| Message ID | 20180906001051.24015-1-avagin@openvz.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [dhowells/mount-api] fs: fix checking an error code of security_fs_context_parse_param | expand |
Andrei Vagin <avagin@openvz.org> wrote: > security_fs_context_parse_param() returns 0 if everything is okay. Not quite. It returns 0 to indicate that it processed the argument and that the argument doesn't belong to the filesystem. It returns -ENOPARAM to indicate that the argument should be passed along to the filesystem. Any other error is an actual error. > ret = security_fs_context_parse_param(fc, param); > - if (ret != -ENOPARAM) > + if (ret) So this change is wrong. The change that needs making is to the documentation - in particular lsm_hooks.h. David
> The change that needs making is to the documentation - in particular > lsm_hooks.h. And also the default for security_fs_context_parse_param() needs changing to -ENOPARAM. David
On Thu, Sep 06, 2018 at 11:16:24AM +0100, David Howells wrote: > Andrei Vagin <avagin@openvz.org> wrote: > > > security_fs_context_parse_param() returns 0 if everything is okay. > > Not quite. It returns 0 to indicate that it processed the argument and that > the argument doesn't belong to the filesystem. It returns -ENOPARAM to > indicate that the argument should be passed along to the filesystem. Any > other error is an actual error. > > > ret = security_fs_context_parse_param(fc, param); > > - if (ret != -ENOPARAM) > > + if (ret) > > So this change is wrong. It depends from what point to see on it. Without this patch, the linux-next kernel doesn't boot: VFS: Cannot open root device "vda2" or unknown-block(253,2): error -2 Please append a correct "root=" boot option; here are the available partitions: fd00 25165824 vda driver: virtio_blk fd01 512000 vda1 5065bd2c-01 fd02 23601152 vda2 5065bd2c-02 fd03 1044480 vda3 5065bd2c-03 Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(253,2) CPU: 1 PID: 1 Comm: swapper/0 Not tainted 4.19.0-rc1-00106-g679a89690477 #38 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20180531_142017-buildhw-08.phx2.fedoraproject.org-1.fc28 04/01/2014 Call Trace: dump_stack+0x85/0xc0 panic+0xec/0x251 mount_block_root+0x23e/0x2e7 ? do_early_param+0x8e/0x8e prepare_namespace+0x135/0x16b kernel_init_freeable+0x28b/0x2af ? rest_init+0xb9/0xb9 kernel_init+0xa/0x10e ret_from_fork+0x3a/0x50 Kernel Offset: 0x10000000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) ---[ end Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(253,2) ]--- I agree that I haven't understood the idea of this code. I found that security_fs_context_parse_param returns 0 by default and decided that this patch would fix the problem. I have sent an update version of the patch. Pls, take a look at it. And we need to push this patch to linux-next. We can't run CRIU tests for linux-next without it. Thanks, Andrei > > The change that needs making is to the documentation - in particular > lsm_hooks.h. > > David
On Thu, Sep 06, 2018 at 11:18:52AM +0100, David Howells wrote: > > The change that needs making is to the documentation - in particular > > lsm_hooks.h. > > And also the default for security_fs_context_parse_param() needs changing to > -ENOPARAM. apparmor_fs_context_parse_param() should be fixed too, it never returns -ENOPARAM. > > David
Andrei Vagin <avagin@gmail.com> wrote: > apparmor_fs_context_parse_param() should be fixed too, it never returns > -ENOPARAM. Fixed, thanks. David
diff --git a/fs/fs_context.c b/fs/fs_context.c index a82679441031..16bf2cb57534 100644 --- a/fs/fs_context.c +++ b/fs/fs_context.c @@ -146,7 +146,7 @@ int vfs_parse_fs_param(struct fs_context *fc, struct fs_parameter *param) return ret; ret = security_fs_context_parse_param(fc, param); - if (ret != -ENOPARAM) + if (ret) /* Param belongs to the LSM or is disallowed by the LSM; so * don't pass to the FS. */