diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2014-08-10 02:10:41 +0200 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-08-10 02:10:41 +0200 |
commit | 77e40aae766ccbbbb0324cb92ab22e6e998375d7 (patch) | |
tree | fb4e8e840aaeeaac62249d7585249c4634886baa /fs | |
parent | Merge branch 'stable-3.17' of git://git.infradead.org/users/pcmoore/selinux (diff) | |
parent | proc: Point /proc/mounts at /proc/thread-self/mounts instead of /proc/self/mo... (diff) | |
download | linux-77e40aae766ccbbbb0324cb92ab22e6e998375d7.tar.xz linux-77e40aae766ccbbbb0324cb92ab22e6e998375d7.zip |
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull namespace updates from Eric Biederman:
"This is a bunch of small changes built against 3.16-rc6. The most
significant change for users is the first patch which makes setns
drmatically faster by removing unneded rcu handling.
The next chunk of changes are so that "mount -o remount,.." will not
allow the user namespace root to drop flags on a mount set by the
system wide root. Aks this forces read-only mounts to stay read-only,
no-dev mounts to stay no-dev, no-suid mounts to stay no-suid, no-exec
mounts to stay no exec and it prevents unprivileged users from messing
with a mounts atime settings. I have included my test case as the
last patch in this series so people performing backports can verify
this change works correctly.
The next change fixes a bug in NFS that was discovered while auditing
nsproxy users for the first optimization. Today you can oops the
kernel by reading /proc/fs/nfsfs/{servers,volumes} if you are clever
with pid namespaces. I rebased and fixed the build of the
!CONFIG_NFS_FS case yesterday when a build bot caught my typo. Given
that no one to my knowledge bases anything on my tree fixing the typo
in place seems more responsible that requiring a typo-fix to be
backported as well.
The last change is a small semantic cleanup introducing
/proc/thread-self and pointing /proc/mounts and /proc/net at it. This
prevents several kinds of problemantic corner cases. It is a
user-visible change so it has a minute chance of causing regressions
so the change to /proc/mounts and /proc/net are individual one line
commits that can be trivially reverted. Unfortunately I lost and
could not find the email of the original reporter so he is not
credited. From at least one perspective this change to /proc/net is a
refgression fix to allow pthread /proc/net uses that were broken by
the introduction of the network namespace"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
proc: Point /proc/mounts at /proc/thread-self/mounts instead of /proc/self/mounts
proc: Point /proc/net at /proc/thread-self/net instead of /proc/self/net
proc: Implement /proc/thread-self to point at the directory of the current thread
proc: Have net show up under /proc/<tgid>/task/<tid>
NFS: Fix /proc/fs/nfsfs/servers and /proc/fs/nfsfs/volumes
mnt: Add tests for unprivileged remount cases that have found to be faulty
mnt: Change the default remount atime from relatime to the existing value
mnt: Correct permission checks in do_remount
mnt: Move the test for MNT_LOCK_READONLY from change_mount_flags into do_remount
mnt: Only change user settable mount flags in remount
namespaces: Use task_lock and not rcu to protect nsproxy
Diffstat (limited to 'fs')
-rw-r--r-- | fs/namespace.c | 65 | ||||
-rw-r--r-- | fs/nfs/client.c | 95 | ||||
-rw-r--r-- | fs/nfs/inode.c | 3 | ||||
-rw-r--r-- | fs/nfs/internal.h | 9 | ||||
-rw-r--r-- | fs/nfs/netns.h | 3 | ||||
-rw-r--r-- | fs/proc/Makefile | 1 | ||||
-rw-r--r-- | fs/proc/base.c | 18 | ||||
-rw-r--r-- | fs/proc/inode.c | 7 | ||||
-rw-r--r-- | fs/proc/internal.h | 6 | ||||
-rw-r--r-- | fs/proc/proc_net.c | 6 | ||||
-rw-r--r-- | fs/proc/root.c | 5 | ||||
-rw-r--r-- | fs/proc/thread_self.c | 85 | ||||
-rw-r--r-- | fs/proc_namespace.c | 8 |
13 files changed, 246 insertions, 65 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index 2a1447c946e7..0acabea58319 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -890,8 +890,21 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root, mnt->mnt.mnt_flags = old->mnt.mnt_flags & ~(MNT_WRITE_HOLD|MNT_MARKED); /* Don't allow unprivileged users to change mount flags */ - if ((flag & CL_UNPRIVILEGED) && (mnt->mnt.mnt_flags & MNT_READONLY)) - mnt->mnt.mnt_flags |= MNT_LOCK_READONLY; + if (flag & CL_UNPRIVILEGED) { + mnt->mnt.mnt_flags |= MNT_LOCK_ATIME; + + if (mnt->mnt.mnt_flags & MNT_READONLY) + mnt->mnt.mnt_flags |= MNT_LOCK_READONLY; + + if (mnt->mnt.mnt_flags & MNT_NODEV) + mnt->mnt.mnt_flags |= MNT_LOCK_NODEV; + + if (mnt->mnt.mnt_flags & MNT_NOSUID) + mnt->mnt.mnt_flags |= MNT_LOCK_NOSUID; + + if (mnt->mnt.mnt_flags & MNT_NOEXEC) + mnt->mnt.mnt_flags |= MNT_LOCK_NOEXEC; + } /* Don't allow unprivileged users to reveal what is under a mount */ if ((flag & CL_UNPRIVILEGED) && list_empty(&old->mnt_expire)) @@ -1896,9 +1909,6 @@ static int change_mount_flags(struct vfsmount *mnt, int ms_flags) if (readonly_request == __mnt_is_readonly(mnt)) return 0; - if (mnt->mnt_flags & MNT_LOCK_READONLY) - return -EPERM; - if (readonly_request) error = mnt_make_readonly(real_mount(mnt)); else @@ -1924,6 +1934,33 @@ static int do_remount(struct path *path, int flags, int mnt_flags, if (path->dentry != path->mnt->mnt_root) return -EINVAL; + /* Don't allow changing of locked mnt flags. + * + * No locks need to be held here while testing the various + * MNT_LOCK flags because those flags can never be cleared + * once they are set. + */ + if ((mnt->mnt.mnt_flags & MNT_LOCK_READONLY) && + !(mnt_flags & MNT_READONLY)) { + return -EPERM; + } + if ((mnt->mnt.mnt_flags & MNT_LOCK_NODEV) && + !(mnt_flags & MNT_NODEV)) { + return -EPERM; + } + if ((mnt->mnt.mnt_flags & MNT_LOCK_NOSUID) && + !(mnt_flags & MNT_NOSUID)) { + return -EPERM; + } + if ((mnt->mnt.mnt_flags & MNT_LOCK_NOEXEC) && + !(mnt_flags & MNT_NOEXEC)) { + return -EPERM; + } + if ((mnt->mnt.mnt_flags & MNT_LOCK_ATIME) && + ((mnt->mnt.mnt_flags & MNT_ATIME_MASK) != (mnt_flags & MNT_ATIME_MASK))) { + return -EPERM; + } + err = security_sb_remount(sb, data); if (err) return err; @@ -1937,7 +1974,7 @@ static int do_remount(struct path *path, int flags, int mnt_flags, err = do_remount_sb(sb, flags, data, 0); if (!err) { lock_mount_hash(); - mnt_flags |= mnt->mnt.mnt_flags & MNT_PROPAGATION_MASK; + mnt_flags |= mnt->mnt.mnt_flags & ~MNT_USER_SETTABLE_MASK; mnt->mnt.mnt_flags = mnt_flags; touch_mnt_namespace(mnt->mnt_ns); unlock_mount_hash(); @@ -2122,7 +2159,7 @@ static int do_new_mount(struct path *path, const char *fstype, int flags, */ if (!(type->fs_flags & FS_USERNS_DEV_MOUNT)) { flags |= MS_NODEV; - mnt_flags |= MNT_NODEV; + mnt_flags |= MNT_NODEV | MNT_LOCK_NODEV; } } @@ -2436,6 +2473,14 @@ long do_mount(const char *dev_name, const char *dir_name, if (flags & MS_RDONLY) mnt_flags |= MNT_READONLY; + /* The default atime for remount is preservation */ + if ((flags & MS_REMOUNT) && + ((flags & (MS_NOATIME | MS_NODIRATIME | MS_RELATIME | + MS_STRICTATIME)) == 0)) { + mnt_flags &= ~MNT_ATIME_MASK; + mnt_flags |= path.mnt->mnt_flags & MNT_ATIME_MASK; + } + flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE | MS_BORN | MS_NOATIME | MS_NODIRATIME | MS_RELATIME| MS_KERNMOUNT | MS_STRICTATIME); @@ -2972,13 +3017,13 @@ static void *mntns_get(struct task_struct *task) struct mnt_namespace *ns = NULL; struct nsproxy *nsproxy; - rcu_read_lock(); - nsproxy = task_nsproxy(task); + task_lock(task); + nsproxy = task->nsproxy; if (nsproxy) { ns = nsproxy->mnt_ns; get_mnt_ns(ns); } - rcu_read_unlock(); + task_unlock(task); return ns; } diff --git a/fs/nfs/client.c b/fs/nfs/client.c index 1d09289c8f0e..180d1ec9c32e 100644 --- a/fs/nfs/client.c +++ b/fs/nfs/client.c @@ -1205,7 +1205,7 @@ static const struct file_operations nfs_server_list_fops = { .open = nfs_server_list_open, .read = seq_read, .llseek = seq_lseek, - .release = seq_release, + .release = seq_release_net, .owner = THIS_MODULE, }; @@ -1226,7 +1226,7 @@ static const struct file_operations nfs_volume_list_fops = { .open = nfs_volume_list_open, .read = seq_read, .llseek = seq_lseek, - .release = seq_release, + .release = seq_release_net, .owner = THIS_MODULE, }; @@ -1236,19 +1236,8 @@ static const struct file_operations nfs_volume_list_fops = { */ static int nfs_server_list_open(struct inode *inode, struct file *file) { - struct seq_file *m; - int ret; - struct pid_namespace *pid_ns = file->f_dentry->d_sb->s_fs_info; - struct net *net = pid_ns->child_reaper->nsproxy->net_ns; - - ret = seq_open(file, &nfs_server_list_ops); - if (ret < 0) - return ret; - - m = file->private_data; - m->private = net; - - return 0; + return seq_open_net(inode, file, &nfs_server_list_ops, + sizeof(struct seq_net_private)); } /* @@ -1256,7 +1245,7 @@ static int nfs_server_list_open(struct inode *inode, struct file *file) */ static void *nfs_server_list_start(struct seq_file *m, loff_t *_pos) { - struct nfs_net *nn = net_generic(m->private, nfs_net_id); + struct nfs_net *nn = net_generic(seq_file_net(m), nfs_net_id); /* lock the list against modification */ spin_lock(&nn->nfs_client_lock); @@ -1268,7 +1257,7 @@ static void *nfs_server_list_start(struct seq_file *m, loff_t *_pos) */ static void *nfs_server_list_next(struct seq_file *p, void *v, loff_t *pos) { - struct nfs_net *nn = net_generic(p->private, nfs_net_id); + struct nfs_net *nn = net_generic(seq_file_net(p), nfs_net_id); return seq_list_next(v, &nn->nfs_client_list, pos); } @@ -1278,7 +1267,7 @@ static void *nfs_server_list_next(struct seq_file *p, void *v, loff_t *pos) */ static void nfs_server_list_stop(struct seq_file *p, void *v) { - struct nfs_net *nn = net_generic(p->private, nfs_net_id); + struct nfs_net *nn = net_generic(seq_file_net(p), nfs_net_id); spin_unlock(&nn->nfs_client_lock); } @@ -1289,7 +1278,7 @@ static void nfs_server_list_stop(struct seq_file *p, void *v) static int nfs_server_list_show(struct seq_file *m, void *v) { struct nfs_client *clp; - struct nfs_net *nn = net_generic(m->private, nfs_net_id); + struct nfs_net *nn = net_generic(seq_file_net(m), nfs_net_id); /* display header on line 1 */ if (v == &nn->nfs_client_list) { @@ -1321,19 +1310,8 @@ static int nfs_server_list_show(struct seq_file *m, void *v) */ static int nfs_volume_list_open(struct inode *inode, struct file *file) { - struct seq_file *m; - int ret; - struct pid_namespace *pid_ns = file->f_dentry->d_sb->s_fs_info; - struct net *net = pid_ns->child_reaper->nsproxy->net_ns; - - ret = seq_open(file, &nfs_volume_list_ops); - if (ret < 0) - return ret; - - m = file->private_data; - m->private = net; - - return 0; + return seq_open_net(inode, file, &nfs_server_list_ops, + sizeof(struct seq_net_private)); } /* @@ -1341,7 +1319,7 @@ static int nfs_volume_list_open(struct inode *inode, struct file *file) */ static void *nfs_volume_list_start(struct seq_file *m, loff_t *_pos) { - struct nfs_net *nn = net_generic(m->private, nfs_net_id); + struct nfs_net *nn = net_generic(seq_file_net(m), nfs_net_id); /* lock the list against modification */ spin_lock(&nn->nfs_client_lock); @@ -1353,7 +1331,7 @@ static void *nfs_volume_list_start(struct seq_file *m, loff_t *_pos) */ static void *nfs_volume_list_next(struct seq_file *p, void *v, loff_t *pos) { - struct nfs_net *nn = net_generic(p->private, nfs_net_id); + struct nfs_net *nn = net_generic(seq_file_net(p), nfs_net_id); return seq_list_next(v, &nn->nfs_volume_list, pos); } @@ -1363,7 +1341,7 @@ static void *nfs_volume_list_next(struct seq_file *p, void *v, loff_t *pos) */ static void nfs_volume_list_stop(struct seq_file *p, void *v) { - struct nfs_net *nn = net_generic(p->private, nfs_net_id); + struct nfs_net *nn = net_generic(seq_file_net(p), nfs_net_id); spin_unlock(&nn->nfs_client_lock); } @@ -1376,7 +1354,7 @@ static int nfs_volume_list_show(struct seq_file *m, void *v) struct nfs_server *server; struct nfs_client *clp; char dev[8], fsid[17]; - struct nfs_net *nn = net_generic(m->private, nfs_net_id); + struct nfs_net *nn = net_generic(seq_file_net(m), nfs_net_id); /* display header on line 1 */ if (v == &nn->nfs_volume_list) { @@ -1407,6 +1385,45 @@ static int nfs_volume_list_show(struct seq_file *m, void *v) return 0; } +int nfs_fs_proc_net_init(struct net *net) +{ + struct nfs_net *nn = net_generic(net, nfs_net_id); + struct proc_dir_entry *p; + + nn->proc_nfsfs = proc_net_mkdir(net, "nfsfs", net->proc_net); + if (!nn->proc_nfsfs) + goto error_0; + + /* a file of servers with which we're dealing */ + p = proc_create("servers", S_IFREG|S_IRUGO, + nn->proc_nfsfs, &nfs_server_list_fops); + if (!p) + goto error_1; + + /* a file of volumes that we have mounted */ + p = proc_create("volumes", S_IFREG|S_IRUGO, + nn->proc_nfsfs, &nfs_volume_list_fops); + if (!p) + goto error_2; + return 0; + +error_2: + remove_proc_entry("servers", nn->proc_nfsfs); +error_1: + remove_proc_entry("fs/nfsfs", NULL); +error_0: + return -ENOMEM; +} + +void nfs_fs_proc_net_exit(struct net *net) +{ + struct nfs_net *nn = net_generic(net, nfs_net_id); + + remove_proc_entry("volumes", nn->proc_nfsfs); + remove_proc_entry("servers", nn->proc_nfsfs); + remove_proc_entry("fs/nfsfs", NULL); +} + /* * initialise the /proc/fs/nfsfs/ directory */ @@ -1419,14 +1436,12 @@ int __init nfs_fs_proc_init(void) goto error_0; /* a file of servers with which we're dealing */ - p = proc_create("servers", S_IFREG|S_IRUGO, - proc_fs_nfs, &nfs_server_list_fops); + p = proc_symlink("servers", proc_fs_nfs, "../../net/nfsfs/servers"); if (!p) goto error_1; /* a file of volumes that we have mounted */ - p = proc_create("volumes", S_IFREG|S_IRUGO, - proc_fs_nfs, &nfs_volume_list_fops); + p = proc_symlink("volumes", proc_fs_nfs, "../../net/nfsfs/volumes"); if (!p) goto error_2; return 0; diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c index abd37a380535..68921b01b792 100644 --- a/fs/nfs/inode.c +++ b/fs/nfs/inode.c @@ -1840,11 +1840,12 @@ EXPORT_SYMBOL_GPL(nfs_net_id); static int nfs_net_init(struct net *net) { nfs_clients_init(net); - return 0; + return nfs_fs_proc_net_init(net); } static void nfs_net_exit(struct net *net) { + nfs_fs_proc_net_exit(net); nfs_cleanup_cb_ident_idr(net); } diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h index 617f36611d4a..e2a45ae5014e 100644 --- a/fs/nfs/internal.h +++ b/fs/nfs/internal.h @@ -195,7 +195,16 @@ extern struct rpc_clnt *nfs4_find_or_create_ds_client(struct nfs_client *, #ifdef CONFIG_PROC_FS extern int __init nfs_fs_proc_init(void); extern void nfs_fs_proc_exit(void); +extern int nfs_fs_proc_net_init(struct net *net); +extern void nfs_fs_proc_net_exit(struct net *net); #else +static inline int nfs_fs_proc_net_init(struct net *net) +{ + return 0; +} +static inline void nfs_fs_proc_net_exit(struct net *net) +{ +} static inline int nfs_fs_proc_init(void) { return 0; diff --git a/fs/nfs/netns.h b/fs/nfs/netns.h index 8ee1fab83268..ef221fb8a183 100644 --- a/fs/nfs/netns.h +++ b/fs/nfs/netns.h @@ -29,6 +29,9 @@ struct nfs_net { #endif spinlock_t nfs_client_lock; struct timespec boot_time; +#ifdef CONFIG_PROC_FS + struct proc_dir_entry *proc_nfsfs; +#endif }; extern int nfs_net_id; diff --git a/fs/proc/Makefile b/fs/proc/Makefile index 239493ec718e..7151ea428041 100644 --- a/fs/proc/Makefile +++ b/fs/proc/Makefile @@ -23,6 +23,7 @@ proc-y += version.o proc-y += softirqs.o proc-y += namespaces.o proc-y += self.o +proc-y += thread_self.o proc-$(CONFIG_PROC_SYSCTL) += proc_sysctl.o proc-$(CONFIG_NET) += proc_net.o proc-$(CONFIG_PROC_KCORE) += kcore.o diff --git a/fs/proc/base.c b/fs/proc/base.c index 043c83cb51f9..baf852b648ad 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -2814,7 +2814,7 @@ retry: return iter; } -#define TGID_OFFSET (FIRST_PROCESS_ENTRY + 1) +#define TGID_OFFSET (FIRST_PROCESS_ENTRY + 2) /* for the /proc/ directory itself, after non-process stuff has been done */ int proc_pid_readdir(struct file *file, struct dir_context *ctx) @@ -2826,14 +2826,19 @@ int proc_pid_readdir(struct file *file, struct dir_context *ctx) if (pos >= PID_MAX_LIMIT + TGID_OFFSET) return 0; - if (pos == TGID_OFFSET - 1) { + if (pos == TGID_OFFSET - 2) { struct inode *inode = ns->proc_self->d_inode; if (!dir_emit(ctx, "self", 4, inode->i_ino, DT_LNK)) return 0; - iter.tgid = 0; - } else { - iter.tgid = pos - TGID_OFFSET; + ctx->pos = pos = pos + 1; + } + if (pos == TGID_OFFSET - 1) { + struct inode *inode = ns->proc_thread_self->d_inode; + if (!dir_emit(ctx, "thread-self", 11, inode->i_ino, DT_LNK)) + return 0; + ctx->pos = pos = pos + 1; } + iter.tgid = pos - TGID_OFFSET; iter.task = NULL; for (iter = next_tgid(ns, iter); iter.task; @@ -2862,6 +2867,9 @@ static const struct pid_entry tid_base_stuff[] = { DIR("fd", S_IRUSR|S_IXUSR, proc_fd_inode_operations, proc_fd_operations), DIR("fdinfo", S_IRUSR|S_IXUSR, proc_fdinfo_inode_operations, proc_fdinfo_operations), DIR("ns", S_IRUSR|S_IXUGO, proc_ns_dir_inode_operations, proc_ns_dir_operations), +#ifdef CONFIG_NET + DIR("net", S_IRUGO|S_IXUGO, proc_net_inode_operations, proc_net_operations), +#endif REG("environ", S_IRUSR, proc_environ_operations), ONE("auxv", S_IRUSR, proc_pid_auxv), ONE("status", S_IRUGO, proc_pid_status), diff --git a/fs/proc/inode.c b/fs/proc/inode.c index 0adbc02d60e3..333080d7a671 100644 --- a/fs/proc/inode.c +++ b/fs/proc/inode.c @@ -442,6 +442,7 @@ struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de) int proc_fill_super(struct super_block *s) { struct inode *root_inode; + int ret; s->s_flags |= MS_NODIRATIME | MS_NOSUID | MS_NOEXEC; s->s_blocksize = 1024; @@ -463,5 +464,9 @@ int proc_fill_super(struct super_block *s) return -ENOMEM; } - return proc_setup_self(s); + ret = proc_setup_self(s); + if (ret) { + return ret; + } + return proc_setup_thread_self(s); } diff --git a/fs/proc/internal.h b/fs/proc/internal.h index a024cf7b260f..7da13e49128a 100644 --- a/fs/proc/internal.h +++ b/fs/proc/internal.h @@ -231,6 +231,12 @@ static inline int proc_net_init(void) { return 0; } extern int proc_setup_self(struct super_block *); /* + * proc_thread_self.c + */ +extern int proc_setup_thread_self(struct super_block *); +extern void proc_thread_self_init(void); + +/* * proc_sysctl.c */ #ifdef CONFIG_PROC_SYSCTL diff --git a/fs/proc/proc_net.c b/fs/proc/proc_net.c index 4677bb7dc7c2..39481028ec08 100644 --- a/fs/proc/proc_net.c +++ b/fs/proc/proc_net.c @@ -113,9 +113,11 @@ static struct net *get_proc_task_net(struct inode *dir) rcu_read_lock(); task = pid_task(proc_pid(dir), PIDTYPE_PID); if (task != NULL) { - ns = task_nsproxy(task); + task_lock(task); + ns = task->nsproxy; if (ns != NULL) net = get_net(ns->net_ns); + task_unlock(task); } rcu_read_unlock(); @@ -224,7 +226,7 @@ static struct pernet_operations __net_initdata proc_net_ns_ops = { int __init proc_net_init(void) { - proc_symlink("net", NULL, "self/net"); + proc_symlink("net", NULL, "thread-self/net"); return register_pernet_subsys(&proc_net_ns_ops); } diff --git a/fs/proc/root.c b/fs/proc/root.c index 574bafc41f0b..6296c7626963 100644 --- a/fs/proc/root.c +++ b/fs/proc/root.c @@ -149,6 +149,8 @@ static void proc_kill_sb(struct super_block *sb) ns = (struct pid_namespace *)sb->s_fs_info; if (ns->proc_self) dput(ns->proc_self); + if (ns->proc_thread_self) + dput(ns->proc_thread_self); kill_anon_super(sb); put_pid_ns(ns); } @@ -170,7 +172,8 @@ void __init proc_root_init(void) return; proc_self_init(); - proc_symlink("mounts", NULL, "self/mounts"); + proc_thread_self_init(); + proc_symlink("mounts", NULL, "thread-self/mounts"); proc_net_init(); diff --git a/fs/proc/thread_self.c b/fs/proc/thread_self.c new file mode 100644 index 000000000000..59075b509df3 --- /dev/null +++ b/fs/proc/thread_self.c @@ -0,0 +1,85 @@ +#include <linux/sched.h> +#include <linux/namei.h> +#include <linux/slab.h> +#include <linux/pid_namespace.h> +#include "internal.h" + +/* + * /proc/thread_self: + */ +static int proc_thread_self_readlink(struct dentry *dentry, char __user *buffer, + int buflen) +{ + struct pid_namespace *ns = dentry->d_sb->s_fs_info; + pid_t tgid = task_tgid_nr_ns(current, ns); + pid_t pid = task_pid_nr_ns(current, ns); + char tmp[PROC_NUMBUF + 6 + PROC_NUMBUF]; + if (!pid) + return -ENOENT; + sprintf(tmp, "%d/task/%d", tgid, pid); + return readlink_copy(buffer, buflen, tmp); +} + +static void *proc_thread_self_follow_link(struct dentry *dentry, struct nameidata *nd) +{ + struct pid_namespace *ns = dentry->d_sb->s_fs_info; + pid_t tgid = task_tgid_nr_ns(current, ns); + pid_t pid = task_pid_nr_ns(current, ns); + char *name = ERR_PTR(-ENOENT); + if (pid) { + name = kmalloc(PROC_NUMBUF + 6 + PROC_NUMBUF, GFP_KERNEL); + if (!name) + name = ERR_PTR(-ENOMEM); + else + sprintf(name, "%d/task/%d", tgid, pid); + } + nd_set_link(nd, name); + return NULL; +} + +static const struct inode_operations proc_thread_self_inode_operations = { + .readlink = proc_thread_self_readlink, + .follow_link = proc_thread_self_follow_link, + .put_link = kfree_put_link, +}; + +static unsigned thread_self_inum; + +int proc_setup_thread_self(struct super_block *s) +{ + struct inode *root_inode = s->s_root->d_inode; + struct pid_namespace *ns = s->s_fs_info; + struct dentry *thread_self; + + mutex_lock(&root_inode->i_mutex); + thread_self = d_alloc_name(s->s_root, "thread-self"); + if (thread_self) { + struct inode *inode = new_inode_pseudo(s); + if (inode) { + inode->i_ino = thread_self_inum; + inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; + inode->i_mode = S_IFLNK | S_IRWXUGO; + inode->i_uid = GLOBAL_ROOT_UID; + inode->i_gid = GLOBAL_ROOT_GID; + inode->i_op = &proc_thread_self_inode_operations; + d_add(thread_self, inode); + } else { + dput(thread_self); + thread_self = ERR_PTR(-ENOMEM); + } + } else { + thread_self = ERR_PTR(-ENOMEM); + } + mutex_unlock(&root_inode->i_mutex); + if (IS_ERR(thread_self)) { + pr_err("proc_fill_super: can't allocate /proc/thread_self\n"); + return PTR_ERR(thread_self); + } + ns->proc_thread_self = thread_self; + return 0; +} + +void __init proc_thread_self_init(void) +{ + proc_alloc_inum(&thread_self_inum); +} diff --git a/fs/proc_namespace.c b/fs/proc_namespace.c index 1a81373947f3..73ca1740d839 100644 --- a/fs/proc_namespace.c +++ b/fs/proc_namespace.c @@ -232,17 +232,15 @@ static int mounts_open_common(struct inode *inode, struct file *file, if (!task) goto err; - rcu_read_lock(); - nsp = task_nsproxy(task); + task_lock(task); + nsp = task->nsproxy; if (!nsp || !nsp->mnt_ns) { - rcu_read_unlock(); + task_unlock(task); put_task_struct(task); goto err; } ns = nsp->mnt_ns; get_mnt_ns(ns); - rcu_read_unlock(); - task_lock(task); if (!task->fs) { task_unlock(task); put_task_struct(task); |