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proc: restrict access to /proc/PID/io 

/proc/PID/io may be used for gathering private information.  E.g.  for
openssh and vsftpd daemons wchars/rchars may be used to learn the
precise password length.  Restrict it to processes being able to ptrace
the target process.

ptrace_may_access() is needed to prevent keeping open file descriptor of
"io" file, executing setuid binary and gathering io information of the
setuid'ed process.

Signed-off-by: Vasiliy Kulikov <segoon@openwall.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Vasiliy Kulikov 2011-06-24 16:08:38 +04:00 committed by Linus Torvalds
parent b0af8dfdd6
commit 1d1221f375
1 changed files with 5 additions and 2 deletions
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7
fs/proc/base.c
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@ -2708,6 +2708,9 @@ static int do_io_accounting(struct task_struct *task, char *buffer, int whole)
struct task_io_accounting acct = task->ioac;
unsigned long flags;
if (!ptrace_may_access(task, PTRACE_MODE_READ))
return -EACCES;
if (whole && lock_task_sighand(task, &flags)) {
struct task_struct *t = task;
@ -2839,7 +2842,7 @@ static const struct pid_entry tgid_base_stuff[] = {
REG("coredump_filter", S_IRUGO|S_IWUSR, proc_coredump_filter_operations),
#endif
#ifdef CONFIG_TASK_IO_ACCOUNTING
INF("io", S_IRUGO, proc_tgid_io_accounting),
INF("io", S_IRUSR, proc_tgid_io_accounting),
#endif
#ifdef CONFIG_HARDWALL
INF("hardwall", S_IRUGO, proc_pid_hardwall),
@ -3181,7 +3184,7 @@ static const struct pid_entry tid_base_stuff[] = {
REG("make-it-fail", S_IRUGO|S_IWUSR, proc_fault_inject_operations),
#endif
#ifdef CONFIG_TASK_IO_ACCOUNTING
INF("io", S_IRUGO, proc_tid_io_accounting),
INF("io", S_IRUSR, proc_tid_io_accounting),
#endif
#ifdef CONFIG_HARDWALL
INF("hardwall", S_IRUGO, proc_pid_hardwall),