Re: [PATCH] uprobe: add support for overlayfs
* Steven Rostedt [2018-04-10 20:00:59]:
> On Tue, 10 Apr 2018 16:10:30 -0700
> Howard McLauchlan wrote:
>
> > uprobes cannot successfully attach to binaries located in a directory
> > mounted with overlayfs.
> >
> > To verify, create directories for mounting overlayfs
> > (upper,lower,work,merge), move some binary into merge/ and use readelf
> > to obtain some known instruction of the binary. I used /bin/true and the
> > entry instruction(0x13b0):
> >
> > $ mount -t overlay overlay -o
> > lowerdir=lower,upperdir=upper,workdir=work merge
> > $ cd /sys/kernel/debug/tracing
> > $ echo 'p:true_entry PATH_TO_MERGE/merge/true:0x13b0' > uprobe_events
> > $ echo 1 > events/uprobes/true_entry/enable
> >
> > This returns 'bash: echo: write error: Input/output error' and dmesg
> > tells us 'event trace: Could not enable event true_entry'
>
> I tried the above and verified that it is a problem and your patch
> solves it.
>
> Thanks, I'll apply it and start my tests on it.
>
> -- Steve
>
> >
> > This change makes create_trace_uprobe() look for the real inode of a
> > dentry. In the case of normal filesystems, this simplifies to just
> > returning the inode. In the case of overlayfs(and similar fs) we will
> > obtain the underlying dentry and corresponding inode, upon which uprobes
> > can successfully register.
> >
> > Running the example above with the patch applied, we can see that the
> > uprobe is enabled and will output to trace as expected.
> >
Looks good to me.
Reviewed-by: Srikar Dronamraju
> > Reviewed-by: Josef Bacik
> > Signed-off-by: Howard McLauchlan
> > ---
> > kernel/trace/trace_uprobe.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
> > index 2014f4351ae0..17c65fa4136d 100644
> > --- a/kernel/trace/trace_uprobe.c
> > +++ b/kernel/trace/trace_uprobe.c
> > @@ -446,7 +446,7 @@ static int create_trace_uprobe(int argc, char **argv)
> > if (ret)
> > goto fail_address_parse;
> >
> > - inode = igrab(d_inode(path.dentry));
> > + inode = igrab(d_real_inode(path.dentry));
> > path_put(&path);
> >
> > if (!inode || !S_ISREG(inode->i_mode)) {
>
Re: [PATCH] uprobe: add support for overlayfs
On Tue, 10 Apr 2018 20:00:59 -0400
Steven Rostedt wrote:
> On Tue, 10 Apr 2018 16:10:30 -0700
> Howard McLauchlan wrote:
>
> > uprobes cannot successfully attach to binaries located in a directory
> > mounted with overlayfs.
> >
> > To verify, create directories for mounting overlayfs
> > (upper,lower,work,merge), move some binary into merge/ and use readelf
> > to obtain some known instruction of the binary. I used /bin/true and the
> > entry instruction(0x13b0):
> >
> > $ mount -t overlay overlay -o
> > lowerdir=lower,upperdir=upper,workdir=work merge
> > $ cd /sys/kernel/debug/tracing
> > $ echo 'p:true_entry PATH_TO_MERGE/merge/true:0x13b0' > uprobe_events
> > $ echo 1 > events/uprobes/true_entry/enable
> >
> > This returns 'bash: echo: write error: Input/output error' and dmesg
> > tells us 'event trace: Could not enable event true_entry'
>
> I tried the above and verified that it is a problem and your patch
> solves it.
>
> Thanks, I'll apply it and start my tests on it.
This looks good to me.
Reviewed-by: Masami Hiramatsu
Thanks!
>
> -- Steve
>
> >
> > This change makes create_trace_uprobe() look for the real inode of a
> > dentry. In the case of normal filesystems, this simplifies to just
> > returning the inode. In the case of overlayfs(and similar fs) we will
> > obtain the underlying dentry and corresponding inode, upon which uprobes
> > can successfully register.
> >
> > Running the example above with the patch applied, we can see that the
> > uprobe is enabled and will output to trace as expected.
> >
> > Reviewed-by: Josef Bacik
> > Signed-off-by: Howard McLauchlan
> > ---
> > kernel/trace/trace_uprobe.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
> > index 2014f4351ae0..17c65fa4136d 100644
> > --- a/kernel/trace/trace_uprobe.c
> > +++ b/kernel/trace/trace_uprobe.c
> > @@ -446,7 +446,7 @@ static int create_trace_uprobe(int argc, char **argv)
> > if (ret)
> > goto fail_address_parse;
> >
> > - inode = igrab(d_inode(path.dentry));
> > + inode = igrab(d_real_inode(path.dentry));
> > path_put(&path);
> >
> > if (!inode || !S_ISREG(inode->i_mode)) {
>
--
Masami Hiramatsu
Re: [PATCH] uprobe: add support for overlayfs
On Tue, 10 Apr 2018 16:10:30 -0700
Howard McLauchlan wrote:
> uprobes cannot successfully attach to binaries located in a directory
> mounted with overlayfs.
>
> To verify, create directories for mounting overlayfs
> (upper,lower,work,merge), move some binary into merge/ and use readelf
> to obtain some known instruction of the binary. I used /bin/true and the
> entry instruction(0x13b0):
>
> $ mount -t overlay overlay -o
> lowerdir=lower,upperdir=upper,workdir=work merge
> $ cd /sys/kernel/debug/tracing
> $ echo 'p:true_entry PATH_TO_MERGE/merge/true:0x13b0' > uprobe_events
> $ echo 1 > events/uprobes/true_entry/enable
>
> This returns 'bash: echo: write error: Input/output error' and dmesg
> tells us 'event trace: Could not enable event true_entry'
I tried the above and verified that it is a problem and your patch
solves it.
Thanks, I'll apply it and start my tests on it.
-- Steve
>
> This change makes create_trace_uprobe() look for the real inode of a
> dentry. In the case of normal filesystems, this simplifies to just
> returning the inode. In the case of overlayfs(and similar fs) we will
> obtain the underlying dentry and corresponding inode, upon which uprobes
> can successfully register.
>
> Running the example above with the patch applied, we can see that the
> uprobe is enabled and will output to trace as expected.
>
> Reviewed-by: Josef Bacik
> Signed-off-by: Howard McLauchlan
> ---
> kernel/trace/trace_uprobe.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
> index 2014f4351ae0..17c65fa4136d 100644
> --- a/kernel/trace/trace_uprobe.c
> +++ b/kernel/trace/trace_uprobe.c
> @@ -446,7 +446,7 @@ static int create_trace_uprobe(int argc, char **argv)
> if (ret)
> goto fail_address_parse;
>
> - inode = igrab(d_inode(path.dentry));
> + inode = igrab(d_real_inode(path.dentry));
> path_put(&path);
>
> if (!inode || !S_ISREG(inode->i_mode)) {
Re: [PATCH] uprobe: add support for overlayfs
On Tue, Feb 27, 2018 at 04:40:14PM -0800, Howard McLauchlan wrote: > uprobes cannot successfully attach to binaries located in a directory > mounted with overlayfs. > > To verify, create directories for mounting overlayfs > (upper,lower,work,merge), move some binary into merge/ and use readelf > to obtain some known instruction of the binary. I used /bin/true and the > entry instruction(0x13b0): > > $ mount -t overlay overlay -o > lowerdir=lower,upperdir=upper,workdir=work merge > $ cd /sys/kernel/debug/tracing > $ echo 'p:true_entry PATH_TO_MERGE/merge/true:0x13b0' > uprobe_events > $ echo 1 > events/uprobes/true_entry/enable > > This returns 'bash: echo: write error: Input/output error' and dmesg > tells us 'event trace: Could not enable event true_entry' > > This change makes create_trace_uprobe() look for the real inode of a > dentry. In the case of normal filesystems, this simplifies to just > returning the inode. In the case of overlayfs(and similar fs) we will > obtain the underlying dentry and corresponding inode, upon which uprobes > can successfully register. > > Running the example above with the patch applied, we can see that the > uprobe is enabled and will output to trace as expected. > > Signed-off-by: Howard McLauchlan Reviewed-by: Josef Bacik Thanks, Josef
