coredump masking: add an interface for core dump filter
This patch adds an interface to set/reset flags which determines each memory
segment should be dumped or not when a core file is generated.
/proc/<pid>/coredump_filter file is provided to access the flags. You can
change the flag status for a particular process by writing to or reading from
the file.
The flag status is inherited to the child process when it is created.
Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: David Howells <dhowells@redhat.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 49b3ab0..3c77d5a 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -72,6 +72,7 @@
#include <linux/poll.h>
#include <linux/nsproxy.h>
#include <linux/oom.h>
+#include <linux/elf.h>
#include "internal.h"
/* NOTE:
@@ -1785,6 +1786,91 @@
#endif
+#if defined(USE_ELF_CORE_DUMP) && defined(CONFIG_ELF_CORE)
+static ssize_t proc_coredump_filter_read(struct file *file, char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ struct task_struct *task = get_proc_task(file->f_dentry->d_inode);
+ struct mm_struct *mm;
+ char buffer[PROC_NUMBUF];
+ size_t len;
+ int ret;
+
+ if (!task)
+ return -ESRCH;
+
+ ret = 0;
+ mm = get_task_mm(task);
+ if (mm) {
+ len = snprintf(buffer, sizeof(buffer), "%08lx\n",
+ ((mm->flags & MMF_DUMP_FILTER_MASK) >>
+ MMF_DUMP_FILTER_SHIFT));
+ mmput(mm);
+ ret = simple_read_from_buffer(buf, count, ppos, buffer, len);
+ }
+
+ put_task_struct(task);
+
+ return ret;
+}
+
+static ssize_t proc_coredump_filter_write(struct file *file,
+ const char __user *buf,
+ size_t count,
+ loff_t *ppos)
+{
+ struct task_struct *task;
+ struct mm_struct *mm;
+ char buffer[PROC_NUMBUF], *end;
+ unsigned int val;
+ int ret;
+ int i;
+ unsigned long mask;
+
+ ret = -EFAULT;
+ memset(buffer, 0, sizeof(buffer));
+ if (count > sizeof(buffer) - 1)
+ count = sizeof(buffer) - 1;
+ if (copy_from_user(buffer, buf, count))
+ goto out_no_task;
+
+ ret = -EINVAL;
+ val = (unsigned int)simple_strtoul(buffer, &end, 0);
+ if (*end == '\n')
+ end++;
+ if (end - buffer == 0)
+ goto out_no_task;
+
+ ret = -ESRCH;
+ task = get_proc_task(file->f_dentry->d_inode);
+ if (!task)
+ goto out_no_task;
+
+ ret = end - buffer;
+ mm = get_task_mm(task);
+ if (!mm)
+ goto out_no_mm;
+
+ for (i = 0, mask = 1; i < MMF_DUMP_FILTER_BITS; i++, mask <<= 1) {
+ if (val & mask)
+ set_bit(i + MMF_DUMP_FILTER_SHIFT, &mm->flags);
+ else
+ clear_bit(i + MMF_DUMP_FILTER_SHIFT, &mm->flags);
+ }
+
+ mmput(mm);
+ out_no_mm:
+ put_task_struct(task);
+ out_no_task:
+ return ret;
+}
+
+static const struct file_operations proc_coredump_filter_operations = {
+ .read = proc_coredump_filter_read,
+ .write = proc_coredump_filter_write,
+};
+#endif
+
/*
* /proc/self:
*/
@@ -2005,6 +2091,9 @@
#ifdef CONFIG_FAULT_INJECTION
REG("make-it-fail", S_IRUGO|S_IWUSR, fault_inject),
#endif
+#if defined(USE_ELF_CORE_DUMP) && defined(CONFIG_ELF_CORE)
+ REG("coredump_filter", S_IRUGO|S_IWUSR, coredump_filter),
+#endif
#ifdef CONFIG_TASK_IO_ACCOUNTING
INF("io", S_IRUGO, pid_io_accounting),
#endif