On Fri, 16 Jun 2006 14:41:57 +0200
Petr Baudis <[email protected]> wrote:
> All tasks calling setuid() from root to non-root during their lifetime
> will not be able to access their /proc/self/fd. This is troublesome
> because the fstatat() and other *at() routines are emulated by accessing
> /proc/self/fd/*/path and that will break with setuid()ing programs,
> leading to various weird consequences (e.g. with the latest glibc,
> nftw() does not work with setuid()ing programs on ppc and furthermore
> causes the LSB testsuite to fail because of this).
Odd. Did something actually change in glibc to make this start happening?
> This kernel patch fixes the problem by letting the process access its
> own /proc/self/fd - as far as I can see, this should be reasonably safe
> since for the process, this does not reveal "anything new". Feel free to
> comment on this.
>
Eric, Chris - any thought on this one?
Thanks.
>
> So far it's got one positive review on LKML and not much attention
> otherwise; Pavel Machek hinted me to steer it your way...
>
> diff --git a/fs/proc/base.c b/fs/proc/base.c
> index 6cc77dc..ea36a25 100644
> --- a/fs/proc/base.c
> +++ b/fs/proc/base.c
> @@ -1368,7 +1368,9 @@ static struct inode *proc_pid_make_inode
> ei->type = ino;
> inode->i_uid = 0;
> inode->i_gid = 0;
> - if (ino == PROC_TGID_INO || ino == PROC_TID_INO || task_dumpable(task)) {
> + if (ino == PROC_TGID_INO || ino == PROC_TID_INO ||
> + ((ino == PROC_TGID_FD || ino == PROC_TID_FD || ino >= PROC_TID_FD_DIR) && task == current) ||
> + task_dumpable(task)) {
> inode->i_uid = task->euid;
> inode->i_gid = task->egid;
> }
> @@ -1398,7 +1400,9 @@ static int pid_revalidate(struct dentry
> struct inode *inode = dentry->d_inode;
> struct task_struct *task = proc_task(inode);
> if (pid_alive(task)) {
> - if (proc_type(inode) == PROC_TGID_INO || proc_type(inode) == PROC_TID_INO || task_dumpable(task)) {
> + if (proc_type(inode) == PROC_TGID_INO || proc_type(inode) == PROC_TID_INO ||
> + ((proc_type(inode) == PROC_TGID_FD || proc_type(inode) == PROC_TID_FD) && task == current) ||
> + task_dumpable(task)) {
> inode->i_uid = task->euid;
> inode->i_gid = task->egid;
> } else {
> @@ -1425,7 +1429,7 @@ static int tid_fd_revalidate(struct dent
> if (fcheck_files(files, fd)) {
> rcu_read_unlock();
> put_files_struct(files);
> - if (task_dumpable(task)) {
> + if (task_dumpable(task) || task == current) {
> inode->i_uid = task->euid;
> inode->i_gid = task->egid;
> } else {
>
>
> --
> Petr "Pasky" Baudis
> Stuff: http://pasky.or.cz/
> Right now I am having amnesia and deja-vu at the same time. I think
> I have forgotten this before.
-
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