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>

10 files changed, 103 insertions, 101 deletions

diff --git a/arch/s390/kernel/traps.c b/arch/s390/kernel/traps.c
index 1a2fdb6991df..a4d29025ddbd 100644
--- a/arch/s390/kernel/traps.c
+++ b/arch/s390/kernel/traps.c
@@ -24,6 +24,7 @@
 #include <linux/smp.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
+#include <linux/seq_file.h>
 #include <linux/delay.h>
 #include <linux/module.h>
 #include <linux/kdebug.h>
@@ -218,41 +219,40 @@ void show_registers(struct pt_regs *regs)
 }       
 
 /* This is called from fs/proc/array.c */
-char *task_show_regs(struct task_struct *task, char *buffer)
+void task_show_regs(struct seq_file *m, struct task_struct *task)
 {
         struct pt_regs *regs;
 
         regs = task_pt_regs(task);
-        buffer += sprintf(buffer, "task: %p, ksp: %p\n",
+        seq_printf(m, "task: %p, ksp: %p\n",
                        task, (void *)task->thread.ksp);
-        buffer += sprintf(buffer, "User PSW : %p %p\n",
+        seq_printf(m, "User PSW : %p %p\n",
                        (void *) regs->psw.mask, (void *)regs->psw.addr);
 
-        buffer += sprintf(buffer, "User GPRS: " FOURLONG,
+        seq_printf(m, "User GPRS: " FOURLONG,
                           regs->gprs[0], regs->gprs[1],
                           regs->gprs[2], regs->gprs[3]);
-        buffer += sprintf(buffer, "           " FOURLONG,
+        seq_printf(m, "           " FOURLONG,
                           regs->gprs[4], regs->gprs[5],
                           regs->gprs[6], regs->gprs[7]);
-        buffer += sprintf(buffer, "           " FOURLONG,
+        seq_printf(m, "           " FOURLONG,
                           regs->gprs[8], regs->gprs[9],
                           regs->gprs[10], regs->gprs[11]);
-        buffer += sprintf(buffer, "           " FOURLONG,
+        seq_printf(m, "           " FOURLONG,
                           regs->gprs[12], regs->gprs[13],
                           regs->gprs[14], regs->gprs[15]);
-        buffer += sprintf(buffer, "User ACRS: %08x %08x %08x %08x\n",
+        seq_printf(m, "User ACRS: %08x %08x %08x %08x\n",
                           task->thread.acrs[0], task->thread.acrs[1],
                           task->thread.acrs[2], task->thread.acrs[3]);
-        buffer += sprintf(buffer, "           %08x %08x %08x %08x\n",
+        seq_printf(m, "           %08x %08x %08x %08x\n",
                           task->thread.acrs[4], task->thread.acrs[5],
                           task->thread.acrs[6], task->thread.acrs[7]);
-        buffer += sprintf(buffer, "           %08x %08x %08x %08x\n",
+        seq_printf(m, "           %08x %08x %08x %08x\n",
                           task->thread.acrs[8], task->thread.acrs[9],
                           task->thread.acrs[10], task->thread.acrs[11]);
-        buffer += sprintf(buffer, "           %08x %08x %08x %08x\n",
+        seq_printf(m, "           %08x %08x %08x %08x\n",
                           task->thread.acrs[12], task->thread.acrs[13],
                           task->thread.acrs[14], task->thread.acrs[15]);
-        return buffer;
 }
 
 static DEFINE_SPINLOCK(die_lock);
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;
 }
 
 /*
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 9c3e548a6754..8a19a8a1a3e6 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2274,7 +2274,7 @@ static const struct pid_entry tgid_base_stuff[] = {
         DIR("fdinfo",     S_IRUSR|S_IXUSR, fdinfo),
         REG("environ",    S_IRUSR, environ),
         INF("auxv",       S_IRUSR, pid_auxv),
-        INF("status",     S_IRUGO, pid_status),
+        ONE("status",     S_IRUGO, pid_status),
         INF("limits",     S_IRUSR, pid_limits),
 #ifdef CONFIG_SCHED_DEBUG
         REG("sched",      S_IRUGO|S_IWUSR, pid_sched),
@@ -2605,7 +2605,7 @@ static const struct pid_entry tid_base_stuff[] = {
         DIR("fdinfo",    S_IRUSR|S_IXUSR, fdinfo),
         REG("environ",   S_IRUSR, environ),
         INF("auxv",      S_IRUSR, pid_auxv),
-        INF("status",    S_IRUGO, pid_status),
+        ONE("status",    S_IRUGO, pid_status),
         INF("limits",    S_IRUSR, pid_limits),
 #ifdef CONFIG_SCHED_DEBUG
         REG("sched",     S_IRUGO|S_IWUSR, pid_sched),
diff --git a/fs/proc/internal.h b/fs/proc/internal.h
index 45bdbfc704e7..ea496ffeabe7 100644
--- a/fs/proc/internal.h
+++ b/fs/proc/internal.h
@@ -53,7 +53,8 @@ extern int proc_tid_stat(struct seq_file *m, struct pid_namespace *ns,
                                 struct pid *pid, struct task_struct *task);
 extern int proc_tgid_stat(struct seq_file *m, struct pid_namespace *ns,
                                 struct pid *pid, struct task_struct *task);
-extern int proc_pid_status(struct task_struct *, char *);
+extern int proc_pid_status(struct seq_file *m, struct pid_namespace *ns,
+                                struct pid *pid, struct task_struct *task);
 extern int proc_pid_statm(struct seq_file *m, struct pid_namespace *ns,
                                 struct pid *pid, struct task_struct *task);
 extern loff_t mem_lseek(struct file *file, loff_t offset, int orig);
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 38338ed98cc6..a34c440f8d25 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -9,13 +9,14 @@
 #include <linux/mempolicy.h>
 #include <linux/swap.h>
 #include <linux/swapops.h>
+#include <linux/seq_file.h>
 
 #include <asm/elf.h>
 #include <asm/uaccess.h>
 #include <asm/tlbflush.h>
 #include "internal.h"
 
-char *task_mem(struct mm_struct *mm, char *buffer)
+void task_mem(struct seq_file *m, struct mm_struct *mm)
 {
         unsigned long data, text, lib;
         unsigned long hiwater_vm, total_vm, hiwater_rss, total_rss;
@@ -37,7 +38,7 @@ char *task_mem(struct mm_struct *mm, char *buffer)
         data = mm->total_vm - mm->shared_vm - mm->stack_vm;
         text = (PAGE_ALIGN(mm->end_code) - (mm->start_code & PAGE_MASK)) >> 10;
         lib = (mm->exec_vm << (PAGE_SHIFT-10)) - text;
-        buffer += sprintf(buffer,
+        seq_printf(m,
                 "VmPeak:\t%8lu kB\n"
                 "VmSize:\t%8lu kB\n"
                 "VmLck:\t%8lu kB\n"
@@ -56,7 +57,6 @@ char *task_mem(struct mm_struct *mm, char *buffer)
                 data << (PAGE_SHIFT-10),
                 mm->stack_vm << (PAGE_SHIFT-10), text, lib,
                 (PTRS_PER_PTE*sizeof(pte_t)*mm->nr_ptes) >> 10);
-        return buffer;
 }
 
 unsigned long task_vsize(struct mm_struct *mm)
diff --git a/fs/proc/task_nommu.c b/fs/proc/task_nommu.c
index 1932c2ca3457..cee0231c6cec 100644
--- a/fs/proc/task_nommu.c
+++ b/fs/proc/task_nommu.c
@@ -12,7 +12,7 @@
  * each process that owns it. Non-shared memory is counted
  * accurately.
  */
-char *task_mem(struct mm_struct *mm, char *buffer)
+void task_mem(struct seq_file *m, struct mm_struct *mm)
 {
         struct vm_list_struct *vml;
         unsigned long bytes = 0, sbytes = 0, slack = 0;
@@ -58,14 +58,13 @@ char *task_mem(struct mm_struct *mm, char *buffer)
 
         bytes += kobjsize(current); /* includes kernel stack */
 
-        buffer += sprintf(buffer,
+        seq_printf(m,
                 "Mem:\t%8lu bytes\n"
                 "Slack:\t%8lu bytes\n"
                 "Shared:\t%8lu bytes\n",
                 bytes, slack, sbytes);
 
         up_read(&mm->mmap_sem);
-        return buffer;
 }
 
 unsigned long task_vsize(struct mm_struct *mm)
diff --git a/include/asm-s390/processor.h b/include/asm-s390/processor.h
index 4f744609cd11..dfec2d011c0d 100644
--- a/include/asm-s390/processor.h
+++ b/include/asm-s390/processor.h
@@ -161,6 +161,7 @@ struct stack_frame {
 /* Forward declaration, a strange C thing */
 struct task_struct;
 struct mm_struct;
+struct seq_file;
 
 /* Free all resources held by a thread. */
 extern void release_thread(struct task_struct *);
@@ -177,7 +178,7 @@ extern unsigned long thread_saved_pc(struct task_struct *t);
 /*
  * Print register of task into buffer. Used in fs/proc/array.c.
  */
-extern char *task_show_regs(struct task_struct *task, char *buffer);
+extern void task_show_regs(struct seq_file *m, struct task_struct *task);
 
 extern void show_registers(struct pt_regs *regs);
 extern void show_code(struct pt_regs *regs);
diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h
index ecae585ec3da..f8c9a2752f06 100644
--- a/include/linux/cpuset.h
+++ b/include/linux/cpuset.h
@@ -57,7 +57,9 @@ extern int cpuset_memory_pressure_enabled;
 extern void __cpuset_memory_pressure_bump(void);
 
 extern const struct file_operations proc_cpuset_operations;
-extern char *cpuset_task_status_allowed(struct task_struct *task, char *buffer);
+struct seq_file;
+extern void cpuset_task_status_allowed(struct seq_file *m,
+                                        struct task_struct *task);
 
 extern void cpuset_lock(void);
 extern void cpuset_unlock(void);
@@ -126,10 +128,9 @@ static inline int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
 
 static inline void cpuset_memory_pressure_bump(void) {}
 
-static inline char *cpuset_task_status_allowed(struct task_struct *task,
-                                                        char *buffer)
+static inline void cpuset_task_status_allowed(struct seq_file *m,
+                                                struct task_struct *task)
 {
-        return buffer;
 }
 
 static inline void cpuset_lock(void) {}
diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h
index b04ebf09fb91..e4a8f9aef188 100644
--- a/include/linux/proc_fs.h
+++ b/include/linux/proc_fs.h
@@ -118,7 +118,8 @@ struct dentry *proc_pid_lookup(struct inode *dir, struct dentry * dentry, struct
 int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir);
 unsigned long task_vsize(struct mm_struct *);
 int task_statm(struct mm_struct *, int *, int *, int *, int *);
-char *task_mem(struct mm_struct *, char *);
+void task_mem(struct seq_file *, struct mm_struct *);
+void clear_refs_smap(struct mm_struct *mm);
 
 struct proc_dir_entry *de_get(struct proc_dir_entry *de);
 void de_put(struct proc_dir_entry *de);
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 67b2bfe27814..3e296ed81d4d 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -2255,13 +2255,14 @@ const struct file_operations proc_cpuset_operations = {
 #endif /* CONFIG_PROC_PID_CPUSET */
 
 /* Display task cpus_allowed, mems_allowed in /proc/<pid>/status file. */
-char *cpuset_task_status_allowed(struct task_struct *task, char *buffer)
-{
-        buffer += sprintf(buffer, "Cpus_allowed:\t");
-        buffer += cpumask_scnprintf(buffer, PAGE_SIZE, task->cpus_allowed);
-        buffer += sprintf(buffer, "\n");
-        buffer += sprintf(buffer, "Mems_allowed:\t");
-        buffer += nodemask_scnprintf(buffer, PAGE_SIZE, task->mems_allowed);
-        buffer += sprintf(buffer, "\n");
-        return buffer;
+void cpuset_task_status_allowed(struct seq_file *m, struct task_struct *task)
+{
+        seq_printf(m, "Cpus_allowed:\t");
+        m->count += cpumask_scnprintf(m->buf + m->count, m->size - m->count,
+                                        task->cpus_allowed);
+        seq_printf(m, "\n");
+        seq_printf(m, "Mems_allowed:\t");
+        m->count += nodemask_scnprintf(m->buf + m->count, m->size - m->count,
+                                        task->mems_allowed);
+        seq_printf(m, "\n");
 }