diff options
Diffstat (limited to 'common/recipes-kernel/linux/linux-yocto-4.9.21/0044-prctl-Add-speculation-control-prctls.patch')
| -rw-r--r-- | common/recipes-kernel/linux/linux-yocto-4.9.21/0044-prctl-Add-speculation-control-prctls.patch | 239 |
1 files changed, 239 insertions, 0 deletions
diff --git a/common/recipes-kernel/linux/linux-yocto-4.9.21/0044-prctl-Add-speculation-control-prctls.patch b/common/recipes-kernel/linux/linux-yocto-4.9.21/0044-prctl-Add-speculation-control-prctls.patch new file mode 100644 index 00000000..1baf848c --- /dev/null +++ b/common/recipes-kernel/linux/linux-yocto-4.9.21/0044-prctl-Add-speculation-control-prctls.patch @@ -0,0 +1,239 @@ +From 93715f38b4419faa4f84a9bb536f11d89c5c7427 Mon Sep 17 00:00:00 2001 +From: Thomas Gleixner <tglx@linutronix.de> +Date: Sun, 29 Apr 2018 15:20:11 +0200 +Subject: [PATCH 44/93] prctl: Add speculation control prctls + +commit b617cfc858161140d69cc0b5cc211996b557a1c7 upstream + +Add two new prctls to control aspects of speculation related vulnerabilites +and their mitigations to provide finer grained control over performance +impacting mitigations. + +PR_GET_SPECULATION_CTRL returns the state of the speculation misfeature +which is selected with arg2 of prctl(2). The return value uses bit 0-2 with +the following meaning: + +Bit Define Description +0 PR_SPEC_PRCTL Mitigation can be controlled per task by + PR_SET_SPECULATION_CTRL +1 PR_SPEC_ENABLE The speculation feature is enabled, mitigation is + disabled +2 PR_SPEC_DISABLE The speculation feature is disabled, mitigation is + enabled + +If all bits are 0 the CPU is not affected by the speculation misfeature. + +If PR_SPEC_PRCTL is set, then the per task control of the mitigation is +available. If not set, prctl(PR_SET_SPECULATION_CTRL) for the speculation +misfeature will fail. + +PR_SET_SPECULATION_CTRL allows to control the speculation misfeature, which +is selected by arg2 of prctl(2) per task. arg3 is used to hand in the +control value, i.e. either PR_SPEC_ENABLE or PR_SPEC_DISABLE. + +The common return values are: + +EINVAL prctl is not implemented by the architecture or the unused prctl() + arguments are not 0 +ENODEV arg2 is selecting a not supported speculation misfeature + +PR_SET_SPECULATION_CTRL has these additional return values: + +ERANGE arg3 is incorrect, i.e. it's not either PR_SPEC_ENABLE or PR_SPEC_DISABLE +ENXIO prctl control of the selected speculation misfeature is disabled + +The first supported controlable speculation misfeature is +PR_SPEC_STORE_BYPASS. Add the define so this can be shared between +architectures. + +Based on an initial patch from Tim Chen and mostly rewritten. + +Signed-off-by: Thomas Gleixner <tglx@linutronix.de> +Reviewed-by: Ingo Molnar <mingo@kernel.org> +Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> +Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> +Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> +--- + Documentation/spec_ctrl.txt | 86 +++++++++++++++++++++++++++++++++++++++++++++ + include/linux/nospec.h | 5 +++ + include/uapi/linux/prctl.h | 11 ++++++ + kernel/sys.c | 22 ++++++++++++ + 4 files changed, 124 insertions(+) + create mode 100644 Documentation/spec_ctrl.txt + +diff --git a/Documentation/spec_ctrl.txt b/Documentation/spec_ctrl.txt +new file mode 100644 +index 0000000..ddbebcd +--- /dev/null ++++ b/Documentation/spec_ctrl.txt +@@ -0,0 +1,86 @@ ++=================== ++Speculation Control ++=================== ++ ++Quite some CPUs have speculation related misfeatures which are in fact ++vulnerabilites causing data leaks in various forms even accross privilege ++domains. ++ ++The kernel provides mitigation for such vulnerabilities in various ++forms. Some of these mitigations are compile time configurable and some on ++the kernel command line. ++ ++There is also a class of mitigations which are very expensive, but they can ++be restricted to a certain set of processes or tasks in controlled ++environments. The mechanism to control these mitigations is via ++:manpage:`prctl(2)`. ++ ++There are two prctl options which are related to this: ++ ++ * PR_GET_SPECULATION_CTRL ++ ++ * PR_SET_SPECULATION_CTRL ++ ++PR_GET_SPECULATION_CTRL ++----------------------- ++ ++PR_GET_SPECULATION_CTRL returns the state of the speculation misfeature ++which is selected with arg2 of prctl(2). The return value uses bits 0-2 with ++the following meaning: ++ ++==== ================ =================================================== ++Bit Define Description ++==== ================ =================================================== ++0 PR_SPEC_PRCTL Mitigation can be controlled per task by ++ PR_SET_SPECULATION_CTRL ++1 PR_SPEC_ENABLE The speculation feature is enabled, mitigation is ++ disabled ++2 PR_SPEC_DISABLE The speculation feature is disabled, mitigation is ++ enabled ++==== ================ =================================================== ++ ++If all bits are 0 the CPU is not affected by the speculation misfeature. ++ ++If PR_SPEC_PRCTL is set, then the per task control of the mitigation is ++available. If not set, prctl(PR_SET_SPECULATION_CTRL) for the speculation ++misfeature will fail. ++ ++PR_SET_SPECULATION_CTRL ++----------------------- ++PR_SET_SPECULATION_CTRL allows to control the speculation misfeature, which ++is selected by arg2 of :manpage:`prctl(2)` per task. arg3 is used to hand ++in the control value, i.e. either PR_SPEC_ENABLE or PR_SPEC_DISABLE. ++ ++Common error codes ++------------------ ++======= ================================================================= ++Value Meaning ++======= ================================================================= ++EINVAL The prctl is not implemented by the architecture or unused ++ prctl(2) arguments are not 0 ++ ++ENODEV arg2 is selecting a not supported speculation misfeature ++======= ================================================================= ++ ++PR_SET_SPECULATION_CTRL error codes ++----------------------------------- ++======= ================================================================= ++Value Meaning ++======= ================================================================= ++0 Success ++ ++ERANGE arg3 is incorrect, i.e. it's neither PR_SPEC_ENABLE nor ++ PR_SPEC_DISABLE ++ ++ENXIO Control of the selected speculation misfeature is not possible. ++ See PR_GET_SPECULATION_CTRL. ++======= ================================================================= ++ ++Speculation misfeature controls ++------------------------------- ++- PR_SPEC_STORE_BYPASS: Speculative Store Bypass ++ ++ Invocations: ++ * prctl(PR_GET_SPECULATION_CTRL, PR_SPEC_STORE_BYPASS, 0, 0, 0); ++ * prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_STORE_BYPASS, PR_SPEC_ENABLE, 0, 0); ++ * prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_STORE_BYPASS, PR_SPEC_DISABLE, 0, 0); +diff --git a/include/linux/nospec.h b/include/linux/nospec.h +index e791ebc..700bb8a 100644 +--- a/include/linux/nospec.h ++++ b/include/linux/nospec.h +@@ -55,4 +55,9 @@ static inline unsigned long array_index_mask_nospec(unsigned long index, + \ + (typeof(_i)) (_i & _mask); \ + }) ++ ++/* Speculation control prctl */ ++int arch_prctl_spec_ctrl_get(unsigned long which); ++int arch_prctl_spec_ctrl_set(unsigned long which, unsigned long ctrl); ++ + #endif /* _LINUX_NOSPEC_H */ +diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h +index a8d0759..3b316be 100644 +--- a/include/uapi/linux/prctl.h ++++ b/include/uapi/linux/prctl.h +@@ -197,4 +197,15 @@ struct prctl_mm_map { + # define PR_CAP_AMBIENT_LOWER 3 + # define PR_CAP_AMBIENT_CLEAR_ALL 4 + ++/* Per task speculation control */ ++#define PR_GET_SPECULATION_CTRL 52 ++#define PR_SET_SPECULATION_CTRL 53 ++/* Speculation control variants */ ++# define PR_SPEC_STORE_BYPASS 0 ++/* Return and control values for PR_SET/GET_SPECULATION_CTRL */ ++# define PR_SPEC_NOT_AFFECTED 0 ++# define PR_SPEC_PRCTL (1UL << 0) ++# define PR_SPEC_ENABLE (1UL << 1) ++# define PR_SPEC_DISABLE (1UL << 2) ++ + #endif /* _LINUX_PRCTL_H */ +diff --git a/kernel/sys.c b/kernel/sys.c +index 89d5be4..312c985 100644 +--- a/kernel/sys.c ++++ b/kernel/sys.c +@@ -53,6 +53,8 @@ + #include <linux/uidgid.h> + #include <linux/cred.h> + ++#include <linux/nospec.h> ++ + #include <linux/kmsg_dump.h> + /* Move somewhere else to avoid recompiling? */ + #include <generated/utsrelease.h> +@@ -2072,6 +2074,16 @@ static int prctl_get_tid_address(struct task_struct *me, int __user **tid_addr) + } + #endif + ++int __weak arch_prctl_spec_ctrl_get(unsigned long which) ++{ ++ return -EINVAL; ++} ++ ++int __weak arch_prctl_spec_ctrl_set(unsigned long which, unsigned long ctrl) ++{ ++ return -EINVAL; ++} ++ + SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3, + unsigned long, arg4, unsigned long, arg5) + { +@@ -2270,6 +2282,16 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3, + case PR_GET_FP_MODE: + error = GET_FP_MODE(me); + break; ++ case PR_GET_SPECULATION_CTRL: ++ if (arg3 || arg4 || arg5) ++ return -EINVAL; ++ error = arch_prctl_spec_ctrl_get(arg2); ++ break; ++ case PR_SET_SPECULATION_CTRL: ++ if (arg4 || arg5) ++ return -EINVAL; ++ error = arch_prctl_spec_ctrl_set(arg2, arg3); ++ break; + default: + error = -EINVAL; + break; +-- +2.7.4 + |