Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull more vfs updates from Al Viro:
"Embarrassing braino fix + pipe page accounting + fixing an eyesore in
find_filesystem() (checking that s1 is equal to prefix of s2 of given
length can be done in many ways, but "compare strlen(s1) with length
and then do strncmp()" is not a good one...)"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
[regression] fix braino in fs/dlm/user.c
pipe: limit the per-user amount of pages allocated in pipes
find_filesystem(): simplify comparison
diff --git a/Documentation/sysctl/fs.txt b/Documentation/sysctl/fs.txt
index 88152f2..302b5ed 100644
--- a/Documentation/sysctl/fs.txt
+++ b/Documentation/sysctl/fs.txt
@@ -32,6 +32,8 @@
- nr_open
- overflowuid
- overflowgid
+- pipe-user-pages-hard
+- pipe-user-pages-soft
- protected_hardlinks
- protected_symlinks
- suid_dumpable
@@ -159,6 +161,27 @@
==============================================================
+pipe-user-pages-hard:
+
+Maximum total number of pages a non-privileged user may allocate for pipes.
+Once this limit is reached, no new pipes may be allocated until usage goes
+below the limit again. When set to 0, no limit is applied, which is the default
+setting.
+
+==============================================================
+
+pipe-user-pages-soft:
+
+Maximum total number of pages a non-privileged user may allocate for pipes
+before the pipe size gets limited to a single page. Once this limit is reached,
+new pipes will be limited to a single page in size for this user in order to
+limit total memory usage, and trying to increase them using fcntl() will be
+denied until usage goes below the limit again. The default value allows to
+allocate up to 1024 pipes at their default size. When set to 0, no limit is
+applied.
+
+==============================================================
+
protected_hardlinks:
A long-standing class of security issues is the hardlink-based
diff --git a/fs/dlm/user.c b/fs/dlm/user.c
index 1925d6d..58c2f4a 100644
--- a/fs/dlm/user.c
+++ b/fs/dlm/user.c
@@ -516,7 +516,7 @@
return -EINVAL;
kbuf = memdup_user_nul(buf, count);
- if (!IS_ERR(kbuf))
+ if (IS_ERR(kbuf))
return PTR_ERR(kbuf);
if (check_version(kbuf)) {
diff --git a/fs/filesystems.c b/fs/filesystems.c
index 5797d45..c5618db 100644
--- a/fs/filesystems.c
+++ b/fs/filesystems.c
@@ -46,9 +46,9 @@
static struct file_system_type **find_filesystem(const char *name, unsigned len)
{
struct file_system_type **p;
- for (p=&file_systems; *p; p=&(*p)->next)
- if (strlen((*p)->name) == len &&
- strncmp((*p)->name, name, len) == 0)
+ for (p = &file_systems; *p; p = &(*p)->next)
+ if (strncmp((*p)->name, name, len) == 0 &&
+ !(*p)->name[len])
break;
return p;
}
diff --git a/fs/pipe.c b/fs/pipe.c
index 42cf8dd..ab8dad3 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -38,6 +38,12 @@
*/
unsigned int pipe_min_size = PAGE_SIZE;
+/* Maximum allocatable pages per user. Hard limit is unset by default, soft
+ * matches default values.
+ */
+unsigned long pipe_user_pages_hard;
+unsigned long pipe_user_pages_soft = PIPE_DEF_BUFFERS * INR_OPEN_CUR;
+
/*
* We use a start+len construction, which provides full use of the
* allocated memory.
@@ -583,20 +589,49 @@
return retval;
}
+static void account_pipe_buffers(struct pipe_inode_info *pipe,
+ unsigned long old, unsigned long new)
+{
+ atomic_long_add(new - old, &pipe->user->pipe_bufs);
+}
+
+static bool too_many_pipe_buffers_soft(struct user_struct *user)
+{
+ return pipe_user_pages_soft &&
+ atomic_long_read(&user->pipe_bufs) >= pipe_user_pages_soft;
+}
+
+static bool too_many_pipe_buffers_hard(struct user_struct *user)
+{
+ return pipe_user_pages_hard &&
+ atomic_long_read(&user->pipe_bufs) >= pipe_user_pages_hard;
+}
+
struct pipe_inode_info *alloc_pipe_info(void)
{
struct pipe_inode_info *pipe;
pipe = kzalloc(sizeof(struct pipe_inode_info), GFP_KERNEL);
if (pipe) {
- pipe->bufs = kzalloc(sizeof(struct pipe_buffer) * PIPE_DEF_BUFFERS, GFP_KERNEL);
+ unsigned long pipe_bufs = PIPE_DEF_BUFFERS;
+ struct user_struct *user = get_current_user();
+
+ if (!too_many_pipe_buffers_hard(user)) {
+ if (too_many_pipe_buffers_soft(user))
+ pipe_bufs = 1;
+ pipe->bufs = kzalloc(sizeof(struct pipe_buffer) * pipe_bufs, GFP_KERNEL);
+ }
+
if (pipe->bufs) {
init_waitqueue_head(&pipe->wait);
pipe->r_counter = pipe->w_counter = 1;
- pipe->buffers = PIPE_DEF_BUFFERS;
+ pipe->buffers = pipe_bufs;
+ pipe->user = user;
+ account_pipe_buffers(pipe, 0, pipe_bufs);
mutex_init(&pipe->mutex);
return pipe;
}
+ free_uid(user);
kfree(pipe);
}
@@ -607,6 +642,8 @@
{
int i;
+ account_pipe_buffers(pipe, pipe->buffers, 0);
+ free_uid(pipe->user);
for (i = 0; i < pipe->buffers; i++) {
struct pipe_buffer *buf = pipe->bufs + i;
if (buf->ops)
@@ -998,6 +1035,7 @@
memcpy(bufs + head, pipe->bufs, tail * sizeof(struct pipe_buffer));
}
+ account_pipe_buffers(pipe, pipe->buffers, nr_pages);
pipe->curbuf = 0;
kfree(pipe->bufs);
pipe->bufs = bufs;
@@ -1069,6 +1107,11 @@
if (!capable(CAP_SYS_RESOURCE) && size > pipe_max_size) {
ret = -EPERM;
goto out;
+ } else if ((too_many_pipe_buffers_hard(pipe->user) ||
+ too_many_pipe_buffers_soft(pipe->user)) &&
+ !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN)) {
+ ret = -EPERM;
+ goto out;
}
ret = pipe_set_size(pipe, nr_pages);
break;
diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h
index eb8b8ac..24f5470 100644
--- a/include/linux/pipe_fs_i.h
+++ b/include/linux/pipe_fs_i.h
@@ -42,6 +42,7 @@
* @fasync_readers: reader side fasync
* @fasync_writers: writer side fasync
* @bufs: the circular array of pipe buffers
+ * @user: the user who created this pipe
**/
struct pipe_inode_info {
struct mutex mutex;
@@ -57,6 +58,7 @@
struct fasync_struct *fasync_readers;
struct fasync_struct *fasync_writers;
struct pipe_buffer *bufs;
+ struct user_struct *user;
};
/*
@@ -123,6 +125,8 @@
void pipe_double_lock(struct pipe_inode_info *, struct pipe_inode_info *);
extern unsigned int pipe_max_size, pipe_min_size;
+extern unsigned long pipe_user_pages_hard;
+extern unsigned long pipe_user_pages_soft;
int pipe_proc_fn(struct ctl_table *, int, void __user *, size_t *, loff_t *);
diff --git a/include/linux/sched.h b/include/linux/sched.h
index f1e81e1..a10494a 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -835,6 +835,7 @@
#endif
unsigned long locked_shm; /* How many pages of mlocked shm ? */
unsigned long unix_inflight; /* How many files in flight in unix sockets */
+ atomic_long_t pipe_bufs; /* how many pages are allocated in pipe buffers */
#ifdef CONFIG_KEYS
struct key *uid_keyring; /* UID specific keyring */
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 9142036..97715fd 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1757,6 +1757,20 @@
.proc_handler = &pipe_proc_fn,
.extra1 = &pipe_min_size,
},
+ {
+ .procname = "pipe-user-pages-hard",
+ .data = &pipe_user_pages_hard,
+ .maxlen = sizeof(pipe_user_pages_hard),
+ .mode = 0644,
+ .proc_handler = proc_doulongvec_minmax,
+ },
+ {
+ .procname = "pipe-user-pages-soft",
+ .data = &pipe_user_pages_soft,
+ .maxlen = sizeof(pipe_user_pages_soft),
+ .mode = 0644,
+ .proc_handler = proc_doulongvec_minmax,
+ },
{ }
};
