On Thu, Oct 26, 2017 at 04:06:22PM -0500, Zach Riggle wrote:
> Friendly ping :)
>
> I've updated the patch with v2 which addresses the style issue
I'll have a look at it soon.
>
> *Zach Riggle*
>
> On Tue, Oct 24, 2017 at 10:34 PM, Zach Riggle <zachrig...@gmail.com> wrote:
>
> > Previously, it was possible to get a handle to the "real" /proc/self/mem
> > by creating a symlink to it and opening the symlink, or opening e.g.
> > "./mem" after chdir'ing to "/proc/self"
When is this a problem? Symlinking to /proc/self seems to be a quite weird
usecase.
> >
> > $ ln -s /proc/self self
> > $ cat self/maps
> > 60000000-602bc000 r-xp 00000000 fc:01 270375
> > /usr/bin/qemu-arm-static
> > 604bc000-6050f000 rw-p 002bc000 fc:01 270375
> > /usr/bin/qemu-arm-static
> > ...
> >
> > Signed-off-by: Zach Riggle <zachrig...@gmail.com>
> > ---
> > linux-user/syscall.c | 47 ++++++++++++++++++++++++++++-------------------
> > 1 file changed, 28 insertions(+), 19 deletions(-)
> >
> > diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> > index 9bf901fa11..6c1f28a1f7 100644
> > --- a/linux-user/syscall.c
> > +++ b/linux-user/syscall.c
> > @@ -7496,26 +7496,35 @@ static int open_self_auxv(void *cpu_env, int fd)
> >
> > static int is_proc_myself(const char *filename, const char *entry)
> > {
> > - if (!strncmp(filename, "/proc/", strlen("/proc/"))) {
> > - filename += strlen("/proc/");
> > - if (!strncmp(filename, "self/", strlen("self/"))) {
> > - filename += strlen("self/");
> > - } else if (*filename >= '1' && *filename <= '9') {
> > - char myself[80];
> > - snprintf(myself, sizeof(myself), "%d/", getpid());
> > - if (!strncmp(filename, myself, strlen(myself))) {
> > - filename += strlen(myself);
> > - } else {
> > - return 0;
> > - }
> > - } else {
> > - return 0;
> > - }
> > - if (!strcmp(filename, entry)) {
> > - return 1;
> > - }
> > + char proc_self_entry[PATH_MAX + 1];
> > + char proc_self_entry_realpath[PATH_MAX + 1];
> > + char filename_realpath[PATH_MAX + 1];
> > +
> > + if (PATH_MAX < snprintf(proc_self_entry,
> > + sizeof(proc_self_entry),
> > + "/proc/self/%s",
> > + entry)) {
> > + /* Full path to "entry" is too long to fit in the buffer */
> > + return 0;
> > }
> > - return 0;
> > +
> > + if (!realpath(filename, filename_realpath)) {
> > + /* File does not exist, or can't be canonicalized */
> > + return 0;
> > + }
> > +
> > + if (!realpath(proc_self_entry, proc_self_entry_realpath)) {
> > + /* Procfs entry does not exist */
> > + return 0;
> > + }
> > +
> > + if (strcmp(filename_realpath, proc_self_entry_realpath) != 0) {
> > + /* Paths are different */
> > + return 0;
> > + }
> > +
> > + /* filename refers to /proc/self/<entry> */
> > + return 1;
> > }
> >
> > #if defined(HOST_WORDS_BIGENDIAN) != defined(TARGET_WORDS_BIGENDIAN)
> > --
> > 2.14.3
> >
> >
