From 31b07093c44a7a442394d44423e21d783f5523b8 Mon Sep 17 00:00:00 2001 From: KOSAKI Motohiro Date: Thu, 9 Apr 2009 13:57:59 +0900 Subject: proc: mounts_poll() make consistent to mdstat_poll In recently sysfs_poll discussion, Neil Brown pointed out /proc/mounts also should be fixed. SUSv3 says "Regular files shall always poll TRUE for reading and writing". see http://www.opengroup.org/onlinepubs/009695399/functions/poll.html Then, mounts_poll()'s default should be "POLLIN | POLLRDNORM". it mean always readable. In addition, event trigger should use "POLLERR | POLLPRI" instead POLLERR. it makes consistent to mdstat_poll() and sysfs_poll(). and, select(2) can handle POLLPRI easily. Reported-by: Neil Brown Signed-off-by: KOSAKI Motohiro Cc: Ram Pai Cc: Miklos Szeredi Cc: Al Viro Signed-off-by: Greg Kroah-Hartman --- fs/proc/base.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'fs/proc/base.c') diff --git a/fs/proc/base.c b/fs/proc/base.c index f71559784bf..aa763ab0077 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -648,14 +648,14 @@ static unsigned mounts_poll(struct file *file, poll_table *wait) { struct proc_mounts *p = file->private_data; struct mnt_namespace *ns = p->ns; - unsigned res = 0; + unsigned res = POLLIN | POLLRDNORM; poll_wait(file, &ns->poll, wait); spin_lock(&vfsmount_lock); if (p->event != ns->event) { p->event = ns->event; - res = POLLERR; + res |= POLLERR | POLLPRI; } spin_unlock(&vfsmount_lock); -- cgit v1.2.3-70-g09d2 From f83ce3e6b02d5e48b3a43b001390e2b58820389d Mon Sep 17 00:00:00 2001 From: Jake Edge Date: Mon, 4 May 2009 12:51:14 -0600 Subject: proc: avoid information leaks to non-privileged processes By using the same test as is used for /proc/pid/maps and /proc/pid/smaps, only allow processes that can ptrace() a given process to see information that might be used to bypass address space layout randomization (ASLR). These include eip, esp, wchan, and start_stack in /proc/pid/stat as well as the non-symbolic output from /proc/pid/wchan. ASLR can be bypassed by sampling eip as shown by the proof-of-concept code at http://code.google.com/p/fuzzyaslr/ As part of a presentation (http://www.cr0.org/paper/to-jt-linux-alsr-leak.pdf) esp and wchan were also noted as possibly usable information leaks as well. The start_stack address also leaks potentially useful information. Cc: Stable Team Signed-off-by: Jake Edge Acked-by: Arjan van de Ven Acked-by: "Eric W. Biederman" Signed-off-by: Linus Torvalds --- fs/proc/array.c | 13 +++++++++---- fs/proc/base.c | 5 ++++- 2 files changed, 13 insertions(+), 5 deletions(-) (limited to 'fs/proc/base.c') diff --git a/fs/proc/array.c b/fs/proc/array.c index 7e4877d9dcb..725a650bbbb 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -80,6 +80,7 @@ #include #include #include +#include #include #include @@ -352,6 +353,7 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns, char state; pid_t ppid = 0, pgid = -1, sid = -1; int num_threads = 0; + int permitted; struct mm_struct *mm; unsigned long long start_time; unsigned long cmin_flt = 0, cmaj_flt = 0; @@ -364,11 +366,14 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns, state = *get_task_state(task); vsize = eip = esp = 0; + permitted = ptrace_may_access(task, PTRACE_MODE_READ); mm = get_task_mm(task); if (mm) { vsize = task_vsize(mm); - eip = KSTK_EIP(task); - esp = KSTK_ESP(task); + if (permitted) { + eip = KSTK_EIP(task); + esp = KSTK_ESP(task); + } } get_task_comm(tcomm, task); @@ -424,7 +429,7 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns, unlock_task_sighand(task, &flags); } - if (!whole || num_threads < 2) + if (permitted && (!whole || num_threads < 2)) wchan = get_wchan(task); if (!whole) { min_flt = task->min_flt; @@ -476,7 +481,7 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns, rsslim, mm ? mm->start_code : 0, mm ? mm->end_code : 0, - mm ? mm->start_stack : 0, + (permitted && mm) ? mm->start_stack : 0, esp, eip, /* The signal information here is obsolete. diff --git a/fs/proc/base.c b/fs/proc/base.c index aa763ab0077..fb45615943c 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -322,7 +322,10 @@ static int proc_pid_wchan(struct task_struct *task, char *buffer) wchan = get_wchan(task); if (lookup_symbol_name(wchan, symname) < 0) - return sprintf(buffer, "%lu", wchan); + if (!ptrace_may_access(task, PTRACE_MODE_READ)) + return 0; + else + return sprintf(buffer, "%lu", wchan); else return sprintf(buffer, "%s", symname); } -- cgit v1.2.3-70-g09d2