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authorDavid Howells <dhowells@redhat.com>2008-11-14 02:39:19 +0300
committerJames Morris <jmorris@namei.org>2008-11-14 02:39:19 +0300
commitc69e8d9c01db2adc503464993c358901c9af9de4 (patch)
treebed94aaa9aeb7a7834d1c880f72b62a11a752c78 /fs/proc/array.c
parent86a264abe542cfececb4df129bc45a0338d8cdb9 (diff)
downloadlinux-c69e8d9c01db2adc503464993c358901c9af9de4.tar.xz
CRED: Use RCU to access another task's creds and to release a task's own creds
Use RCU to access another task's creds and to release a task's own creds. This means that it will be possible for the credentials of a task to be replaced without another task (a) requiring a full lock to read them, and (b) seeing deallocated memory. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: James Morris <jmorris@namei.org> Acked-by: Serge Hallyn <serue@us.ibm.com> Signed-off-by: James Morris <jmorris@namei.org>
Diffstat (limited to 'fs/proc/array.c')
-rw-r--r--fs/proc/array.c32
1 files changed, 21 insertions, 11 deletions
diff --git a/fs/proc/array.c b/fs/proc/array.c
index 62fe9b2009b6..7e4877d9dcb5 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -159,6 +159,7 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns,
struct group_info *group_info;
int g;
struct fdtable *fdt = NULL;
+ const struct cred *cred;
pid_t ppid, tpid;
rcu_read_lock();
@@ -170,6 +171,7 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns,
if (tracer)
tpid = task_pid_nr_ns(tracer, ns);
}
+ cred = get_cred((struct cred *) __task_cred(p));
seq_printf(m,
"State:\t%s\n"
"Tgid:\t%d\n"
@@ -182,8 +184,8 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns,
task_tgid_nr_ns(p, ns),
pid_nr_ns(pid, ns),
ppid, tpid,
- p->cred->uid, p->cred->euid, p->cred->suid, p->cred->fsuid,
- p->cred->gid, p->cred->egid, p->cred->sgid, p->cred->fsgid);
+ cred->uid, cred->euid, cred->suid, cred->fsuid,
+ cred->gid, cred->egid, cred->sgid, cred->fsgid);
task_lock(p);
if (p->files)
@@ -194,13 +196,12 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns,
fdt ? fdt->max_fds : 0);
rcu_read_unlock();
- group_info = p->cred->group_info;
- get_group_info(group_info);
+ group_info = cred->group_info;
task_unlock(p);
for (g = 0; g < min(group_info->ngroups, NGROUPS_SMALL); g++)
seq_printf(m, "%d ", GROUP_AT(group_info, g));
- put_group_info(group_info);
+ put_cred(cred);
seq_printf(m, "\n");
}
@@ -262,7 +263,7 @@ static inline void task_sig(struct seq_file *m, struct task_struct *p)
blocked = p->blocked;
collect_sigign_sigcatch(p, &ignored, &caught);
num_threads = atomic_read(&p->signal->count);
- qsize = atomic_read(&p->cred->user->sigpending);
+ qsize = atomic_read(&__task_cred(p)->user->sigpending);
qlim = p->signal->rlim[RLIMIT_SIGPENDING].rlim_cur;
unlock_task_sighand(p, &flags);
}
@@ -293,12 +294,21 @@ static void render_cap_t(struct seq_file *m, const char *header,
static inline void task_cap(struct seq_file *m, struct task_struct *p)
{
- struct cred *cred = p->cred;
+ const struct cred *cred;
+ kernel_cap_t cap_inheritable, cap_permitted, cap_effective, cap_bset;
- render_cap_t(m, "CapInh:\t", &cred->cap_inheritable);
- render_cap_t(m, "CapPrm:\t", &cred->cap_permitted);
- render_cap_t(m, "CapEff:\t", &cred->cap_effective);
- render_cap_t(m, "CapBnd:\t", &cred->cap_bset);
+ rcu_read_lock();
+ cred = __task_cred(p);
+ cap_inheritable = cred->cap_inheritable;
+ cap_permitted = cred->cap_permitted;
+ cap_effective = cred->cap_effective;
+ cap_bset = cred->cap_bset;
+ rcu_read_unlock();
+
+ render_cap_t(m, "CapInh:\t", &cap_inheritable);
+ render_cap_t(m, "CapPrm:\t", &cap_permitted);
+ render_cap_t(m, "CapEff:\t", &cap_effective);
+ render_cap_t(m, "CapBnd:\t", &cap_bset);
}
static inline void task_context_switch_counts(struct seq_file *m,