| Message ID | 20200226063551.65363-4-ruscur@russell.cc (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | set_memory() routines and STRICT_MODULE_RWX | expand |
On Wed, Feb 26, 2020 at 05:35:46PM +1100, Russell Currey wrote: > Very rudimentary, just > > echo 1 > [debugfs]/check_wx_pages > > and check the kernel log. Useful for testing strict module RWX. > > Updated the Kconfig entry to reflect this. Oh, I like this! This would be handy to have on all architectures. Reviewed-by: Kees Cook <keescook@chromium.org> -Kees > > Also fixed a typo. > > Signed-off-by: Russell Currey <ruscur@russell.cc> > --- > arch/powerpc/Kconfig.debug | 6 ++++-- > arch/powerpc/mm/ptdump/ptdump.c | 21 ++++++++++++++++++++- > 2 files changed, 24 insertions(+), 3 deletions(-) > > diff --git a/arch/powerpc/Kconfig.debug b/arch/powerpc/Kconfig.debug > index 0b063830eea8..e37960ef68c6 100644 > --- a/arch/powerpc/Kconfig.debug > +++ b/arch/powerpc/Kconfig.debug > @@ -370,7 +370,7 @@ config PPC_PTDUMP > If you are unsure, say N. > > config PPC_DEBUG_WX > - bool "Warn on W+X mappings at boot" > + bool "Warn on W+X mappings at boot & enable manual checks at runtime" > depends on PPC_PTDUMP && STRICT_KERNEL_RWX > help > Generate a warning if any W+X mappings are found at boot. > @@ -384,7 +384,9 @@ config PPC_DEBUG_WX > of other unfixed kernel bugs easier. > > There is no runtime or memory usage effect of this option > - once the kernel has booted up - it's a one time check. > + once the kernel has booted up, it only automatically checks once. > + > + Enables the "check_wx_pages" debugfs entry for checking at runtime. > > If in doubt, say "Y". > > diff --git a/arch/powerpc/mm/ptdump/ptdump.c b/arch/powerpc/mm/ptdump/ptdump.c > index 206156255247..a15e19a3b14e 100644 > --- a/arch/powerpc/mm/ptdump/ptdump.c > +++ b/arch/powerpc/mm/ptdump/ptdump.c > @@ -4,7 +4,7 @@ > * > * This traverses the kernel pagetables and dumps the > * information about the used sections of memory to > - * /sys/kernel/debug/kernel_pagetables. > + * /sys/kernel/debug/kernel_page_tables. > * > * Derived from the arm64 implementation: > * Copyright (c) 2014, The Linux Foundation, Laura Abbott. > @@ -413,6 +413,25 @@ void ptdump_check_wx(void) > else > pr_info("Checked W+X mappings: passed, no W+X pages found\n"); > } > + > +static int check_wx_debugfs_set(void *data, u64 val) > +{ > + if (val != 1ULL) > + return -EINVAL; > + > + ptdump_check_wx(); > + > + return 0; > +} > + > +DEFINE_SIMPLE_ATTRIBUTE(check_wx_fops, NULL, check_wx_debugfs_set, "%llu\n"); > + > +static int ptdump_check_wx_init(void) > +{ > + return debugfs_create_file("check_wx_pages", 0200, NULL, > + NULL, &check_wx_fops) ? 0 : -ENOMEM; > +} > +device_initcall(ptdump_check_wx_init); > #endif > > static int ptdump_init(void) > -- > 2.25.1 >
*thread necromancy* Is this patch still something folks are working on? It'd be nice to be able to trigger this check at runtime. -Kees On Wed, Feb 26, 2020 at 05:35:46PM +1100, Russell Currey wrote: > Very rudimentary, just > > echo 1 > [debugfs]/check_wx_pages > > and check the kernel log. Useful for testing strict module RWX. > > Updated the Kconfig entry to reflect this. > > Also fixed a typo. > > Signed-off-by: Russell Currey <ruscur@russell.cc> > --- > arch/powerpc/Kconfig.debug | 6 ++++-- > arch/powerpc/mm/ptdump/ptdump.c | 21 ++++++++++++++++++++- > 2 files changed, 24 insertions(+), 3 deletions(-) > > diff --git a/arch/powerpc/Kconfig.debug b/arch/powerpc/Kconfig.debug > index 0b063830eea8..e37960ef68c6 100644 > --- a/arch/powerpc/Kconfig.debug > +++ b/arch/powerpc/Kconfig.debug > @@ -370,7 +370,7 @@ config PPC_PTDUMP > If you are unsure, say N. > > config PPC_DEBUG_WX > - bool "Warn on W+X mappings at boot" > + bool "Warn on W+X mappings at boot & enable manual checks at runtime" > depends on PPC_PTDUMP && STRICT_KERNEL_RWX > help > Generate a warning if any W+X mappings are found at boot. > @@ -384,7 +384,9 @@ config PPC_DEBUG_WX > of other unfixed kernel bugs easier. > > There is no runtime or memory usage effect of this option > - once the kernel has booted up - it's a one time check. > + once the kernel has booted up, it only automatically checks once. > + > + Enables the "check_wx_pages" debugfs entry for checking at runtime. > > If in doubt, say "Y". > > diff --git a/arch/powerpc/mm/ptdump/ptdump.c b/arch/powerpc/mm/ptdump/ptdump.c > index 206156255247..a15e19a3b14e 100644 > --- a/arch/powerpc/mm/ptdump/ptdump.c > +++ b/arch/powerpc/mm/ptdump/ptdump.c > @@ -4,7 +4,7 @@ > * > * This traverses the kernel pagetables and dumps the > * information about the used sections of memory to > - * /sys/kernel/debug/kernel_pagetables. > + * /sys/kernel/debug/kernel_page_tables. > * > * Derived from the arm64 implementation: > * Copyright (c) 2014, The Linux Foundation, Laura Abbott. > @@ -413,6 +413,25 @@ void ptdump_check_wx(void) > else > pr_info("Checked W+X mappings: passed, no W+X pages found\n"); > } > + > +static int check_wx_debugfs_set(void *data, u64 val) > +{ > + if (val != 1ULL) > + return -EINVAL; > + > + ptdump_check_wx(); > + > + return 0; > +} > + > +DEFINE_SIMPLE_ATTRIBUTE(check_wx_fops, NULL, check_wx_debugfs_set, "%llu\n"); > + > +static int ptdump_check_wx_init(void) > +{ > + return debugfs_create_file("check_wx_pages", 0200, NULL, > + NULL, &check_wx_fops) ? 0 : -ENOMEM; > +} > +device_initcall(ptdump_check_wx_init); > #endif > > static int ptdump_init(void) > -- > 2.25.1 >
Le 06/04/2022 à 20:55, Kees Cook a écrit : > *thread necromancy* > > Is this patch still something folks are working on? It'd be nice to be > able to trigger this check at runtime. The series was taken over by Jordan. v15 of the series was accepted, but that particular patch was dropped in v11 (see https://patchwork.ozlabs.org/project/linuxppc-dev/cover/20210429031602.2606654-1-jniethe5@gmail.com/) The comment was: Some patches were dropped from this revision: powerpc/mm/ptdump: debugfs handler for W+X checks at runtime - Will use Christophe's generic ptdump series Not sure what happened after that. Christophe > > -Kees > > On Wed, Feb 26, 2020 at 05:35:46PM +1100, Russell Currey wrote: >> Very rudimentary, just >> >> echo 1 > [debugfs]/check_wx_pages >> >> and check the kernel log. Useful for testing strict module RWX. >> >> Updated the Kconfig entry to reflect this. >> >> Also fixed a typo. >> >> Signed-off-by: Russell Currey <ruscur@russell.cc> >> --- >> arch/powerpc/Kconfig.debug | 6 ++++-- >> arch/powerpc/mm/ptdump/ptdump.c | 21 ++++++++++++++++++++- >> 2 files changed, 24 insertions(+), 3 deletions(-) >> >> diff --git a/arch/powerpc/Kconfig.debug b/arch/powerpc/Kconfig.debug >> index 0b063830eea8..e37960ef68c6 100644 >> --- a/arch/powerpc/Kconfig.debug >> +++ b/arch/powerpc/Kconfig.debug >> @@ -370,7 +370,7 @@ config PPC_PTDUMP >> If you are unsure, say N. >> >> config PPC_DEBUG_WX >> - bool "Warn on W+X mappings at boot" >> + bool "Warn on W+X mappings at boot & enable manual checks at runtime" >> depends on PPC_PTDUMP && STRICT_KERNEL_RWX >> help >> Generate a warning if any W+X mappings are found at boot. >> @@ -384,7 +384,9 @@ config PPC_DEBUG_WX >> of other unfixed kernel bugs easier. >> >> There is no runtime or memory usage effect of this option >> - once the kernel has booted up - it's a one time check. >> + once the kernel has booted up, it only automatically checks once. >> + >> + Enables the "check_wx_pages" debugfs entry for checking at runtime. >> >> If in doubt, say "Y". >> >> diff --git a/arch/powerpc/mm/ptdump/ptdump.c b/arch/powerpc/mm/ptdump/ptdump.c >> index 206156255247..a15e19a3b14e 100644 >> --- a/arch/powerpc/mm/ptdump/ptdump.c >> +++ b/arch/powerpc/mm/ptdump/ptdump.c >> @@ -4,7 +4,7 @@ >> * >> * This traverses the kernel pagetables and dumps the >> * information about the used sections of memory to >> - * /sys/kernel/debug/kernel_pagetables. >> + * /sys/kernel/debug/kernel_page_tables. >> * >> * Derived from the arm64 implementation: >> * Copyright (c) 2014, The Linux Foundation, Laura Abbott. >> @@ -413,6 +413,25 @@ void ptdump_check_wx(void) >> else >> pr_info("Checked W+X mappings: passed, no W+X pages found\n"); >> } >> + >> +static int check_wx_debugfs_set(void *data, u64 val) >> +{ >> + if (val != 1ULL) >> + return -EINVAL; >> + >> + ptdump_check_wx(); >> + >> + return 0; >> +} >> + >> +DEFINE_SIMPLE_ATTRIBUTE(check_wx_fops, NULL, check_wx_debugfs_set, "%llu\n"); >> + >> +static int ptdump_check_wx_init(void) >> +{ >> + return debugfs_create_file("check_wx_pages", 0200, NULL, >> + NULL, &check_wx_fops) ? 0 : -ENOMEM; >> +} >> +device_initcall(ptdump_check_wx_init); >> #endif >> >> static int ptdump_init(void) >> -- >> 2.25.1 >> >
diff --git a/arch/powerpc/Kconfig.debug b/arch/powerpc/Kconfig.debug index 0b063830eea8..e37960ef68c6 100644 --- a/arch/powerpc/Kconfig.debug +++ b/arch/powerpc/Kconfig.debug @@ -370,7 +370,7 @@ config PPC_PTDUMP If you are unsure, say N. config PPC_DEBUG_WX - bool "Warn on W+X mappings at boot" + bool "Warn on W+X mappings at boot & enable manual checks at runtime" depends on PPC_PTDUMP && STRICT_KERNEL_RWX help Generate a warning if any W+X mappings are found at boot. @@ -384,7 +384,9 @@ config PPC_DEBUG_WX of other unfixed kernel bugs easier. There is no runtime or memory usage effect of this option - once the kernel has booted up - it's a one time check. + once the kernel has booted up, it only automatically checks once. + + Enables the "check_wx_pages" debugfs entry for checking at runtime. If in doubt, say "Y". diff --git a/arch/powerpc/mm/ptdump/ptdump.c b/arch/powerpc/mm/ptdump/ptdump.c index 206156255247..a15e19a3b14e 100644 --- a/arch/powerpc/mm/ptdump/ptdump.c +++ b/arch/powerpc/mm/ptdump/ptdump.c @@ -4,7 +4,7 @@ * * This traverses the kernel pagetables and dumps the * information about the used sections of memory to - * /sys/kernel/debug/kernel_pagetables. + * /sys/kernel/debug/kernel_page_tables. * * Derived from the arm64 implementation: * Copyright (c) 2014, The Linux Foundation, Laura Abbott. @@ -413,6 +413,25 @@ void ptdump_check_wx(void) else pr_info("Checked W+X mappings: passed, no W+X pages found\n"); } + +static int check_wx_debugfs_set(void *data, u64 val) +{ + if (val != 1ULL) + return -EINVAL; + + ptdump_check_wx(); + + return 0; +} + +DEFINE_SIMPLE_ATTRIBUTE(check_wx_fops, NULL, check_wx_debugfs_set, "%llu\n"); + +static int ptdump_check_wx_init(void) +{ + return debugfs_create_file("check_wx_pages", 0200, NULL, + NULL, &check_wx_fops) ? 0 : -ENOMEM; +} +device_initcall(ptdump_check_wx_init); #endif static int ptdump_init(void)
Very rudimentary, just echo 1 > [debugfs]/check_wx_pages and check the kernel log. Useful for testing strict module RWX. Updated the Kconfig entry to reflect this. Also fixed a typo. Signed-off-by: Russell Currey <ruscur@russell.cc> --- arch/powerpc/Kconfig.debug | 6 ++++-- arch/powerpc/mm/ptdump/ptdump.c | 21 ++++++++++++++++++++- 2 files changed, 24 insertions(+), 3 deletions(-)