2 files changed, 78 insertions, 58 deletions

diff --git a/include/linux/capability.h b/include/linux/capability.h
index b5750d0b96e0..d567af247ed8 100644
--- a/include/linux/capability.h
+++ b/include/linux/capability.h
@@ -99,6 +99,13 @@ typedef struct kernel_cap_struct {
         __u32 cap[_KERNEL_CAPABILITY_U32S];
 } kernel_cap_t;
 
+/* exact same as vfs_cap_data but in cpu endian and always filled completely */
+struct cpu_vfs_cap_data {
+        __u32 magic_etc;
+        kernel_cap_t permitted;
+        kernel_cap_t inheritable;
+};
+
 #define _USER_CAP_HEADER_SIZE  (sizeof(struct __user_cap_header_struct))
 #define _KERNEL_CAP_T_SIZE     (sizeof(kernel_cap_t))
 
diff --git a/security/commoncap.c b/security/commoncap.c
index f88119cb2bc2..d7eff5797b91 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -202,17 +202,70 @@ int cap_inode_killpriv(struct dentry *dentry)
         return inode->i_op->removexattr(dentry, XATTR_NAME_CAPS);
 }
 
-static inline int cap_from_disk(struct vfs_cap_data *caps,
-                                struct linux_binprm *bprm, unsigned size)
+static inline int bprm_caps_from_vfs_caps(struct cpu_vfs_cap_data *caps,
+                                          struct linux_binprm *bprm)
 {
+        unsigned i;
+        int ret = 0;
+
+        if (caps->magic_etc & VFS_CAP_FLAGS_EFFECTIVE)
+                bprm->cap_effective = true;
+        else
+                bprm->cap_effective = false;
+
+        CAP_FOR_EACH_U32(i) {
+                __u32 permitted = caps->permitted.cap[i];
+                __u32 inheritable = caps->inheritable.cap[i];
+
+                /*
+                 * pP' = (X & fP) | (pI & fI)
+                 */
+                bprm->cap_post_exec_permitted.cap[i] =
+                        (current->cap_bset.cap[i] & permitted) |
+                        (current->cap_inheritable.cap[i] & inheritable);
+
+                if (permitted & ~bprm->cap_post_exec_permitted.cap[i]) {
+                        /*
+                         * insufficient to execute correctly
+                         */
+                        ret = -EPERM;
+                }
+        }
+
+        /*
+         * For legacy apps, with no internal support for recognizing they
+         * do not have enough capabilities, we return an error if they are
+         * missing some "forced" (aka file-permitted) capabilities.
+         */
+        return bprm->cap_effective ? ret : 0;
+}
+
+int get_vfs_caps_from_disk(const struct dentry *dentry, struct cpu_vfs_cap_data *cpu_caps)
+{
+        struct inode *inode = dentry->d_inode;
         __u32 magic_etc;
         unsigned tocopy, i;
-        int ret;
+        int size;
+        struct vfs_cap_data caps;
+
+        memset(cpu_caps, 0, sizeof(struct cpu_vfs_cap_data));
+
+        if (!inode || !inode->i_op || !inode->i_op->getxattr)
+                return -ENODATA;
+
+        size = inode->i_op->getxattr((struct dentry *)dentry, XATTR_NAME_CAPS, &caps,
+                                   XATTR_CAPS_SZ);
+        if (size == -ENODATA || size == -EOPNOTSUPP) {
+                /* no data, that's ok */
+                return -ENODATA;
+        }
+        if (size < 0)
+                return size;
 
         if (size < sizeof(magic_etc))
                 return -EINVAL;
 
-        magic_etc = le32_to_cpu(caps->magic_etc);
+        cpu_caps->magic_etc = magic_etc = le32_to_cpu(caps.magic_etc);
 
         switch ((magic_etc & VFS_CAP_REVISION_MASK)) {
         case VFS_CAP_REVISION_1:
@@ -229,46 +282,13 @@ static inline int cap_from_disk(struct vfs_cap_data *caps,
                 return -EINVAL;
         }
 
-        if (magic_etc & VFS_CAP_FLAGS_EFFECTIVE) {
-                bprm->cap_effective = true;
-        } else {
-                bprm->cap_effective = false;
-        }
-
-        ret = 0;
-
         CAP_FOR_EACH_U32(i) {
-                __u32 value_cpu;
-
-                if (i >= tocopy) {
-                        /*
-                         * Legacy capability sets have no upper bits
-                         */
-                        bprm->cap_post_exec_permitted.cap[i] = 0;
-                        continue;
-                }
-                /*
-                 * pP' = (X & fP) | (pI & fI)
-                 */
-                value_cpu = le32_to_cpu(caps->data[i].permitted);
-                bprm->cap_post_exec_permitted.cap[i] =
-                        (current->cap_bset.cap[i] & value_cpu) |
-                        (current->cap_inheritable.cap[i] &
-                                le32_to_cpu(caps->data[i].inheritable));
-                if (value_cpu & ~bprm->cap_post_exec_permitted.cap[i]) {
-                        /*
-                         * insufficient to execute correctly
-                         */
-                        ret = -EPERM;
-                }
+                if (i >= tocopy)
+                        break;
+                cpu_caps->permitted.cap[i] = le32_to_cpu(caps.data[i].permitted);
+                cpu_caps->inheritable.cap[i] = le32_to_cpu(caps.data[i].inheritable);
         }
-
-        /*
-         * For legacy apps, with no internal support for recognizing they
-         * do not have enough capabilities, we return an error if they are
-         * missing some "forced" (aka file-permitted) capabilities.
-         */
-        return bprm->cap_effective ? ret : 0;
+        return 0;
 }
 
 /* Locate any VFS capabilities: */
@@ -276,8 +296,7 @@ static int get_file_caps(struct linux_binprm *bprm)
 {
         struct dentry *dentry;
         int rc = 0;
-        struct vfs_cap_data vcaps;
-        struct inode *inode;
+        struct cpu_vfs_cap_data vcaps;
 
         bprm_clear_caps(bprm);
 
@@ -288,24 +307,18 @@ static int get_file_caps(struct linux_binprm *bprm)
                 return 0;
 
         dentry = dget(bprm->file->f_dentry);
-        inode = dentry->d_inode;
-        if (!inode->i_op || !inode->i_op->getxattr)
-                goto out;
 
-        rc = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS, &vcaps,
-                                   XATTR_CAPS_SZ);
-        if (rc == -ENODATA || rc == -EOPNOTSUPP) {
-                /* no data, that's ok */
-                rc = 0;
+        rc = get_vfs_caps_from_disk(dentry, &vcaps);
+        if (rc < 0) {
+                if (rc == -EINVAL)
+                        printk(KERN_NOTICE "%s: get_vfs_caps_from_disk returned %d for %s\n",
+                                __func__, rc, bprm->filename);
+                else if (rc == -ENODATA)
+                        rc = 0;
                 goto out;
         }
-        if (rc < 0)
-                goto out;
 
-        rc = cap_from_disk(&vcaps, bprm, rc);
-        if (rc == -EINVAL)
-                printk(KERN_NOTICE "%s: cap_from_disk returned %d for %s\n",
-                       __func__, rc, bprm->filename);
+        rc = bprm_caps_from_vfs_caps(&vcaps, bprm);
 
 out:
         dput(dentry);