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 <[email protected]>
---
fs/proc/base.c | 89 ++++++++++++++++++++++++++++++++++++++++
include/linux/sched.h | 14 ++++++
kernel/fork.c | 2
3 files changed, 105 insertions(+)
Index: linux-2.6.22-rc2-mm1/fs/proc/base.c
===================================================================
--- linux-2.6.22-rc2-mm1.orig/fs/proc/base.c
+++ linux-2.6.22-rc2-mm1/fs/proc/base.c
@@ -73,6 +73,7 @@
#include <linux/poll.h>
#include <linux/nsproxy.h>
#include <linux/oom.h>
+#include <linux/elf.h>
#include "internal.h"
/* NOTE:
@@ -1808,6 +1809,91 @@ static const struct inode_operations pro
#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:
*/
@@ -2036,6 +2122,9 @@ static const struct pid_entry tgid_base_
#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
Index: linux-2.6.22-rc2-mm1/include/linux/sched.h
===================================================================
--- linux-2.6.22-rc2-mm1.orig/include/linux/sched.h
+++ linux-2.6.22-rc2-mm1/include/linux/sched.h
@@ -328,8 +328,22 @@ extern void set_dumpable(struct mm_struc
extern int get_dumpable(struct mm_struct *mm);
/* mm flags */
+/* dumpable bits */
#define MMF_DUMPABLE 0 /* core dump is permitted */
#define MMF_DUMP_SECURELY 1 /* core file is readable only by root */
+#define MMF_DUMPABLE_BITS 2
+
+/* coredump filter bits */
+#define MMF_DUMP_ANON_PRIVATE 2
+#define MMF_DUMP_ANON_SHARED 3
+#define MMF_DUMP_MAPPED_PRIVATE 4
+#define MMF_DUMP_MAPPED_SHARED 5
+#define MMF_DUMP_FILTER_SHIFT MMF_DUMPABLE_BITS
+#define MMF_DUMP_FILTER_BITS 4
+#define MMF_DUMP_FILTER_MASK \
+ (((1 << MMF_DUMP_FILTER_BITS) - 1) << MMF_DUMP_FILTER_SHIFT)
+#define MMF_DUMP_FILTER_DEFAULT \
+ ((1 << MMF_DUMP_ANON_PRIVATE) | (1 << MMF_DUMP_ANON_SHARED))
struct mm_struct {
struct vm_area_struct * mmap; /* list of VMAs */
Index: linux-2.6.22-rc2-mm1/kernel/fork.c
===================================================================
--- linux-2.6.22-rc2-mm1.orig/kernel/fork.c
+++ linux-2.6.22-rc2-mm1/kernel/fork.c
@@ -335,6 +335,8 @@ static struct mm_struct * mm_init(struct
atomic_set(&mm->mm_count, 1);
init_rwsem(&mm->mmap_sem);
INIT_LIST_HEAD(&mm->mmlist);
+ mm->flags = (current->mm) ? current->mm->flags
+ : MMF_DUMP_FILTER_DEFAULT;
mm->core_waiters = 0;
mm->nr_ptes = 0;
set_mm_counter(mm, file_rss, 0);
-
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