linux-kernel - [PATCH v3 24/27] core: implement getprlimit and setprlimit syscalls

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1259363167-9347-24-git-send-email-jslaby@suse.cz>
Date:	Sat, 28 Nov 2009 00:06:04 +0100
From:	Jiri Slaby <jslaby@...e.cz>
To:	jirislaby@...il.com
Cc:	mingo@...e.hu, nhorman@...driver.com, sfr@...b.auug.org.au,
	linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
	marcin.slusarz@...il.com, tglx@...utronix.de, mingo@...hat.com,
	hpa@...or.com, torvalds@...ux-foundation.org, oleg@...hat.com,
	James Morris <jmorris@...ei.org>,
	Heiko Carstens <heiko.carstens@...ibm.com>
Subject: [PATCH v3 24/27] core: implement getprlimit and setprlimit syscalls

This patch adds the code to support the sys_setprlimit and set_getprlimit
syscalls which modify the rlim values of a selected process.

All rlim users now either use newly added accessors or doesn't need them
due to
- locking
- a process was just forked and nobody else knows about it yet (and
  nobody can't thus read/write limits)

Based on Neil's work. Thank him.

Signed-off-by: Jiri Slaby <jslaby@...e.cz>
Acked-by: Neil Horman <nhorman@...driver.com>
Cc: James Morris <jmorris@...ei.org>
Cc: Heiko Carstens <heiko.carstens@...ibm.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Ingo Molnar <mingo@...e.hu>
---
 include/linux/syscalls.h |    4 ++
 kernel/sys.c             |   86 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 90 insertions(+), 0 deletions(-)

diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index a990ace..6fd7ba6 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -702,11 +702,15 @@ asmlinkage long sys_newuname(struct new_utsname __user *name);
 
 asmlinkage long sys_getrlimit(unsigned int resource,
 				struct rlimit __user *rlim);
+asmlinkage long sys_getprlimit(pid_t pid, unsigned int resource,
+				struct rlimit __user *rlim);
 #if defined(COMPAT_RLIM_OLD_INFINITY) || !(defined(CONFIG_IA64))
 asmlinkage long sys_old_getrlimit(unsigned int resource, struct rlimit __user *rlim);
 #endif
 asmlinkage long sys_setrlimit(unsigned int resource,
 				struct rlimit __user *rlim);
+asmlinkage long sys_setprlimit(pid_t pid, unsigned int resource,
+				struct rlimit __user *rlim);
 asmlinkage long sys_getrusage(int who, struct rusage __user *ru);
 asmlinkage long sys_umask(int mask);
 
diff --git a/kernel/sys.c b/kernel/sys.c
index c4065c5..626148f 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1212,6 +1212,61 @@ SYSCALL_DEFINE2(getrlimit, unsigned int, resource, struct rlimit __user *, rlim)
 	}
 }
 
+static int check_prlimit_permission(struct task_struct *task)
+{
+	const struct cred *cred = current_cred(), *tcred;
+	int ret = 0;
+
+	rcu_read_lock();
+	tcred = __task_cred(task);
+	if ((cred->uid != tcred->euid ||
+	     cred->uid != tcred->suid ||
+	     cred->uid != tcred->uid  ||
+	     cred->gid != tcred->egid ||
+	     cred->gid != tcred->sgid ||
+	     cred->gid != tcred->gid) &&
+	     !capable(CAP_SYS_RESOURCE)) {
+		ret = -EPERM;
+	}
+	rcu_read_unlock();
+	return ret;
+}
+
+SYSCALL_DEFINE3(getprlimit, pid_t, pid, unsigned int, resource,
+		struct rlimit __user *, rlim)
+{
+	struct rlimit val;
+	struct task_struct *tsk;
+	int ret;
+
+	if (resource >= RLIM_NLIMITS)
+		return -EINVAL;
+
+	read_lock(&tasklist_lock);
+
+	tsk = find_task_by_vpid(pid);
+	if (!tsk || !tsk->sighand) {
+		ret = -ESRCH;
+		goto err_unlock;
+	}
+
+	ret = check_prlimit_permission(tsk);
+	if (ret)
+		goto err_unlock;
+
+	task_lock(tsk->group_leader);
+	val = tsk->signal->rlim[resource];
+	task_unlock(tsk->group_leader);
+
+	read_unlock(&tasklist_lock);
+
+	return copy_to_user(rlim, &val, sizeof(*rlim)) ? -EFAULT : 0;
+err_unlock:
+	read_unlock(&tasklist_lock);
+	return ret;
+}
+
+
 #ifdef __ARCH_WANT_SYS_OLD_GETRLIMIT
 
 /*
@@ -1310,6 +1365,37 @@ SYSCALL_DEFINE2(setrlimit, unsigned int, resource, struct rlimit __user *, rlim)
 	return do_setrlimit(current, resource, &new_rlim);
 }
 
+SYSCALL_DEFINE3(setprlimit, pid_t, pid, unsigned int, resource,
+		struct rlimit __user *, rlim)
+{
+	struct task_struct *tsk;
+	struct rlimit new_rlim;
+	int ret;
+
+	if (resource >= RLIM_NLIMITS)
+		return -EINVAL;
+
+	if (copy_from_user(&new_rlim, rlim, sizeof(*rlim)))
+		return -EFAULT;
+
+	rcu_read_lock();
+	tsk = find_task_by_vpid(pid);
+	if (!tsk) {
+		rcu_read_unlock();
+		return -ESRCH;
+	}
+	get_task_struct(tsk);
+	rcu_read_unlock();
+
+	ret = check_prlimit_permission(tsk);
+	if (!ret)
+		ret = do_setrlimit(tsk, resource, &new_rlim);
+
+	put_task_struct(tsk);
+
+	return ret;
+}
+
 /*
  * It would make sense to put struct rusage in the task_struct,
  * except that would make the task_struct be *really big*.  After
-- 
1.6.5.3

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/