aboutsummaryrefslogtreecommitdiffstats
path: root/fs/exec.c
diff options
context:
space:
mode:
authorNeil Horman <nhorman@tuxdriver.com>2009-09-23 15:56:56 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-09-24 07:21:00 -0700
commita293980c2e261bd5b0d2a77340dd04f684caff58 (patch)
tree69f2b2747548deafb146c18953ebce21ae1f02d4 /fs/exec.c
parent725eae32df7754044809973034429a47e6035158 (diff)
downloadmrst-s0i3-test-a293980c2e261bd5b0d2a77340dd04f684caff58.tar.gz
mrst-s0i3-test-a293980c2e261bd5b0d2a77340dd04f684caff58.tar.xz
mrst-s0i3-test-a293980c2e261bd5b0d2a77340dd04f684caff58.zip
exec: let do_coredump() limit the number of concurrent dumps to pipes
Introduce core pipe limiting sysctl. Since we can dump cores to pipe, rather than directly to the filesystem, we create a condition in which a user can create a very high load on the system simply by running bad applications. If the pipe reader specified in core_pattern is poorly written, we can have lots of ourstandig resources and processes in the system. This sysctl introduces an ability to limit that resource consumption. core_pipe_limit defines how many in-flight dumps may be run in parallel, dumps beyond this value are skipped and a note is made in the kernel log. A special value of 0 in core_pipe_limit denotes unlimited core dumps may be handled (this is the default value). [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Neil Horman <nhorman@tuxdriver.com> Reported-by: Earl Chew <earl_chew@agilent.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Andi Kleen <andi@firstfloor.org> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/exec.c')
-rw-r--r--fs/exec.c23
1 files changed, 18 insertions, 5 deletions
diff --git a/fs/exec.c b/fs/exec.c
index 735d9c18ec7..dc022dd15d5 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -63,6 +63,7 @@
int core_uses_pid;
char core_pattern[CORENAME_MAX_SIZE] = "core";
+unsigned int core_pipe_limit;
int suid_dumpable = 0;
/* The maximal length of core_pattern is also specified in sysctl.c */
@@ -1744,7 +1745,8 @@ void do_coredump(long signr, int exit_code, struct pt_regs *regs)
unsigned long core_limit = current->signal->rlim[RLIMIT_CORE].rlim_cur;
char **helper_argv = NULL;
int helper_argc = 0;
- char *delimit;
+ int dump_count = 0;
+ static atomic_t core_dump_count = ATOMIC_INIT(0);
audit_core_dumps(signr);
@@ -1826,28 +1828,36 @@ void do_coredump(long signr, int exit_code, struct pt_regs *regs)
goto fail_unlock;
}
+ 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 = argv_split(GFP_KERNEL, corename+1, &helper_argc);
if (!helper_argv) {
printk(KERN_WARNING "%s failed to allocate memory\n",
__func__);
- goto fail_unlock;
+ goto fail_dropcount;
}
core_limit = RLIM_INFINITY;
/* SIGPIPE can happen, but it's just never processed */
- if (call_usermodehelper_pipe(corename+1, helper_argv, NULL,
+ if (call_usermodehelper_pipe(helper_argv[0], helper_argv, NULL,
&file)) {
printk(KERN_INFO "Core dump to %s pipe failed\n",
corename);
- goto fail_unlock;
+ goto fail_dropcount;
}
} else
file = filp_open(corename,
O_CREAT | 2 | O_NOFOLLOW | O_LARGEFILE | flag,
0600);
if (IS_ERR(file))
- goto fail_unlock;
+ goto fail_dropcount;
inode = file->f_path.dentry->d_inode;
if (inode->i_nlink > 1)
goto close_fail; /* multiple links - don't dump */
@@ -1877,6 +1887,9 @@ void do_coredump(long signr, int exit_code, struct pt_regs *regs)
current->signal->group_exit_code |= 0x80;
close_fail:
filp_close(file, NULL);
+fail_dropcount:
+ if (dump_count)
+ atomic_dec(&core_dump_count);
fail_unlock:
if (helper_argv)
argv_free(helper_argv);