Messages in this thread |  | | | Subject | open("foo", 3) | | From | Miklos Szeredi <> | | Date | Sat, 20 Aug 2005 18:28:38 +0200 |
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Linus et Al,
Access mode of 3 is undocumented but it does do something halfway sane on all linuxes (checked back to 2.0.X).
The open requires both read and write permission to succeed, but the resulting file descriptor can neither be read nor written.
The responsible code in filp_open() is this:
namei_flags = flags; if ((namei_flags+1) & O_ACCMODE) namei_flags++; /* ... */ error = open_namei(filename, namei_flags, mode, &nd); if (!error) return dentry_open(nd.dentry, nd.mnt, flags); And in dentry_open():
f->f_mode = ((flags+1) & O_ACCMODE) | /* ... */ Note, that open_namei() is checking permissions, and dentry_open() sets f->f_mode, but calculates it differently.
My question is: is this deliberate or accidental? Wouldn't it be more logical to not require any permission to open such file? Or is there some security concern with that?
Thanks, Miklos - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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