PR_PAC_RESET_KEYS(2const)

NAME
PR_PAC_RESET_KEYS - reset the calling thread's pointer authentication code keys

LIBRARY
Standard C library (libc, -lc)

SYNOPSIS
#include <linux/prctl.h>  /* Definition of PR_* constants */
#include <sys/prctl.h>

int prctl(PR_PAC_RESET_KEYS, unsigned long keys, 0L, 0L, 0L);

DESCRIPTION
Securely reset the thread's pointer authentication keys to fresh random values generated by the kernel.

The set of keys to be reset is specified by keys, which must be a logical OR of zero or more of the following:

PR_PAC_APIAKEY
    instruction authentication key A

PR_PAC_APIBKEY
    instruction authentication key B

PR_PAC_APDAKEY
    data authentication key A

PR_PAC_APDBKEY
    data authentication key B

PR_PAC_APGAKEY
    generic authentication “A” key.

    (Yes folks, there really is no generic B key.)

As a special case, if keys is zero, then all the keys are reset. Since new keys could be added in future, this is the recommended way to completely wipe the existing keys when establishing a clean execution context.

There is no need to use PR_PAC_RESET_KEYS in preparation for calling execve(2), since execve(2) resets all the pointer authentication keys.

RETURN VALUE
On success, 0 is returned. On error, -1 is returned, and errno is set to indicate the error.

ERRORS

EINVAL
    keys contains set bits that are invalid or unsupported on this platform.

STANDARDS
Linux. arm64 only.

HISTORY
Linux 5.0 (arm64).

CAVEATS
Because the compiler or run-time environment may be using some or all of the keys, a successful PR_PAC_RESET_KEYS may crash the calling process. The conditions for using it safely are complex and system-dependent. Don't use it unless you know what you are doing.

SEE ALSO
prctl(2)

For more information, see the kernel source file Documentation/arm64/pointer-authentication.rst (or Documentation/arm64/pointer-authentication.txt before Linux 5.3).