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-rw-r--r--arch/x86/kernel/entry_64.S51
-rw-r--r--arch/x86/kernel/ptrace.c165
-rw-r--r--arch/x86/kernel/vsyscall_64.c2
3 files changed, 155 insertions, 63 deletions
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 2fac1343a90b..df088bb03fb3 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -404,8 +404,8 @@ GLOBAL(system_call_after_swapgs)
* and short:
*/
ENABLE_INTERRUPTS(CLBR_NONE)
- SAVE_ARGS 8,0
- movq %rax,ORIG_RAX-ARGOFFSET(%rsp)
+ SAVE_ARGS 8, 0, rax_enosys=1
+ movq_cfi rax,(ORIG_RAX-ARGOFFSET)
movq %rcx,RIP-ARGOFFSET(%rsp)
CFI_REL_OFFSET rip,RIP-ARGOFFSET
testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags+THREAD_INFO(%rsp,RIP-ARGOFFSET)
@@ -417,7 +417,7 @@ system_call_fastpath:
andl $__SYSCALL_MASK,%eax
cmpl $__NR_syscall_max,%eax
#endif
- ja badsys
+ ja ret_from_sys_call /* and return regs->ax */
movq %r10,%rcx
call *sys_call_table(,%rax,8) # XXX: rip relative
movq %rax,RAX-ARGOFFSET(%rsp)
@@ -476,28 +476,8 @@ sysret_signal:
FIXUP_TOP_OF_STACK %r11, -ARGOFFSET
jmp int_check_syscall_exit_work
-badsys:
- movq $-ENOSYS,RAX-ARGOFFSET(%rsp)
- jmp ret_from_sys_call
-
#ifdef CONFIG_AUDITSYSCALL
/*
- * Fast path for syscall audit without full syscall trace.
- * We just call __audit_syscall_entry() directly, and then
- * jump back to the normal fast path.
- */
-auditsys:
- movq %r10,%r9 /* 6th arg: 4th syscall arg */
- movq %rdx,%r8 /* 5th arg: 3rd syscall arg */
- movq %rsi,%rcx /* 4th arg: 2nd syscall arg */
- movq %rdi,%rdx /* 3rd arg: 1st syscall arg */
- movq %rax,%rsi /* 2nd arg: syscall number */
- movl $AUDIT_ARCH_X86_64,%edi /* 1st arg: audit arch */
- call __audit_syscall_entry
- LOAD_ARGS 0 /* reload call-clobbered registers */
- jmp system_call_fastpath
-
- /*
* Return fast path for syscall audit. Call __audit_syscall_exit()
* directly and then jump back to the fast path with TIF_SYSCALL_AUDIT
* masked off.
@@ -514,18 +494,25 @@ sysret_audit:
/* Do syscall tracing */
tracesys:
-#ifdef CONFIG_AUDITSYSCALL
- testl $(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT),TI_flags+THREAD_INFO(%rsp,RIP-ARGOFFSET)
- jz auditsys
-#endif
+ leaq -REST_SKIP(%rsp), %rdi
+ movq $AUDIT_ARCH_X86_64, %rsi
+ call syscall_trace_enter_phase1
+ test %rax, %rax
+ jnz tracesys_phase2 /* if needed, run the slow path */
+ LOAD_ARGS 0 /* else restore clobbered regs */
+ jmp system_call_fastpath /* and return to the fast path */
+
+tracesys_phase2:
SAVE_REST
- movq $-ENOSYS,RAX(%rsp) /* ptrace can change this for a bad syscall */
FIXUP_TOP_OF_STACK %rdi
- movq %rsp,%rdi
- call syscall_trace_enter
+ movq %rsp, %rdi
+ movq $AUDIT_ARCH_X86_64, %rsi
+ movq %rax,%rdx
+ call syscall_trace_enter_phase2
+
/*
* Reload arg registers from stack in case ptrace changed them.
- * We don't reload %rax because syscall_trace_enter() returned
+ * We don't reload %rax because syscall_trace_entry_phase2() returned
* the value it wants us to use in the table lookup.
*/
LOAD_ARGS ARGOFFSET, 1
@@ -536,7 +523,7 @@ tracesys:
andl $__SYSCALL_MASK,%eax
cmpl $__NR_syscall_max,%eax
#endif
- ja int_ret_from_sys_call /* RAX(%rsp) set to -ENOSYS above */
+ ja int_ret_from_sys_call /* RAX(%rsp) is already set */
movq %r10,%rcx /* fixup for C */
call *sys_call_table(,%rax,8)
movq %rax,RAX-ARGOFFSET(%rsp)
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 678c0ada3b3c..29576c244699 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -1441,24 +1441,126 @@ void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs,
force_sig_info(SIGTRAP, &info, tsk);
}
-
-#ifdef CONFIG_X86_32
-# define IS_IA32 1
-#elif defined CONFIG_IA32_EMULATION
-# define IS_IA32 is_compat_task()
-#else
-# define IS_IA32 0
+static void do_audit_syscall_entry(struct pt_regs *regs, u32 arch)
+{
+#ifdef CONFIG_X86_64
+ if (arch == AUDIT_ARCH_X86_64) {
+ audit_syscall_entry(arch, regs->orig_ax, regs->di,
+ regs->si, regs->dx, regs->r10);
+ } else
#endif
+ {
+ audit_syscall_entry(arch, regs->orig_ax, regs->bx,
+ regs->cx, regs->dx, regs->si);
+ }
+}
/*
- * We must return the syscall number to actually look up in the table.
- * This can be -1L to skip running any syscall at all.
+ * We can return 0 to resume the syscall or anything else to go to phase
+ * 2. If we resume the syscall, we need to put something appropriate in
+ * regs->orig_ax.
+ *
+ * NB: We don't have full pt_regs here, but regs->orig_ax and regs->ax
+ * are fully functional.
+ *
+ * For phase 2's benefit, our return value is:
+ * 0: resume the syscall
+ * 1: go to phase 2; no seccomp phase 2 needed
+ * anything else: go to phase 2; pass return value to seccomp
*/
-long syscall_trace_enter(struct pt_regs *regs)
+unsigned long syscall_trace_enter_phase1(struct pt_regs *regs, u32 arch)
+{
+ unsigned long ret = 0;
+ u32 work;
+
+ BUG_ON(regs != task_pt_regs(current));
+
+ work = ACCESS_ONCE(current_thread_info()->flags) &
+ _TIF_WORK_SYSCALL_ENTRY;
+
+ /*
+ * If TIF_NOHZ is set, we are required to call user_exit() before
+ * doing anything that could touch RCU.
+ */
+ if (work & _TIF_NOHZ) {
+ user_exit();
+ work &= ~TIF_NOHZ;
+ }
+
+#ifdef CONFIG_SECCOMP
+ /*
+ * Do seccomp first -- it should minimize exposure of other
+ * code, and keeping seccomp fast is probably more valuable
+ * than the rest of this.
+ */
+ if (work & _TIF_SECCOMP) {
+ struct seccomp_data sd;
+
+ sd.arch = arch;
+ sd.nr = regs->orig_ax;
+ sd.instruction_pointer = regs->ip;
+#ifdef CONFIG_X86_64
+ if (arch == AUDIT_ARCH_X86_64) {
+ sd.args[0] = regs->di;
+ sd.args[1] = regs->si;
+ sd.args[2] = regs->dx;
+ sd.args[3] = regs->r10;
+ sd.args[4] = regs->r8;
+ sd.args[5] = regs->r9;
+ } else
+#endif
+ {
+ sd.args[0] = regs->bx;
+ sd.args[1] = regs->cx;
+ sd.args[2] = regs->dx;
+ sd.args[3] = regs->si;
+ sd.args[4] = regs->di;
+ sd.args[5] = regs->bp;
+ }
+
+ BUILD_BUG_ON(SECCOMP_PHASE1_OK != 0);
+ BUILD_BUG_ON(SECCOMP_PHASE1_SKIP != 1);
+
+ ret = seccomp_phase1(&sd);
+ if (ret == SECCOMP_PHASE1_SKIP) {
+ regs->orig_ax = -1;
+ ret = 0;
+ } else if (ret != SECCOMP_PHASE1_OK) {
+ return ret; /* Go directly to phase 2 */
+ }
+
+ work &= ~_TIF_SECCOMP;
+ }
+#endif
+
+ /* Do our best to finish without phase 2. */
+ if (work == 0)
+ return ret; /* seccomp and/or nohz only (ret == 0 here) */
+
+#ifdef CONFIG_AUDITSYSCALL
+ if (work == _TIF_SYSCALL_AUDIT) {
+ /*
+ * If there is no more work to be done except auditing,
+ * then audit in phase 1. Phase 2 always audits, so, if
+ * we audit here, then we can't go on to phase 2.
+ */
+ do_audit_syscall_entry(regs, arch);
+ return 0;
+ }
+#endif
+
+ return 1; /* Something is enabled that we can't handle in phase 1 */
+}
+
+/* Returns the syscall nr to run (which should match regs->orig_ax). */
+long syscall_trace_enter_phase2(struct pt_regs *regs, u32 arch,
+ unsigned long phase1_result)
{
long ret = 0;
+ u32 work = ACCESS_ONCE(current_thread_info()->flags) &
+ _TIF_WORK_SYSCALL_ENTRY;
- user_exit();
+ BUG_ON(regs != task_pt_regs(current));
/*
* If we stepped into a sysenter/syscall insn, it trapped in
@@ -1467,17 +1569,21 @@ long syscall_trace_enter(struct pt_regs *regs)
* do_debug() and we need to set it again to restore the user
* state. If we entered on the slow path, TF was already set.
*/
- if (test_thread_flag(TIF_SINGLESTEP))
+ if (work & _TIF_SINGLESTEP)
regs->flags |= X86_EFLAGS_TF;
- /* do the secure computing check first */
- if (secure_computing(regs->orig_ax)) {
+#ifdef CONFIG_SECCOMP
+ /*
+ * Call seccomp_phase2 before running the other hooks so that
+ * they can see any changes made by a seccomp tracer.
+ */
+ if (phase1_result > 1 && seccomp_phase2(phase1_result)) {
/* seccomp failures shouldn't expose any additional code. */
- ret = -1L;
- goto out;
+ return -1;
}
+#endif
- if (unlikely(test_thread_flag(TIF_SYSCALL_EMU)))
+ if (unlikely(work & _TIF_SYSCALL_EMU))
ret = -1L;
if ((ret || test_thread_flag(TIF_SYSCALL_TRACE)) &&
@@ -1487,23 +1593,22 @@ long syscall_trace_enter(struct pt_regs *regs)
if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
trace_sys_enter(regs, regs->orig_ax);
- if (IS_IA32)
- audit_syscall_entry(AUDIT_ARCH_I386,
- regs->orig_ax,
- regs->bx, regs->cx,
- regs->dx, regs->si);
-#ifdef CONFIG_X86_64
- else
- audit_syscall_entry(AUDIT_ARCH_X86_64,
- regs->orig_ax,
- regs->di, regs->si,
- regs->dx, regs->r10);
-#endif
+ do_audit_syscall_entry(regs, arch);
-out:
return ret ?: regs->orig_ax;
}
+long syscall_trace_enter(struct pt_regs *regs)
+{
+ u32 arch = is_ia32_task() ? AUDIT_ARCH_I386 : AUDIT_ARCH_X86_64;
+ unsigned long phase1_result = syscall_trace_enter_phase1(regs, arch);
+
+ if (phase1_result == 0)
+ return regs->orig_ax;
+ else
+ return syscall_trace_enter_phase2(regs, arch, phase1_result);
+}
+
void syscall_trace_leave(struct pt_regs *regs)
{
bool step;
diff --git a/arch/x86/kernel/vsyscall_64.c b/arch/x86/kernel/vsyscall_64.c
index e1e1e80fc6a6..957779f4eb40 100644
--- a/arch/x86/kernel/vsyscall_64.c
+++ b/arch/x86/kernel/vsyscall_64.c
@@ -216,7 +216,7 @@ bool emulate_vsyscall(struct pt_regs *regs, unsigned long address)
*/
regs->orig_ax = syscall_nr;
regs->ax = -ENOSYS;
- tmp = secure_computing(syscall_nr);
+ tmp = secure_computing();
if ((!tmp && regs->orig_ax != syscall_nr) || regs->ip != address) {
warn_bad_vsyscall(KERN_DEBUG, regs,
"seccomp tried to change syscall nr or ip");
generated by cgit v1.2.3 (git 2.25.1) at 2024-08-01 18:33:57 +0000