From d7e7528bcd456f5c36ad4a202ccfb43c5aa98bc4 Mon Sep 17 00:00:00 2001 From: Eric Paris Date: Tue, 3 Jan 2012 14:23:06 -0500 Subject: Audit: push audit success and retcode into arch ptrace.h The audit system previously expected arches calling to audit_syscall_exit to supply as arguments if the syscall was a success and what the return code was. Audit also provides a helper AUDITSC_RESULT which was supposed to simplify things by converting from negative retcodes to an audit internal magic value stating success or failure. This helper was wrong and could indicate that a valid pointer returned to userspace was a failed syscall. The fix is to fix the layering foolishness. We now pass audit_syscall_exit a struct pt_reg and it in turns calls back into arch code to collect the return value and to determine if the syscall was a success or failure. We also define a generic is_syscall_success() macro which determines success/failure based on if the value is < -MAX_ERRNO. This works for arches like x86 which do not use a separate mechanism to indicate syscall failure. We make both the is_syscall_success() and regs_return_value() static inlines instead of macros. The reason is because the audit function must take a void* for the regs. (uml calls theirs struct uml_pt_regs instead of just struct pt_regs so audit_syscall_exit can't take a struct pt_regs). Since the audit function takes a void* we need to use static inlines to cast it back to the arch correct structure to dereference it. The other major change is that on some arches, like ia64, MIPS and ppc, we change regs_return_value() to give us the negative value on syscall failure. THE only other user of this macro, kretprobe_example.c, won't notice and it makes the value signed consistently for the audit functions across all archs. In arch/sh/kernel/ptrace_64.c I see that we were using regs[9] in the old audit code as the return value. But the ptrace_64.h code defined the macro regs_return_value() as regs[3]. I have no idea which one is correct, but this patch now uses the regs_return_value() function, so it now uses regs[3]. For powerpc we previously used regs->result but now use the regs_return_value() function which uses regs->gprs[3]. regs->gprs[3] is always positive so the regs_return_value(), much like ia64 makes it negative before calling the audit code when appropriate. Signed-off-by: Eric Paris Acked-by: H. Peter Anvin [for x86 portion] Acked-by: Tony Luck [for ia64] Acked-by: Richard Weinberger [for uml] Acked-by: David S. Miller [for sparc] Acked-by: Ralf Baechle [for mips] Acked-by: Benjamin Herrenschmidt [for ppc] --- arch/x86/ia32/ia32entry.S | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) (limited to 'arch/x86/ia32/ia32entry.S') diff --git a/arch/x86/ia32/ia32entry.S b/arch/x86/ia32/ia32entry.S index 3e27456..64ced0b 100644 --- a/arch/x86/ia32/ia32entry.S +++ b/arch/x86/ia32/ia32entry.S @@ -14,6 +14,7 @@ #include #include #include +#include /* Avoid __ASSEMBLER__'ifying just for this. */ #include @@ -208,12 +209,11 @@ sysexit_from_sys_call: TRACE_IRQS_ON sti movl %eax,%esi /* second arg, syscall return value */ - cmpl $0,%eax /* is it < 0? */ - setl %al /* 1 if so, 0 if not */ + cmpl $-MAX_ERRNO,%eax /* is it an error ? */ + setbe %al /* 1 if so, 0 if not */ movzbl %al,%edi /* zero-extend that into %edi */ - inc %edi /* first arg, 0->1(AUDITSC_SUCCESS), 1->2(AUDITSC_FAILURE) */ - call audit_syscall_exit - movl RAX-ARGOFFSET(%rsp),%eax /* reload syscall return value */ + call __audit_syscall_exit + movq RAX-ARGOFFSET(%rsp),%rax /* reload syscall return value */ movl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT),%edi cli TRACE_IRQS_OFF -- cgit v1.1 From f031cd25568a390dc2c9c3a4015054183753449a Mon Sep 17 00:00:00 2001 From: Eric Paris Date: Tue, 3 Jan 2012 14:23:06 -0500 Subject: audit: ia32entry.S sign extend error codes when calling 64 bit code In the ia32entry syscall exit audit fastpath we have assembly code which calls __audit_syscall_exit directly. This code was, however, zeroes the upper 32 bits of the return code. It then proceeded to call code which expects longs to be 64bits long. In order to handle code which expects longs to be 64bit we sign extend the return code if that code is an error. Thus the __audit_syscall_exit function can correctly handle using the values in snprintf("%ld"). This fixes the regression introduced in 5cbf1565f29eb57a86a. Old record: type=SYSCALL msg=audit(1306197182.256:281): arch=40000003 syscall=192 success=no exit=4294967283 New record: type=SYSCALL msg=audit(1306197182.256:281): arch=40000003 syscall=192 success=no exit=-13 Signed-off-by: Eric Paris Acked-by: H. Peter Anvin --- arch/x86/ia32/ia32entry.S | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'arch/x86/ia32/ia32entry.S') diff --git a/arch/x86/ia32/ia32entry.S b/arch/x86/ia32/ia32entry.S index 64ced0b..025f0f0 100644 --- a/arch/x86/ia32/ia32entry.S +++ b/arch/x86/ia32/ia32entry.S @@ -210,7 +210,9 @@ sysexit_from_sys_call: sti movl %eax,%esi /* second arg, syscall return value */ cmpl $-MAX_ERRNO,%eax /* is it an error ? */ - setbe %al /* 1 if so, 0 if not */ + jbe 1f + movslq %eax, %rsi /* if error sign extend to 64 bits */ +1: setbe %al /* 1 if error, 0 if not */ movzbl %al,%edi /* zero-extend that into %edi */ call __audit_syscall_exit movq RAX-ARGOFFSET(%rsp),%rax /* reload syscall return value */ -- cgit v1.1 From b05d8447e7821695bc2fa3359431f7a664232743 Mon Sep 17 00:00:00 2001 From: Eric Paris Date: Tue, 3 Jan 2012 14:23:06 -0500 Subject: audit: inline audit_syscall_entry to reduce burden on archs Every arch calls: if (unlikely(current->audit_context)) audit_syscall_entry() which requires knowledge about audit (the existance of audit_context) in the arch code. Just do it all in static inline in audit.h so that arch's can remain blissfully ignorant. Signed-off-by: Eric Paris --- arch/x86/ia32/ia32entry.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/x86/ia32/ia32entry.S') diff --git a/arch/x86/ia32/ia32entry.S b/arch/x86/ia32/ia32entry.S index 025f0f0..cecfd9a 100644 --- a/arch/x86/ia32/ia32entry.S +++ b/arch/x86/ia32/ia32entry.S @@ -192,7 +192,7 @@ sysexit_from_sys_call: movl %ebx,%edx /* 3rd arg: 1st syscall arg */ movl %eax,%esi /* 2nd arg: syscall number */ movl $AUDIT_ARCH_I386,%edi /* 1st arg: audit arch */ - call audit_syscall_entry + call __audit_syscall_entry movl RAX-ARGOFFSET(%rsp),%eax /* reload syscall number */ cmpq $(IA32_NR_syscalls-1),%rax ja ia32_badsys -- cgit v1.1