Messages in this thread Patch in this message | | | Date | Wed, 24 Feb 2010 13:50:53 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH] supress uid comparison test if core output files are pipes |
| |
On Mon, 22 Feb 2010 15:44:29 -0500 Neil Horman <nhorman@tuxdriver.com> wrote:
> Modify uid check in do_coredump so as to not apply it in the case of pipes > > So this just got noticed in testing. The end of do_coredump validates the uid > of the inode for the created file against the uid of the crashing process to > ensure that no one can pre-create a core file with different ownership and grab > the information contained in the core when they shouldn' tbe able to. This > causes failures when using pipes for a core dumps if the crashing process is not > root, which is the uid of the pipe when it is created. > > The fix is simple. Since the check for matching uid's isn't relevant for pipes > (a process can't create a pipe that the uermodehelper code will open anyway), we > can just just skip it in the event ispipe is non-zero > > Signed-off-by: Neil Horman <nhorman@tuxdriver.com> > > > exec.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/fs/exec.c b/fs/exec.c > index 6303d18..6af2214 100644 > --- a/fs/exec.c > +++ b/fs/exec.c > @@ -1987,8 +1987,9 @@ void do_coredump(long signr, int exit_code, struct pt_regs *regs) > /* > * Dont allow local users get cute and trick others to coredump > * into their pre-created files: > + * Note, this is not relevant for pipes > */ > - if (inode->i_uid != current_fsuid()) > + if (!ispipe && (inode->i_uid != current_fsuid())) > goto close_fail; > if (!cprm.file->f_op) > goto close_fail;
hm, this actually appears to fix a regression, added by:
commit c46f739dd39db3b07ab5deb4e3ec81e1c04a91af Author: Ingo Molnar <mingo@elte.hu> AuthorDate: Wed Nov 28 13:59:18 2007 +0100 Commit: Linus Torvalds <torvalds@woody.linux-foundation.org> CommitDate: Wed Nov 28 10:58:01 2007 -0800
vfs: coredumping fix
fix: http://bugzilla.kernel.org/show_bug.cgi?id=3043
only allow coredumping to the same uid that the coredumping task runs under.
Signed-off-by: Ingo Molnar <mingo@elte.hu> Acked-by: Alan Cox <alan@redhat.com> Acked-by: Christoph Hellwig <hch@lst.de> Acked-by: Al Viro <viro@ftp.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/exec.c b/fs/exec.c index 4ccaaa4..282240a 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1780,6 +1780,12 @@ int do_coredump(long signr, int exit_code, struct pt_regs * regs) but keep the previous behaviour for now. */ if (!ispipe && !S_ISREG(inode->i_mode)) goto close_fail; + /* + * Dont allow local users get cute and trick others to coredump + * into their pre-created files: + */ + if (inode->i_uid != current->fsuid) + goto close_fail; if (!file->f_op) goto close_fail; if (!file->f_op->write)
| |