From ca5ef2759daa86981dbdbee31f4802e82b459b29 Mon Sep 17 00:00:00 2001 From: Adrian Ratiu Date: Fri, 2 Aug 2024 11:02:25 +0300 Subject: proc: add config & param to block forcing mem writes [ Upstream commit 41e8149c8892ed1962bd15350b3c3e6e90cba7f4 ] This adds a Kconfig option and boot param to allow removing the FOLL_FORCE flag from /proc/pid/mem write calls because it can be abused. The traditional forcing behavior is kept as default because it can break GDB and some other use cases. Previously we tried a more sophisticated approach allowing distributions to fine-tune /proc/pid/mem behavior, however that got NAK-ed by Linus [1], who prefers this simpler approach with semantics also easier to understand for users. Link: https://lore.kernel.org/lkml/CAHk-=wiGWLChxYmUA5HrT5aopZrB7_2VTa0NLZcxORgkUe5tEQ@mail.gmail.com/ [1] Cc: Doug Anderson Cc: Jeff Xu Cc: Jann Horn Cc: Kees Cook Cc: Ard Biesheuvel Cc: Christian Brauner Suggested-by: Linus Torvalds Signed-off-by: Linus Torvalds Signed-off-by: Adrian Ratiu Link: https://lore.kernel.org/r/20240802080225.89408-1-adrian.ratiu@collabora.com Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin --- Documentation/admin-guide/kernel-parameters.txt | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'Documentation') diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 8df4c1c5c619..18c8fc60db93 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -4540,6 +4540,16 @@ printk.time= Show timing data prefixed to each printk message line Format: (1/Y/y=enable, 0/N/n=disable) + proc_mem.force_override= [KNL] + Format: {always | ptrace | never} + Traditionally /proc/pid/mem allows memory permissions to be + overridden without restrictions. This option may be set to + restrict that. Can be one of: + - 'always': traditional behavior always allows mem overrides. + - 'ptrace': only allow mem overrides for active ptracers. + - 'never': never allow mem overrides. + If not specified, default is the CONFIG_PROC_MEM_* choice. + processor.max_cstate= [HW,ACPI] Limit processor to maximum C-state max_cstate=9 overrides any DMI blacklist limit. -- cgit v1.2.3