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NFSv4: Fix OPEN w/create access mode checking

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POSIX states that open("foo", O_CREAT|O_RDONLY, 000) should succeed if
the file "foo" does not already exist. With the current NFS client,
it will fail with an EACCES error because of the permissions checks in
nfs4_opendata_access().

Fix is to turn that test off if the server says that we created the file.

Reported-by: "Frank S. Filz" <ffilzlnx@mindspring.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
This commit is contained in:
Trond Myklebust 2014-07-10 08:54:32 -04:00
parent 31434f496a
commit f3792d63d2
1 changed files with 13 additions and 5 deletions
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18
fs/nfs/nfs4proc.c
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@ -1952,6 +1952,14 @@ static int _nfs4_recover_proc_open(struct nfs4_opendata *data)
return status;
}
/*
* Additional permission checks in order to distinguish between an
* open for read, and an open for execute. This works around the
* fact that NFSv4 OPEN treats read and execute permissions as being
* the same.
* Note that in the non-execute case, we want to turn off permission
* checking if we just created a new file (POSIX open() semantics).
*/
static int nfs4_opendata_access(struct rpc_cred *cred,
struct nfs4_opendata *opendata,
struct nfs4_state *state, fmode_t fmode,
@ -1966,14 +1974,14 @@ static int nfs4_opendata_access(struct rpc_cred *cred,
return 0;
mask = 0;
/* don't check MAY_WRITE - a newly created file may not have
* write mode bits, but POSIX allows the creating process to write.
* use openflags to check for exec, because fmode won't
* always have FMODE_EXEC set when file open for exec. */
/*
* Use openflags to check for exec, because fmode won't
* always have FMODE_EXEC set when file open for exec.
*/
if (openflags & __FMODE_EXEC) {
/* ONLY check for exec rights */
mask = MAY_EXEC;
} else if (fmode & FMODE_READ)
} else if ((fmode & FMODE_READ) && !opendata->file_created)
mask = MAY_READ;
cache.cred = cred;