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| author | Johannes Berg <johannes.berg@intel.com> | 2025-02-10 19:09:25 +0300 |
|---|---|---|
| committer | Johannes Berg <johannes.berg@intel.com> | 2025-03-18 13:03:14 +0300 |
| commit | d1d7f01f7cd35e16c6bcef5a0e31988b5c9980f9 (patch) | |
| tree | ac2a7b2c4ccc6a9f1749c48eca519d615d125942 /arch/um/os-Linux | |
| parent | 5550187c4c21740942c32a9ae56f9f472a104cb4 (diff) | |
| download | linux-d1d7f01f7cd35e16c6bcef5a0e31988b5c9980f9.tar.xz | |
um: mark rodata read-only and implement _nofault accesses
Mark read-only data actually read-only (simple mprotect), and
to be able to test it also implement _nofault accesses. This
works by setting up a new "segv_continue" pointer in current,
and then when we hit a segfault we change the signal return
context so that we continue at that address. The code using
this sets it up so that it jumps to a label and then aborts
the access that way, returning -EFAULT.
It's possible to optimize the ___backtrack_faulted() thing by
using asm goto (compiler version dependent) and/or gcc's (not
sure if clang has it) &&label extension, but at least in one
attempt I made the && caused the compiler to not load -EFAULT
into the register in case of jumping to the &&label from the
fault handler. So leave it like this for now.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Co-developed-by: Benjamin Berg <benjamin.berg@intel.com>
Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Link: https://patch.msgid.link/20250210160926.420133-2-benjamin@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Diffstat (limited to 'arch/um/os-Linux')
| -rw-r--r-- | arch/um/os-Linux/signal.c | 4 | ||||
| -rw-r--r-- | arch/um/os-Linux/skas/process.c | 8 |
2 files changed, 6 insertions, 6 deletions
diff --git a/arch/um/os-Linux/signal.c b/arch/um/os-Linux/signal.c index 9ea7269ffb77..e71e5b4878d1 100644 --- a/arch/um/os-Linux/signal.c +++ b/arch/um/os-Linux/signal.c @@ -21,7 +21,7 @@ #include <sys/ucontext.h> #include <timetravel.h> -void (*sig_info[NSIG])(int, struct siginfo *, struct uml_pt_regs *) = { +void (*sig_info[NSIG])(int, struct siginfo *, struct uml_pt_regs *, void *mc) = { [SIGTRAP] = relay_signal, [SIGFPE] = relay_signal, [SIGILL] = relay_signal, @@ -47,7 +47,7 @@ static void sig_handler_common(int sig, struct siginfo *si, mcontext_t *mc) if ((sig != SIGIO) && (sig != SIGWINCH)) unblock_signals_trace(); - (*sig_info[sig])(sig, si, &r); + (*sig_info[sig])(sig, si, &r, mc); errno = save_errno; } diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c index e2f8f156402f..ae2aea062f06 100644 --- a/arch/um/os-Linux/skas/process.c +++ b/arch/um/os-Linux/skas/process.c @@ -166,7 +166,7 @@ static void get_skas_faultinfo(int pid, struct faultinfo *fi) static void handle_segv(int pid, struct uml_pt_regs *regs) { get_skas_faultinfo(pid, ®s->faultinfo); - segv(regs->faultinfo, 0, 1, NULL); + segv(regs->faultinfo, 0, 1, NULL, NULL); } static void handle_trap(int pid, struct uml_pt_regs *regs) @@ -525,7 +525,7 @@ void userspace(struct uml_pt_regs *regs) get_skas_faultinfo(pid, ®s->faultinfo); (*sig_info[SIGSEGV])(SIGSEGV, (struct siginfo *)&si, - regs); + regs, NULL); } else handle_segv(pid, regs); break; @@ -533,7 +533,7 @@ void userspace(struct uml_pt_regs *regs) handle_trap(pid, regs); break; case SIGTRAP: - relay_signal(SIGTRAP, (struct siginfo *)&si, regs); + relay_signal(SIGTRAP, (struct siginfo *)&si, regs, NULL); break; case SIGALRM: break; @@ -543,7 +543,7 @@ void userspace(struct uml_pt_regs *regs) case SIGFPE: case SIGWINCH: block_signals_trace(); - (*sig_info[sig])(sig, (struct siginfo *)&si, regs); + (*sig_info[sig])(sig, (struct siginfo *)&si, regs, NULL); unblock_signals_trace(); break; default: |