Messages in this thread | | | Date | Tue, 11 Apr 2023 17:40:15 +0800 | Subject | Re: [PATCH v3 6/7] erofs: handle long xattr name prefixes properly | From | Gao Xiang <> |
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On 2023/4/11 17:35, Jingbo Xu wrote: > 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> > --- > v3: introduce infix_len to struct getxattr_iter, and refactor the > implementation of xattr_entrymatch(), erofs_xattr_long_entrymatch(), and > xattr_namematch() accordingly. > > The erofs_xattr_long_entrymatch() of v2 version will advance > it->name.name pointer by pf->infix_len prematurely, as the following > xattr_namematch() may fail (-ENOATTR) since mismatching. And then > it->name.name will be compared with the next xattr entry, while > it->name.name has been mistakenly modified in the previous round. This > will cause -ENOATTR error on the existing xattr.
Yes, please also help add a new erofs-utils testcase for this.
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Thanks, Gao Xiang
> > --- > fs/erofs/xattr.c | 68 +++++++++++++++++++++++++++++++++++++++--------- > 1 file changed, 56 insertions(+), 12 deletions(-) > > diff --git a/fs/erofs/xattr.c b/fs/erofs/xattr.c > index 684571e83a2c..a04724c816e5 100644 > --- 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; > } >
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