From: Zach Riggle <zachrig...@gmail.com>
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 | 44 +++++++++++++++++++++++++-------------------
1 file changed, 25 insertions(+), 19 deletions(-)
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 9bf901fa11..8fef3bb28e 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -7496,26 +7496,32 @@ 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
