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authorChristoph Hellwig <hch@lst.de>2017-05-27 13:07:20 +0300
committerJeff Layton <jlayton@redhat.com>2017-06-01 18:29:07 +0300
commit94073ad77fff221b5e66b8b9863a546ba212d6a3 (patch)
treeca80a24ec3db6859b9dabe65ad18c637cecb3299 /fs/fcntl.c
parenta75d30c772078546ac00399a94ecdc82df1a4d72 (diff)
downloadlinux-94073ad77fff221b5e66b8b9863a546ba212d6a3.tar.xz
fs/locks: don't mess with the address limit in compat_fcntl64
Instead write a proper compat syscall that calls common helpers. [ jlayton: fix pointer dereferencing in fixup_compat_flock ] Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Jeff Layton <jlayton@redhat.com>
Diffstat (limited to 'fs/fcntl.c')
-rw-r--r--fs/fcntl.c118
1 files changed, 67 insertions, 51 deletions
diff --git a/fs/fcntl.c b/fs/fcntl.c
index ed4283d500a3..bbf80344c125 100644
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -506,76 +506,92 @@ convert_fcntl_cmd(unsigned int cmd)
return cmd;
}
+/*
+ * GETLK was successful and we need to return the data, but it needs to fit in
+ * the compat structure.
+ * l_start shouldn't be too big, unless the original start + end is greater than
+ * COMPAT_OFF_T_MAX, in which case the app was asking for trouble, so we return
+ * -EOVERFLOW in that case. l_len could be too big, in which case we just
+ * truncate it, and only allow the app to see that part of the conflicting lock
+ * that might make sense to it anyway
+ */
+static int fixup_compat_flock(struct flock *flock)
+{
+ if (flock->l_start > COMPAT_OFF_T_MAX)
+ return -EOVERFLOW;
+ if (flock->l_len > COMPAT_OFF_T_MAX)
+ flock->l_len = COMPAT_OFF_T_MAX;
+ return 0;
+}
+
COMPAT_SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd,
compat_ulong_t, arg)
{
- mm_segment_t old_fs;
- struct flock f;
- long ret;
- unsigned int conv_cmd;
+ struct fd f = fdget_raw(fd);
+ struct flock flock;
+ long err = -EBADF;
+
+ if (!f.file)
+ return err;
+
+ if (unlikely(f.file->f_mode & FMODE_PATH)) {
+ if (!check_fcntl_cmd(cmd))
+ goto out_put;
+ }
+
+ err = security_file_fcntl(f.file, cmd, arg);
+ if (err)
+ goto out_put;
switch (cmd) {
case F_GETLK:
+ err = get_compat_flock(&flock, compat_ptr(arg));
+ if (err)
+ break;
+ err = fcntl_getlk(f.file, convert_fcntl_cmd(cmd), &flock);
+ if (err)
+ break;
+ err = fixup_compat_flock(&flock);
+ if (err)
+ return err;
+ err = put_compat_flock(&flock, compat_ptr(arg));
+ break;
+ case F_GETLK64:
+ case F_OFD_GETLK:
+ err = get_compat_flock64(&flock, compat_ptr(arg));
+ if (err)
+ break;
+ err = fcntl_getlk(f.file, convert_fcntl_cmd(cmd), &flock);
+ if (err)
+ break;
+ err = fixup_compat_flock(&flock);
+ if (err)
+ return err;
+ err = put_compat_flock64(&flock, compat_ptr(arg));
+ break;
case F_SETLK:
case F_SETLKW:
- ret = get_compat_flock(&f, compat_ptr(arg));
- if (ret != 0)
+ err = get_compat_flock(&flock, compat_ptr(arg));
+ if (err)
break;
- old_fs = get_fs();
- set_fs(KERNEL_DS);
- ret = sys_fcntl(fd, cmd, (unsigned long)&f);
- set_fs(old_fs);
- if (cmd == F_GETLK && ret == 0) {
- /* GETLK was successful and we need to return the data...
- * but it needs to fit in the compat structure.
- * l_start shouldn't be too big, unless the original
- * start + end is greater than COMPAT_OFF_T_MAX, in which
- * case the app was asking for trouble, so we return
- * -EOVERFLOW in that case.
- * l_len could be too big, in which case we just truncate it,
- * and only allow the app to see that part of the conflicting
- * lock that might make sense to it anyway
- */
-
- if (f.l_start > COMPAT_OFF_T_MAX)
- ret = -EOVERFLOW;
- if (f.l_len > COMPAT_OFF_T_MAX)
- f.l_len = COMPAT_OFF_T_MAX;
- if (ret == 0)
- ret = put_compat_flock(&f, compat_ptr(arg));
- }
+ err = fcntl_setlk(fd, f.file, convert_fcntl_cmd(cmd), &flock);
break;
-
- case F_GETLK64:
case F_SETLK64:
case F_SETLKW64:
- case F_OFD_GETLK:
case F_OFD_SETLK:
case F_OFD_SETLKW:
- ret = get_compat_flock64(&f, compat_ptr(arg));
- if (ret != 0)
+ err = get_compat_flock64(&flock, compat_ptr(arg));
+ if (err)
break;
- old_fs = get_fs();
- set_fs(KERNEL_DS);
- conv_cmd = convert_fcntl_cmd(cmd);
- ret = sys_fcntl(fd, conv_cmd, (unsigned long)&f);
- set_fs(old_fs);
- if ((conv_cmd == F_GETLK || conv_cmd == F_OFD_GETLK) && ret == 0) {
- /* need to return lock information - see above for commentary */
- if (f.l_start > COMPAT_LOFF_T_MAX)
- ret = -EOVERFLOW;
- if (f.l_len > COMPAT_LOFF_T_MAX)
- f.l_len = COMPAT_LOFF_T_MAX;
- if (ret == 0)
- ret = put_compat_flock64(&f, compat_ptr(arg));
- }
+ err = fcntl_setlk(fd, f.file, convert_fcntl_cmd(cmd), &flock);
break;
-
default:
- ret = sys_fcntl(fd, cmd, arg);
+ err = do_fcntl(fd, cmd, arg, f.file);
break;
}
- return ret;
+out_put:
+ fdput(f);
+ return err;
}
COMPAT_SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd,