On Tue 11-05-10 17:48:51, Jan Kara wrote:
> On Thu 06-05-10 14:30:02, Andrew Morton wrote:
> >
> > (switched to email. Please respond via emailed reply-to-all, not via the
> > bugzilla web interface).
> >
> > On Wed, 5 May 2010 13:01:22 GMT
> > [email protected] wrote:
> >
> > > https://bugzilla.kernel.org/show_bug.cgi?id=15909
> > >
> > > Summary: open("a/",O_NOFOLLOW) fails with ELOOP if "a" is a
> > > symbolic link to a directory.
> > > Product: File System
> > > Version: 2.5
> > > Kernel Version: 2.6.34-rc6
> > > Platform: All
> > > OS/Version: Linux
> > > Tree: Mainline
> > > Status: NEW
> > > Severity: high
> > > Priority: P1
> > > Component: Other
> > > AssignedTo: [email protected]
> > > ReportedBy: [email protected]
> > > Regression: No
> > >
> > >
> > > mkdir c
> > > ln -s c a
> > >
> > > f=open("a/",O_RDONLY+O_NOFOLLOW)
> > >
> > > fails with ELOOP. However, this open should behave like open("a/.") not
> > > like
> > > open("a") according to path_resolution(7). In kernel version 2.6.32 the
> > > open
> > > worked as documented.
> > >
> > > On a higher level this bug makes
> > >
> > > find a/
> > >
> > > to fail.
> > >
> >
> > It sounds like this 2.6.32->2.6.34-rc6 regression could have pretty
> > serious ramifications for some users. Does anyone know whcih commit
> > might have caused it?
> The patch below fixes the issue for me but someone should have a look
> at it because I'm not really an expert in that code and the code paths are so
> twisted that my mind is currently tied into a knot ;).
>
> Honza
> ---
>
> From d53d3cc6488d9135bb69c3ff7e034b3b624866ed Mon Sep 17 00:00:00 2001
> From: Jan Kara <[email protected]>
> Date: Tue, 11 May 2010 16:34:25 +0200
> Subject: [PATCH] vfs: Fix O_NOFOLLOW behavior for paths with trailing slashes
>
> According to specification
> mkdir d; ln -s d a; open("a/", O_NOFOLLOW | O_RDONLY)
> should return success but currently it did return ELOOP. Fix the code to
> ignore
> O_NOFOLLOW in case the provided path has trailing slashes. This is a
> regression
> caused by path lookup cleanup patch series.
>
> CC: [email protected]
> Signed-off-by: Jan Kara <[email protected]>
...
BTW: It might be worthwhile to add the attached testcase to LTP?
Honza
--
Jan Kara <[email protected]>
SUSE Labs, CR
#define _GNU_SOURCE
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
int do_test(char *p)
{
int err;
char path[16];
strcpy(path, p);
err = open(path, O_NOFOLLOW | O_RDONLY);
if (err >= 0) {
fprintf(stderr, "open(\"%s\", O_NOFOLLOW | O_RDONLY) did not fail!\n", path);
return 1;
}
strcat(path, "/");
err = open(path, O_NOFOLLOW | O_RDONLY);
if (err < 0) {
fprintf(stderr, "open(\"%s\", O_NOFOLLOW | O_RDONLY) failed with %d\n", path, errno);
return 1;
}
strcat(path, ".");
err = open(path, O_NOFOLLOW | O_RDONLY);
if (err < 0) {
fprintf(stderr, "open(\"%s\", O_NOFOLLOW | O_RDONLY) failed with %d\n", path, errno);
return 1;
}
return 0;
}
int main(void)
{
if (mkdir("d", 0700) < 0) {
perror("mkdir");
return 1;
}
if (symlink("d", "a") < 0) {
perror("link");
return 1;
}
if (do_test("a"))
return 1;
return 0;
}
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