[Crash-utility] [PATCH v3] Basic support for PaX's split module layout
Mathias Krause
minipli at grsecurity.net
Wed Sep 2 13:23:20 UTC 2020
Does this need further input from my site to get merged? Lianbo acked an
earlier version[1], so this should be fine as is?
Thanks,
Mathias
[1] https://www.redhat.com/archives/crash-utility/2020-August/msg00021.html
Am 25.08.20 um 04:09 schrieb HAGIO KAZUHITO(萩尾 一仁):
> -----Original Message-----
>> PaX and grsecurity kernels split module memory into dedicated r/x and
>> r/w mappings using '*_rw' and '*_rx' named member variables in 'struct
>> module'. To add basic support for such kernels detect the split layout
>> by testing for the corresponding structure members and use these
>> instead.
>>
>> So far we limit ourself to only track module code mappings for such
>> kernels as adding support for separate data mappings violates lots of
>> invariants in the rest of our code base, thereby would require a major
>> rework. However, with that patch applied, module code references can be
>> resolved in backtraces, memory and code dumps, which makes it already
>> very useful for analyzing such kernels.
>>
>> Signed-off-by: Mathias Krause <minipli at grsecurity.net>
>> ---
>> v3:
>> - dump offsets unconditional
>> - fix indention of 'module_init_size' offset dump
>
> Thanks for the update. The v3 patch looks good to me.
>
> Acked-by: Kazuhito Hagio <k-hagio-ab at nec.com>
>
> Thanks,
> Kazu
>
>>
>> v2:
>> - add members to end of struct offset_table
>> - add offsets to dump_offset_table()
>>
>> defs.h | 13 +++++++++++
>> kernel.c | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++----
>> symbols.c | 38 ++++++++++++++++++++++---------
>> 3 files changed, 103 insertions(+), 16 deletions(-)
>>
>> diff --git a/defs.h b/defs.h
>> index 17e98763362b..ae860448ab15 100644
>> --- a/defs.h
>> +++ b/defs.h
>> @@ -654,12 +654,15 @@ struct new_utsname {
>> #define TIMER_BASES (0x20ULL)
>> #define IRQ_DESC_TREE_RADIX (0x40ULL)
>> #define IRQ_DESC_TREE_XARRAY (0x80ULL)
>> +#define KMOD_PAX (0x100ULL)
>>
>> #define XEN() (kt->flags & ARCH_XEN)
>> #define OPENVZ() (kt->flags & ARCH_OPENVZ)
>> #define PVOPS() (kt->flags & ARCH_PVOPS)
>> #define PVOPS_XEN() (kt->flags & ARCH_PVOPS_XEN)
>>
>> +#define PAX_MODULE_SPLIT() (kt->flags2 & KMOD_PAX)
>> +
>> #define XEN_MACHINE_TO_MFN(m) ((ulonglong)(m) >> PAGESHIFT())
>> #define XEN_PFN_TO_PSEUDO(p) ((ulonglong)(p) << PAGESHIFT())
>>
>> @@ -2089,6 +2092,14 @@ struct offset_table { /* stash of commonly-used offsets */
>> long size_class_size;
>> long gendisk_private_data;
>> long zram_table_entry;
>> + long module_core_size_rw;
>> + long module_core_size_rx;
>> + long module_init_size_rw;
>> + long module_init_size_rx;
>> + long module_module_core_rw;
>> + long module_module_core_rx;
>> + long module_module_init_rw;
>> + long module_module_init_rx;
>> };
>>
>> struct size_table { /* stash of commonly-used sizes */
>> @@ -2313,6 +2324,8 @@ struct array_table {
>> * in the offset table, size table or array_table.
>> */
>> #define OFFSET(X) (OFFSET_verify(offset_table.X, (char *)__FUNCTION__, __FILE__, __LINE__, #X))
>> +#define MODULE_OFFSET(X,Y) (PAX_MODULE_SPLIT() ? OFFSET(Y) : OFFSET(X))
>> +#define MODULE_OFFSET2(X,T) MODULE_OFFSET(X, X##_##T)
>> #define SIZE(X) (SIZE_verify(size_table.X, (char *)__FUNCTION__, __FILE__, __LINE__, #X))
>> #define INVALID_OFFSET (-1)
>> #define INVALID_MEMBER(X) (offset_table.X == INVALID_OFFSET)
>> diff --git a/kernel.c b/kernel.c
>> index f179375f2d3d..f0268adccd4a 100644
>> --- a/kernel.c
>> +++ b/kernel.c
>> @@ -3540,6 +3540,62 @@ module_init(void)
>> "module_core");
>> MEMBER_OFFSET_INIT(module_module_init, "module",
>> "module_init");
>> + } else if (MEMBER_EXISTS("module", "module_core_rx")) {
>> + if (CRASHDEBUG(1))
>> + error(INFO, "PaX module layout detected.\n");
>> + kt->flags2 |= KMOD_PAX;
>> +
>> + MEMBER_OFFSET_INIT(module_core_size_rw, "module",
>> + "core_size_rw");
>> + MEMBER_OFFSET_INIT(module_core_size_rx, "module",
>> + "core_size_rx");
>> +
>> + MEMBER_OFFSET_INIT(module_init_size_rw, "module",
>> + "init_size_rw");
>> + MEMBER_OFFSET_INIT(module_init_size_rx, "module",
>> + "init_size_rx");
>> +
>> + MEMBER_OFFSET_INIT(module_module_core_rw, "module",
>> + "module_core_rw");
>> + MEMBER_OFFSET_INIT(module_module_core_rx, "module",
>> + "module_core_rx");
>> +
>> + MEMBER_OFFSET_INIT(module_module_init_rw, "module",
>> + "module_init_rw");
>> + MEMBER_OFFSET_INIT(module_module_init_rx, "module",
>> + "module_init_rx");
>> + } else if (MEMBER_EXISTS("module_layout", "base_rx")) {
>> + if (CRASHDEBUG(1))
>> + error(INFO, "PaX module layout detected.\n");
>> + kt->flags2 |= KMOD_PAX;
>> +
>> + ASSIGN_OFFSET(module_core_size_rw) =
>> + MEMBER_OFFSET("module", "core_layout") +
>> + MEMBER_OFFSET("module_layout", "size_rw");
>> + ASSIGN_OFFSET(module_core_size_rx) =
>> + MEMBER_OFFSET("module", "core_layout") +
>> + MEMBER_OFFSET("module_layout", "size_rx");
>> +
>> + ASSIGN_OFFSET(module_init_size_rw) =
>> + MEMBER_OFFSET("module", "init_layout") +
>> + MEMBER_OFFSET("module_layout", "size_rw");
>> + ASSIGN_OFFSET(module_init_size_rx) =
>> + MEMBER_OFFSET("module", "init_layout") +
>> + MEMBER_OFFSET("module_layout", "size_rx");
>> +
>> + ASSIGN_OFFSET(module_module_core_rw) =
>> + MEMBER_OFFSET("module", "core_layout") +
>> + MEMBER_OFFSET("module_layout", "base_rw");
>> + ASSIGN_OFFSET(module_module_core_rx) =
>> + MEMBER_OFFSET("module", "core_layout") +
>> + MEMBER_OFFSET("module_layout", "base_rx");
>> +
>> + ASSIGN_OFFSET(module_module_init_rw) =
>> + MEMBER_OFFSET("module", "init_layout") +
>> + MEMBER_OFFSET("module_layout", "base_rw");
>> + ASSIGN_OFFSET(module_module_init_rx) =
>> + MEMBER_OFFSET("module", "init_layout") +
>> + MEMBER_OFFSET("module_layout", "base_rx");
>> } else {
>> ASSIGN_OFFSET(module_core_size) =
>> MEMBER_OFFSET("module", "core_layout") +
>> @@ -3682,10 +3738,10 @@ module_init(void)
>> case KALLSYMS_V2:
>> if (THIS_KERNEL_VERSION >= LINUX(2,6,27)) {
>> numksyms = UINT(modbuf + OFFSET(module_num_symtab));
>> - size = UINT(modbuf + OFFSET(module_core_size));
>> + size = UINT(modbuf + MODULE_OFFSET2(module_core_size, rx));
>> } else {
>> numksyms = ULONG(modbuf + OFFSET(module_num_symtab));
>> - size = ULONG(modbuf + OFFSET(module_core_size));
>> + size = ULONG(modbuf + MODULE_OFFSET2(module_core_size, rx));
>> }
>>
>> if (!size) {
>> @@ -3792,7 +3848,7 @@ verify_modules(void)
>> break;
>> case KMOD_V2:
>> mod_base = ULONG(modbuf +
>> - OFFSET(module_module_core));
>> + MODULE_OFFSET2(module_module_core, rx));
>> break;
>> }
>>
>> @@ -3816,10 +3872,10 @@ verify_modules(void)
>> OFFSET(module_name);
>> if (THIS_KERNEL_VERSION >= LINUX(2,6,27))
>> mod_size = UINT(modbuf +
>> - OFFSET(module_core_size));
>> + MODULE_OFFSET2(module_core_size, rx));
>> else
>> mod_size = ULONG(modbuf +
>> - OFFSET(module_core_size));
>> + MODULE_OFFSET2(module_core_size, rx));
>> if (strlen(module_name) < MAX_MOD_NAME)
>> strcpy(buf, module_name);
>> else
>> @@ -5997,6 +6053,8 @@ dump_kernel_table(int verbose)
>> fprintf(fp, "%sIRQ_DESC_TREE_RADIX", others++ ? "|" : "");
>> if (kt->flags2 & IRQ_DESC_TREE_XARRAY)
>> fprintf(fp, "%sIRQ_DESC_TREE_XARRAY", others++ ? "|" : "");
>> + if (kt->flags2 & KMOD_PAX)
>> + fprintf(fp, "%sKMOD_PAX", others++ ? "|" : "");
>> fprintf(fp, ")\n");
>>
>> fprintf(fp, " stext: %lx\n", kt->stext);
>> diff --git a/symbols.c b/symbols.c
>> index 2fecaee093a2..311fdb7df29e 100644
>> --- a/symbols.c
>> +++ b/symbols.c
>> @@ -1766,17 +1766,17 @@ store_module_symbols_v2(ulong total, int mods_installed)
>>
>> if (THIS_KERNEL_VERSION >= LINUX(2,6,27)) {
>> nksyms = UINT(modbuf + OFFSET(module_num_symtab));
>> - size = UINT(modbuf + OFFSET(module_core_size));
>> + size = UINT(modbuf + MODULE_OFFSET2(module_core_size, rx));
>> } else {
>> nksyms = ULONG(modbuf + OFFSET(module_num_symtab));
>> - size = ULONG(modbuf + OFFSET(module_core_size));
>> + size = ULONG(modbuf + MODULE_OFFSET2(module_core_size, rx));
>> }
>>
>> mod_name = modbuf + OFFSET(module_name);
>>
>> lm = &st->load_modules[m++];
>> BZERO(lm, sizeof(struct load_module));
>> - lm->mod_base = ULONG(modbuf + OFFSET(module_module_core));
>> + lm->mod_base = ULONG(modbuf + MODULE_OFFSET2(module_module_core, rx));
>> lm->module_struct = mod;
>> lm->mod_size = size;
>> if (strlen(mod_name) < MAX_MOD_NAME)
>> @@ -1795,23 +1795,23 @@ store_module_symbols_v2(ulong total, int mods_installed)
>> lm->mod_flags = MOD_EXT_SYMS;
>> lm->mod_ext_symcnt = mcnt;
>> lm->mod_init_module_ptr = ULONG(modbuf +
>> - OFFSET(module_module_init));
>> + MODULE_OFFSET2(module_module_init, rx));
>> if (VALID_MEMBER(module_percpu))
>> lm->mod_percpu = ULONG(modbuf + OFFSET(module_percpu));
>> if (THIS_KERNEL_VERSION >= LINUX(2,6,27)) {
>> lm->mod_etext_guess = lm->mod_base +
>> - UINT(modbuf + OFFSET(module_core_text_size));
>> + UINT(modbuf + MODULE_OFFSET(module_core_text_size, module_core_size_rx));
>> lm->mod_init_size =
>> - UINT(modbuf + OFFSET(module_init_size));
>> + UINT(modbuf + MODULE_OFFSET2(module_init_size, rx));
>> lm->mod_init_text_size =
>> - UINT(modbuf + OFFSET(module_init_text_size));
>> + UINT(modbuf + MODULE_OFFSET(module_init_text_size, module_init_size_rx));
>> } else {
>> lm->mod_etext_guess = lm->mod_base +
>> - ULONG(modbuf + OFFSET(module_core_text_size));
>> + ULONG(modbuf + MODULE_OFFSET(module_core_text_size, module_core_size_rx));
>> lm->mod_init_size =
>> - ULONG(modbuf + OFFSET(module_init_size));
>> + ULONG(modbuf + MODULE_OFFSET2(module_init_size, rx));
>> lm->mod_init_text_size =
>> - ULONG(modbuf + OFFSET(module_init_text_size));
>> + ULONG(modbuf + MODULE_OFFSET(module_init_text_size, module_init_size_rx));
>> }
>> lm->mod_text_start = lm->mod_base;
>>
>> @@ -9119,12 +9119,28 @@ dump_offset_table(char *spec, ulong makestruct)
>> OFFSET(module_core_size));
>> fprintf(fp, " module_core_text_size: %ld\n",
>> OFFSET(module_core_text_size));
>> - fprintf(fp, " module_init_size: %ld\n",
>> + fprintf(fp, " module_init_size: %ld\n",
>> OFFSET(module_init_size));
>> fprintf(fp, " module_init_text_size: %ld\n",
>> OFFSET(module_init_text_size));
>> fprintf(fp, " module_module_init: %ld\n",
>> OFFSET(module_module_init));
>> + fprintf(fp, " module_module_core_rx: %ld\n",
>> + OFFSET(module_module_core_rx));
>> + fprintf(fp, " module_module_core_rw: %ld\n",
>> + OFFSET(module_module_core_rw));
>> + fprintf(fp, " module_core_size_rx: %ld\n",
>> + OFFSET(module_core_size_rx));
>> + fprintf(fp, " module_core_size_rw: %ld\n",
>> + OFFSET(module_core_size_rw));
>> + fprintf(fp, " module_module_init_rx: %ld\n",
>> + OFFSET(module_module_init_rx));
>> + fprintf(fp, " module_module_init_rw: %ld\n",
>> + OFFSET(module_module_init_rw));
>> + fprintf(fp, " module_init_size_rx: %ld\n",
>> + OFFSET(module_init_size_rx));
>> + fprintf(fp, " module_init_size_rw: %ld\n",
>> + OFFSET(module_init_size_rw));
>> fprintf(fp, " module_num_symtab: %ld\n",
>> OFFSET(module_num_symtab));
>> fprintf(fp, " module_symtab: %ld\n",
>> --
>> 2.20.1
>>
>>
>> --
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>> Crash-utility at redhat.com
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>
>
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