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authorJarkko Sakkinen <jarkko.sakkinen@intel.com>2012-03-21 16:34:05 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-03-21 17:54:58 -0700
commit6d9d88d07e132259c35f9493b15429e19198489c (patch)
tree96f880fd4f2a07de312f0db576c2484ab5d09457
parent08ab9b10d43aca091fdff58b69fc1ec89c5b8a83 (diff)
tmpfs: security xattr setting on inode creation
Adds to generic xattr support introduced in Linux 3.0 by implementing initxattrs callback. This enables consulting of security attributes from LSM and EVM when inode is created. [hughd@google.com: moved under CONFIG_TMPFS_XATTR, with memcpy in shmem_xattr_alloc] Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@intel.com> Reviewed-by: James Morris <james.l.morris@oracle.com> Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/shmem.c88
1 files changed, 72 insertions, 16 deletions
diff --git a/mm/shmem.c b/mm/shmem.c
index b7e195571862..7cc80833b74a 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1178,6 +1178,12 @@ static struct inode *shmem_get_inode(struct super_block *sb, const struct inode
static const struct inode_operations shmem_symlink_inode_operations;
static const struct inode_operations shmem_short_symlink_operations;
+#ifdef CONFIG_TMPFS_XATTR
+static int shmem_initxattrs(struct inode *, const struct xattr *, void *);
+#else
+#define shmem_initxattrs NULL
+#endif
+
static int
shmem_write_begin(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned flags,
@@ -1490,7 +1496,7 @@ shmem_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
if (inode) {
error = security_inode_init_security(inode, dir,
&dentry->d_name,
- NULL, NULL);
+ shmem_initxattrs, NULL);
if (error) {
if (error != -EOPNOTSUPP) {
iput(inode);
@@ -1630,7 +1636,7 @@ static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *s
return -ENOSPC;
error = security_inode_init_security(inode, dir, &dentry->d_name,
- NULL, NULL);
+ shmem_initxattrs, NULL);
if (error) {
if (error != -EOPNOTSUPP) {
iput(inode);
@@ -1704,6 +1710,66 @@ static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *co
* filesystem level, though.
*/
+/*
+ * Allocate new xattr and copy in the value; but leave the name to callers.
+ */
+static struct shmem_xattr *shmem_xattr_alloc(const void *value, size_t size)
+{
+ struct shmem_xattr *new_xattr;
+ size_t len;
+
+ /* wrap around? */
+ len = sizeof(*new_xattr) + size;
+ if (len <= sizeof(*new_xattr))
+ return NULL;
+
+ new_xattr = kmalloc(len, GFP_KERNEL);
+ if (!new_xattr)
+ return NULL;
+
+ new_xattr->size = size;
+ memcpy(new_xattr->value, value, size);
+ return new_xattr;
+}
+
+/*
+ * Callback for security_inode_init_security() for acquiring xattrs.
+ */
+static int shmem_initxattrs(struct inode *inode,
+ const struct xattr *xattr_array,
+ void *fs_info)
+{
+ struct shmem_inode_info *info = SHMEM_I(inode);
+ const struct xattr *xattr;
+ struct shmem_xattr *new_xattr;
+ size_t len;
+
+ for (xattr = xattr_array; xattr->name != NULL; xattr++) {
+ new_xattr = shmem_xattr_alloc(xattr->value, xattr->value_len);
+ if (!new_xattr)
+ return -ENOMEM;
+
+ len = strlen(xattr->name) + 1;
+ new_xattr->name = kmalloc(XATTR_SECURITY_PREFIX_LEN + len,
+ GFP_KERNEL);
+ if (!new_xattr->name) {
+ kfree(new_xattr);
+ return -ENOMEM;
+ }
+
+ memcpy(new_xattr->name, XATTR_SECURITY_PREFIX,
+ XATTR_SECURITY_PREFIX_LEN);
+ memcpy(new_xattr->name + XATTR_SECURITY_PREFIX_LEN,
+ xattr->name, len);
+
+ spin_lock(&info->lock);
+ list_add(&new_xattr->list, &info->xattr_list);
+ spin_unlock(&info->lock);
+ }
+
+ return 0;
+}
+
static int shmem_xattr_get(struct dentry *dentry, const char *name,
void *buffer, size_t size)
{
@@ -1731,24 +1797,17 @@ static int shmem_xattr_get(struct dentry *dentry, const char *name,
return ret;
}
-static int shmem_xattr_set(struct dentry *dentry, const char *name,
+static int shmem_xattr_set(struct inode *inode, const char *name,
const void *value, size_t size, int flags)
{
- struct inode *inode = dentry->d_inode;
struct shmem_inode_info *info = SHMEM_I(inode);
struct shmem_xattr *xattr;
struct shmem_xattr *new_xattr = NULL;
- size_t len;
int err = 0;
/* value == NULL means remove */
if (value) {
- /* wrap around? */
- len = sizeof(*new_xattr) + size;
- if (len <= sizeof(*new_xattr))
- return -ENOMEM;
-
- new_xattr = kmalloc(len, GFP_KERNEL);
+ new_xattr = shmem_xattr_alloc(value, size);
if (!new_xattr)
return -ENOMEM;
@@ -1757,9 +1816,6 @@ static int shmem_xattr_set(struct dentry *dentry, const char *name,
kfree(new_xattr);
return -ENOMEM;
}
-
- new_xattr->size = size;
- memcpy(new_xattr->value, value, size);
}
spin_lock(&info->lock);
@@ -1858,7 +1914,7 @@ static int shmem_setxattr(struct dentry *dentry, const char *name,
if (size == 0)
value = ""; /* empty EA, do not remove */
- return shmem_xattr_set(dentry, name, value, size, flags);
+ return shmem_xattr_set(dentry->d_inode, name, value, size, flags);
}
@@ -1878,7 +1934,7 @@ static int shmem_removexattr(struct dentry *dentry, const char *name)
if (err)
return err;
- return shmem_xattr_set(dentry, name, NULL, 0, XATTR_REPLACE);
+ return shmem_xattr_set(dentry->d_inode, name, NULL, 0, XATTR_REPLACE);
}
static bool xattr_is_trusted(const char *name)