ext4 crypto: filename encryption modifications

Modifies htree_dirblock_to_tree, dx_make_map, ext4_match search_dir,
and ext4_find_dest_de to support fname crypto.  Filename encryption
feature is not yet enabled at this patch.

Signed-off-by: Uday Savagaonkar <savagaon@google.com>
Signed-off-by: Ildar Muslukhov <ildarm@google.com>
Signed-off-by: Michael Halcrow <mhalcrow@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

1 files changed, 204 insertions, 44 deletions

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 85add9a9e1cd..4c84db862891 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -253,8 +253,9 @@ static struct dx_frame *dx_probe(const struct qstr *d_name,
                                  struct dx_hash_info *hinfo,
                                  struct dx_frame *frame);
 static void dx_release(struct dx_frame *frames);
-static int dx_make_map(struct ext4_dir_entry_2 *de, unsigned blocksize,
-                       struct dx_hash_info *hinfo, struct dx_map_entry map[]);
+static int dx_make_map(struct inode *dir, struct ext4_dir_entry_2 *de,
+                       unsigned blocksize, struct dx_hash_info *hinfo,
+                       struct dx_map_entry map[]);
 static void dx_sort_map(struct dx_map_entry *map, unsigned count);
 static struct ext4_dir_entry_2 *dx_move_dirents(char *from, char *to,
                 struct dx_map_entry *offsets, int count, unsigned blocksize);
@@ -968,7 +969,8 @@ static int htree_dirblock_to_tree(struct file *dir_file,
         struct buffer_head *bh;
         struct ext4_dir_entry_2 *de, *top;
         int err = 0, count = 0;
-        struct ext4_str tmp_str;
+        struct ext4_fname_crypto_ctx *ctx = NULL;
+        struct ext4_str fname_crypto_str = {.name = NULL, .len = 0}, tmp_str;
 
         dxtrace(printk(KERN_INFO "In htree dirblock_to_tree: block %lu\n",
                                                         (unsigned long)block));
@@ -980,6 +982,24 @@ static int htree_dirblock_to_tree(struct file *dir_file,
         top = (struct ext4_dir_entry_2 *) ((char *) de +
                                            dir->i_sb->s_blocksize -
                                            EXT4_DIR_REC_LEN(0));
+#ifdef CONFIG_EXT4_FS_ENCRYPTION
+        /* Check if the directory is encrypted */
+        ctx = ext4_get_fname_crypto_ctx(dir, EXT4_NAME_LEN);
+        if (IS_ERR(ctx)) {
+                err = PTR_ERR(ctx);
+                brelse(bh);
+                return err;
+        }
+        if (ctx != NULL) {
+                err = ext4_fname_crypto_alloc_buffer(ctx, EXT4_NAME_LEN,
+                                                     &fname_crypto_str);
+                if (err < 0) {
+                        ext4_put_fname_crypto_ctx(&ctx);
+                        brelse(bh);
+                        return err;
+                }
+        }
+#endif
         for (; de < top; de = ext4_next_entry(de, dir->i_sb->s_blocksize)) {
                 if (ext4_check_dir_entry(dir, NULL, de, bh,
                                 bh->b_data, bh->b_size,
@@ -988,24 +1008,52 @@ static int htree_dirblock_to_tree(struct file *dir_file,
                         /* silently ignore the rest of the block */
                         break;
                 }
+#ifdef CONFIG_EXT4_FS_ENCRYPTION
+                err = ext4_fname_disk_to_hash(ctx, de, hinfo);
+                if (err < 0) {
+                        count = err;
+                        goto errout;
+                }
+#else
                 ext4fs_dirhash(de->name, de->name_len, hinfo);
+#endif
                 if ((hinfo->hash < start_hash) ||
                     ((hinfo->hash == start_hash) &&
                      (hinfo->minor_hash < start_minor_hash)))
                         continue;
                 if (de->inode == 0)
                         continue;
-                tmp_str.name = de->name;
-                tmp_str.len = de->name_len;
-                err = ext4_htree_store_dirent(dir_file,
-                           hinfo->hash, hinfo->minor_hash, de, &tmp_str);
+                if (ctx == NULL) {
+                        /* Directory is not encrypted */
+                        tmp_str.name = de->name;
+                        tmp_str.len = de->name_len;
+                        err = ext4_htree_store_dirent(dir_file,
+                                   hinfo->hash, hinfo->minor_hash, de,
+                                   &tmp_str);
+                } else {
+                        /* Directory is encrypted */
+                        err = ext4_fname_disk_to_usr(ctx, de,
+                                                     &fname_crypto_str);
+                        if (err < 0) {
+                                count = err;
+                                goto errout;
+                        }
+                        err = ext4_htree_store_dirent(dir_file,
+                                   hinfo->hash, hinfo->minor_hash, de,
+                                        &fname_crypto_str);
+                }
                 if (err != 0) {
-                        brelse(bh);
-                        return err;
+                        count = err;
+                        goto errout;
                 }
                 count++;
         }
+errout:
         brelse(bh);
+#ifdef CONFIG_EXT4_FS_ENCRYPTION
+        ext4_put_fname_crypto_ctx(&ctx);
+        ext4_fname_crypto_free_buffer(&fname_crypto_str);
+#endif
         return count;
 }
 
@@ -1138,17 +1186,33 @@ static inline int search_dirblock(struct buffer_head *bh,
  * Create map of hash values, offsets, and sizes, stored at end of block.
  * Returns number of entries mapped.
  */
-static int dx_make_map(struct ext4_dir_entry_2 *de, unsigned blocksize,
-                       struct dx_hash_info *hinfo,
+static int dx_make_map(struct inode *dir, struct ext4_dir_entry_2 *de,
+                       unsigned blocksize, struct dx_hash_info *hinfo,
                        struct dx_map_entry *map_tail)
 {
         int count = 0;
         char *base = (char *) de;
         struct dx_hash_info h = *hinfo;
+#ifdef CONFIG_EXT4_FS_ENCRYPTION
+        struct ext4_fname_crypto_ctx *ctx = NULL;
+        int err;
+
+        ctx = ext4_get_fname_crypto_ctx(dir, EXT4_NAME_LEN);
+        if (IS_ERR(ctx))
+                return PTR_ERR(ctx);
+#endif
 
         while ((char *) de < base + blocksize) {
                 if (de->name_len && de->inode) {
+#ifdef CONFIG_EXT4_FS_ENCRYPTION
+                        err = ext4_fname_disk_to_hash(ctx, de, &h);
+                        if (err < 0) {
+                                ext4_put_fname_crypto_ctx(&ctx);
+                                return err;
+                        }
+#else
                         ext4fs_dirhash(de->name, de->name_len, &h);
+#endif
                         map_tail--;
                         map_tail->hash = h.hash;
                         map_tail->offs = ((char *) de - base)>>2;
@@ -1159,6 +1223,9 @@ static int dx_make_map(struct ext4_dir_entry_2 *de, unsigned blocksize,
                 /* XXX: do we need to check rec_len == 0 case? -Chris */
                 de = ext4_next_entry(de, blocksize);
         }
+#ifdef CONFIG_EXT4_FS_ENCRYPTION
+        ext4_put_fname_crypto_ctx(&ctx);
+#endif
         return count;
 }
 
@@ -1209,57 +1276,107 @@ static void dx_insert_block(struct dx_frame *frame, u32 hash, ext4_lblk_t block)
  * `len <= EXT4_NAME_LEN' is guaranteed by caller.
  * `de != NULL' is guaranteed by caller.
  */
-static inline int ext4_match (int len, const char * const name,
-                              struct ext4_dir_entry_2 * de)
+static inline int ext4_match(struct ext4_fname_crypto_ctx *ctx,
+                             struct ext4_str *fname_crypto_str,
+                             int len, const char * const name,
+                             struct ext4_dir_entry_2 *de)
 {
-        if (len != de->name_len)
-                return 0;
+        int res;
+
         if (!de->inode)
                 return 0;
-        return !memcmp(name, de->name, len);
+
+#ifdef CONFIG_EXT4_FS_ENCRYPTION
+        if (ctx) {
+                /* Directory is encrypted */
+                res = ext4_fname_disk_to_usr(ctx, de, fname_crypto_str);
+                if (res < 0)
+                        return res;
+                if (len != res)
+                        return 0;
+                res = memcmp(name, fname_crypto_str->name, len);
+                return (res == 0) ? 1 : 0;
+        }
+#endif
+        if (len != de->name_len)
+                return 0;
+        res = memcmp(name, de->name, len);
+        return (res == 0) ? 1 : 0;
 }
 
 /*
  * Returns 0 if not found, -1 on failure, and 1 on success
  */
-int search_dir(struct buffer_head *bh,
-               char *search_buf,
-               int buf_size,
-               struct inode *dir,
-               const struct qstr *d_name,
-               unsigned int offset,
-               struct ext4_dir_entry_2 **res_dir)
+int search_dir(struct buffer_head *bh, char *search_buf, int buf_size,
+               struct inode *dir, const struct qstr *d_name,
+               unsigned int offset, struct ext4_dir_entry_2 **res_dir)
 {
         struct ext4_dir_entry_2 * de;
         char * dlimit;
         int de_len;
         const char *name = d_name->name;
         int namelen = d_name->len;
+        struct ext4_fname_crypto_ctx *ctx = NULL;
+        struct ext4_str fname_crypto_str = {.name = NULL, .len = 0};
+        int res;
+
+        ctx = ext4_get_fname_crypto_ctx(dir, EXT4_NAME_LEN);
+        if (IS_ERR(ctx))
+                return -1;
+
+        if (ctx != NULL) {
+                /* Allocate buffer to hold maximum name length */
+                res = ext4_fname_crypto_alloc_buffer(ctx, EXT4_NAME_LEN,
+                                                     &fname_crypto_str);
+                if (res < 0) {
+                        ext4_put_fname_crypto_ctx(&ctx);
+                        return -1;
+                }
+        }
 
         de = (struct ext4_dir_entry_2 *)search_buf;
         dlimit = search_buf + buf_size;
         while ((char *) de < dlimit) {
                 /* this code is executed quadratically often */
                 /* do minimal checking `by hand' */
+                if ((char *) de + de->name_len <= dlimit) {
+                        res = ext4_match(ctx, &fname_crypto_str, namelen,
+                                         name, de);
+                        if (res < 0) {
+                                res = -1;
+                                goto return_result;
+                        }
+                        if (res > 0) {
+                                /* found a match - just to be sure, do
+                                 * a full check */
+                                if (ext4_check_dir_entry(dir, NULL, de, bh,
+                                                bh->b_data,
+                                                 bh->b_size, offset)) {
+                                        res = -1;
+                                        goto return_result;
+                                }
+                                *res_dir = de;
+                                res = 1;
+                                goto return_result;
+                        }
 
-                if ((char *) de + namelen <= dlimit &&
-                    ext4_match (namelen, name, de)) {
-                        /* found a match - just to be sure, do a full check */
-                        if (ext4_check_dir_entry(dir, NULL, de, bh, bh->b_data,
-                                                 bh->b_size, offset))
-                                return -1;
-                        *res_dir = de;
-                        return 1;
                 }
                 /* prevent looping on a bad block */
                 de_len = ext4_rec_len_from_disk(de->rec_len,
                                                 dir->i_sb->s_blocksize);
-                if (de_len <= 0)
-                        return -1;
+                if (de_len <= 0) {
+                        res = -1;
+                        goto return_result;
+                }
                 offset += de_len;
                 de = (struct ext4_dir_entry_2 *) ((char *) de + de_len);
         }
-        return 0;
+
+        res = 0;
+return_result:
+        ext4_put_fname_crypto_ctx(&ctx);
+        ext4_fname_crypto_free_buffer(&fname_crypto_str);
+        return res;
 }
 
 static int is_dx_internal_node(struct inode *dir, ext4_lblk_t block,
@@ -1448,6 +1565,9 @@ static struct buffer_head * ext4_dx_find_entry(struct inode *dir, const struct q
         ext4_lblk_t block;
         int retval;
 
+#ifdef CONFIG_EXT4_FS_ENCRYPTION
+        *res_dir = NULL;
+#endif
         frame = dx_probe(d_name, dir, &hinfo, frames);
         if (IS_ERR(frame))
                 return (struct buffer_head *) frame;
@@ -1656,7 +1776,7 @@ static struct ext4_dir_entry_2 *do_split(handle_t *handle, struct inode *dir,
 
         /* create map in the end of data2 block */
         map = (struct dx_map_entry *) (data2 + blocksize);
-        count = dx_make_map((struct ext4_dir_entry_2 *) data1,
+        count = dx_make_map(dir, (struct ext4_dir_entry_2 *) data1,
                              blocksize, hinfo, map);
         map -= count;
         dx_sort_map(map, count);
@@ -1679,7 +1799,8 @@ static struct ext4_dir_entry_2 *do_split(handle_t *handle, struct inode *dir,
                                         hash2, split, count-split));
 
         /* Fancy dance to stay within two buffers */
-        de2 = dx_move_dirents(data1, data2, map + split, count - split, blocksize);
+        de2 = dx_move_dirents(data1, data2, map + split, count - split,
+                              blocksize);
         de = dx_pack_dirents(data1, blocksize);
         de->rec_len = ext4_rec_len_to_disk(data1 + (blocksize - csum_size) -
                                            (char *) de,
@@ -1735,15 +1856,48 @@ int ext4_find_dest_de(struct inode *dir, struct inode *inode,
         int nlen, rlen;
         unsigned int offset = 0;
         char *top;
+        struct ext4_fname_crypto_ctx *ctx = NULL;
+        struct ext4_str fname_crypto_str = {.name = NULL, .len = 0};
+        int res;
+
+        ctx = ext4_get_fname_crypto_ctx(dir, EXT4_NAME_LEN);
+        if (IS_ERR(ctx))
+                return -1;
+
+        if (ctx != NULL) {
+                /* Calculate record length needed to store the entry */
+                res = ext4_fname_crypto_namelen_on_disk(ctx, namelen);
+                if (res < 0) {
+                        ext4_put_fname_crypto_ctx(&ctx);
+                        return res;
+                }
+                reclen = EXT4_DIR_REC_LEN(res);
+
+                /* Allocate buffer to hold maximum name length */
+                res = ext4_fname_crypto_alloc_buffer(ctx, EXT4_NAME_LEN,
+                                                     &fname_crypto_str);
+                if (res < 0) {
+                        ext4_put_fname_crypto_ctx(&ctx);
+                        return -1;
+                }
+        }
 
         de = (struct ext4_dir_entry_2 *)buf;
         top = buf + buf_size - reclen;
         while ((char *) de <= top) {
                 if (ext4_check_dir_entry(dir, NULL, de, bh,
-                                         buf, buf_size, offset))
-                        return -EIO;
-                if (ext4_match(namelen, name, de))
-                        return -EEXIST;
+                                         buf, buf_size, offset)) {
+                        res = -EIO;
+                        goto return_result;
+                }
+                /* Provide crypto context and crypto buffer to ext4 match */
+                res = ext4_match(ctx, &fname_crypto_str, namelen, name, de);
+                if (res < 0)
+                        goto return_result;
+                if (res > 0) {
+                        res = -EEXIST;
+                        goto return_result;
+                }
                 nlen = EXT4_DIR_REC_LEN(de->name_len);
                 rlen = ext4_rec_len_from_disk(de->rec_len, buf_size);
                 if ((de->inode ? rlen - nlen : rlen) >= reclen)
@@ -1751,11 +1905,17 @@ int ext4_find_dest_de(struct inode *dir, struct inode *inode,
                 de = (struct ext4_dir_entry_2 *)((char *)de + rlen);
                 offset += rlen;
         }
-        if ((char *) de > top)
-                return -ENOSPC;
 
-        *dest_de = de;
-        return 0;
+        if ((char *) de > top)
+                res = -ENOSPC;
+        else {
+                *dest_de = de;
+                res = 0;
+        }
+return_result:
+        ext4_put_fname_crypto_ctx(&ctx);
+        ext4_fname_crypto_free_buffer(&fname_crypto_str);
+        return res;
 }
 
 int ext4_insert_dentry(struct inode *dir,