From dac494bf54f764a114f16621ef04f534dd754ac1 Mon Sep 17 00:00:00 2001 From: Benjamin Berg Date: Mon, 2 Jun 2025 15:00:47 +0200 Subject: um: Add stub side of SECCOMP/futex based process handling This adds the stub side for the new seccomp process management code. In this case we do register save/restore through the signal handler mcontext. Add special code for handling TLS, which for x86_64 means setting the FS_BASE/GS_BASE registers while for i386 it means calling the set_thread_area syscall. Co-authored-by: Johannes Berg Signed-off-by: Benjamin Berg Signed-off-by: Benjamin Berg Link: https://patch.msgid.link/20250602130052.545733-3-benjamin@sipsolutions.net Signed-off-by: Johannes Berg --- arch/um/include/shared/common-offsets.h | 2 ++ arch/um/include/shared/skas/stub-data.h | 14 ++++++++++++++ 2 files changed, 16 insertions(+) (limited to 'arch/um/include/shared') diff --git a/arch/um/include/shared/common-offsets.h b/arch/um/include/shared/common-offsets.h index 73f3a4792ed8..93e7097a2922 100644 --- a/arch/um/include/shared/common-offsets.h +++ b/arch/um/include/shared/common-offsets.h @@ -14,3 +14,5 @@ DEFINE(UM_THREAD_SIZE, THREAD_SIZE); DEFINE(UM_NSEC_PER_SEC, NSEC_PER_SEC); DEFINE(UM_NSEC_PER_USEC, NSEC_PER_USEC); + +DEFINE(UM_KERN_GDT_ENTRY_TLS_ENTRIES, GDT_ENTRY_TLS_ENTRIES); diff --git a/arch/um/include/shared/skas/stub-data.h b/arch/um/include/shared/skas/stub-data.h index 81a4cace032c..81ac2cd12112 100644 --- a/arch/um/include/shared/skas/stub-data.h +++ b/arch/um/include/shared/skas/stub-data.h @@ -11,6 +11,10 @@ #include #include #include +#include + +#define FUTEX_IN_CHILD 0 +#define FUTEX_IN_KERN 1 struct stub_init_data { unsigned long stub_start; @@ -52,6 +56,16 @@ struct stub_data { /* 128 leaves enough room for additional fields in the struct */ struct stub_syscall syscall_data[(UM_KERN_PAGE_SIZE - 128) / sizeof(struct stub_syscall)] __aligned(16); + /* data shared with signal handler (only used in seccomp mode) */ + short restart_wait; + unsigned int futex; + int signal; + unsigned short si_offset; + unsigned short mctx_offset; + + /* seccomp architecture specific state restore */ + struct stub_data_arch arch_data; + /* Stack for our signal handlers and for calling into . */ unsigned char sigstack[UM_KERN_PAGE_SIZE] __aligned(UM_KERN_PAGE_SIZE); }; -- cgit v1.2.3