Re: [PATCH] hw/9pfs: Follow native symlinks when security-model=mapped

[Andrey Erokhin <language.lawyer@gmail.com>]

[-- Attachment #1: Type: text/plain, Size: 2030 bytes --]

On 21/11/2025 17:20, Christian Schoenebeck wrote:
> Andrey, just some minor issues from my side below:
> 
> Git commit log message should not exceed 76 characters per line.

TBH, I'm not used to sending patches by git, it was just an e-mail message, not a commit message
>> QEMU issues:
>> https://gitlab.com/qemu-project/qemu/-/issues/173 (from
>> https://bugs.launchpad.net/qemu/+bug/1831354)
>> https://gitlab.com/qemu-project/qemu/-/issues/3088 (dup of the first one)
> 
> This should be:
> 
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/173

Fixed in the attached patch. Or should I start a new [PATCH v2] thread?

> The other links can be dropped. They are already linked by #173.
> 
>> Signed-off-by: Andrey Erokhin <language.lawyer@gmail.com>
>>
>>
>> diff --git a/hw/9pfs/9p-local.c b/hw/9pfs/9p-local.c
>> index 31e216227c..b4f8be2c81 100644
>> --- a/hw/9pfs/9p-local.c
>> +++ b/hw/9pfs/9p-local.c
>> @@ -468,12 +468,14 @@ static ssize_t local_readlink(FsContext *fs_ctx,
>> V9fsPath *fs_path,
>>
>>            fd = local_open_nofollow(fs_ctx, fs_path->data, O_RDONLY, 0);
>>            if (fd == -1) {
>> +            if (errno == ELOOP) goto native_symlink;
>>                return -1;
>>            }
> 
> scripts/checkpatch.pl complaints:
> 
> ERROR: trailing statements should be on next line
> #33: FILE: hw/9pfs/9p-local.c:471:
> +            if (errno == ELOOP) goto native_symlink;
> 
> ERROR: braces {} are necessary for all arms of this statement
> #33: FILE: hw/9pfs/9p-local.c:471:
> +            if (errno == ELOOP) goto native_symlink;
> [...]

Fixed

>>            tsize = RETRY_ON_EINTR(read(fd, (void *)buf, bufsz));
>>            close_preserve_errno(fd);
>>        } else if ((fs_ctx->export_flags & V9FS_SM_PASSTHROUGH) ||
>>                   (fs_ctx->export_flags & V9FS_SM_NONE)) {
>> +native_symlink:;
> 
> Semicolon is unnecessary here, isn't it?
https://port70.net/~nsz/c/c11/n1570.html#6.8.1 Labeled statements:

labeled-statement:
	identifier : statement

Can't be a declaration

[-- Attachment #2: 0001-hw-9pfs-follow-native-symlinks-in-security-model-map.patch --]
[-- Type: text/x-patch, Size: 1085 bytes --]

hw/9pfs: follow native symlinks in security-model=mapped

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/173

Signed-off-by: Andrey Erokhin <language.lawyer@gmail.com>
---
 hw/9pfs/9p-local.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/hw/9pfs/9p-local.c b/hw/9pfs/9p-local.c
index 31e216227c..5ce97b76a6 100644
--- a/hw/9pfs/9p-local.c
+++ b/hw/9pfs/9p-local.c
@@ -468,12 +468,16 @@ static ssize_t local_readlink(FsContext *fs_ctx, V9fsPath *fs_path,
 
         fd = local_open_nofollow(fs_ctx, fs_path->data, O_RDONLY, 0);
         if (fd == -1) {
+            if (errno == ELOOP) {
+                goto native_symlink;
+            }
             return -1;
         }
         tsize = RETRY_ON_EINTR(read(fd, (void *)buf, bufsz));
         close_preserve_errno(fd);
     } else if ((fs_ctx->export_flags & V9FS_SM_PASSTHROUGH) ||
                (fs_ctx->export_flags & V9FS_SM_NONE)) {
+    native_symlink:;
         char *dirpath = g_path_get_dirname(fs_path->data);
         char *name = g_path_get_basename(fs_path->data);
         int dirfd;
-- 
2.34.1