Le 25/10/2017 à 05:34, Zach Riggle a écrit : > 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". > > $ 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 */
I think it doesn't work with /proc/map/exe (or other soft link in /proc/self) as realpath will give the path of the executable and not the path inside /proc so it will be true for any process with the same executable (which in our case is qemu for all). Thanks, Laurent