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samples/seccomp: fix 64-bit comparison macros
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commit 916cafdc95843fb9af5fd5f83ca499d75473d107 upstream.

There were some bugs in the JNE64 and JLT64 comparision macros. This fixes
them, improves comments, and cleans up the file while we are at it.

Reported-by: Stephen Röttger <sroettger@google.com>
Signed-off-by: Mathias Svensson <idolf@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: James Morris <james.l.morris@oracle.com>
Signed-off-by: Willy Tarreau <w@1wt.eu>
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@wtarreau
Mathias Svensson authored and wtarreau committed Jun 20, 2017
1 parent 1ba4fc4 commit 109b421
Showing 1 changed file with 72 additions and 53 deletions.
125 changes: 72 additions & 53 deletions samples/seccomp/bpf-helper.h
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Expand Up @@ -138,7 +138,7 @@ union arg64 {
#define ARG_32(idx) \
BPF_STMT(BPF_LD+BPF_W+BPF_ABS, LO_ARG(idx))

/* Loads hi into A and lo in X */
/* Loads lo into M[0] and hi into M[1] and A */
#define ARG_64(idx) \
BPF_STMT(BPF_LD+BPF_W+BPF_ABS, LO_ARG(idx)), \
BPF_STMT(BPF_ST, 0), /* lo -> M[0] */ \
Expand All @@ -153,88 +153,107 @@ union arg64 {
BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (value), 1, 0), \
jt

/* Checks the lo, then swaps to check the hi. A=lo,X=hi */
#define JA32(value, jt) \
BPF_JUMP(BPF_JMP+BPF_JSET+BPF_K, (value), 0, 1), \
jt

#define JGE32(value, jt) \
BPF_JUMP(BPF_JMP+BPF_JGE+BPF_K, (value), 0, 1), \
jt

#define JGT32(value, jt) \
BPF_JUMP(BPF_JMP+BPF_JGT+BPF_K, (value), 0, 1), \
jt

#define JLE32(value, jt) \
BPF_JUMP(BPF_JMP+BPF_JGT+BPF_K, (value), 1, 0), \
jt

#define JLT32(value, jt) \
BPF_JUMP(BPF_JMP+BPF_JGE+BPF_K, (value), 1, 0), \
jt

/*
* All the JXX64 checks assume lo is saved in M[0] and hi is saved in both
* A and M[1]. This invariant is kept by restoring A if necessary.
*/
#define JEQ64(lo, hi, jt) \
/* if (hi != arg.hi) goto NOMATCH; */ \
BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (hi), 0, 5), \
BPF_STMT(BPF_LD+BPF_MEM, 0), /* swap in lo */ \
/* if (lo != arg.lo) goto NOMATCH; */ \
BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (lo), 0, 2), \
BPF_STMT(BPF_LD+BPF_MEM, 1), /* passed: swap hi back in */ \
BPF_STMT(BPF_LD+BPF_MEM, 1), \
jt, \
BPF_STMT(BPF_LD+BPF_MEM, 1) /* failed: swap hi back in */
BPF_STMT(BPF_LD+BPF_MEM, 1)

#define JNE64(lo, hi, jt) \
BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (hi), 5, 0), \
BPF_STMT(BPF_LD+BPF_MEM, 0), /* swap in lo */ \
/* if (hi != arg.hi) goto MATCH; */ \
BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (hi), 0, 3), \
BPF_STMT(BPF_LD+BPF_MEM, 0), \
/* if (lo != arg.lo) goto MATCH; */ \
BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (lo), 2, 0), \
BPF_STMT(BPF_LD+BPF_MEM, 1), /* passed: swap hi back in */ \
BPF_STMT(BPF_LD+BPF_MEM, 1), \
jt, \
BPF_STMT(BPF_LD+BPF_MEM, 1) /* failed: swap hi back in */

#define JA32(value, jt) \
BPF_JUMP(BPF_JMP+BPF_JSET+BPF_K, (value), 0, 1), \
jt
BPF_STMT(BPF_LD+BPF_MEM, 1)

#define JA64(lo, hi, jt) \
/* if (hi & arg.hi) goto MATCH; */ \
BPF_JUMP(BPF_JMP+BPF_JSET+BPF_K, (hi), 3, 0), \
BPF_STMT(BPF_LD+BPF_MEM, 0), /* swap in lo */ \
BPF_STMT(BPF_LD+BPF_MEM, 0), \
/* if (lo & arg.lo) goto MATCH; */ \
BPF_JUMP(BPF_JMP+BPF_JSET+BPF_K, (lo), 0, 2), \
BPF_STMT(BPF_LD+BPF_MEM, 1), /* passed: swap hi back in */ \
BPF_STMT(BPF_LD+BPF_MEM, 1), \
jt, \
BPF_STMT(BPF_LD+BPF_MEM, 1) /* failed: swap hi back in */
BPF_STMT(BPF_LD+BPF_MEM, 1)

#define JGE32(value, jt) \
BPF_JUMP(BPF_JMP+BPF_JGE+BPF_K, (value), 0, 1), \
jt

#define JLT32(value, jt) \
BPF_JUMP(BPF_JMP+BPF_JGE+BPF_K, (value), 1, 0), \
jt

/* Shortcut checking if hi > arg.hi. */
#define JGE64(lo, hi, jt) \
/* if (hi > arg.hi) goto MATCH; */ \
BPF_JUMP(BPF_JMP+BPF_JGT+BPF_K, (hi), 4, 0), \
/* if (hi != arg.hi) goto NOMATCH; */ \
BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (hi), 0, 5), \
BPF_STMT(BPF_LD+BPF_MEM, 0), /* swap in lo */ \
BPF_STMT(BPF_LD+BPF_MEM, 0), \
/* if (lo >= arg.lo) goto MATCH; */ \
BPF_JUMP(BPF_JMP+BPF_JGE+BPF_K, (lo), 0, 2), \
BPF_STMT(BPF_LD+BPF_MEM, 1), /* passed: swap hi back in */ \
jt, \
BPF_STMT(BPF_LD+BPF_MEM, 1) /* failed: swap hi back in */

#define JLT64(lo, hi, jt) \
BPF_JUMP(BPF_JMP+BPF_JGE+BPF_K, (hi), 0, 4), \
BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (hi), 0, 5), \
BPF_STMT(BPF_LD+BPF_MEM, 0), /* swap in lo */ \
BPF_JUMP(BPF_JMP+BPF_JGT+BPF_K, (lo), 2, 0), \
BPF_STMT(BPF_LD+BPF_MEM, 1), /* passed: swap hi back in */ \
BPF_STMT(BPF_LD+BPF_MEM, 1), \
jt, \
BPF_STMT(BPF_LD+BPF_MEM, 1) /* failed: swap hi back in */
BPF_STMT(BPF_LD+BPF_MEM, 1)

#define JGT32(value, jt) \
BPF_JUMP(BPF_JMP+BPF_JGT+BPF_K, (value), 0, 1), \
jt

#define JLE32(value, jt) \
BPF_JUMP(BPF_JMP+BPF_JGT+BPF_K, (value), 1, 0), \
jt

/* Check hi > args.hi first, then do the GE checking */
#define JGT64(lo, hi, jt) \
/* if (hi > arg.hi) goto MATCH; */ \
BPF_JUMP(BPF_JMP+BPF_JGT+BPF_K, (hi), 4, 0), \
/* if (hi != arg.hi) goto NOMATCH; */ \
BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (hi), 0, 5), \
BPF_STMT(BPF_LD+BPF_MEM, 0), /* swap in lo */ \
BPF_STMT(BPF_LD+BPF_MEM, 0), \
/* if (lo > arg.lo) goto MATCH; */ \
BPF_JUMP(BPF_JMP+BPF_JGT+BPF_K, (lo), 0, 2), \
BPF_STMT(BPF_LD+BPF_MEM, 1), /* passed: swap hi back in */ \
BPF_STMT(BPF_LD+BPF_MEM, 1), \
jt, \
BPF_STMT(BPF_LD+BPF_MEM, 1) /* failed: swap hi back in */
BPF_STMT(BPF_LD+BPF_MEM, 1)

#define JLE64(lo, hi, jt) \
BPF_JUMP(BPF_JMP+BPF_JGT+BPF_K, (hi), 6, 0), \
BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (hi), 0, 3), \
BPF_STMT(BPF_LD+BPF_MEM, 0), /* swap in lo */ \
/* if (hi < arg.hi) goto MATCH; */ \
BPF_JUMP(BPF_JMP+BPF_JGE+BPF_K, (hi), 0, 4), \
/* if (hi != arg.hi) goto NOMATCH; */ \
BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (hi), 0, 5), \
BPF_STMT(BPF_LD+BPF_MEM, 0), \
/* if (lo <= arg.lo) goto MATCH; */ \
BPF_JUMP(BPF_JMP+BPF_JGT+BPF_K, (lo), 2, 0), \
BPF_STMT(BPF_LD+BPF_MEM, 1), /* passed: swap hi back in */ \
BPF_STMT(BPF_LD+BPF_MEM, 1), \
jt, \
BPF_STMT(BPF_LD+BPF_MEM, 1)

#define JLT64(lo, hi, jt) \
/* if (hi < arg.hi) goto MATCH; */ \
BPF_JUMP(BPF_JMP+BPF_JGE+BPF_K, (hi), 0, 4), \
/* if (hi != arg.hi) goto NOMATCH; */ \
BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (hi), 0, 5), \
BPF_STMT(BPF_LD+BPF_MEM, 0), \
/* if (lo < arg.lo) goto MATCH; */ \
BPF_JUMP(BPF_JMP+BPF_JGE+BPF_K, (lo), 2, 0), \
BPF_STMT(BPF_LD+BPF_MEM, 1), \
jt, \
BPF_STMT(BPF_LD+BPF_MEM, 1) /* failed: swap hi back in */
BPF_STMT(BPF_LD+BPF_MEM, 1)

#define LOAD_SYSCALL_NR \
BPF_STMT(BPF_LD+BPF_W+BPF_ABS, \
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