summaryrefslogtreecommitdiffstats
path: root/fs/coredump.c
diff options
context:
space:
mode:
authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
commit2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch)
tree848558de17fb3008cdf4d861b01ac7781903ce39 /fs/coredump.c
parentInitial commit. (diff)
downloadlinux-2c3c1048746a4622d8c89a29670120dc8fab93c4.tar.xz
linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.zip
Adding upstream version 6.1.76.upstream/6.1.76
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'fs/coredump.c')
-rw-r--r--fs/coredump.c1197
1 files changed, 1197 insertions, 0 deletions
diff --git a/fs/coredump.c b/fs/coredump.c
new file mode 100644
index 000000000..4d332f147
--- /dev/null
+++ b/fs/coredump.c
@@ -0,0 +1,1197 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/slab.h>
+#include <linux/file.h>
+#include <linux/fdtable.h>
+#include <linux/freezer.h>
+#include <linux/mm.h>
+#include <linux/stat.h>
+#include <linux/fcntl.h>
+#include <linux/swap.h>
+#include <linux/ctype.h>
+#include <linux/string.h>
+#include <linux/init.h>
+#include <linux/pagemap.h>
+#include <linux/perf_event.h>
+#include <linux/highmem.h>
+#include <linux/spinlock.h>
+#include <linux/key.h>
+#include <linux/personality.h>
+#include <linux/binfmts.h>
+#include <linux/coredump.h>
+#include <linux/sched/coredump.h>
+#include <linux/sched/signal.h>
+#include <linux/sched/task_stack.h>
+#include <linux/utsname.h>
+#include <linux/pid_namespace.h>
+#include <linux/module.h>
+#include <linux/namei.h>
+#include <linux/mount.h>
+#include <linux/security.h>
+#include <linux/syscalls.h>
+#include <linux/tsacct_kern.h>
+#include <linux/cn_proc.h>
+#include <linux/audit.h>
+#include <linux/kmod.h>
+#include <linux/fsnotify.h>
+#include <linux/fs_struct.h>
+#include <linux/pipe_fs_i.h>
+#include <linux/oom.h>
+#include <linux/compat.h>
+#include <linux/fs.h>
+#include <linux/path.h>
+#include <linux/timekeeping.h>
+#include <linux/sysctl.h>
+#include <linux/elf.h>
+
+#include <linux/uaccess.h>
+#include <asm/mmu_context.h>
+#include <asm/tlb.h>
+#include <asm/exec.h>
+
+#include <trace/events/task.h>
+#include "internal.h"
+
+#include <trace/events/sched.h>
+
+static bool dump_vma_snapshot(struct coredump_params *cprm);
+static void free_vma_snapshot(struct coredump_params *cprm);
+
+static int core_uses_pid;
+static unsigned int core_pipe_limit;
+static char core_pattern[CORENAME_MAX_SIZE] = "core";
+static int core_name_size = CORENAME_MAX_SIZE;
+
+struct core_name {
+ char *corename;
+ int used, size;
+};
+
+static int expand_corename(struct core_name *cn, int size)
+{
+ char *corename = krealloc(cn->corename, size, GFP_KERNEL);
+
+ if (!corename)
+ return -ENOMEM;
+
+ if (size > core_name_size) /* racy but harmless */
+ core_name_size = size;
+
+ cn->size = ksize(corename);
+ cn->corename = corename;
+ return 0;
+}
+
+static __printf(2, 0) int cn_vprintf(struct core_name *cn, const char *fmt,
+ va_list arg)
+{
+ int free, need;
+ va_list arg_copy;
+
+again:
+ free = cn->size - cn->used;
+
+ va_copy(arg_copy, arg);
+ need = vsnprintf(cn->corename + cn->used, free, fmt, arg_copy);
+ va_end(arg_copy);
+
+ if (need < free) {
+ cn->used += need;
+ return 0;
+ }
+
+ if (!expand_corename(cn, cn->size + need - free + 1))
+ goto again;
+
+ return -ENOMEM;
+}
+
+static __printf(2, 3) int cn_printf(struct core_name *cn, const char *fmt, ...)
+{
+ va_list arg;
+ int ret;
+
+ va_start(arg, fmt);
+ ret = cn_vprintf(cn, fmt, arg);
+ va_end(arg);
+
+ return ret;
+}
+
+static __printf(2, 3)
+int cn_esc_printf(struct core_name *cn, const char *fmt, ...)
+{
+ int cur = cn->used;
+ va_list arg;
+ int ret;
+
+ va_start(arg, fmt);
+ ret = cn_vprintf(cn, fmt, arg);
+ va_end(arg);
+
+ if (ret == 0) {
+ /*
+ * Ensure that this coredump name component can't cause the
+ * resulting corefile path to consist of a ".." or ".".
+ */
+ if ((cn->used - cur == 1 && cn->corename[cur] == '.') ||
+ (cn->used - cur == 2 && cn->corename[cur] == '.'
+ && cn->corename[cur+1] == '.'))
+ cn->corename[cur] = '!';
+
+ /*
+ * Empty names are fishy and could be used to create a "//" in a
+ * corefile name, causing the coredump to happen one directory
+ * level too high. Enforce that all components of the core
+ * pattern are at least one character long.
+ */
+ if (cn->used == cur)
+ ret = cn_printf(cn, "!");
+ }
+
+ for (; cur < cn->used; ++cur) {
+ if (cn->corename[cur] == '/')
+ cn->corename[cur] = '!';
+ }
+ return ret;
+}
+
+static int cn_print_exe_file(struct core_name *cn, bool name_only)
+{
+ struct file *exe_file;
+ char *pathbuf, *path, *ptr;
+ int ret;
+
+ exe_file = get_mm_exe_file(current->mm);
+ if (!exe_file)
+ return cn_esc_printf(cn, "%s (path unknown)", current->comm);
+
+ pathbuf = kmalloc(PATH_MAX, GFP_KERNEL);
+ if (!pathbuf) {
+ ret = -ENOMEM;
+ goto put_exe_file;
+ }
+
+ path = file_path(exe_file, pathbuf, PATH_MAX);
+ if (IS_ERR(path)) {
+ ret = PTR_ERR(path);
+ goto free_buf;
+ }
+
+ if (name_only) {
+ ptr = strrchr(path, '/');
+ if (ptr)
+ path = ptr + 1;
+ }
+ ret = cn_esc_printf(cn, "%s", path);
+
+free_buf:
+ kfree(pathbuf);
+put_exe_file:
+ fput(exe_file);
+ return ret;
+}
+
+/* format_corename will inspect the pattern parameter, and output a
+ * name into corename, which must have space for at least
+ * CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
+ */
+static int format_corename(struct core_name *cn, struct coredump_params *cprm,
+ size_t **argv, int *argc)
+{
+ const struct cred *cred = current_cred();
+ const char *pat_ptr = core_pattern;
+ int ispipe = (*pat_ptr == '|');
+ bool was_space = false;
+ int pid_in_pattern = 0;
+ int err = 0;
+
+ cn->used = 0;
+ cn->corename = NULL;
+ if (expand_corename(cn, core_name_size))
+ return -ENOMEM;
+ cn->corename[0] = '\0';
+
+ if (ispipe) {
+ int argvs = sizeof(core_pattern) / 2;
+ (*argv) = kmalloc_array(argvs, sizeof(**argv), GFP_KERNEL);
+ if (!(*argv))
+ return -ENOMEM;
+ (*argv)[(*argc)++] = 0;
+ ++pat_ptr;
+ if (!(*pat_ptr))
+ return -ENOMEM;
+ }
+
+ /* Repeat as long as we have more pattern to process and more output
+ space */
+ while (*pat_ptr) {
+ /*
+ * Split on spaces before doing template expansion so that
+ * %e and %E don't get split if they have spaces in them
+ */
+ if (ispipe) {
+ if (isspace(*pat_ptr)) {
+ if (cn->used != 0)
+ was_space = true;
+ pat_ptr++;
+ continue;
+ } else if (was_space) {
+ was_space = false;
+ err = cn_printf(cn, "%c", '\0');
+ if (err)
+ return err;
+ (*argv)[(*argc)++] = cn->used;
+ }
+ }
+ if (*pat_ptr != '%') {
+ err = cn_printf(cn, "%c", *pat_ptr++);
+ } else {
+ switch (*++pat_ptr) {
+ /* single % at the end, drop that */
+ case 0:
+ goto out;
+ /* Double percent, output one percent */
+ case '%':
+ err = cn_printf(cn, "%c", '%');
+ break;
+ /* pid */
+ case 'p':
+ pid_in_pattern = 1;
+ err = cn_printf(cn, "%d",
+ task_tgid_vnr(current));
+ break;
+ /* global pid */
+ case 'P':
+ err = cn_printf(cn, "%d",
+ task_tgid_nr(current));
+ break;
+ case 'i':
+ err = cn_printf(cn, "%d",
+ task_pid_vnr(current));
+ break;
+ case 'I':
+ err = cn_printf(cn, "%d",
+ task_pid_nr(current));
+ break;
+ /* uid */
+ case 'u':
+ err = cn_printf(cn, "%u",
+ from_kuid(&init_user_ns,
+ cred->uid));
+ break;
+ /* gid */
+ case 'g':
+ err = cn_printf(cn, "%u",
+ from_kgid(&init_user_ns,
+ cred->gid));
+ break;
+ case 'd':
+ err = cn_printf(cn, "%d",
+ __get_dumpable(cprm->mm_flags));
+ break;
+ /* signal that caused the coredump */
+ case 's':
+ err = cn_printf(cn, "%d",
+ cprm->siginfo->si_signo);
+ break;
+ /* UNIX time of coredump */
+ case 't': {
+ time64_t time;
+
+ time = ktime_get_real_seconds();
+ err = cn_printf(cn, "%lld", time);
+ break;
+ }
+ /* hostname */
+ case 'h':
+ down_read(&uts_sem);
+ err = cn_esc_printf(cn, "%s",
+ utsname()->nodename);
+ up_read(&uts_sem);
+ break;
+ /* executable, could be changed by prctl PR_SET_NAME etc */
+ case 'e':
+ err = cn_esc_printf(cn, "%s", current->comm);
+ break;
+ /* file name of executable */
+ case 'f':
+ err = cn_print_exe_file(cn, true);
+ break;
+ case 'E':
+ err = cn_print_exe_file(cn, false);
+ break;
+ /* core limit size */
+ case 'c':
+ err = cn_printf(cn, "%lu",
+ rlimit(RLIMIT_CORE));
+ break;
+ default:
+ break;
+ }
+ ++pat_ptr;
+ }
+
+ if (err)
+ return err;
+ }
+
+out:
+ /* Backward compatibility with core_uses_pid:
+ *
+ * If core_pattern does not include a %p (as is the default)
+ * and core_uses_pid is set, then .%pid will be appended to
+ * the filename. Do not do this for piped commands. */
+ if (!ispipe && !pid_in_pattern && core_uses_pid) {
+ err = cn_printf(cn, ".%d", task_tgid_vnr(current));
+ if (err)
+ return err;
+ }
+ return ispipe;
+}
+
+static int zap_process(struct task_struct *start, int exit_code)
+{
+ struct task_struct *t;
+ int nr = 0;
+
+ /* Allow SIGKILL, see prepare_signal() */
+ start->signal->flags = SIGNAL_GROUP_EXIT;
+ start->signal->group_exit_code = exit_code;
+ start->signal->group_stop_count = 0;
+
+ for_each_thread(start, t) {
+ task_clear_jobctl_pending(t, JOBCTL_PENDING_MASK);
+ if (t != current && !(t->flags & PF_POSTCOREDUMP)) {
+ sigaddset(&t->pending.signal, SIGKILL);
+ signal_wake_up(t, 1);
+ nr++;
+ }
+ }
+
+ return nr;
+}
+
+static int zap_threads(struct task_struct *tsk,
+ struct core_state *core_state, int exit_code)
+{
+ struct signal_struct *signal = tsk->signal;
+ int nr = -EAGAIN;
+
+ spin_lock_irq(&tsk->sighand->siglock);
+ if (!(signal->flags & SIGNAL_GROUP_EXIT) && !signal->group_exec_task) {
+ signal->core_state = core_state;
+ nr = zap_process(tsk, exit_code);
+ clear_tsk_thread_flag(tsk, TIF_SIGPENDING);
+ tsk->flags |= PF_DUMPCORE;
+ atomic_set(&core_state->nr_threads, nr);
+ }
+ spin_unlock_irq(&tsk->sighand->siglock);
+ return nr;
+}
+
+static int coredump_wait(int exit_code, struct core_state *core_state)
+{
+ struct task_struct *tsk = current;
+ int core_waiters = -EBUSY;
+
+ init_completion(&core_state->startup);
+ core_state->dumper.task = tsk;
+ core_state->dumper.next = NULL;
+
+ core_waiters = zap_threads(tsk, core_state, exit_code);
+ if (core_waiters > 0) {
+ struct core_thread *ptr;
+
+ wait_for_completion_state(&core_state->startup,
+ TASK_UNINTERRUPTIBLE|TASK_FREEZABLE);
+ /*
+ * Wait for all the threads to become inactive, so that
+ * all the thread context (extended register state, like
+ * fpu etc) gets copied to the memory.
+ */
+ ptr = core_state->dumper.next;
+ while (ptr != NULL) {
+ wait_task_inactive(ptr->task, TASK_ANY);
+ ptr = ptr->next;
+ }
+ }
+
+ return core_waiters;
+}
+
+static void coredump_finish(bool core_dumped)
+{
+ struct core_thread *curr, *next;
+ struct task_struct *task;
+
+ spin_lock_irq(&current->sighand->siglock);
+ if (core_dumped && !__fatal_signal_pending(current))
+ current->signal->group_exit_code |= 0x80;
+ next = current->signal->core_state->dumper.next;
+ current->signal->core_state = NULL;
+ spin_unlock_irq(&current->sighand->siglock);
+
+ while ((curr = next) != NULL) {
+ next = curr->next;
+ task = curr->task;
+ /*
+ * see coredump_task_exit(), curr->task must not see
+ * ->task == NULL before we read ->next.
+ */
+ smp_mb();
+ curr->task = NULL;
+ wake_up_process(task);
+ }
+}
+
+static bool dump_interrupted(void)
+{
+ /*
+ * SIGKILL or freezing() interrupt the coredumping. Perhaps we
+ * can do try_to_freeze() and check __fatal_signal_pending(),
+ * but then we need to teach dump_write() to restart and clear
+ * TIF_SIGPENDING.
+ */
+ return fatal_signal_pending(current) || freezing(current);
+}
+
+static void wait_for_dump_helpers(struct file *file)
+{
+ struct pipe_inode_info *pipe = file->private_data;
+
+ pipe_lock(pipe);
+ pipe->readers++;
+ pipe->writers--;
+ wake_up_interruptible_sync(&pipe->rd_wait);
+ kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
+ pipe_unlock(pipe);
+
+ /*
+ * We actually want wait_event_freezable() but then we need
+ * to clear TIF_SIGPENDING and improve dump_interrupted().
+ */
+ wait_event_interruptible(pipe->rd_wait, pipe->readers == 1);
+
+ pipe_lock(pipe);
+ pipe->readers--;
+ pipe->writers++;
+ pipe_unlock(pipe);
+}
+
+/*
+ * umh_pipe_setup
+ * helper function to customize the process used
+ * to collect the core in userspace. Specifically
+ * it sets up a pipe and installs it as fd 0 (stdin)
+ * for the process. Returns 0 on success, or
+ * PTR_ERR on failure.
+ * Note that it also sets the core limit to 1. This
+ * is a special value that we use to trap recursive
+ * core dumps
+ */
+static int umh_pipe_setup(struct subprocess_info *info, struct cred *new)
+{
+ struct file *files[2];
+ struct coredump_params *cp = (struct coredump_params *)info->data;
+ int err = create_pipe_files(files, 0);
+ if (err)
+ return err;
+
+ cp->file = files[1];
+
+ err = replace_fd(0, files[0], 0);
+ fput(files[0]);
+ /* and disallow core files too */
+ current->signal->rlim[RLIMIT_CORE] = (struct rlimit){1, 1};
+
+ return err;
+}
+
+void do_coredump(const kernel_siginfo_t *siginfo)
+{
+ struct core_state core_state;
+ struct core_name cn;
+ struct mm_struct *mm = current->mm;
+ struct linux_binfmt * binfmt;
+ const struct cred *old_cred;
+ struct cred *cred;
+ int retval = 0;
+ int ispipe;
+ size_t *argv = NULL;
+ int argc = 0;
+ /* require nonrelative corefile path and be extra careful */
+ bool need_suid_safe = false;
+ bool core_dumped = false;
+ static atomic_t core_dump_count = ATOMIC_INIT(0);
+ struct coredump_params cprm = {
+ .siginfo = siginfo,
+ .regs = signal_pt_regs(),
+ .limit = rlimit(RLIMIT_CORE),
+ /*
+ * We must use the same mm->flags while dumping core to avoid
+ * inconsistency of bit flags, since this flag is not protected
+ * by any locks.
+ */
+ .mm_flags = mm->flags,
+ .vma_meta = NULL,
+ };
+
+ audit_core_dumps(siginfo->si_signo);
+
+ binfmt = mm->binfmt;
+ if (!binfmt || !binfmt->core_dump)
+ goto fail;
+ if (!__get_dumpable(cprm.mm_flags))
+ goto fail;
+
+ cred = prepare_creds();
+ if (!cred)
+ goto fail;
+ /*
+ * We cannot trust fsuid as being the "true" uid of the process
+ * nor do we know its entire history. We only know it was tainted
+ * so we dump it as root in mode 2, and only into a controlled
+ * environment (pipe handler or fully qualified path).
+ */
+ if (__get_dumpable(cprm.mm_flags) == SUID_DUMP_ROOT) {
+ /* Setuid core dump mode */
+ cred->fsuid = GLOBAL_ROOT_UID; /* Dump root private */
+ need_suid_safe = true;
+ }
+
+ retval = coredump_wait(siginfo->si_signo, &core_state);
+ if (retval < 0)
+ goto fail_creds;
+
+ old_cred = override_creds(cred);
+
+ ispipe = format_corename(&cn, &cprm, &argv, &argc);
+
+ if (ispipe) {
+ int argi;
+ int dump_count;
+ char **helper_argv;
+ struct subprocess_info *sub_info;
+
+ if (ispipe < 0) {
+ printk(KERN_WARNING "format_corename failed\n");
+ printk(KERN_WARNING "Aborting core\n");
+ goto fail_unlock;
+ }
+
+ if (cprm.limit == 1) {
+ /* See umh_pipe_setup() which sets RLIMIT_CORE = 1.
+ *
+ * Normally core limits are irrelevant to pipes, since
+ * we're not writing to the file system, but we use
+ * cprm.limit of 1 here as a special value, this is a
+ * consistent way to catch recursive crashes.
+ * We can still crash if the core_pattern binary sets
+ * RLIM_CORE = !1, but it runs as root, and can do
+ * lots of stupid things.
+ *
+ * Note that we use task_tgid_vnr here to grab the pid
+ * of the process group leader. That way we get the
+ * right pid if a thread in a multi-threaded
+ * core_pattern process dies.
+ */
+ printk(KERN_WARNING
+ "Process %d(%s) has RLIMIT_CORE set to 1\n",
+ task_tgid_vnr(current), current->comm);
+ printk(KERN_WARNING "Aborting core\n");
+ goto fail_unlock;
+ }
+ cprm.limit = RLIM_INFINITY;
+
+ dump_count = atomic_inc_return(&core_dump_count);
+ if (core_pipe_limit && (core_pipe_limit < dump_count)) {
+ printk(KERN_WARNING "Pid %d(%s) over core_pipe_limit\n",
+ task_tgid_vnr(current), current->comm);
+ printk(KERN_WARNING "Skipping core dump\n");
+ goto fail_dropcount;
+ }
+
+ helper_argv = kmalloc_array(argc + 1, sizeof(*helper_argv),
+ GFP_KERNEL);
+ if (!helper_argv) {
+ printk(KERN_WARNING "%s failed to allocate memory\n",
+ __func__);
+ goto fail_dropcount;
+ }
+ for (argi = 0; argi < argc; argi++)
+ helper_argv[argi] = cn.corename + argv[argi];
+ helper_argv[argi] = NULL;
+
+ retval = -ENOMEM;
+ sub_info = call_usermodehelper_setup(helper_argv[0],
+ helper_argv, NULL, GFP_KERNEL,
+ umh_pipe_setup, NULL, &cprm);
+ if (sub_info)
+ retval = call_usermodehelper_exec(sub_info,
+ UMH_WAIT_EXEC);
+
+ kfree(helper_argv);
+ if (retval) {
+ printk(KERN_INFO "Core dump to |%s pipe failed\n",
+ cn.corename);
+ goto close_fail;
+ }
+ } else {
+ struct user_namespace *mnt_userns;
+ struct inode *inode;
+ int open_flags = O_CREAT | O_RDWR | O_NOFOLLOW |
+ O_LARGEFILE | O_EXCL;
+
+ if (cprm.limit < binfmt->min_coredump)
+ goto fail_unlock;
+
+ if (need_suid_safe && cn.corename[0] != '/') {
+ printk(KERN_WARNING "Pid %d(%s) can only dump core "\
+ "to fully qualified path!\n",
+ task_tgid_vnr(current), current->comm);
+ printk(KERN_WARNING "Skipping core dump\n");
+ goto fail_unlock;
+ }
+
+ /*
+ * Unlink the file if it exists unless this is a SUID
+ * binary - in that case, we're running around with root
+ * privs and don't want to unlink another user's coredump.
+ */
+ if (!need_suid_safe) {
+ /*
+ * If it doesn't exist, that's fine. If there's some
+ * other problem, we'll catch it at the filp_open().
+ */
+ do_unlinkat(AT_FDCWD, getname_kernel(cn.corename));
+ }
+
+ /*
+ * There is a race between unlinking and creating the
+ * file, but if that causes an EEXIST here, that's
+ * fine - another process raced with us while creating
+ * the corefile, and the other process won. To userspace,
+ * what matters is that at least one of the two processes
+ * writes its coredump successfully, not which one.
+ */
+ if (need_suid_safe) {
+ /*
+ * Using user namespaces, normal user tasks can change
+ * their current->fs->root to point to arbitrary
+ * directories. Since the intention of the "only dump
+ * with a fully qualified path" rule is to control where
+ * coredumps may be placed using root privileges,
+ * current->fs->root must not be used. Instead, use the
+ * root directory of init_task.
+ */
+ struct path root;
+
+ task_lock(&init_task);
+ get_fs_root(init_task.fs, &root);
+ task_unlock(&init_task);
+ cprm.file = file_open_root(&root, cn.corename,
+ open_flags, 0600);
+ path_put(&root);
+ } else {
+ cprm.file = filp_open(cn.corename, open_flags, 0600);
+ }
+ if (IS_ERR(cprm.file))
+ goto fail_unlock;
+
+ inode = file_inode(cprm.file);
+ if (inode->i_nlink > 1)
+ goto close_fail;
+ if (d_unhashed(cprm.file->f_path.dentry))
+ goto close_fail;
+ /*
+ * AK: actually i see no reason to not allow this for named
+ * pipes etc, but keep the previous behaviour for now.
+ */
+ if (!S_ISREG(inode->i_mode))
+ goto close_fail;
+ /*
+ * Don't dump core if the filesystem changed owner or mode
+ * of the file during file creation. This is an issue when
+ * a process dumps core while its cwd is e.g. on a vfat
+ * filesystem.
+ */
+ mnt_userns = file_mnt_user_ns(cprm.file);
+ if (!uid_eq(i_uid_into_mnt(mnt_userns, inode),
+ current_fsuid())) {
+ pr_info_ratelimited("Core dump to %s aborted: cannot preserve file owner\n",
+ cn.corename);
+ goto close_fail;
+ }
+ if ((inode->i_mode & 0677) != 0600) {
+ pr_info_ratelimited("Core dump to %s aborted: cannot preserve file permissions\n",
+ cn.corename);
+ goto close_fail;
+ }
+ if (!(cprm.file->f_mode & FMODE_CAN_WRITE))
+ goto close_fail;
+ if (do_truncate(mnt_userns, cprm.file->f_path.dentry,
+ 0, 0, cprm.file))
+ goto close_fail;
+ }
+
+ /* get us an unshared descriptor table; almost always a no-op */
+ /* The cell spufs coredump code reads the file descriptor tables */
+ retval = unshare_files();
+ if (retval)
+ goto close_fail;
+ if (!dump_interrupted()) {
+ /*
+ * umh disabled with CONFIG_STATIC_USERMODEHELPER_PATH="" would
+ * have this set to NULL.
+ */
+ if (!cprm.file) {
+ pr_info("Core dump to |%s disabled\n", cn.corename);
+ goto close_fail;
+ }
+ if (!dump_vma_snapshot(&cprm))
+ goto close_fail;
+
+ file_start_write(cprm.file);
+ core_dumped = binfmt->core_dump(&cprm);
+ /*
+ * Ensures that file size is big enough to contain the current
+ * file postion. This prevents gdb from complaining about
+ * a truncated file if the last "write" to the file was
+ * dump_skip.
+ */
+ if (cprm.to_skip) {
+ cprm.to_skip--;
+ dump_emit(&cprm, "", 1);
+ }
+ file_end_write(cprm.file);
+ free_vma_snapshot(&cprm);
+ }
+ if (ispipe && core_pipe_limit)
+ wait_for_dump_helpers(cprm.file);
+close_fail:
+ if (cprm.file)
+ filp_close(cprm.file, NULL);
+fail_dropcount:
+ if (ispipe)
+ atomic_dec(&core_dump_count);
+fail_unlock:
+ kfree(argv);
+ kfree(cn.corename);
+ coredump_finish(core_dumped);
+ revert_creds(old_cred);
+fail_creds:
+ put_cred(cred);
+fail:
+ return;
+}
+
+/*
+ * Core dumping helper functions. These are the only things you should
+ * do on a core-file: use only these functions to write out all the
+ * necessary info.
+ */
+static int __dump_emit(struct coredump_params *cprm, const void *addr, int nr)
+{
+ struct file *file = cprm->file;
+ loff_t pos = file->f_pos;
+ ssize_t n;
+ if (cprm->written + nr > cprm->limit)
+ return 0;
+
+
+ if (dump_interrupted())
+ return 0;
+ n = __kernel_write(file, addr, nr, &pos);
+ if (n != nr)
+ return 0;
+ file->f_pos = pos;
+ cprm->written += n;
+ cprm->pos += n;
+
+ return 1;
+}
+
+static int __dump_skip(struct coredump_params *cprm, size_t nr)
+{
+ static char zeroes[PAGE_SIZE];
+ struct file *file = cprm->file;
+ if (file->f_mode & FMODE_LSEEK) {
+ if (dump_interrupted() ||
+ vfs_llseek(file, nr, SEEK_CUR) < 0)
+ return 0;
+ cprm->pos += nr;
+ return 1;
+ } else {
+ while (nr > PAGE_SIZE) {
+ if (!__dump_emit(cprm, zeroes, PAGE_SIZE))
+ return 0;
+ nr -= PAGE_SIZE;
+ }
+ return __dump_emit(cprm, zeroes, nr);
+ }
+}
+
+int dump_emit(struct coredump_params *cprm, const void *addr, int nr)
+{
+ if (cprm->to_skip) {
+ if (!__dump_skip(cprm, cprm->to_skip))
+ return 0;
+ cprm->to_skip = 0;
+ }
+ return __dump_emit(cprm, addr, nr);
+}
+EXPORT_SYMBOL(dump_emit);
+
+void dump_skip_to(struct coredump_params *cprm, unsigned long pos)
+{
+ cprm->to_skip = pos - cprm->pos;
+}
+EXPORT_SYMBOL(dump_skip_to);
+
+void dump_skip(struct coredump_params *cprm, size_t nr)
+{
+ cprm->to_skip += nr;
+}
+EXPORT_SYMBOL(dump_skip);
+
+#ifdef CONFIG_ELF_CORE
+static int dump_emit_page(struct coredump_params *cprm, struct page *page)
+{
+ struct bio_vec bvec = {
+ .bv_page = page,
+ .bv_offset = 0,
+ .bv_len = PAGE_SIZE,
+ };
+ struct iov_iter iter;
+ struct file *file = cprm->file;
+ loff_t pos;
+ ssize_t n;
+
+ if (cprm->to_skip) {
+ if (!__dump_skip(cprm, cprm->to_skip))
+ return 0;
+ cprm->to_skip = 0;
+ }
+ if (cprm->written + PAGE_SIZE > cprm->limit)
+ return 0;
+ if (dump_interrupted())
+ return 0;
+ pos = file->f_pos;
+ iov_iter_bvec(&iter, ITER_SOURCE, &bvec, 1, PAGE_SIZE);
+ n = __kernel_write_iter(cprm->file, &iter, &pos);
+ if (n != PAGE_SIZE)
+ return 0;
+ file->f_pos = pos;
+ cprm->written += PAGE_SIZE;
+ cprm->pos += PAGE_SIZE;
+
+ return 1;
+}
+
+int dump_user_range(struct coredump_params *cprm, unsigned long start,
+ unsigned long len)
+{
+ unsigned long addr;
+
+ for (addr = start; addr < start + len; addr += PAGE_SIZE) {
+ struct page *page;
+
+ /*
+ * To avoid having to allocate page tables for virtual address
+ * ranges that have never been used yet, and also to make it
+ * easy to generate sparse core files, use a helper that returns
+ * NULL when encountering an empty page table entry that would
+ * otherwise have been filled with the zero page.
+ */
+ page = get_dump_page(addr);
+ if (page) {
+ int stop = !dump_emit_page(cprm, page);
+ put_page(page);
+ if (stop)
+ return 0;
+ } else {
+ dump_skip(cprm, PAGE_SIZE);
+ }
+ }
+ return 1;
+}
+#endif
+
+int dump_align(struct coredump_params *cprm, int align)
+{
+ unsigned mod = (cprm->pos + cprm->to_skip) & (align - 1);
+ if (align & (align - 1))
+ return 0;
+ if (mod)
+ cprm->to_skip += align - mod;
+ return 1;
+}
+EXPORT_SYMBOL(dump_align);
+
+#ifdef CONFIG_SYSCTL
+
+void validate_coredump_safety(void)
+{
+ if (suid_dumpable == SUID_DUMP_ROOT &&
+ core_pattern[0] != '/' && core_pattern[0] != '|') {
+ pr_warn(
+"Unsafe core_pattern used with fs.suid_dumpable=2.\n"
+"Pipe handler or fully qualified core dump path required.\n"
+"Set kernel.core_pattern before fs.suid_dumpable.\n"
+ );
+ }
+}
+
+static int proc_dostring_coredump(struct ctl_table *table, int write,
+ void *buffer, size_t *lenp, loff_t *ppos)
+{
+ int error = proc_dostring(table, write, buffer, lenp, ppos);
+
+ if (!error)
+ validate_coredump_safety();
+ return error;
+}
+
+static struct ctl_table coredump_sysctls[] = {
+ {
+ .procname = "core_uses_pid",
+ .data = &core_uses_pid,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec,
+ },
+ {
+ .procname = "core_pattern",
+ .data = core_pattern,
+ .maxlen = CORENAME_MAX_SIZE,
+ .mode = 0644,
+ .proc_handler = proc_dostring_coredump,
+ },
+ {
+ .procname = "core_pipe_limit",
+ .data = &core_pipe_limit,
+ .maxlen = sizeof(unsigned int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec,
+ },
+ { }
+};
+
+static int __init init_fs_coredump_sysctls(void)
+{
+ register_sysctl_init("kernel", coredump_sysctls);
+ return 0;
+}
+fs_initcall(init_fs_coredump_sysctls);
+#endif /* CONFIG_SYSCTL */
+
+/*
+ * The purpose of always_dump_vma() is to make sure that special kernel mappings
+ * that are useful for post-mortem analysis are included in every core dump.
+ * In that way we ensure that the core dump is fully interpretable later
+ * without matching up the same kernel and hardware config to see what PC values
+ * meant. These special mappings include - vDSO, vsyscall, and other
+ * architecture specific mappings
+ */
+static bool always_dump_vma(struct vm_area_struct *vma)
+{
+ /* Any vsyscall mappings? */
+ if (vma == get_gate_vma(vma->vm_mm))
+ return true;
+
+ /*
+ * Assume that all vmas with a .name op should always be dumped.
+ * If this changes, a new vm_ops field can easily be added.
+ */
+ if (vma->vm_ops && vma->vm_ops->name && vma->vm_ops->name(vma))
+ return true;
+
+ /*
+ * arch_vma_name() returns non-NULL for special architecture mappings,
+ * such as vDSO sections.
+ */
+ if (arch_vma_name(vma))
+ return true;
+
+ return false;
+}
+
+#define DUMP_SIZE_MAYBE_ELFHDR_PLACEHOLDER 1
+
+/*
+ * Decide how much of @vma's contents should be included in a core dump.
+ */
+static unsigned long vma_dump_size(struct vm_area_struct *vma,
+ unsigned long mm_flags)
+{
+#define FILTER(type) (mm_flags & (1UL << MMF_DUMP_##type))
+
+ /* always dump the vdso and vsyscall sections */
+ if (always_dump_vma(vma))
+ goto whole;
+
+ if (vma->vm_flags & VM_DONTDUMP)
+ return 0;
+
+ /* support for DAX */
+ if (vma_is_dax(vma)) {
+ if ((vma->vm_flags & VM_SHARED) && FILTER(DAX_SHARED))
+ goto whole;
+ if (!(vma->vm_flags & VM_SHARED) && FILTER(DAX_PRIVATE))
+ goto whole;
+ return 0;
+ }
+
+ /* Hugetlb memory check */
+ if (is_vm_hugetlb_page(vma)) {
+ if ((vma->vm_flags & VM_SHARED) && FILTER(HUGETLB_SHARED))
+ goto whole;
+ if (!(vma->vm_flags & VM_SHARED) && FILTER(HUGETLB_PRIVATE))
+ goto whole;
+ return 0;
+ }
+
+ /* Do not dump I/O mapped devices or special mappings */
+ if (vma->vm_flags & VM_IO)
+ return 0;
+
+ /* By default, dump shared memory if mapped from an anonymous file. */
+ if (vma->vm_flags & VM_SHARED) {
+ if (file_inode(vma->vm_file)->i_nlink == 0 ?
+ FILTER(ANON_SHARED) : FILTER(MAPPED_SHARED))
+ goto whole;
+ return 0;
+ }
+
+ /* Dump segments that have been written to. */
+ if ((!IS_ENABLED(CONFIG_MMU) || vma->anon_vma) && FILTER(ANON_PRIVATE))
+ goto whole;
+ if (vma->vm_file == NULL)
+ return 0;
+
+ if (FILTER(MAPPED_PRIVATE))
+ goto whole;
+
+ /*
+ * If this is the beginning of an executable file mapping,
+ * dump the first page to aid in determining what was mapped here.
+ */
+ if (FILTER(ELF_HEADERS) &&
+ vma->vm_pgoff == 0 && (vma->vm_flags & VM_READ)) {
+ if ((READ_ONCE(file_inode(vma->vm_file)->i_mode) & 0111) != 0)
+ return PAGE_SIZE;
+
+ /*
+ * ELF libraries aren't always executable.
+ * We'll want to check whether the mapping starts with the ELF
+ * magic, but not now - we're holding the mmap lock,
+ * so copy_from_user() doesn't work here.
+ * Use a placeholder instead, and fix it up later in
+ * dump_vma_snapshot().
+ */
+ return DUMP_SIZE_MAYBE_ELFHDR_PLACEHOLDER;
+ }
+
+#undef FILTER
+
+ return 0;
+
+whole:
+ return vma->vm_end - vma->vm_start;
+}
+
+/*
+ * Helper function for iterating across a vma list. It ensures that the caller
+ * will visit `gate_vma' prior to terminating the search.
+ */
+static struct vm_area_struct *coredump_next_vma(struct ma_state *mas,
+ struct vm_area_struct *vma,
+ struct vm_area_struct *gate_vma)
+{
+ if (gate_vma && (vma == gate_vma))
+ return NULL;
+
+ vma = mas_next(mas, ULONG_MAX);
+ if (vma)
+ return vma;
+ return gate_vma;
+}
+
+static void free_vma_snapshot(struct coredump_params *cprm)
+{
+ if (cprm->vma_meta) {
+ int i;
+ for (i = 0; i < cprm->vma_count; i++) {
+ struct file *file = cprm->vma_meta[i].file;
+ if (file)
+ fput(file);
+ }
+ kvfree(cprm->vma_meta);
+ cprm->vma_meta = NULL;
+ }
+}
+
+/*
+ * Under the mmap_lock, take a snapshot of relevant information about the task's
+ * VMAs.
+ */
+static bool dump_vma_snapshot(struct coredump_params *cprm)
+{
+ struct vm_area_struct *gate_vma, *vma = NULL;
+ struct mm_struct *mm = current->mm;
+ MA_STATE(mas, &mm->mm_mt, 0, 0);
+ int i = 0;
+
+ /*
+ * Once the stack expansion code is fixed to not change VMA bounds
+ * under mmap_lock in read mode, this can be changed to take the
+ * mmap_lock in read mode.
+ */
+ if (mmap_write_lock_killable(mm))
+ return false;
+
+ cprm->vma_data_size = 0;
+ gate_vma = get_gate_vma(mm);
+ cprm->vma_count = mm->map_count + (gate_vma ? 1 : 0);
+
+ cprm->vma_meta = kvmalloc_array(cprm->vma_count, sizeof(*cprm->vma_meta), GFP_KERNEL);
+ if (!cprm->vma_meta) {
+ mmap_write_unlock(mm);
+ return false;
+ }
+
+ while ((vma = coredump_next_vma(&mas, vma, gate_vma)) != NULL) {
+ struct core_vma_metadata *m = cprm->vma_meta + i;
+
+ m->start = vma->vm_start;
+ m->end = vma->vm_end;
+ m->flags = vma->vm_flags;
+ m->dump_size = vma_dump_size(vma, cprm->mm_flags);
+ m->pgoff = vma->vm_pgoff;
+ m->file = vma->vm_file;
+ if (m->file)
+ get_file(m->file);
+ i++;
+ }
+
+ mmap_write_unlock(mm);
+
+ for (i = 0; i < cprm->vma_count; i++) {
+ struct core_vma_metadata *m = cprm->vma_meta + i;
+
+ if (m->dump_size == DUMP_SIZE_MAYBE_ELFHDR_PLACEHOLDER) {
+ char elfmag[SELFMAG];
+
+ if (copy_from_user(elfmag, (void __user *)m->start, SELFMAG) ||
+ memcmp(elfmag, ELFMAG, SELFMAG) != 0) {
+ m->dump_size = 0;
+ } else {
+ m->dump_size = PAGE_SIZE;
+ }
+ }
+
+ cprm->vma_data_size += m->dump_size;
+ }
+
+ return true;
+}