linux-kernel - Re: [PATCH] hfsplus: Fix bug causing custom uid and gid being unable to be assigned with mount

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Message-ID: <CD80923F-4422-416B-AAC1-A676D37C564F@live.com>
Date:   Tue, 6 Dec 2022 08:49:34 +0000
From:   Aditya Garg <gargaditya08@...e.com>
To:     Viacheslav Dubeyko <slava@...eyko.com>
CC:     "willy@...radead.org" <willy@...radead.org>,
        "ira.weiny@...el.com" <ira.weiny@...el.com>,
        "axboe@...nel.dk" <axboe@...nel.dk>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "bvanassche@....org" <bvanassche@....org>,
        "keescook@...omium.org" <keescook@...omium.org>,
        "songmuchun@...edance.com" <songmuchun@...edance.com>,
        "torvalds@...ux-foundation.org" <torvalds@...ux-foundation.org>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] hfsplus: Fix bug causing custom uid and gid being unable
 to be assigned with mount


> Well initially I when I tried to investigate what’s wrong, and found that the old logic was the culprit, I did some logging to see what exactly was wrong. The log patch is here btw :- https://github.com/AdityaGarg8/linux/commit/f668fb012f595d83053020b88b9439c295b4dc21
> 
> So I saw that the old logic was always false, no matter whether I mounted with uid or not.
> 
> I tried to see what makes this true, but couldn't succeed. So, I thought of a simpler approach and changed the logic itself.
> 
> To be honest, I dunno what is the old logic for. Maybe instead of completely removing the old logic, I could use an OR?
> 
> If you think its more logical, I can make this change :-
> 
> -	if (!i_gid_read(inode) && !mode)
> +	if ((test_bit(HFSPLUS_SB_UID, &sbi->flags)) || (!i_uid_read(inode) && !mode))
> 
> Thanks
> Aditya
> 
> 

I continuation with this message, I also think the bits should be set only if (!uid_valid(sbi->uid) is false, else the bits may be set even if UID is invalid? So, do you think the change given below should be good for this?

diff --git a/fs/hfsplus/options.c b/fs/hfsplus/options.c
index 047e05c57..c94a58762 100644
--- a/fs/hfsplus/options.c
+++ b/fs/hfsplus/options.c
@@ -140,6 +140,8 @@ int hfsplus_parse_options(char *input, struct hfsplus_sb_info *sbi)
 			if (!uid_valid(sbi->uid)) {
 				pr_err("invalid uid specified\n");
 				return 0;
+			} else {
+				set_bit(HFSPLUS_SB_UID, &sbi->flags);
 			}
 			break;
 		case opt_gid:
@@ -151,6 +153,8 @@ int hfsplus_parse_options(char *input, struct hfsplus_sb_info *sbi)
 			if (!gid_valid(sbi->gid)) {
 				pr_err("invalid gid specified\n");
 				return 0;
+			} else {
+				set_bit(HFSPLUS_SB_GID, &sbi->flags);
 			}
 			break;
 		case opt_part: