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Commit de4bb3b9 authored by Heiko Carstens's avatar Heiko Carstens Committed by James Morris
Browse files

samples/seccomp: fix endianness bug in LO_ARG define 



The LO_ARG define needs to consider endianness also for 32 bit builds.

The "bpf_fancy" test case didn't work on s390 in 32 bit and compat mode
because the LO_ARG define resulted in a BPF program which read the upper
halve of the 64 bit system call arguments instead of the lower halves.

Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarJames Morris <james.l.morris@oracle.com>
parent 66372841

samples/seccomp/bpf-helper.h

+10 −5
Original line number Diff line number Diff line
@@ -59,6 +59,16 @@ void seccomp_bpf_print(struct sock_filter *filter, size_t count); 
#define FIND_LABEL(labels, label) seccomp_bpf_label((labels), #label)



#define EXPAND(...) __VA_ARGS__



/* Ensure that we load the logically correct offset. */

#if __BYTE_ORDER == __LITTLE_ENDIAN

#define LO_ARG(idx) offsetof(struct seccomp_data, args[(idx)])

#elif __BYTE_ORDER == __BIG_ENDIAN

#define LO_ARG(idx) offsetof(struct seccomp_data, args[(idx)]) + sizeof(__u32)

#else

#error "Unknown endianness"

#endif



/* Map all width-sensitive operations */

#if __BITS_PER_LONG == 32
@@ -70,21 +80,16 @@ void seccomp_bpf_print(struct sock_filter *filter, size_t count); 
#define JLE(x, jt) JLE32(x, EXPAND(jt))

#define JA(x, jt) JA32(x, EXPAND(jt))

#define ARG(i) ARG_32(i)

#define LO_ARG(idx) offsetof(struct seccomp_data, args[(idx)])



#elif __BITS_PER_LONG == 64



/* Ensure that we load the logically correct offset. */

#if __BYTE_ORDER == __LITTLE_ENDIAN

#define ENDIAN(_lo, _hi) _lo, _hi

#define LO_ARG(idx) offsetof(struct seccomp_data, args[(idx)])

#define HI_ARG(idx) offsetof(struct seccomp_data, args[(idx)]) + sizeof(__u32)

#elif __BYTE_ORDER == __BIG_ENDIAN

#define ENDIAN(_lo, _hi) _hi, _lo

#define LO_ARG(idx) offsetof(struct seccomp_data, args[(idx)]) + sizeof(__u32)

#define HI_ARG(idx) offsetof(struct seccomp_data, args[(idx)])

#else

#error "Unknown endianness"

#endif



union arg64 {