed key */ |
| 58 | 60 | #define KEYCTL_INVALIDATE 21 /* invalidate a key */ |
| 59 | 61 | #define KEYCTL_GET_PERSISTENT 22 /* get a user's persistent keyring */ |
| 62 | +#define KEYCTL_DH_COMPUTE 23 /* Compute Diffie-Hellman values */ | |
| 63 | + | |
| 64 | +/* keyctl structures */ | |
| 65 | +struct keyctl_dh_params { | |
| 66 | + __s32 private; | |
| 67 | + __s32 prime; | |
| 68 | + __s32 base; | |
| 69 | +}; | |
| 60 | 70 | |
| 61 | 71 | #endif /* _LINUX_KEYCTL_H */ |