From b4e9c9549f62329d2412f899635fddc5212b9cd4 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Mon, 1 Jun 2020 19:42:40 -0400 Subject: [PATCH] introduction of regset ->get() wrappers, switching ELF coredumps to those Two new helpers: given a process and regset, dump into a buffer. regset_get() takes a buffer and size, regset_get_alloc() takes size and allocates a buffer. Return value in both cases is the amount of data actually dumped in case of success or -E... on error. In both cases the size is capped by regset->n * regset->size, so ->get() is called with offset 0 and size no more than what regset expects. binfmt_elf.c callers of ->get() are switched to using those; the other caller (copy_regset_to_user()) will need some preparations to switch. Signed-off-by: Al Viro --- fs/binfmt_elf.c | 54 ++++++++++++++++++++---------------------- include/linux/regset.h | 9 +++++++ kernel/Makefile | 2 +- kernel/regset.c | 54 ++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 90 insertions(+), 29 deletions(-) create mode 100644 kernel/regset.c diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index 9fe3b51c116a..e922a6abdca8 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -1821,7 +1821,7 @@ static int fill_thread_core_info(struct elf_thread_core_info *t, long signr, size_t *total) { unsigned int i; - unsigned int regset0_size = regset_size(t->task, &view->regsets[0]); + int regset0_size; /* * NT_PRSTATUS is the one special case, because the regset data @@ -1830,8 +1830,10 @@ static int fill_thread_core_info(struct elf_thread_core_info *t, * We assume that regset 0 is NT_PRSTATUS. */ fill_prstatus(&t->prstatus, t->task, signr); - (void) view->regsets[0].get(t->task, &view->regsets[0], 0, regset0_size, - &t->prstatus.pr_reg, NULL); + regset0_size = regset_get(t->task, &view->regsets[0], + sizeof(t->prstatus.pr_reg), &t->prstatus.pr_reg); + if (regset0_size < 0) + return 0; fill_note(&t->notes[0], "CORE", NT_PRSTATUS, PRSTATUS_SIZE(t->prstatus, regset0_size), &t->prstatus); @@ -1846,32 +1848,28 @@ static int fill_thread_core_info(struct elf_thread_core_info *t, */ for (i = 1; i < view->n; ++i) { const struct user_regset *regset = &view->regsets[i]; + int note_type = regset->core_note_type; + bool is_fpreg = note_type == NT_PRFPREG; + void *data; + int ret; + do_thread_regset_writeback(t->task, regset); - if (regset->core_note_type && regset->get && - (!regset->active || regset->active(t->task, regset) > 0)) { - int ret; - size_t size = regset_size(t->task, regset); - void *data = kzalloc(size, GFP_KERNEL); - if (unlikely(!data)) - return 0; - ret = regset->get(t->task, regset, - 0, size, data, NULL); - if (unlikely(ret)) - kfree(data); - else { - if (regset->core_note_type != NT_PRFPREG) - fill_note(&t->notes[i], "LINUX", - regset->core_note_type, - size, data); - else { - SET_PR_FPVALID(&t->prstatus, - 1, regset0_size); - fill_note(&t->notes[i], "CORE", - NT_PRFPREG, size, data); - } - *total += notesize(&t->notes[i]); - } - } + if (!note_type) // not for coredumps + continue; + if (regset->active && regset->active(t->task, regset) <= 0) + continue; + + ret = regset_get_alloc(t->task, regset, ~0U, &data); + if (ret < 0) + continue; + + if (is_fpreg) + SET_PR_FPVALID(&t->prstatus, 1, regset0_size); + + fill_note(&t->notes[i], is_fpreg ? "CORE" : "LINUX", + note_type, ret, data); + + *total += notesize(&t->notes[i]); } return 1; diff --git a/include/linux/regset.h b/include/linux/regset.h index 46d6ae68c455..968a032922d5 100644 --- a/include/linux/regset.h +++ b/include/linux/regset.h @@ -353,6 +353,15 @@ static inline int user_regset_copyin_ignore(unsigned int *pos, return 0; } +extern int regset_get(struct task_struct *target, + const struct user_regset *regset, + unsigned int size, void *data); + +extern int regset_get_alloc(struct task_struct *target, + const struct user_regset *regset, + unsigned int size, + void **data); + /** * copy_regset_to_user - fetch a thread's user_regset data into user memory * @target: thread to be examined diff --git a/kernel/Makefile b/kernel/Makefile index f3218bc5ec69..e6e03380a0f1 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -10,7 +10,7 @@ obj-y = fork.o exec_domain.o panic.o \ extable.o params.o \ kthread.o sys_ni.o nsproxy.o \ notifier.o ksysfs.o cred.o reboot.o \ - async.o range.o smpboot.o ucount.o + async.o range.o smpboot.o ucount.o regset.o obj-$(CONFIG_MODULES) += kmod.o obj-$(CONFIG_MULTIUSER) += groups.o diff --git a/kernel/regset.c b/kernel/regset.c new file mode 100644 index 000000000000..6b39fa0993ec --- /dev/null +++ b/kernel/regset.c @@ -0,0 +1,54 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include +#include +#include + +static int __regset_get(struct task_struct *target, + const struct user_regset *regset, + unsigned int size, + void **data) +{ + void *p = *data, *to_free = NULL; + int res; + + if (!regset->get) + return -EOPNOTSUPP; + if (size > regset->n * regset->size) + size = regset->n * regset->size; + if (!p) { + to_free = p = kzalloc(size, GFP_KERNEL); + if (!p) + return -ENOMEM; + } + res = regset->get(target, regset, 0, size, p, NULL); + if (unlikely(res < 0)) { + kfree(to_free); + return res; + } + *data = p; + if (regset->get_size) { // arm64-only kludge, will go away + unsigned max_size = regset->get_size(target, regset); + if (size > max_size) + size = max_size; + } + return size; +} + +int regset_get(struct task_struct *target, + const struct user_regset *regset, + unsigned int size, + void *data) +{ + return __regset_get(target, regset, size, &data); +} +EXPORT_SYMBOL(regset_get); + +int regset_get_alloc(struct task_struct *target, + const struct user_regset *regset, + unsigned int size, + void **data) +{ + *data = NULL; + return __regset_get(target, regset, size, data); +} +EXPORT_SYMBOL(regset_get_alloc); -- 2.20.1