Date: Mon, 24 Jul 2006 13:21:55 +0800 From: "Xin LI" <delphij@gmail.com> To: "=?ISO-2022-JP?B?GyRCTXs+MFs/GyhC?=" <shangjie.li@gmail.com> Cc: freebsd-hackers@freebsd.org, rwatson@freebsd.org Subject: Re: A question about ipcperm() call? Message-ID: <a78074950607232221q7c3f3028xbb22d85dfd677c49@mail.gmail.com> In-Reply-To: <de71d27b0607231907o6a7567bdy81e1a6d613b88c82@mail.gmail.com> References: <de71d27b0607231907o6a7567bdy81e1a6d613b88c82@mail.gmail.com>
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On 7/24/06, $BM{>0[?(B <shangjie.li@gmail.com> wrote:
> The code for ipcperm() call :
> 78 ipcperm(td, perm, mode)
> 79 struct thread *td;
> 80 struct ipc_perm *perm;
> 81 int mode;
> 82 {
> 83 struct ucred *cred = td->td_ucred;
> 84 int error;
> 85
> 86 if (cred->cr_uid != perm->cuid && cred->cr_uid != perm->uid) {
> 87 /*
> 88 * For a non-create/owner, we require privilege to
> 89 * modify the object protections. Note: some other
> 90 * implementations permit IPC_M to be delegated to
> 91 * unprivileged non-creator/owner uids/gids.
> 92 */
> 93 if (mode & IPC_M) {
> 94 error = suser(td);
> 95 if (error)
> 96 return (error);
> 97 }
> 98 /*
> 99 * Try to match against creator/owner group; if not, fall
> 100 * back on other.
> 101 */
> 102 mode >>= 3;
> 103 if (!groupmember(perm->gid, cred) &&
> 104 !groupmember(perm->cgid, cred))
> 105 mode >>= 3;
> 106 } else {
> 107 /*
> 108 * Always permit the creator/owner to update the object
> 109 * protections regardless of whether the object mode
> 110 * permits it.
> 111 */
> 112 if (mode & IPC_M)
> 113 return (0);
> 114 }
> 115
> 116 if ((mode & perm->mode) != mode) {
> 117 if (suser(td) != 0)
> 118 return (EACCES);
> 119 }
> 120 return (0);
> 121 }
>
> why not directly return the error in line 94?
I think it makes sense to remove the assignment and the 'error'
variable. Let's see Robert's opinion.
Cheers,
--
Xin LI <delphij@delphij.net> http://www.delphij.net
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