| Message ID | 20220209170358.3266629-7-atomlin@redhat.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | module: core code clean up | expand |
Le 09/02/2022 à 18:03, Aaron Tomlin a écrit : > No functional change. > > This patch migrates code that makes module text > and rodata memory read-only and non-text memory > non-executable from core module code into > kernel/module/strict_rwx.c. > > Signed-off-by: Aaron Tomlin <atomlin@redhat.com> > --- > kernel/module/Makefile | 1 + > kernel/module/internal.h | 38 +++++++++++++++ > kernel/module/main.c | 97 +------------------------------------- > kernel/module/strict_rwx.c | 84 +++++++++++++++++++++++++++++++++ This file generates many checkpatch WARNINGs and CHECKs. Don't worry too much about the ones telling you to use WARN_ON() instead of BUG_ON() for the time being, but others should be handled. > 4 files changed, 124 insertions(+), 96 deletions(-) > create mode 100644 kernel/module/strict_rwx.c > > diff --git a/kernel/module/Makefile b/kernel/module/Makefile > index fc6d7a053a62..8f2857d9ba1e 100644 > --- a/kernel/module/Makefile > +++ b/kernel/module/Makefile > @@ -10,4 +10,5 @@ obj-$(CONFIG_MODULE_SIG_FORMAT) += signature.o > ifdef CONFIG_MODULES > obj-$(CONFIG_LIVEPATCH) += livepatch.o > obj-$(CONFIG_MODULES_TREE_LOOKUP) += tree_lookup.o > +obj-$(CONFIG_STRICT_MODULE_RWX) += strict_rwx.o > endif > diff --git a/kernel/module/internal.h b/kernel/module/internal.h > index 08b6be037b72..99204447ce86 100644 > --- a/kernel/module/internal.h > +++ b/kernel/module/internal.h > @@ -21,6 +21,17 @@ > #define MODULE_FLAGS_BUF_SIZE (TAINT_FLAGS_COUNT + 4) > #define MODULE_SECT_READ_SIZE (3 /* "0x", "\n" */ + (BITS_PER_LONG / 4)) > > +/* > + * Modules' sections will be aligned on page boundaries > + * to ensure complete separation of code and data, but > + * only when CONFIG_ARCH_HAS_STRICT_MODULE_RWX=y > + */ > +#ifdef CONFIG_ARCH_HAS_STRICT_MODULE_RWX > +# define debug_align(X) ALIGN(X, PAGE_SIZE) You can use PAGE_ALIGN() instead. > +#else > +# define debug_align(X) (X) > +#endif > + > extern struct mutex module_mutex; > extern struct list_head modules; > > @@ -124,3 +135,30 @@ static struct module *mod_find(unsigned long addr) > return NULL; > } > #endif /* CONFIG_MODULES_TREE_LOOKUP */ > + > +#ifdef CONFIG_ARCH_HAS_STRICT_MODULE_RWX This #ifdef is not needed, frob_text() always exists. > +void frob_text(const struct module_layout *layout, int (*set_memory)(unsigned long start, > + int num_pages)); > +#endif /* CONFIG_ARCH_HAS_STRICT_MODULE_RWX */ > + > +#ifdef CONFIG_STRICT_MODULE_RWX > +void frob_rodata(const struct module_layout *layout, > + int (*set_memory)(unsigned long start, int num_pages)); > +void frob_ro_after_init(const struct module_layout *layout, > + int (*set_memory)(unsigned long start, int num_pages)); > +void frob_writable_data(const struct module_layout *layout, > + int (*set_memory)(unsigned long start, int num_pages)); > +void module_enable_ro(const struct module *mod, bool after_init); > +void module_enable_nx(const struct module *mod); > +int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs, > + char *secstrings, struct module *mod); > + > +#else /* !CONFIG_STRICT_MODULE_RWX */ > +static void module_enable_nx(const struct module *mod) { } > +static void module_enable_ro(const struct module *mod, bool after_init) {} > +static int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs, > + char *secstrings, struct module *mod) > +{ > + return 0; > +} > +#endif /* CONFIG_STRICT_MODULE_RWX */ > diff --git a/kernel/module/main.c b/kernel/module/main.c > index f733a719c65d..abdedc15f4f1 100644 > --- a/kernel/module/main.c > +++ b/kernel/module/main.c > @@ -63,17 +63,6 @@ > #define CREATE_TRACE_POINTS > #include <trace/events/module.h> > > -/* > - * Modules' sections will be aligned on page boundaries > - * to ensure complete separation of code and data, but > - * only when CONFIG_ARCH_HAS_STRICT_MODULE_RWX=y > - */ > -#ifdef CONFIG_ARCH_HAS_STRICT_MODULE_RWX > -# define debug_align(X) ALIGN(X, PAGE_SIZE) > -#else > -# define debug_align(X) (X) > -#endif > - > /* > * Mutex protects: > * 1) List of modules (also safely readable with preempt_disable), > @@ -1815,7 +1804,7 @@ static void mod_sysfs_teardown(struct module *mod) > * whether we are strict. > */ > #ifdef CONFIG_ARCH_HAS_STRICT_MODULE_RWX > -static void frob_text(const struct module_layout *layout, > +void frob_text(const struct module_layout *layout, > int (*set_memory)(unsigned long start, int num_pages)) The alignment of the second line is not correct. > { > BUG_ON((unsigned long)layout->base & (PAGE_SIZE-1)); > @@ -1833,90 +1822,6 @@ static void module_enable_x(const struct module *mod) > static void module_enable_x(const struct module *mod) { } > #endif /* CONFIG_ARCH_HAS_STRICT_MODULE_RWX */ > > -#ifdef CONFIG_STRICT_MODULE_RWX > -static void frob_rodata(const struct module_layout *layout, > - int (*set_memory)(unsigned long start, int num_pages)) > -{ > - BUG_ON((unsigned long)layout->base & (PAGE_SIZE-1)); > - BUG_ON((unsigned long)layout->text_size & (PAGE_SIZE-1)); > - BUG_ON((unsigned long)layout->ro_size & (PAGE_SIZE-1)); > - set_memory((unsigned long)layout->base + layout->text_size, > - (layout->ro_size - layout->text_size) >> PAGE_SHIFT); > -} > - > -static void frob_ro_after_init(const struct module_layout *layout, > - int (*set_memory)(unsigned long start, int num_pages)) > -{ > - BUG_ON((unsigned long)layout->base & (PAGE_SIZE-1)); > - BUG_ON((unsigned long)layout->ro_size & (PAGE_SIZE-1)); > - BUG_ON((unsigned long)layout->ro_after_init_size & (PAGE_SIZE-1)); > - set_memory((unsigned long)layout->base + layout->ro_size, > - (layout->ro_after_init_size - layout->ro_size) >> PAGE_SHIFT); > -} > - > -static void frob_writable_data(const struct module_layout *layout, > - int (*set_memory)(unsigned long start, int num_pages)) > -{ > - BUG_ON((unsigned long)layout->base & (PAGE_SIZE-1)); > - BUG_ON((unsigned long)layout->ro_after_init_size & (PAGE_SIZE-1)); > - BUG_ON((unsigned long)layout->size & (PAGE_SIZE-1)); > - set_memory((unsigned long)layout->base + layout->ro_after_init_size, > - (layout->size - layout->ro_after_init_size) >> PAGE_SHIFT); > -} > - > -static void module_enable_ro(const struct module *mod, bool after_init) > -{ > - if (!rodata_enabled) > - return; > - > - set_vm_flush_reset_perms(mod->core_layout.base); > - set_vm_flush_reset_perms(mod->init_layout.base); > - frob_text(&mod->core_layout, set_memory_ro); > - > - frob_rodata(&mod->core_layout, set_memory_ro); > - frob_text(&mod->init_layout, set_memory_ro); > - frob_rodata(&mod->init_layout, set_memory_ro); > - > - if (after_init) > - frob_ro_after_init(&mod->core_layout, set_memory_ro); > -} > - > -static void module_enable_nx(const struct module *mod) > -{ > - frob_rodata(&mod->core_layout, set_memory_nx); > - frob_ro_after_init(&mod->core_layout, set_memory_nx); > - frob_writable_data(&mod->core_layout, set_memory_nx); > - frob_rodata(&mod->init_layout, set_memory_nx); > - frob_writable_data(&mod->init_layout, set_memory_nx); > -} > - > -static int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs, > - char *secstrings, struct module *mod) > -{ > - const unsigned long shf_wx = SHF_WRITE|SHF_EXECINSTR; > - int i; > - > - for (i = 0; i < hdr->e_shnum; i++) { > - if ((sechdrs[i].sh_flags & shf_wx) == shf_wx) { > - pr_err("%s: section %s (index %d) has invalid WRITE|EXEC flags\n", > - mod->name, secstrings + sechdrs[i].sh_name, i); > - return -ENOEXEC; > - } > - } > - > - return 0; > -} > - > -#else /* !CONFIG_STRICT_MODULE_RWX */ > -static void module_enable_nx(const struct module *mod) { } > -static void module_enable_ro(const struct module *mod, bool after_init) {} > -static int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs, > - char *secstrings, struct module *mod) > -{ > - return 0; > -} > -#endif /* CONFIG_STRICT_MODULE_RWX */ > - > void __weak module_memfree(void *module_region) > { > /* > diff --git a/kernel/module/strict_rwx.c b/kernel/module/strict_rwx.c > new file mode 100644 > index 000000000000..1933272056c7 > --- /dev/null > +++ b/kernel/module/strict_rwx.c > @@ -0,0 +1,84 @@ > +// SPDX-License-Identifier: GPL-2.0-or-later > +/* > + * Module strict rwx > + * > + * Copyright (C) 2015 Rusty Russell > + */ > + > +#include <linux/module.h> > +#include <linux/vmalloc.h> > +#include <linux/set_memory.h> > +#include "internal.h" > + > +void frob_rodata(const struct module_layout *layout, > + int (*set_memory)(unsigned long start, int num_pages)) > +{ > + BUG_ON((unsigned long)layout->base & (PAGE_SIZE-1)); Could be: BUG_ON(!PAGE_ALIGNED(layout->base)); Same for all others. > + BUG_ON((unsigned long)layout->text_size & (PAGE_SIZE-1)); > + BUG_ON((unsigned long)layout->ro_size & (PAGE_SIZE-1)); > + set_memory((unsigned long)layout->base + layout->text_size, > + (layout->ro_size - layout->text_size) >> PAGE_SHIFT); > +} > + > +void frob_ro_after_init(const struct module_layout *layout, > + int (*set_memory)(unsigned long start, int num_pages)) > +{ > + BUG_ON((unsigned long)layout->base & (PAGE_SIZE-1)); > + BUG_ON((unsigned long)layout->ro_size & (PAGE_SIZE-1)); > + BUG_ON((unsigned long)layout->ro_after_init_size & (PAGE_SIZE-1)); > + set_memory((unsigned long)layout->base + layout->ro_size, > + (layout->ro_after_init_size - layout->ro_size) >> PAGE_SHIFT); > +} > + > +void frob_writable_data(const struct module_layout *layout, > + int (*set_memory)(unsigned long start, int num_pages)) > +{ > + BUG_ON((unsigned long)layout->base & (PAGE_SIZE-1)); > + BUG_ON((unsigned long)layout->ro_after_init_size & (PAGE_SIZE-1)); > + BUG_ON((unsigned long)layout->size & (PAGE_SIZE-1)); > + set_memory((unsigned long)layout->base + layout->ro_after_init_size, > + (layout->size - layout->ro_after_init_size) >> PAGE_SHIFT); > +} > + > +void module_enable_ro(const struct module *mod, bool after_init) > +{ > + if (!rodata_enabled) > + return; > + > + set_vm_flush_reset_perms(mod->core_layout.base); > + set_vm_flush_reset_perms(mod->init_layout.base); > + frob_text(&mod->core_layout, set_memory_ro); > + > + frob_rodata(&mod->core_layout, set_memory_ro); > + frob_text(&mod->init_layout, set_memory_ro); > + frob_rodata(&mod->init_layout, set_memory_ro); > + > + if (after_init) > + frob_ro_after_init(&mod->core_layout, set_memory_ro); > +} > + > +void module_enable_nx(const struct module *mod) > +{ > + frob_rodata(&mod->core_layout, set_memory_nx); > + frob_ro_after_init(&mod->core_layout, set_memory_nx); > + frob_writable_data(&mod->core_layout, set_memory_nx); > + frob_rodata(&mod->init_layout, set_memory_nx); > + frob_writable_data(&mod->init_layout, set_memory_nx); > +} > + > +int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs, > + char *secstrings, struct module *mod) > +{ > + const unsigned long shf_wx = SHF_WRITE|SHF_EXECINSTR; > + int i; > + > + for (i = 0; i < hdr->e_shnum; i++) { > + if ((sechdrs[i].sh_flags & shf_wx) == shf_wx) { > + pr_err("%s: section %s (index %d) has invalid WRITE|EXEC flags\n", > + mod->name, secstrings + sechdrs[i].sh_name, i); > + return -ENOEXEC; > + } > + } > + > + return 0; > +}
On Thu 2022-02-10 12:21 +0000, Christophe Leroy wrote: > This file generates many checkpatch WARNINGs and CHECKs. > Don't worry too much about the ones telling you to use WARN_ON() instead > of BUG_ON() for the time being, but others should be handled. Yes, with ./scripts/checkpatch.pl --strict'. Please note: I have used '--ignore=ASSIGN_IN_IF,AVOID_BUG' previously on that file. Albeit, I will resolve the check violations e.g. "Alignment should match open parenthesis" etc. > > +# define debug_align(X) ALIGN(X, PAGE_SIZE) > > You can use PAGE_ALIGN() instead. Agreed: PAGE_ALIGN(X) does expand to ALIGN(X, PAGE_SIZE) > > +#ifdef CONFIG_ARCH_HAS_STRICT_MODULE_RWX > > This #ifdef is not needed, frob_text() always exists. I will leave this for you to remove, in your patch [1]. > > + BUG_ON((unsigned long)layout->base & (PAGE_SIZE-1)); > > Could be: > > BUG_ON(!PAGE_ALIGNED(layout->base)); > > > Same for all others. Agreed. [1]: https://lore.kernel.org/lkml/203348805c9ac9851d8939d15cb9802ef047b5e2.1643919758.git.christophe.leroy@csgroup.eu/ Kind regards,
diff --git a/kernel/module/Makefile b/kernel/module/Makefile index fc6d7a053a62..8f2857d9ba1e 100644 --- a/kernel/module/Makefile +++ b/kernel/module/Makefile @@ -10,4 +10,5 @@ obj-$(CONFIG_MODULE_SIG_FORMAT) += signature.o ifdef CONFIG_MODULES obj-$(CONFIG_LIVEPATCH) += livepatch.o obj-$(CONFIG_MODULES_TREE_LOOKUP) += tree_lookup.o +obj-$(CONFIG_STRICT_MODULE_RWX) += strict_rwx.o endif diff --git a/kernel/module/internal.h b/kernel/module/internal.h index 08b6be037b72..99204447ce86 100644 --- a/kernel/module/internal.h +++ b/kernel/module/internal.h @@ -21,6 +21,17 @@ #define MODULE_FLAGS_BUF_SIZE (TAINT_FLAGS_COUNT + 4) #define MODULE_SECT_READ_SIZE (3 /* "0x", "\n" */ + (BITS_PER_LONG / 4)) +/* + * Modules' sections will be aligned on page boundaries + * to ensure complete separation of code and data, but + * only when CONFIG_ARCH_HAS_STRICT_MODULE_RWX=y + */ +#ifdef CONFIG_ARCH_HAS_STRICT_MODULE_RWX +# define debug_align(X) ALIGN(X, PAGE_SIZE) +#else +# define debug_align(X) (X) +#endif + extern struct mutex module_mutex; extern struct list_head modules; @@ -124,3 +135,30 @@ static struct module *mod_find(unsigned long addr) return NULL; } #endif /* CONFIG_MODULES_TREE_LOOKUP */ + +#ifdef CONFIG_ARCH_HAS_STRICT_MODULE_RWX +void frob_text(const struct module_layout *layout, int (*set_memory)(unsigned long start, + int num_pages)); +#endif /* CONFIG_ARCH_HAS_STRICT_MODULE_RWX */ + +#ifdef CONFIG_STRICT_MODULE_RWX +void frob_rodata(const struct module_layout *layout, + int (*set_memory)(unsigned long start, int num_pages)); +void frob_ro_after_init(const struct module_layout *layout, + int (*set_memory)(unsigned long start, int num_pages)); +void frob_writable_data(const struct module_layout *layout, + int (*set_memory)(unsigned long start, int num_pages)); +void module_enable_ro(const struct module *mod, bool after_init); +void module_enable_nx(const struct module *mod); +int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs, + char *secstrings, struct module *mod); + +#else /* !CONFIG_STRICT_MODULE_RWX */ +static void module_enable_nx(const struct module *mod) { } +static void module_enable_ro(const struct module *mod, bool after_init) {} +static int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs, + char *secstrings, struct module *mod) +{ + return 0; +} +#endif /* CONFIG_STRICT_MODULE_RWX */ diff --git a/kernel/module/main.c b/kernel/module/main.c index f733a719c65d..abdedc15f4f1 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c @@ -63,17 +63,6 @@ #define CREATE_TRACE_POINTS #include <trace/events/module.h> -/* - * Modules' sections will be aligned on page boundaries - * to ensure complete separation of code and data, but - * only when CONFIG_ARCH_HAS_STRICT_MODULE_RWX=y - */ -#ifdef CONFIG_ARCH_HAS_STRICT_MODULE_RWX -# define debug_align(X) ALIGN(X, PAGE_SIZE) -#else -# define debug_align(X) (X) -#endif - /* * Mutex protects: * 1) List of modules (also safely readable with preempt_disable), @@ -1815,7 +1804,7 @@ static void mod_sysfs_teardown(struct module *mod) * whether we are strict. */ #ifdef CONFIG_ARCH_HAS_STRICT_MODULE_RWX -static void frob_text(const struct module_layout *layout, +void frob_text(const struct module_layout *layout, int (*set_memory)(unsigned long start, int num_pages)) { BUG_ON((unsigned long)layout->base & (PAGE_SIZE-1)); @@ -1833,90 +1822,6 @@ static void module_enable_x(const struct module *mod) static void module_enable_x(const struct module *mod) { } #endif /* CONFIG_ARCH_HAS_STRICT_MODULE_RWX */ -#ifdef CONFIG_STRICT_MODULE_RWX -static void frob_rodata(const struct module_layout *layout, - int (*set_memory)(unsigned long start, int num_pages)) -{ - BUG_ON((unsigned long)layout->base & (PAGE_SIZE-1)); - BUG_ON((unsigned long)layout->text_size & (PAGE_SIZE-1)); - BUG_ON((unsigned long)layout->ro_size & (PAGE_SIZE-1)); - set_memory((unsigned long)layout->base + layout->text_size, - (layout->ro_size - layout->text_size) >> PAGE_SHIFT); -} - -static void frob_ro_after_init(const struct module_layout *layout, - int (*set_memory)(unsigned long start, int num_pages)) -{ - BUG_ON((unsigned long)layout->base & (PAGE_SIZE-1)); - BUG_ON((unsigned long)layout->ro_size & (PAGE_SIZE-1)); - BUG_ON((unsigned long)layout->ro_after_init_size & (PAGE_SIZE-1)); - set_memory((unsigned long)layout->base + layout->ro_size, - (layout->ro_after_init_size - layout->ro_size) >> PAGE_SHIFT); -} - -static void frob_writable_data(const struct module_layout *layout, - int (*set_memory)(unsigned long start, int num_pages)) -{ - BUG_ON((unsigned long)layout->base & (PAGE_SIZE-1)); - BUG_ON((unsigned long)layout->ro_after_init_size & (PAGE_SIZE-1)); - BUG_ON((unsigned long)layout->size & (PAGE_SIZE-1)); - set_memory((unsigned long)layout->base + layout->ro_after_init_size, - (layout->size - layout->ro_after_init_size) >> PAGE_SHIFT); -} - -static void module_enable_ro(const struct module *mod, bool after_init) -{ - if (!rodata_enabled) - return; - - set_vm_flush_reset_perms(mod->core_layout.base); - set_vm_flush_reset_perms(mod->init_layout.base); - frob_text(&mod->core_layout, set_memory_ro); - - frob_rodata(&mod->core_layout, set_memory_ro); - frob_text(&mod->init_layout, set_memory_ro); - frob_rodata(&mod->init_layout, set_memory_ro); - - if (after_init) - frob_ro_after_init(&mod->core_layout, set_memory_ro); -} - -static void module_enable_nx(const struct module *mod) -{ - frob_rodata(&mod->core_layout, set_memory_nx); - frob_ro_after_init(&mod->core_layout, set_memory_nx); - frob_writable_data(&mod->core_layout, set_memory_nx); - frob_rodata(&mod->init_layout, set_memory_nx); - frob_writable_data(&mod->init_layout, set_memory_nx); -} - -static int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs, - char *secstrings, struct module *mod) -{ - const unsigned long shf_wx = SHF_WRITE|SHF_EXECINSTR; - int i; - - for (i = 0; i < hdr->e_shnum; i++) { - if ((sechdrs[i].sh_flags & shf_wx) == shf_wx) { - pr_err("%s: section %s (index %d) has invalid WRITE|EXEC flags\n", - mod->name, secstrings + sechdrs[i].sh_name, i); - return -ENOEXEC; - } - } - - return 0; -} - -#else /* !CONFIG_STRICT_MODULE_RWX */ -static void module_enable_nx(const struct module *mod) { } -static void module_enable_ro(const struct module *mod, bool after_init) {} -static int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs, - char *secstrings, struct module *mod) -{ - return 0; -} -#endif /* CONFIG_STRICT_MODULE_RWX */ - void __weak module_memfree(void *module_region) { /* diff --git a/kernel/module/strict_rwx.c b/kernel/module/strict_rwx.c new file mode 100644 index 000000000000..1933272056c7 --- /dev/null +++ b/kernel/module/strict_rwx.c @@ -0,0 +1,84 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Module strict rwx + * + * Copyright (C) 2015 Rusty Russell + */ + +#include <linux/module.h> +#include <linux/vmalloc.h> +#include <linux/set_memory.h> +#include "internal.h" + +void frob_rodata(const struct module_layout *layout, + int (*set_memory)(unsigned long start, int num_pages)) +{ + BUG_ON((unsigned long)layout->base & (PAGE_SIZE-1)); + BUG_ON((unsigned long)layout->text_size & (PAGE_SIZE-1)); + BUG_ON((unsigned long)layout->ro_size & (PAGE_SIZE-1)); + set_memory((unsigned long)layout->base + layout->text_size, + (layout->ro_size - layout->text_size) >> PAGE_SHIFT); +} + +void frob_ro_after_init(const struct module_layout *layout, + int (*set_memory)(unsigned long start, int num_pages)) +{ + BUG_ON((unsigned long)layout->base & (PAGE_SIZE-1)); + BUG_ON((unsigned long)layout->ro_size & (PAGE_SIZE-1)); + BUG_ON((unsigned long)layout->ro_after_init_size & (PAGE_SIZE-1)); + set_memory((unsigned long)layout->base + layout->ro_size, + (layout->ro_after_init_size - layout->ro_size) >> PAGE_SHIFT); +} + +void frob_writable_data(const struct module_layout *layout, + int (*set_memory)(unsigned long start, int num_pages)) +{ + BUG_ON((unsigned long)layout->base & (PAGE_SIZE-1)); + BUG_ON((unsigned long)layout->ro_after_init_size & (PAGE_SIZE-1)); + BUG_ON((unsigned long)layout->size & (PAGE_SIZE-1)); + set_memory((unsigned long)layout->base + layout->ro_after_init_size, + (layout->size - layout->ro_after_init_size) >> PAGE_SHIFT); +} + +void module_enable_ro(const struct module *mod, bool after_init) +{ + if (!rodata_enabled) + return; + + set_vm_flush_reset_perms(mod->core_layout.base); + set_vm_flush_reset_perms(mod->init_layout.base); + frob_text(&mod->core_layout, set_memory_ro); + + frob_rodata(&mod->core_layout, set_memory_ro); + frob_text(&mod->init_layout, set_memory_ro); + frob_rodata(&mod->init_layout, set_memory_ro); + + if (after_init) + frob_ro_after_init(&mod->core_layout, set_memory_ro); +} + +void module_enable_nx(const struct module *mod) +{ + frob_rodata(&mod->core_layout, set_memory_nx); + frob_ro_after_init(&mod->core_layout, set_memory_nx); + frob_writable_data(&mod->core_layout, set_memory_nx); + frob_rodata(&mod->init_layout, set_memory_nx); + frob_writable_data(&mod->init_layout, set_memory_nx); +} + +int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs, + char *secstrings, struct module *mod) +{ + const unsigned long shf_wx = SHF_WRITE|SHF_EXECINSTR; + int i; + + for (i = 0; i < hdr->e_shnum; i++) { + if ((sechdrs[i].sh_flags & shf_wx) == shf_wx) { + pr_err("%s: section %s (index %d) has invalid WRITE|EXEC flags\n", + mod->name, secstrings + sechdrs[i].sh_name, i); + return -ENOEXEC; + } + } + + return 0; +}
No functional change. This patch migrates code that makes module text and rodata memory read-only and non-text memory non-executable from core module code into kernel/module/strict_rwx.c. Signed-off-by: Aaron Tomlin <atomlin@redhat.com> --- kernel/module/Makefile | 1 + kernel/module/internal.h | 38 +++++++++++++++ kernel/module/main.c | 97 +------------------------------------- kernel/module/strict_rwx.c | 84 +++++++++++++++++++++++++++++++++ 4 files changed, 124 insertions(+), 96 deletions(-) create mode 100644 kernel/module/strict_rwx.c