proc: seqfile convert proc_pid_status to properly handle pid namespaces

Currently we possibly lookup the pid in the wrong pid namespace.  So
seq_file convert proc_pid_status which ensures the proper pid namespaces is
passed in.

[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: build fix]
[akpm@linux-foundation.org: another build fix]
[akpm@linux-foundation.org: s390 build fix]
[akpm@linux-foundation.org: fix task_name() output]
[akpm@linux-foundation.org: fix nommu build]
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Andrew Morgan <morgan@kernel.org>
Cc: Serge Hallyn <serue@us.ibm.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Paul Menage <menage@google.com>
Cc: Paul Jackson <pj@sgi.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 63 insertions, 65 deletions

diff --git a/fs/proc/array.c b/fs/proc/array.c
index 5540e9575c6d..07d6c4853fe8 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -89,18 +89,21 @@
 do { memcpy(buffer, string, strlen(string)); \
      buffer += strlen(string); } while (0)
 
-static inline char *task_name(struct task_struct *p, char *buf)
+static inline void task_name(struct seq_file *m, struct task_struct *p)
 {
 	int i;
+	char *buf, *end;
 	char *name;
 	char tcomm[sizeof(p->comm)];
 
 	get_task_comm(tcomm, p);
 
-	ADDBUF(buf, "Name:\t");
+	seq_printf(m, "Name:\t");
+	end = m->buf + m->size;
+	buf = m->buf + m->count;
 	name = tcomm;
 	i = sizeof(tcomm);
-	do {
+	while (i && (buf < end)) {
 		unsigned char c = *name;
 		name++;
 		i--;
@@ -108,20 +111,21 @@ static inline char *task_name(struct task_struct *p, char *buf)
 		if (!c)
 			break;
 		if (c == '\\') {
-			buf[1] = c;
-			buf += 2;
+			buf++;
+			if (buf < end)
+				*buf++ = c;
 			continue;
 		}
 		if (c == '\n') {
-			buf[0] = '\\';
-			buf[1] = 'n';
-			buf += 2;
+			*buf++ = '\\';
+			if (buf < end)
+				*buf++ = 'n';
 			continue;
 		}
 		buf++;
-	} while (i);
-	*buf = '\n';
-	return buf+1;
+	}
+	m->count = buf - m->buf;
+	seq_printf(m, "\n");
 }
 
 /*
@@ -152,21 +156,20 @@ static inline const char *get_task_state(struct task_struct *tsk)
 	return *p;
 }
 
-static inline char *task_state(struct task_struct *p, char *buffer)
+static inline void task_state(struct seq_file *m, struct pid_namespace *ns,
+				struct pid *pid, struct task_struct *p)
 {
 	struct group_info *group_info;
 	int g;
 	struct fdtable *fdt = NULL;
-	struct pid_namespace *ns;
 	pid_t ppid, tpid;
 
-	ns = current->nsproxy->pid_ns;
 	rcu_read_lock();
 	ppid = pid_alive(p) ?
 		task_tgid_nr_ns(rcu_dereference(p->real_parent), ns) : 0;
 	tpid = pid_alive(p) && p->ptrace ?
 		task_pid_nr_ns(rcu_dereference(p->parent), ns) : 0;
-	buffer += sprintf(buffer,
+	seq_printf(m,
 		"State:\t%s\n"
 		"Tgid:\t%d\n"
 		"Pid:\t%d\n"
@@ -176,7 +179,7 @@ static inline char *task_state(struct task_struct *p, char *buffer)
 		"Gid:\t%d\t%d\t%d\t%d\n",
 		get_task_state(p),
 		task_tgid_nr_ns(p, ns),
-		task_pid_nr_ns(p, ns),
+		pid_nr_ns(pid, ns),
 		ppid, tpid,
 		p->uid, p->euid, p->suid, p->fsuid,
 		p->gid, p->egid, p->sgid, p->fsgid);
@@ -184,7 +187,7 @@ static inline char *task_state(struct task_struct *p, char *buffer)
 	task_lock(p);
 	if (p->files)
 		fdt = files_fdtable(p->files);
-	buffer += sprintf(buffer,
+	seq_printf(m,
 		"FDSize:\t%d\n"
 		"Groups:\t",
 		fdt ? fdt->max_fds : 0);
@@ -195,20 +198,18 @@ static inline char *task_state(struct task_struct *p, char *buffer)
 	task_unlock(p);
 
 	for (g = 0; g < min(group_info->ngroups, NGROUPS_SMALL); g++)
-		buffer += sprintf(buffer, "%d ", GROUP_AT(group_info, g));
+		seq_printf(m, "%d ", GROUP_AT(group_info, g));
 	put_group_info(group_info);
 
-	buffer += sprintf(buffer, "\n");
-	return buffer;
+	seq_printf(m, "\n");
 }
 
-static char *render_sigset_t(const char *header, sigset_t *set, char *buffer)
+static void render_sigset_t(struct seq_file *m, const char *header,
+				sigset_t *set)
 {
-	int i, len;
+	int i;
 
-	len = strlen(header);
-	memcpy(buffer, header, len);
-	buffer += len;
+	seq_printf(m, "%s", header);
 
 	i = _NSIG;
 	do {
@@ -219,12 +220,10 @@ static char *render_sigset_t(const char *header, sigset_t *set, char *buffer)
 		if (sigismember(set, i+2)) x |= 2;
 		if (sigismember(set, i+3)) x |= 4;
 		if (sigismember(set, i+4)) x |= 8;
-		*buffer++ = (x < 10 ? '0' : 'a' - 10) + x;
+		seq_printf(m, "%x", x);
 	} while (i >= 4);
 
-	*buffer++ = '\n';
-	*buffer = 0;
-	return buffer;
+	seq_printf(m, "\n");
 }
 
 static void collect_sigign_sigcatch(struct task_struct *p, sigset_t *ign,
@@ -242,7 +241,7 @@ static void collect_sigign_sigcatch(struct task_struct *p, sigset_t *ign,
 	}
 }
 
-static inline char *task_sig(struct task_struct *p, char *buffer)
+static inline void task_sig(struct seq_file *m, struct task_struct *p)
 {
 	unsigned long flags;
 	sigset_t pending, shpending, blocked, ignored, caught;
@@ -269,67 +268,66 @@ static inline char *task_sig(struct task_struct *p, char *buffer)
 	}
 	rcu_read_unlock();
 
-	buffer += sprintf(buffer, "Threads:\t%d\n", num_threads);
-	buffer += sprintf(buffer, "SigQ:\t%lu/%lu\n", qsize, qlim);
+	seq_printf(m, "Threads:\t%d\n", num_threads);
+	seq_printf(m, "SigQ:\t%lu/%lu\n", qsize, qlim);
 
 	/* render them all */
-	buffer = render_sigset_t("SigPnd:\t", &pending, buffer);
-	buffer = render_sigset_t("ShdPnd:\t", &shpending, buffer);
-	buffer = render_sigset_t("SigBlk:\t", &blocked, buffer);
-	buffer = render_sigset_t("SigIgn:\t", &ignored, buffer);
-	buffer = render_sigset_t("SigCgt:\t", &caught, buffer);
-
-	return buffer;
+	render_sigset_t(m, "SigPnd:\t", &pending);
+	render_sigset_t(m, "ShdPnd:\t", &shpending);
+	render_sigset_t(m, "SigBlk:\t", &blocked);
+	render_sigset_t(m, "SigIgn:\t", &ignored);
+	render_sigset_t(m, "SigCgt:\t", &caught);
 }
 
-static char *render_cap_t(const char *header, kernel_cap_t *a, char *buffer)
+static void render_cap_t(struct seq_file *m, const char *header,
+			kernel_cap_t *a)
 {
 	unsigned __capi;
 
-	buffer += sprintf(buffer, "%s", header);
+	seq_printf(m, "%s", header);
 	CAP_FOR_EACH_U32(__capi) {
-		buffer += sprintf(buffer, "%08x",
-				  a->cap[(_LINUX_CAPABILITY_U32S-1) - __capi]);
+		seq_printf(m, "%08x",
+			   a->cap[(_LINUX_CAPABILITY_U32S-1) - __capi]);
 	}
-	return buffer + sprintf(buffer, "\n");
+	seq_printf(m, "\n");
 }
 
-static inline char *task_cap(struct task_struct *p, char *buffer)
+static inline void task_cap(struct seq_file *m, struct task_struct *p)
 {
-	buffer = render_cap_t("CapInh:\t", &p->cap_inheritable, buffer);
-	buffer = render_cap_t("CapPrm:\t", &p->cap_permitted, buffer);
-	return render_cap_t("CapEff:\t", &p->cap_effective, buffer);
+	render_cap_t(m, "CapInh:\t", &p->cap_inheritable);
+	render_cap_t(m, "CapPrm:\t", &p->cap_permitted);
+	render_cap_t(m, "CapEff:\t", &p->cap_effective);
 }
 
-static inline char *task_context_switch_counts(struct task_struct *p,
-						char *buffer)
+static inline void task_context_switch_counts(struct seq_file *m,
+						struct task_struct *p)
 {
-	return buffer + sprintf(buffer, "voluntary_ctxt_switches:\t%lu\n"
-			    "nonvoluntary_ctxt_switches:\t%lu\n",
-			    p->nvcsw,
-			    p->nivcsw);
+	seq_printf(m,	"voluntary_ctxt_switches:\t%lu\n"
+			"nonvoluntary_ctxt_switches:\t%lu\n",
+			p->nvcsw,
+			p->nivcsw);
 }
 
-int proc_pid_status(struct task_struct *task, char *buffer)
+int proc_pid_status(struct seq_file *m, struct pid_namespace *ns,
+			struct pid *pid, struct task_struct *task)
 {
-	char *orig = buffer;
 	struct mm_struct *mm = get_task_mm(task);
 
-	buffer = task_name(task, buffer);
-	buffer = task_state(task, buffer);
+	task_name(m, task);
+	task_state(m, ns, pid, task);
 
 	if (mm) {
-		buffer = task_mem(mm, buffer);
+		task_mem(m, mm);
 		mmput(mm);
 	}
-	buffer = task_sig(task, buffer);
-	buffer = task_cap(task, buffer);
-	buffer = cpuset_task_status_allowed(task, buffer);
+	task_sig(m, task);
+	task_cap(m, task);
+	cpuset_task_status_allowed(m, task);
 #if defined(CONFIG_S390)
-	buffer = task_show_regs(task, buffer);
+	task_show_regs(m, task);
 #endif
-	buffer = task_context_switch_counts(task, buffer);
-	return buffer - orig;
+	task_context_switch_counts(m, task);
+	return 0;
 }
 
 /*