erofs: handle long xattr name prefixes properly

Make .{list,get}xattr routines adapted to long xattr name prefixes.
When the bit 7 of erofs_xattr_entry.e_name_index is set, it indicates
that it refers to a long xattr name prefix.

Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Acked-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20230411093537.127286-1-jefflexu@linux.alibaba.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

diff --git a/fs/erofs/xattr.c b/fs/erofs/xattr.c
index 684571e..a04724c 100644 (file)
--- a/fs/erofs/xattr.c
+++ b/fs/erofs/xattr.c
@@ -297,17 +297,45 @@ struct getxattr_iter {
        struct xattr_iter it;
 
        char *buffer;
-       int buffer_size, index;
+       int buffer_size, index, infix_len;
        struct qstr name;
 };
 
+static int erofs_xattr_long_entrymatch(struct getxattr_iter *it,
+                                      struct erofs_xattr_entry *entry)
+{
+       struct erofs_sb_info *sbi = EROFS_SB(it->it.sb);
+       struct erofs_xattr_prefix_item *pf = sbi->xattr_prefixes +
+               (entry->e_name_index & EROFS_XATTR_LONG_PREFIX_MASK);
+
+       if (pf >= sbi->xattr_prefixes + sbi->xattr_prefix_count)
+               return -ENOATTR;
+
+       if (it->index != pf->prefix->base_index ||
+           it->name.len != entry->e_name_len + pf->infix_len)
+               return -ENOATTR;
+
+       if (memcmp(it->name.name, pf->prefix->infix, pf->infix_len))
+               return -ENOATTR;
+
+       it->infix_len = pf->infix_len;
+       return 0;
+}
+
 static int xattr_entrymatch(struct xattr_iter *_it,
                            struct erofs_xattr_entry *entry)
 {
        struct getxattr_iter *it = container_of(_it, struct getxattr_iter, it);
 
-       return (it->index != entry->e_name_index ||
-               it->name.len != entry->e_name_len) ? -ENOATTR : 0;
+       /* should also match the infix for long name prefixes */
+       if (entry->e_name_index & EROFS_XATTR_LONG_PREFIX)
+               return erofs_xattr_long_entrymatch(it, entry);
+
+       if (it->index != entry->e_name_index ||
+           it->name.len != entry->e_name_len)
+               return -ENOATTR;
+       it->infix_len = 0;
+       return 0;
 }
 
 static int xattr_namematch(struct xattr_iter *_it,
@@ -315,7 +343,9 @@ static int xattr_namematch(struct xattr_iter *_it,
 {
        struct getxattr_iter *it = container_of(_it, struct getxattr_iter, it);
 
-       return memcmp(buf, it->name.name + processed, len) ? -ENOATTR : 0;
+       if (memcmp(buf, it->name.name + it->infix_len + processed, len))
+               return -ENOATTR;
+       return 0;
 }
 
 static int xattr_checkbuffer(struct xattr_iter *_it,
@@ -487,12 +517,24 @@ static int xattr_entrylist(struct xattr_iter *_it,
 {
        struct listxattr_iter *it =
                container_of(_it, struct listxattr_iter, it);
-       unsigned int prefix_len;
-       const char *prefix;
-
-       const struct xattr_handler *h =
-               erofs_xattr_handler(entry->e_name_index);
+       unsigned int base_index = entry->e_name_index;
+       unsigned int prefix_len, infix_len = 0;
+       const char *prefix, *infix = NULL;
+       const struct xattr_handler *h;
+
+       if (entry->e_name_index & EROFS_XATTR_LONG_PREFIX) {
+               struct erofs_sb_info *sbi = EROFS_SB(_it->sb);
+               struct erofs_xattr_prefix_item *pf = sbi->xattr_prefixes +
+                       (entry->e_name_index & EROFS_XATTR_LONG_PREFIX_MASK);
+
+               if (pf >= sbi->xattr_prefixes + sbi->xattr_prefix_count)
+                       return 1;
+               infix = pf->prefix->infix;
+               infix_len = pf->infix_len;
+               base_index = pf->prefix->base_index;
+       }
 
+       h = erofs_xattr_handler(base_index);
        if (!h || (h->list && !h->list(it->dentry)))
                return 1;
 
@@ -500,16 +542,18 @@ static int xattr_entrylist(struct xattr_iter *_it,
        prefix_len = strlen(prefix);
 
        if (!it->buffer) {
-               it->buffer_ofs += prefix_len + entry->e_name_len + 1;
+               it->buffer_ofs += prefix_len + infix_len +
+                                       entry->e_name_len + 1;
                return 1;
        }
 
-       if (it->buffer_ofs + prefix_len
+       if (it->buffer_ofs + prefix_len + infix_len +
                + entry->e_name_len + 1 > it->buffer_size)
                return -ERANGE;
 
        memcpy(it->buffer + it->buffer_ofs, prefix, prefix_len);
-       it->buffer_ofs += prefix_len;
+       memcpy(it->buffer + it->buffer_ofs + prefix_len, infix, infix_len);
+       it->buffer_ofs += prefix_len + infix_len;
        return 0;
 }