| Message ID | 20190410190823.109172-1-joel@joelfernandes.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2,1/3] module: Prepare for addition of new ro_after_init sections | expand |
On Wed, Apr 10, 2019 at 03:08:21PM -0400, Joel Fernandes (Google) wrote: > For the purposes of hardening modules by adding sections to > ro_after_init sections, prepare for addition of new ro_after_init > entries which we do in future patches. Create a table to which new > entries could be added later. This makes it less error prone and reduce > code duplication. > > Cc: paulmck@linux.vnet.ibm.com > Cc: rostedt@goodmis.org > Cc: mathieu.desnoyers@efficios.com > Cc: rcu@vger.kernel.org > Cc: kernel-hardening@lists.openwall.com > Cc: kernel-team@android.com > Suggested-by: keescook@chromium.org > Reviewed-by: keescook@chromium.org > Acked-by: rostedt@goodmis.org > Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> > > --- > kernel/module.c | 41 +++++++++++++++++++++++------------------ > 1 file changed, 23 insertions(+), 18 deletions(-) > > diff --git a/kernel/module.c b/kernel/module.c > index 524da609c884..1acddb93282a 100644 > --- a/kernel/module.c > +++ b/kernel/module.c > @@ -3300,11 +3300,27 @@ static bool blacklisted(const char *module_name) > } > core_param(module_blacklist, module_blacklist, charp, 0400); > > +/* > + * Mark ro_after_init section with SHF_RO_AFTER_INIT so that > + * layout_sections() can put it in the right place. > + * Note: ro_after_init sections also have SHF_{WRITE,ALLOC} set. > + */ > +static char *ro_after_init_sections[] = { > + ".data..ro_after_init", > + > + /* > + * __jump_table structures are never modified, with the exception of > + * entries that refer to code in the __init section, which are > + * annotated as such at module load time. > + */ > + "__jump_table", > +}; > + > static struct module *layout_and_allocate(struct load_info *info, int flags) > { > struct module *mod; > unsigned int ndx; > - int err; > + int err, i; > > err = check_modinfo(info->mod, info, flags); > if (err) > @@ -3319,23 +3335,12 @@ static struct module *layout_and_allocate(struct load_info *info, int flags) > /* We will do a special allocation for per-cpu sections later. */ > info->sechdrs[info->index.pcpu].sh_flags &= ~(unsigned long)SHF_ALLOC; > > - /* > - * Mark ro_after_init section with SHF_RO_AFTER_INIT so that > - * layout_sections() can put it in the right place. > - * Note: ro_after_init sections also have SHF_{WRITE,ALLOC} set. > - */ > - ndx = find_sec(info, ".data..ro_after_init"); > - if (ndx) > - info->sechdrs[ndx].sh_flags |= SHF_RO_AFTER_INIT; > - /* > - * Mark the __jump_table section as ro_after_init as well: these data > - * structures are never modified, with the exception of entries that > - * refer to code in the __init section, which are annotated as such > - * at module load time. > - */ > - ndx = find_sec(info, "__jump_table"); > - if (ndx) > - info->sechdrs[ndx].sh_flags |= SHF_RO_AFTER_INIT; > + /* Set sh_flags for read-only after init sections */ > + for (i = 0; ro_after_init_sections[i]; i++) { Seems the fixup for this based on Kees suggestion of using NULL got squashed into 2/3, so allow me to send a v3 to fix this ;-) Sorry! I am doing that now. The patches applied together are still code-correct thought. thanks, - Joel
diff --git a/kernel/module.c b/kernel/module.c index 524da609c884..1acddb93282a 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -3300,11 +3300,27 @@ static bool blacklisted(const char *module_name) } core_param(module_blacklist, module_blacklist, charp, 0400); +/* + * Mark ro_after_init section with SHF_RO_AFTER_INIT so that + * layout_sections() can put it in the right place. + * Note: ro_after_init sections also have SHF_{WRITE,ALLOC} set. + */ +static char *ro_after_init_sections[] = { + ".data..ro_after_init", + + /* + * __jump_table structures are never modified, with the exception of + * entries that refer to code in the __init section, which are + * annotated as such at module load time. + */ + "__jump_table", +}; + static struct module *layout_and_allocate(struct load_info *info, int flags) { struct module *mod; unsigned int ndx; - int err; + int err, i; err = check_modinfo(info->mod, info, flags); if (err) @@ -3319,23 +3335,12 @@ static struct module *layout_and_allocate(struct load_info *info, int flags) /* We will do a special allocation for per-cpu sections later. */ info->sechdrs[info->index.pcpu].sh_flags &= ~(unsigned long)SHF_ALLOC; - /* - * Mark ro_after_init section with SHF_RO_AFTER_INIT so that - * layout_sections() can put it in the right place. - * Note: ro_after_init sections also have SHF_{WRITE,ALLOC} set. - */ - ndx = find_sec(info, ".data..ro_after_init"); - if (ndx) - info->sechdrs[ndx].sh_flags |= SHF_RO_AFTER_INIT; - /* - * Mark the __jump_table section as ro_after_init as well: these data - * structures are never modified, with the exception of entries that - * refer to code in the __init section, which are annotated as such - * at module load time. - */ - ndx = find_sec(info, "__jump_table"); - if (ndx) - info->sechdrs[ndx].sh_flags |= SHF_RO_AFTER_INIT; + /* Set sh_flags for read-only after init sections */ + for (i = 0; ro_after_init_sections[i]; i++) { + ndx = find_sec(info, ro_after_init_sections[i]); + if (ndx) + info->sechdrs[ndx].sh_flags |= SHF_RO_AFTER_INIT; + } /* Determine total sizes, and put offsets in sh_entsize. For now this is done generically; there doesn't appear to be any