File prctl.2-Add-PR_PAC_RESET_KEYS-arm64.patch of Package man-pages.21614
From 8165500d4c9c7a3a247524a0705b81fe6e9296c8 Mon Sep 17 00:00:00 2001 From: Dave Martin <Dave.Martin@arm.com> Date: Tue, 9 Jun 2020 13:30:57 +0200 Subject: [PATCH 1/2] prctl.2: Add PR_PAC_RESET_KEYS (arm64) Add documentation for the PR_PAC_RESET_KEYS ioctl added in Linux 5.0 for arm64. Signed-off-by: Dave Martin <Dave.Martin@arm.com> Cc: Will Deacon <will@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Amit Daniel Kachhap <amit.kachhap@arm.com> Cc: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com> --- man2/prctl.2 | 79 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 79 insertions(+) Index: b/man2/prctl.2 =================================================================== --- a/man2/prctl.2 +++ b/man2/prctl.2 @@ -831,6 +831,77 @@ behavior. A value of 1 indicates .BR execve (2) will operate in the privilege-restricting mode described above. +.\" prctl PR_PAC_RESET_KEYS +.\" commit ba830885656414101b2f8ca88786524d4bb5e8c1 +.TP +.BR PR_PAC_RESET_KEYS " (since Linux 5.0, only on arm64)" +Securely reset the thread's pointer authentication keys +to fresh random values generated by the kernel. +.IP +The set of keys to be reset is specified by +.IR arg2 , +which must be a logical OR of zero or more of the following: +.RS +.TP +.B PR_PAC_APIAKEY +instruction authentication key A +.TP +.B PR_PAC_APIBKEY +instruction authentication key B +.TP +.B PR_PAC_APDAKEY +data authentication key A +.TP +.B PR_PAC_APDBKEY +data authentication key B +.TP +.B PR_PAC_APGAKEY +generic authentication \(lqA\(rq key. +.IP +(Yes folks, there really is no generic B key.) +.RE +.IP +As a special case, if +.I arg2 +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. +Note that there is no need to use +.BR PR_PAC_RESET_KEYS +in preparation for calling +.BR execve (2), +since +.BR execve (2) +resets all the pointer authentication keys. +.IP +The remaining arguments +.IR arg3 ", " arg4 " and " arg5 +must all be zero. +.IP +If the arguments are invalid, +and in particular if +.I arg2 +contains set bits that are unrecognized +or that correspond to a key not available on this platform, +the call fails with error +.BR EINVAL . +.IP +.B Warning: +Because the compiler or run-time environment +may be using some or all of the keys, +a successful +.IP +For more information, see the kernel source file +.I Documentation/arm64/pointer\-authentication.rst +.\"commit b693d0b372afb39432e1c49ad7b3454855bc6bed +(or +.I Documentation/arm64/pointer\-authentication.txt +before Linux 5.3). +.B 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. .TP .BR PR_SET_PDEATHSIG " (since Linux 2.1.57)" Set the parent death signal @@ -1500,6 +1571,14 @@ or and .IR arg3 does not specify a valid capability. +.B EINVAL +.I option +is +.B PR_PAC_RESET_KEYS +and the arguments are invalid or unsupported. +See the description of +.B PR_PAC_RESET_KEYS +above for details. .TP .B ENXIO .I option
