Merge branch 'cgroup/for-3.7-fixes' into cgroup/for-3.8

This is to receive device_cgroup fixes so that further device_cgroup
changes can be made in cgroup/for-3.8.

Signed-off-by: Tejun Heo <tj@kernel.org>

4 files changed, 103 insertions, 42 deletions

diff --git a/security/apparmor/Makefile b/security/apparmor/Makefile
index 7b3021cebbea..5706b74c857f 100644
--- a/security/apparmor/Makefile
+++ b/security/apparmor/Makefile
@@ -57,7 +57,7 @@ cmd_make-rlim = echo "static const char *const rlim_names[RLIM_NLIMITS] = {" \
 
 $(obj)/capability.o : $(obj)/capability_names.h
 $(obj)/resource.o : $(obj)/rlim_names.h
-$(obj)/capability_names.h : $(srctree)/include/linux/capability.h \
+$(obj)/capability_names.h : $(srctree)/include/uapi/linux/capability.h \
                             $(src)/Makefile
         $(call cmd,make-caps)
 $(obj)/rlim_names.h : $(srctree)/include/uapi/asm-generic/resource.h \
diff --git a/security/apparmor/policy.c b/security/apparmor/policy.c
index cf5fd220309b..813200384d97 100644
--- a/security/apparmor/policy.c
+++ b/security/apparmor/policy.c
@@ -724,6 +724,8 @@ fail:
  */
 static void free_profile(struct aa_profile *profile)
 {
+        struct aa_profile *p;
+
         AA_DEBUG("%s(%p)\n", __func__, profile);
 
         if (!profile)
@@ -751,7 +753,27 @@ static void free_profile(struct aa_profile *profile)
         aa_put_dfa(profile->xmatch);
         aa_put_dfa(profile->policy.dfa);
 
-        aa_put_profile(profile->replacedby);
+        /* put the profile reference for replacedby, but not via
+         * put_profile(kref_put).
+         * replacedby can form a long chain that can result in cascading
+         * frees that blows the stack because kref_put makes a nested fn
+         * call (it looks like recursion, with free_profile calling
+         * free_profile) for each profile in the chain lp#1056078.
+         */
+        for (p = profile->replacedby; p; ) {
+                if (atomic_dec_and_test(&p->base.count.refcount)) {
+                        /* no more refs on p, grab its replacedby */
+                        struct aa_profile *next = p->replacedby;
+                        /* break the chain */
+                        p->replacedby = NULL;
+                        /* now free p, chain is broken */
+                        free_profile(p);
+
+                        /* follow up with next profile in the chain */
+                        p = next;
+                } else
+                        break;
+        }
 
         kzfree(profile);
 }
diff --git a/security/device_cgroup.c b/security/device_cgroup.c
index 44dfc415a379..b08d20c66c2e 100644
--- a/security/device_cgroup.c
+++ b/security/device_cgroup.c
@@ -42,7 +42,10 @@ struct dev_exception_item {
 struct dev_cgroup {
         struct cgroup_subsys_state css;
         struct list_head exceptions;
-        bool deny_all;
+        enum {
+                DEVCG_DEFAULT_ALLOW,
+                DEVCG_DEFAULT_DENY,
+        } behavior;
 };
 
 static inline struct dev_cgroup *css_to_devcgroup(struct cgroup_subsys_state *s)
@@ -161,8 +164,8 @@ static void dev_exception_clean(struct dev_cgroup *dev_cgroup)
         struct dev_exception_item *ex, *tmp;
 
         list_for_each_entry_safe(ex, tmp, &dev_cgroup->exceptions, list) {
-                list_del(&ex->list);
-                kfree(ex);
+                list_del_rcu(&ex->list);
+                kfree_rcu(ex, rcu);
         }
 }
 
@@ -182,13 +185,13 @@ static struct cgroup_subsys_state *devcgroup_create(struct cgroup *cgroup)
         parent_cgroup = cgroup->parent;
 
         if (parent_cgroup == NULL)
-                dev_cgroup->deny_all = false;
+                dev_cgroup->behavior = DEVCG_DEFAULT_ALLOW;
         else {
                 parent_dev_cgroup = cgroup_to_devcgroup(parent_cgroup);
                 mutex_lock(&devcgroup_mutex);
                 ret = dev_exceptions_copy(&dev_cgroup->exceptions,
                                           &parent_dev_cgroup->exceptions);
-                dev_cgroup->deny_all = parent_dev_cgroup->deny_all;
+                dev_cgroup->behavior = parent_dev_cgroup->behavior;
                 mutex_unlock(&devcgroup_mutex);
                 if (ret) {
                         kfree(dev_cgroup);
@@ -260,7 +263,7 @@ static int devcgroup_seq_read(struct cgroup *cgroup, struct cftype *cft,
          * - List the exceptions in case the default policy is to deny
          * This way, the file remains as a "whitelist of devices"
          */
-        if (devcgroup->deny_all == false) {
+        if (devcgroup->behavior == DEVCG_DEFAULT_ALLOW) {
                 set_access(acc, ACC_MASK);
                 set_majmin(maj, ~0);
                 set_majmin(min, ~0);
@@ -295,7 +298,7 @@ static int may_access(struct dev_cgroup *dev_cgroup,
         struct dev_exception_item *ex;
         bool match = false;
 
-        list_for_each_entry(ex, &dev_cgroup->exceptions, list) {
+        list_for_each_entry_rcu(ex, &dev_cgroup->exceptions, list) {
                 if ((refex->type & DEV_BLOCK) && !(ex->type & DEV_BLOCK))
                         continue;
                 if ((refex->type & DEV_CHAR) && !(ex->type & DEV_CHAR))
@@ -314,12 +317,12 @@ static int may_access(struct dev_cgroup *dev_cgroup,
          * In two cases we'll consider this new exception valid:
          * - the dev cgroup has its default policy to allow + exception list:
          *   the new exception should *not* match any of the exceptions
-         *   (!deny_all, !match)
+         *   (behavior == DEVCG_DEFAULT_ALLOW, !match)
          * - the dev cgroup has its default policy to deny + exception list:
          *   the new exception *should* match the exceptions
-         *   (deny_all, match)
+         *   (behavior == DEVCG_DEFAULT_DENY, match)
          */
-        if (dev_cgroup->deny_all == match)
+        if ((dev_cgroup->behavior == DEVCG_DEFAULT_DENY) == match)
                 return 1;
         return 0;
 }
@@ -341,6 +344,19 @@ static int parent_has_perm(struct dev_cgroup *childcg,
         return may_access(parent, ex);
 }
 
+/**
+ * may_allow_all - checks if it's possible to change the behavior to
+ *                 allow based on parent's rules.
+ * @parent: device cgroup's parent
+ * returns: != 0 in case it's allowed, 0 otherwise
+ */
+static inline int may_allow_all(struct dev_cgroup *parent)
+{
+        if (!parent)
+                return 1;
+        return parent->behavior == DEVCG_DEFAULT_ALLOW;
+}
+
 /*
  * Modify the exception list using allow/deny rules.
  * CAP_SYS_ADMIN is needed for this.  It's at least separate from CAP_MKNOD
@@ -358,13 +374,18 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup,
                                    int filetype, const char *buffer)
 {
         const char *b;
-        char *endp;
-        int count;
+        char temp[12];          /* 11 + 1 characters needed for a u32 */
+        int count, rc;
         struct dev_exception_item ex;
+        struct cgroup *p = devcgroup->css.cgroup;
+        struct dev_cgroup *parent = NULL;
 
         if (!capable(CAP_SYS_ADMIN))
                 return -EPERM;
 
+        if (p->parent)
+                parent = cgroup_to_devcgroup(p->parent);
+
         memset(&ex, 0, sizeof(ex));
         b = buffer;
 
@@ -372,14 +393,21 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup,
         case 'a':
                 switch (filetype) {
                 case DEVCG_ALLOW:
-                        if (!parent_has_perm(devcgroup, &ex))
+                        if (!may_allow_all(parent))
                                 return -EPERM;
                         dev_exception_clean(devcgroup);
-                        devcgroup->deny_all = false;
+                        devcgroup->behavior = DEVCG_DEFAULT_ALLOW;
+                        if (!parent)
+                                break;
+
+                        rc = dev_exceptions_copy(&devcgroup->exceptions,
+                                                 &parent->exceptions);
+                        if (rc)
+                                return rc;
                         break;
                 case DEVCG_DENY:
                         dev_exception_clean(devcgroup);
-                        devcgroup->deny_all = true;
+                        devcgroup->behavior = DEVCG_DEFAULT_DENY;
                         break;
                 default:
                         return -EINVAL;
@@ -402,8 +430,16 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup,
                 ex.major = ~0;
                 b++;
         } else if (isdigit(*b)) {
-                ex.major = simple_strtoul(b, &endp, 10);
-                b = endp;
+                memset(temp, 0, sizeof(temp));
+                for (count = 0; count < sizeof(temp) - 1; count++) {
+                        temp[count] = *b;
+                        b++;
+                        if (!isdigit(*b))
+                                break;
+                }
+                rc = kstrtou32(temp, 10, &ex.major);
+                if (rc)
+                        return -EINVAL;
         } else {
                 return -EINVAL;
         }
@@ -416,8 +452,16 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup,
                 ex.minor = ~0;
                 b++;
         } else if (isdigit(*b)) {
-                ex.minor = simple_strtoul(b, &endp, 10);
-                b = endp;
+                memset(temp, 0, sizeof(temp));
+                for (count = 0; count < sizeof(temp) - 1; count++) {
+                        temp[count] = *b;
+                        b++;
+                        if (!isdigit(*b))
+                                break;
+                }
+                rc = kstrtou32(temp, 10, &ex.minor);
+                if (rc)
+                        return -EINVAL;
         } else {
                 return -EINVAL;
         }
@@ -452,7 +496,7 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup,
                  * an matching exception instead. And be silent about it: we
                  * don't want to break compatibility
                  */
-                if (devcgroup->deny_all == false) {
+                if (devcgroup->behavior == DEVCG_DEFAULT_ALLOW) {
                         dev_exception_rm(devcgroup, &ex);
                         return 0;
                 }
@@ -463,7 +507,7 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup,
                  * an matching exception instead. And be silent about it: we
                  * don't want to break compatibility
                  */
-                if (devcgroup->deny_all == true) {
+                if (devcgroup->behavior == DEVCG_DEFAULT_DENY) {
                         dev_exception_rm(devcgroup, &ex);
                         return 0;
                 }
@@ -533,10 +577,10 @@ struct cgroup_subsys devices_subsys = {
  *
  * returns 0 on success, -EPERM case the operation is not permitted
  */
-static int __devcgroup_check_permission(struct dev_cgroup *dev_cgroup,
-                                        short type, u32 major, u32 minor,
+static int __devcgroup_check_permission(short type, u32 major, u32 minor,
                                         short access)
 {
+        struct dev_cgroup *dev_cgroup;
         struct dev_exception_item ex;
         int rc;
 
@@ -547,6 +591,7 @@ static int __devcgroup_check_permission(struct dev_cgroup *dev_cgroup,
         ex.access = access;
 
         rcu_read_lock();
+        dev_cgroup = task_devcgroup(current);
         rc = may_access(dev_cgroup, &ex);
         rcu_read_unlock();
 
@@ -558,7 +603,6 @@ static int __devcgroup_check_permission(struct dev_cgroup *dev_cgroup,
 
 int __devcgroup_inode_permission(struct inode *inode, int mask)
 {
-        struct dev_cgroup *dev_cgroup = task_devcgroup(current);
         short type, access = 0;
 
         if (S_ISBLK(inode->i_mode))
@@ -570,13 +614,12 @@ int __devcgroup_inode_permission(struct inode *inode, int mask)
         if (mask & MAY_READ)
                 access |= ACC_READ;
 
-        return __devcgroup_check_permission(dev_cgroup, type, imajor(inode),
-                                            iminor(inode), access);
+        return __devcgroup_check_permission(type, imajor(inode), iminor(inode),
+                        access);
 }
 
 int devcgroup_inode_mknod(int mode, dev_t dev)
 {
-        struct dev_cgroup *dev_cgroup = task_devcgroup(current);
         short type;
 
         if (!S_ISBLK(mode) && !S_ISCHR(mode))
@@ -587,7 +630,7 @@ int devcgroup_inode_mknod(int mode, dev_t dev)
         else
                 type = DEV_CHAR;
 
-        return __devcgroup_check_permission(dev_cgroup, type, MAJOR(dev),
-                                            MINOR(dev), ACC_MKNOD);
+        return __devcgroup_check_permission(type, MAJOR(dev), MINOR(dev),
+                        ACC_MKNOD);
 
 }
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 24ab4148547c..61a53367d029 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2132,18 +2132,14 @@ static inline void flush_unauthorized_files(const struct cred *cred,
                 return;
 
         devnull = dentry_open(&selinux_null, O_RDWR, cred);
-        if (!IS_ERR(devnull)) {
-                /* replace all the matching ones with this */
-                do {
-                        replace_fd(n - 1, get_file(devnull), 0);
-                } while ((n = iterate_fd(files, n, match_file, cred)) != 0);
+        if (IS_ERR(devnull))
+                devnull = NULL;
+        /* replace all the matching ones with this */
+        do {
+                replace_fd(n - 1, devnull, 0);
+        } while ((n = iterate_fd(files, n, match_file, cred)) != 0);
+        if (devnull)
                 fput(devnull);
-        } else {
-                /* just close all the matching ones */
-                do {
-                        replace_fd(n - 1, NULL, 0);
-                } while ((n = iterate_fd(files, n, match_file, cred)) != 0);
-        }
 }
 
 /*