53 lines
2.0 KiB
Diff
53 lines
2.0 KiB
Diff
From: Aurelien Jarno <aurelien@aurel32.net>
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Date: Tue, 9 Apr 2019 16:53:55 +0200
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Subject: MIPS: scall64-o32: Fix indirect syscall number load
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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Origin: https://git.kernel.org/linus/79b4a9cf0e2ea8203ce777c8d5cfa86c71eae86e
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Commit 4c21b8fd8f14 (MIPS: seccomp: Handle indirect system calls (o32))
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added indirect syscall detection for O32 processes running on MIPS64,
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but it did not work correctly for big endian kernel/processes. The
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reason is that the syscall number is loaded from ARG1 using the lw
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instruction while this is a 64-bit value, so zero is loaded instead of
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the syscall number.
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Fix the code by using the ld instruction instead. When running a 32-bit
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processes on a 64 bit CPU, the values are properly sign-extended, so it
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ensures the value passed to syscall_trace_enter is correct.
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Recent systemd versions with seccomp enabled whitelist the getpid
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syscall for their internal processes (e.g. systemd-journald), but call
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it through syscall(SYS_getpid). This fix therefore allows O32 big endian
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systems with a 64-bit kernel to run recent systemd versions.
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Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
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Cc: <stable@vger.kernel.org> # v3.15+
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Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
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Signed-off-by: Paul Burton <paul.burton@mips.com>
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Cc: Ralf Baechle <ralf@linux-mips.org>
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Cc: James Hogan <jhogan@kernel.org>
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Cc: linux-mips@vger.kernel.org
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Cc: linux-kernel@vger.kernel.org
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---
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arch/mips/kernel/scall64-o32.S | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/arch/mips/kernel/scall64-o32.S b/arch/mips/kernel/scall64-o32.S
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index f158c5894a9a..feb2653490df 100644
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--- a/arch/mips/kernel/scall64-o32.S
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+++ b/arch/mips/kernel/scall64-o32.S
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@@ -125,7 +125,7 @@ trace_a_syscall:
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subu t1, v0, __NR_O32_Linux
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move a1, v0
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bnez t1, 1f /* __NR_syscall at offset 0 */
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- lw a1, PT_R4(sp) /* Arg1 for __NR_syscall case */
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+ ld a1, PT_R4(sp) /* Arg1 for __NR_syscall case */
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.set pop
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1: jal syscall_trace_enter
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--
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2.20.1
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