On Wed, Nov 25, 2015 at 03:31:23PM -0800, Kees Cook wrote: > It may be useful to debug writes to the readonly sections of memory, > so provide a cmdline "rodata=off" to allow for this. > > Suggested-by: H. Peter Anvin <[email protected]> > Signed-off-by: Kees Cook <[email protected]> > --- > Documentation/kernel-parameters.txt | 4 ++++ > init/main.c | 31 +++++++++++++++++++++++++++---- > 2 files changed, 31 insertions(+), 4 deletions(-) > > diff --git a/Documentation/kernel-parameters.txt > b/Documentation/kernel-parameters.txt > index 742f69d18fc8..21cf76dbba90 100644 > --- a/Documentation/kernel-parameters.txt > +++ b/Documentation/kernel-parameters.txt > @@ -3409,6 +3409,10 @@ bytes respectively. Such letter suffixes can also be > entirely omitted. > > ro [KNL] Mount root device read-only on boot > > + rodata= [KNL] > + on Mark read-only kernel memory as read-only (default). > + off Leave read-only kernel memory writable for debugging. > + > root= [KNL] Root filesystem > See name_to_dev_t comment in init/do_mounts.c. > > diff --git a/init/main.c b/init/main.c > index 9e64d7097f1a..06200d2fbf08 100644 > --- a/init/main.c > +++ b/init/main.c > @@ -93,9 +93,6 @@ static int kernel_init(void *); > extern void init_IRQ(void); > extern void fork_init(void); > extern void radix_tree_init(void); > -#ifndef CONFIG_DEBUG_RODATA > -static inline void mark_rodata_ro(void) { } > -#endif > > /* > * Debug helper: via this flag we know that we are in 'early bootup code' > @@ -929,6 +926,32 @@ static int try_to_run_init_process(const char > *init_filename) > > static noinline void __init kernel_init_freeable(void); > > +#ifdef CONFIG_DEBUG_RODATA > +bool disable_mark_readonly; > +static int __init set_debug_rodata(char *str) > +{ > + if (!str) > + return -EINVAL; > + if (!strncmp(str, "on", 2)) > + disable_mark_readonly = false; > + else if (!strncmp(str, "off", 3)) > + disable_mark_readonly = true;
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