| Message ID | 20240227013546.15769-5-zev@bewilderbeest.net |
|---|---|
| State | New |
| Headers | show |
| Series | ARM: prctl: Reject PR_SET_MDWE where not supported | expand |
On Mon, Feb 26, 2024 at 05:35:41PM -0800, Zev Weiss wrote: > There exist systems other than PARISC where MDWE may not be feasible > to support; rather than cluttering up the generic code with additional > arch-specific logic let's add a generic function for checking MDWE > support and allow each arch to override it as needed. > > Signed-off-by: Zev Weiss <zev@bewilderbeest.net> > Cc: <stable@vger.kernel.org> # v6.3+ PA-RISC folk need to ack/review-by this patch. Alternatively, it needs to be restructured to add the arch_memory_deny_write_exec_supported() override without touching the PA-RISC code, which then makes the Arm patch independent of the status of the PA-RISC patch. That will allow the Arm issue to be solved even if an ack is not forthcoming for the PA-RISC parts. Alternatively, I wonder whether akpm would be willing to pick up this patch set as-is.
On 2/27/24 11:24, Russell King (Oracle) wrote: > On Mon, Feb 26, 2024 at 05:35:41PM -0800, Zev Weiss wrote: >> There exist systems other than PARISC where MDWE may not be feasible >> to support; rather than cluttering up the generic code with additional >> arch-specific logic let's add a generic function for checking MDWE >> support and allow each arch to override it as needed. >> >> Signed-off-by: Zev Weiss <zev@bewilderbeest.net> >> Cc: <stable@vger.kernel.org> # v6.3+ > > PA-RISC folk need to ack/review-by this patch. I'm fine with patch 1/2: Acked-by: Helge Deller <deller@gmx.de> # parisc > Alternatively, it needs > to be restructured to add the arch_memory_deny_write_exec_supported() > override without touching the PA-RISC code, which then makes the Arm > patch independent of the status of the PA-RISC patch. That will allow > the Arm issue to be solved even if an ack is not forthcoming for the > PA-RISC parts. >> Alternatively, I wonder whether akpm would be willing to pick up this > patch set as-is. I have no preference, but I think both patches should be pushed together via arm tree or akpm. Helge
On Tue, Feb 27, 2024 at 11:53:59AM PST, Helge Deller wrote: >On 2/27/24 11:24, Russell King (Oracle) wrote: >>On Mon, Feb 26, 2024 at 05:35:41PM -0800, Zev Weiss wrote: >>>There exist systems other than PARISC where MDWE may not be feasible >>>to support; rather than cluttering up the generic code with additional >>>arch-specific logic let's add a generic function for checking MDWE >>>support and allow each arch to override it as needed. >>> >>>Signed-off-by: Zev Weiss <zev@bewilderbeest.net> >>>Cc: <stable@vger.kernel.org> # v6.3+ >> >>PA-RISC folk need to ack/review-by this patch. > >I'm fine with patch 1/2: >Acked-by: Helge Deller <deller@gmx.de> # parisc > >>Alternatively, it needs >>to be restructured to add the arch_memory_deny_write_exec_supported() >>override without touching the PA-RISC code, which then makes the Arm >>patch independent of the status of the PA-RISC patch. That will allow >>the Arm issue to be solved even if an ack is not forthcoming for the >>PA-RISC parts. >>>Alternatively, I wonder whether akpm would be willing to pick up this >>patch set as-is. > >I have no preference, but I think both patches should be pushed >together via arm tree or akpm. > >Helge Ping...Russell, Andrew, any thoughts on how this could move forward? Thanks, Zev
diff --git a/arch/parisc/include/asm/mman.h b/arch/parisc/include/asm/mman.h new file mode 100644 index 000000000000..47c5a1991d10 --- /dev/null +++ b/arch/parisc/include/asm/mman.h @@ -0,0 +1,14 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __ASM_MMAN_H__ +#define __ASM_MMAN_H__ + +#include <uapi/asm/mman.h> + +/* PARISC cannot allow mdwe as it needs writable stacks */ +static inline bool arch_memory_deny_write_exec_supported(void) +{ + return false; +} +#define arch_memory_deny_write_exec_supported arch_memory_deny_write_exec_supported + +#endif /* __ASM_MMAN_H__ */ diff --git a/include/linux/mman.h b/include/linux/mman.h index dc7048824be8..bcb201ab7a41 100644 --- a/include/linux/mman.h +++ b/include/linux/mman.h @@ -162,6 +162,14 @@ calc_vm_flag_bits(unsigned long flags) unsigned long vm_commit_limit(void); +#ifndef arch_memory_deny_write_exec_supported +static inline bool arch_memory_deny_write_exec_supported(void) +{ + return true; +} +#define arch_memory_deny_write_exec_supported arch_memory_deny_write_exec_supported +#endif + /* * Denies creating a writable executable mapping or gaining executable permissions. * diff --git a/kernel/sys.c b/kernel/sys.c index f8e543f1e38a..8bb106a56b3a 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -2408,8 +2408,11 @@ static inline int prctl_set_mdwe(unsigned long bits, unsigned long arg3, if (bits & PR_MDWE_NO_INHERIT && !(bits & PR_MDWE_REFUSE_EXEC_GAIN)) return -EINVAL; - /* PARISC cannot allow mdwe as it needs writable stacks */ - if (IS_ENABLED(CONFIG_PARISC)) + /* + * EOPNOTSUPP might be more appropriate here in principle, but + * existing userspace depends on EINVAL specifically. + */ + if (!arch_memory_deny_write_exec_supported()) return -EINVAL; current_bits = get_current_mdwe();
There exist systems other than PARISC where MDWE may not be feasible to support; rather than cluttering up the generic code with additional arch-specific logic let's add a generic function for checking MDWE support and allow each arch to override it as needed. Signed-off-by: Zev Weiss <zev@bewilderbeest.net> Cc: <stable@vger.kernel.org> # v6.3+ --- arch/parisc/include/asm/mman.h | 14 ++++++++++++++ include/linux/mman.h | 8 ++++++++ kernel/sys.c | 7 +++++-- 3 files changed, 27 insertions(+), 2 deletions(-) create mode 100644 arch/parisc/include/asm/mman.h