Bug description: When I add an audit watch on a file with no arguments, I get perm=rwxa but on ia64, changes to the mode and context aren't audited. I get audit records on i386 and x86_64. See also: https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=239887 The sanity check in audit_match_class() is wrong, AUDIT_BITMASK_SIZE is 64, providing space for 2048 syscalls in 64 * 32bit integers. The comparison only supports 256 syscalls (sizeof __u32 is 4), and silently returns "no match" for valid higher-numbered syscalls. This breaks class-based audit for all syscalls on ia64 since on that architecture syscall numbers start at 1024. It breaks some syscall audit on other architectures also, for example __NR_fchmodat is 306 on x86. I'd suggest adding a printk() in addition to returning 0 - you don't want to silently ignore unknown or unsupported syscalls when auditing. Signed-off-by: Klaus Weidner <klaus(a)atsec.com&gt; --- linux-2.6.18.i686/kernel/auditfilter.c.lspp.80 2007-05-11 17:06:08.000000000 -0500 +++ linux-2.6.18.i686/kernel/auditfilter.c 2007-05-11 17:09:37.000000000 -0500 @@ -306,7 +306,7 @@ int audit_match_class(int class, unsigned syscall) { - if (unlikely(syscall >= AUDIT_BITMASK_SIZE * sizeof(__u32))) + if (unlikely(syscall >= AUDIT_BITMASK_SIZE * 32)) return 0; if (unlikely(class >= AUDIT_SYSCALL_CLASSES || !classes[class])) return 0;

On Mon, May 14, 2007 at 05:51:50PM +0200, Marcus Meissner wrote: > On Mon, May 14, 2007 at 10:46:36AM -0500, Klaus Weidner wrote: > > The sanity check in audit_match_class() is wrong, AUDIT_BITMASK_SIZE is > > 64, providing space for 2048 syscalls in 64 * 32bit integers. The > > comparison only supports 256 syscalls (sizeof __u32 is 4), and silently > > returns "no match" for valid higher-numbered syscalls. [...] > > --- linux-2.6.18.i686/kernel/auditfilter.c.lspp.80 2007-05-11 17:06:08.000000000 -0500 > > +++ linux-2.6.18.i686/kernel/auditfilter.c 2007-05-11 17:09:37.000000000 -0500 > > @@ -306,7 +306,7 @@ > > > > int audit_match_class(int class, unsigned syscall) > > { > > - if (unlikely(syscall >= AUDIT_BITMASK_SIZE * sizeof(__u32))) > > + if (unlikely(syscall >= AUDIT_BITMASK_SIZE * 32)) > > return 0; > > if (unlikely(class >= AUDIT_SYSCALL_CLASSES || !classes[class])) > > return 0; > > You likely need to fix audit_register_class() if this is true. I don't see a problem in audit_register_class() - it correctly uses sizeof(__u32) for allocating the memory since that's counted in bytes, only the comparison needs to count bits.

On Mon, May 14, 2007 at 04:47:29PM -0400, Eric Paris wrote: > On Mon, 2007-05-14 at 10:56 -0500, Klaus Weidner wrote: > > On Mon, May 14, 2007 at 05:51:50PM +0200, Marcus Meissner wrote: > > > On Mon, May 14, 2007 at 10:46:36AM -0500, Klaus Weidner wrote: > > > > The sanity check in audit_match_class() is wrong, AUDIT_BITMASK_SIZE is > > > > 64, providing space for 2048 syscalls in 64 * 32bit integers. The > > > > comparison only supports 256 syscalls (sizeof __u32 is 4), and silently > > > > returns "no match" for valid higher-numbered syscalls. > > [...] > > > > --- linux-2.6.18.i686/kernel/auditfilter.c.lspp.80 2007-05-11 17:06:08.000000000 -0500 > > > > +++ linux-2.6.18.i686/kernel/auditfilter.c 2007-05-11 17:09:37.000000000 -0500 > > > > @@ -306,7 +306,7 @@ > > > > > > > > int audit_match_class(int class, unsigned syscall) > > > > { > > > > - if (unlikely(syscall >= AUDIT_BITMASK_SIZE * sizeof(__u32))) > > > > + if (unlikely(syscall >= AUDIT_BITMASK_SIZE * 32)) > > > > return 0; > > > > if (unlikely(class >= AUDIT_SYSCALL_CLASSES || !classes[class])) > > > > return 0; > > > > > > You likely need to fix audit_register_class() if this is true. > > > > I don't see a problem in audit_register_class() - it correctly uses > > sizeof(__u32) for allocating the memory since that's counted in bytes, > > only the comparison needs to count bits. > > If that's the problem wouldn't we be better to use sizeof(__u32) *8 > rather than hard code the 32 in there? (sidebar: is it portable to > assume sizeof() returns bytes and *8 is the right way to go on all > archs?) That would make it easier to do u32 search/replace in the > future if we ever have to grow this stuff.... The AUDIT_WORD and AUDIT_BIT macros in include/linux/audit.h assume that they'll fit 32 bits into each __u32: #define AUDIT_WORD(nr) ((__u32)((nr)/32)) #define AUDIT_BIT(nr) (1 << ((nr) - AUDIT_WORD(nr)*32)) (If the actual capacity of the __u32 were larger they would continue using only 32 bits.) I think the hardcoded 32 is appropriate. I'm not sure about the exact sizeof() standard semantics, but I remember that the standard doesn't assume 8-bit bytes. However, I think it's safe to assume that a __u32 can fit 32 bits, if not a lot of other code would break also.