Commit f04cf78b authored by Kees Cook's avatar Kees Cook
Browse files

selftests/seccomp: Remove SYSCALL_NUM_RET_SHARE_REG in favor of SYSCALL_RET_SET 



Instead of special-casing the specific case of shared registers, create
a default SYSCALL_RET_SET() macro (mirroring SYSCALL_NUM_SET()), that
writes to the SYSCALL_RET register. For architectures that can't set the
return value (for whatever reason), they can define SYSCALL_RET_SET()
without an associated SYSCALL_RET() macro. This also paves the way for
architectures that need to do special things to set the return value
(e.g. powerpc).

Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/lkml/20200912110820.597135-12-keescook@chromium.org


Acked-by: default avatarChristian Brauner <christian.brauner@ubuntu.com>
parent e4e8e5d2

tools/testing/selftests/seccomp/seccomp_bpf.c

+23 −10
Original line number Diff line number Diff line
@@ -1753,8 +1753,8 @@ TEST_F(TRACE_poke, getpid_runs_normally) 
#elif defined(__s390__)

# define ARCH_REGS		s390_regs

# define SYSCALL_NUM(_regs)	(_regs).gprs[2]

# define SYSCALL_RET(_regs)	(_regs).gprs[2]

# define SYSCALL_NUM_RET_SHARE_REG

# define SYSCALL_RET_SET(_regs, _val)			\

		TH_LOG("Can't modify syscall return on this architecture")

#elif defined(__mips__)

# include <asm/unistd_nr_n32.h>

# include <asm/unistd_nr_n64.h>
@@ -1776,8 +1776,8 @@ TEST_F(TRACE_poke, getpid_runs_normally) 
		else					\

			(_regs).regs[2] = _nr;		\

	} while (0)

# define SYSCALL_RET(_regs)	(_regs).regs[2]

# define SYSCALL_NUM_RET_SHARE_REG

# define SYSCALL_RET_SET(_regs, _val)			\

		TH_LOG("Can't modify syscall return on this architecture")

#elif defined(__xtensa__)

# define ARCH_REGS		struct user_pt_regs

# define SYSCALL_NUM(_regs)	(_regs).syscall
@@ -1804,9 +1804,26 @@ TEST_F(TRACE_poke, getpid_runs_normally) 
		SYSCALL_NUM(_regs) = (_nr);	\

	} while (0)

#endif

/*

 * Most architectures can change the syscall return value by just

 * writing to the SYSCALL_RET register. This is the default if not

 * defined above. If an architecture cannot set the return value

 * (for example when the syscall and return value register is

 * shared), report it with TH_LOG() in an arch-specific definition

 * of SYSCALL_RET_SET() above, and leave SYSCALL_RET undefined.

 */

#if !defined(SYSCALL_RET) && !defined(SYSCALL_RET_SET)

# error "One of SYSCALL_RET or SYSCALL_RET_SET is needed for this arch"

#endif

#ifndef SYSCALL_RET_SET

# define SYSCALL_RET_SET(_regs, _val)		\

	do {					\

		SYSCALL_RET(_regs) = (_val);	\

	} while (0)

#endif



/* When the syscall return can't be changed, stub out the tests for it. */

#ifdef SYSCALL_NUM_RET_SHARE_REG

#ifndef SYSCALL_RET

# define EXPECT_SYSCALL_RETURN(val, action)	EXPECT_EQ(-1, action)

#else

# define EXPECT_SYSCALL_RETURN(val, action)		\
@@ -1870,11 +1887,7 @@ void change_syscall(struct __test_metadata *_metadata, 


	/* If syscall is skipped, change return value. */

	if (syscall == -1)

#ifdef SYSCALL_NUM_RET_SHARE_REG

		TH_LOG("Can't modify syscall return on this architecture");

#else

		SYSCALL_RET(regs) = result;

#endif

		SYSCALL_RET_SET(regs, result);



	/* Flush any register changes made. */

	if (memcmp(&orig, &regs, sizeof(orig)) != 0)

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