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From: "Eric W. Biederman" <ebiederm@xmission.com>
To: linux-kernel@vger.kernel.org
Cc: David Miller <davem@davemloft.net>,
	Greg Kroah-Hartman <greg@kroah.com>,
	Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
	Alexei Starovoitov <alexei.starovoitov@gmail.com>,
	Kees Cook <keescook@chromium.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Alexei Starovoitov <ast@kernel.org>,
	Al Viro <viro@zeniv.linux.org.uk>, bpf <bpf@vger.kernel.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Jakub Kicinski <kuba@kernel.org>,
	Masahiro Yamada <yamada.masahiro@socionext.com>,
	Gary Lin <GLin@suse.com>, Bruno Meneguele <bmeneg@redhat.com>,
	LSM List <linux-security-module@vger.kernel.org>,
	Casey Schaufler <casey@schaufler-ca.com>,
	Luis Chamberlain <mcgrof@kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Christian Brauner <christian.brauner@ubuntu.com>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: [PATCH v3 10/16] exec: Remove do_execve_file
Date: Thu,  2 Jul 2020 11:41:34 -0500
Message-ID: <20200702164140.4468-10-ebiederm@xmission.com> (raw)
In-Reply-To: <87y2o1swee.fsf_-_@x220.int.ebiederm.org>

Now that the last callser has been removed remove this code from exec.

For anyone thinking of resurrecing do_execve_file please note that
the code was buggy in several fundamental ways.

- It did not ensure the file it was passed was read-only and that
  deny_write_access had been called on it.  Which subtlely breaks
  invaniants in exec.

- The caller of do_execve_file was expected to hold and put a
  reference to the file, but an extra reference for use by exec was
  not taken so that when exec put it's reference to the file an
  underflow occured on the file reference count.

- The point of the interface was so that a pathname did not need to
  exist.  Which breaks pathname based LSMs.

Tetsuo Handa originally reported these issues[1].  While it was clear
that deny_write_access was missing the fundamental incompatibility
with the passed in O_RDWR filehandle was not immediately recognized.

All of these issues were fixed by modifying the usermode driver code
to have a path, so it did not need this hack.

Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
[1] https://lore.kernel.org/linux-fsdevel/2a8775b4-1dd5-9d5c-aa42-9872445e0942@i-love.sakura.ne.jp/
v1: https://lkml.kernel.org/r/871rm2f0hi.fsf_-_@x220.int.ebiederm.org
v2: https://lkml.kernel.org/r/87lfk54p0m.fsf_-_@x220.int.ebiederm.org
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 fs/exec.c               | 38 +++++++++-----------------------------
 include/linux/binfmts.h |  1 -
 2 files changed, 9 insertions(+), 30 deletions(-)

diff --git a/fs/exec.c b/fs/exec.c
index e6e8a9a70327..23dfbb820626 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1818,13 +1818,14 @@ static int exec_binprm(struct linux_binprm *bprm)
 /*
  * sys_execve() executes a new program.
  */
-static int __do_execve_file(int fd, struct filename *filename,
-			    struct user_arg_ptr argv,
-			    struct user_arg_ptr envp,
-			    int flags, struct file *file)
+static int do_execveat_common(int fd, struct filename *filename,
+			      struct user_arg_ptr argv,
+			      struct user_arg_ptr envp,
+			      int flags)
 {
 	char *pathbuf = NULL;
 	struct linux_binprm *bprm;
+	struct file *file;
 	struct files_struct *displaced;
 	int retval;
 
@@ -1863,8 +1864,7 @@ static int __do_execve_file(int fd, struct filename *filename,
 	check_unsafe_exec(bprm);
 	current->in_execve = 1;
 
-	if (!file)
-		file = do_open_execat(fd, filename, flags);
+	file = do_open_execat(fd, filename, flags);
 	retval = PTR_ERR(file);
 	if (IS_ERR(file))
 		goto out_unmark;
@@ -1872,9 +1872,7 @@ static int __do_execve_file(int fd, struct filename *filename,
 	sched_exec();
 
 	bprm->file = file;
-	if (!filename) {
-		bprm->filename = "none";
-	} else if (fd == AT_FDCWD || filename->name[0] == '/') {
+	if (fd == AT_FDCWD || filename->name[0] == '/') {
 		bprm->filename = filename->name;
 	} else {
 		if (filename->name[0] == '\0')
@@ -1935,8 +1933,7 @@ static int __do_execve_file(int fd, struct filename *filename,
 	task_numa_free(current, false);
 	free_bprm(bprm);
 	kfree(pathbuf);
-	if (filename)
-		putname(filename);
+	putname(filename);
 	if (displaced)
 		put_files_struct(displaced);
 	return retval;
@@ -1967,27 +1964,10 @@ static int __do_execve_file(int fd, struct filename *filename,
 	if (displaced)
 		reset_files_struct(displaced);
 out_ret:
-	if (filename)
-		putname(filename);
+	putname(filename);
 	return retval;
 }
 
-static int do_execveat_common(int fd, struct filename *filename,
-			      struct user_arg_ptr argv,
-			      struct user_arg_ptr envp,
-			      int flags)
-{
-	return __do_execve_file(fd, filename, argv, envp, flags, NULL);
-}
-
-int do_execve_file(struct file *file, void *__argv, void *__envp)
-{
-	struct user_arg_ptr argv = { .ptr.native = __argv };
-	struct user_arg_ptr envp = { .ptr.native = __envp };
-
-	return __do_execve_file(AT_FDCWD, NULL, argv, envp, 0, file);
-}
-
 int do_execve(struct filename *filename,
 	const char __user *const __user *__argv,
 	const char __user *const __user *__envp)
diff --git a/include/linux/binfmts.h b/include/linux/binfmts.h
index 4a20b7517dd0..7c27d7b57871 100644
--- a/include/linux/binfmts.h
+++ b/include/linux/binfmts.h
@@ -141,6 +141,5 @@ extern int do_execveat(int, struct filename *,
 		       const char __user * const __user *,
 		       const char __user * const __user *,
 		       int);
-int do_execve_file(struct file *file, void *__argv, void *__envp);
 
 #endif /* _LINUX_BINFMTS_H */
-- 
2.25.0


  parent reply index

Thread overview: 136+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <87d066vd4y.fsf@x220.int.ebiederm.org>
     [not found] ` <20200611233134.5vofl53dj5wpwp5j@ast-mbp.dhcp.thefacebook.com>
     [not found]   ` <87bllngirv.fsf@x220.int.ebiederm.org>
     [not found]     ` <CAADnVQ+qNxFjTYBpYW9ZhStMh_oJBS5C_FsxSS=0Mzy=u54MSg@mail.gmail.com>
     [not found]       ` <CAADnVQLuGYX=LamARhrZcze1ej4ELj-y99fLzOCgz60XLPw_cQ@mail.gmail.com>
     [not found]         ` <87ftaxd7ky.fsf@x220.int.ebiederm.org>
     [not found]           ` <20200616015552.isi6j5x732okiky4@ast-mbp.dhcp.thefacebook.com>
     [not found]             ` <87h7v1pskt.fsf@x220.int.ebiederm.org>
     [not found]               ` <20200623183520.5e7fmlt3omwa2lof@ast-mbp.dhcp.thefacebook.com>
     [not found]                 ` <87h7v1mx4z.fsf@x220.int.ebiederm.org>
     [not found]                   ` <20200623194023.lzl34qt2wndhcehk@ast-mbp.dhcp.thefacebook.com>
     [not found]                     ` <b4a805e7-e009-dfdf-d011-be636ce5c4f5@i-love.sakura.ne.jp>
     [not found]                       ` <20200624040054.x5xzkuhiw67cywzl@ast-mbp.dhcp.thefacebook.com>
     [not found]                         ` <5254444e-465e-6dee-287b-bef58526b724@i-love.sakura.ne.jp>
     [not found]                           ` <20200624063940.ctzhf4nnh3cjyxqi@ast-mbp.dhcp.thefacebook.com>
2020-06-24  7:05                             ` [RFC][PATCH] net/bpfilter: Remove this broken and apparently unmantained Tetsuo Handa
2020-06-24 15:41                               ` Casey Schaufler
2020-06-24 17:54                                 ` Alexei Starovoitov
2020-06-24 19:48                                   ` Casey Schaufler
     [not found]                     ` <878sgck6g0.fsf@x220.int.ebiederm.org>
     [not found]                       ` <CAADnVQL8WrfV74v1ChvCKE=pQ_zo+A5EtEBB3CbD=P5ote8_MA@mail.gmail.com>
2020-06-24 23:14                         ` Tetsuo Handa
2020-06-25  1:35                           ` Alexei Starovoitov
2020-06-25  6:38                             ` Tetsuo Handa
2020-06-25  9:57                               ` Greg KH
2020-06-25 11:03                                 ` Tetsuo Handa
2020-06-25 12:07                                   ` Greg KH
2020-06-25 14:21                                     ` Tetsuo Handa
2020-06-25 19:34                                     ` David Miller
2020-06-26  1:36                                       ` Linus Torvalds
2020-06-26  1:51                                         ` Alexei Starovoitov
2020-06-26  4:58                                           ` Tetsuo Handa
2020-06-26  5:41                                             ` Alexei Starovoitov
2020-06-26  6:20                                               ` Tetsuo Handa
2020-06-26  6:39                                                 ` Alexei Starovoitov
2020-06-26 12:51                                         ` [PATCH 00/14] Make the user mode driver code a better citizen Eric W. Biederman
2020-06-26 12:53                                           ` [PATCH 01/14] umh: Capture the pid in umh_pipe_setup Eric W. Biederman
2020-06-26 12:53                                           ` [PATCH 02/14] umh: Move setting PF_UMH into umh_pipe_setup Eric W. Biederman
2020-06-26 12:54                                           ` [PATCH 03/14] umh: Rename the user mode driver helpers for clarity Eric W. Biederman
2020-06-26 12:54                                           ` [PATCH 04/14] umh: Remove call_usermodehelper_setup_file Eric W. Biederman
2020-06-26 12:55                                           ` [PATCH 05/14] umh: Separate the user mode driver and the user mode helper support Eric W. Biederman
2020-06-26 16:22                                             ` Tetsuo Handa
2020-06-26 16:45                                               ` Eric W. Biederman
2020-06-27  1:26                                                 ` Tetsuo Handa
2020-06-27  4:21                                                   ` Eric W. Biederman
2020-06-27  4:36                                                     ` Tetsuo Handa
2020-06-26 12:55                                           ` [PATCH 06/14] umd: For clarity rename umh_info umd_info Eric W. Biederman
2020-06-26 15:37                                             ` Kees Cook
2020-06-26 16:31                                               ` Eric W. Biederman
2020-06-26 12:56                                           ` [PATCH 07/14] umd: Rename umd_info.cmdline umd_info.driver_name Eric W. Biederman
2020-06-26 12:56                                           ` [PATCH 08/14] umd: Transform fork_usermode_blob into fork_usermode_driver Eric W. Biederman
2020-06-26 12:57                                           ` [PATCH 09/14] umh: Stop calling do_execve_file Eric W. Biederman
2020-06-26 12:57                                           ` [PATCH 10/14] exec: Remove do_execve_file Eric W. Biederman
2020-06-26 12:58                                           ` [PATCH 11/14] bpfilter: Move bpfilter_umh back into init data Eric W. Biederman
2020-06-26 12:58                                           ` [PATCH 12/14] umd: Track user space drivers with struct pid Eric W. Biederman
2020-06-26 12:59                                           ` [PATCH 13/14] bpfilter: Take advantage of the facilities of " Eric W. Biederman
2020-06-26 12:59                                           ` [PATCH 14/14] umd: Remove exit_umh Eric W. Biederman
2020-06-26 13:48                                           ` [PATCH 00/14] Make the user mode driver code a better citizen Eric W. Biederman
2020-06-29 19:55                                             ` [PATCH v2 00/15] " Eric W. Biederman
2020-06-29 19:56                                               ` [PATCH v2 01/15] umh: Capture the pid in umh_pipe_setup Eric W. Biederman
2020-06-29 19:57                                               ` [PATCH v2 02/15] umh: Move setting PF_UMH into umh_pipe_setup Eric W. Biederman
2020-06-29 19:57                                               ` [PATCH v2 03/15] umh: Rename the user mode driver helpers for clarity Eric W. Biederman
2020-06-29 19:59                                               ` [PATCH v2 04/15] umh: Remove call_usermodehelper_setup_file Eric W. Biederman
2020-06-29 20:00                                               ` [PATCH v2 05/15] umh: Separate the user mode driver and the user mode helper support Eric W. Biederman
2020-06-30 16:58                                                 ` Linus Torvalds
2020-07-01 17:18                                                   ` Eric W. Biederman
2020-07-01 17:42                                                     ` Alexei Starovoitov
2020-06-29 20:01                                               ` [PATCH v2 06/15] umd: For clarity rename umh_info umd_info Eric W. Biederman
2020-06-29 20:02                                               ` [PATCH v2 07/15] umd: Rename umd_info.cmdline umd_info.driver_name Eric W. Biederman
2020-06-29 20:03                                               ` [PATCH v2 08/15] umd: Transform fork_usermode_blob into fork_usermode_driver Eric W. Biederman
2020-06-29 20:03                                               ` [PATCH v2 09/15] umh: Stop calling do_execve_file Eric W. Biederman
2020-06-29 20:04                                               ` [PATCH v2 10/15] exec: Remove do_execve_file Eric W. Biederman
2020-06-30  5:43                                                 ` Christoph Hellwig
2020-06-30 12:14                                                   ` Eric W. Biederman
2020-06-30 13:38                                                     ` Christoph Hellwig
2020-06-30 14:28                                                       ` Eric W. Biederman
2020-06-30 16:55                                                         ` Alexei Starovoitov
2020-06-29 20:05                                               ` [PATCH v2 11/15] bpfilter: Move bpfilter_umh back into init data Eric W. Biederman
2020-06-29 20:06                                               ` [PATCH v2 12/15] umd: Track user space drivers with struct pid Eric W. Biederman
2020-06-29 20:06                                               ` [PATCH v2 13/15] bpfilter: Take advantage of the facilities of " Eric W. Biederman
2020-06-29 20:07                                               ` [PATCH v2 14/15] umd: Remove exit_umh Eric W. Biederman
2020-06-29 20:08                                               ` [PATCH v2 15/15] umd: Stop using split_argv Eric W. Biederman
2020-06-29 22:12                                               ` [PATCH v2 00/15] Make the user mode driver code a better citizen Alexei Starovoitov
2020-06-30  1:13                                                 ` Eric W. Biederman
2020-06-30  6:16                                                   ` Tetsuo Handa
2020-06-30 12:29                                                 ` Eric W. Biederman
2020-06-30 13:21                                                   ` Tetsuo Handa
2020-07-02 13:08                                                     ` Eric W. Biederman
2020-07-02 13:40                                                       ` Tetsuo Handa
2020-07-02 16:02                                                         ` Eric W. Biederman
2020-07-03 13:19                                                           ` Tetsuo Handa
2020-07-03 22:25                                                             ` Eric W. Biederman
2020-07-04  6:57                                                               ` Tetsuo Handa
2020-07-08  4:46                                                                 ` Eric W. Biederman
2020-06-30 16:52                                                   ` Alexei Starovoitov
2020-07-01 17:12                                                     ` Eric W. Biederman
2020-07-02 16:40                                               ` [PATCH v3 00/16] " Eric W. Biederman
2020-07-02 16:41                                                 ` [PATCH v3 01/16] umh: Capture the pid in umh_pipe_setup Eric W. Biederman
2020-07-02 16:41                                                 ` [PATCH v3 02/16] umh: Move setting PF_UMH into umh_pipe_setup Eric W. Biederman
2020-07-02 16:41                                                 ` [PATCH v3 03/16] umh: Rename the user mode driver helpers for clarity Eric W. Biederman
2020-07-02 16:41                                                 ` [PATCH v3 04/16] umh: Remove call_usermodehelper_setup_file Eric W. Biederman
2020-07-02 16:41                                                 ` [PATCH v3 05/16] umh: Separate the user mode driver and the user mode helper support Eric W. Biederman
2020-07-02 16:41                                                 ` [PATCH v3 06/16] umd: For clarity rename umh_info umd_info Eric W. Biederman
2020-07-02 16:41                                                 ` [PATCH v3 07/16] umd: Rename umd_info.cmdline umd_info.driver_name Eric W. Biederman
2020-07-02 16:41                                                 ` [PATCH v3 08/16] umd: Transform fork_usermode_blob into fork_usermode_driver Eric W. Biederman
2020-07-02 16:41                                                 ` [PATCH v3 09/16] umh: Stop calling do_execve_file Eric W. Biederman
2020-07-02 16:41                                                 ` Eric W. Biederman [this message]
2020-07-08  6:35                                                   ` [PATCH v3 10/16] exec: Remove do_execve_file Luis Chamberlain
2020-07-08 12:41                                                     ` Luis Chamberlain
2020-07-08 13:08                                                       ` Eric W. Biederman
2020-07-08 13:32                                                         ` Luis Chamberlain
2020-07-12 21:02                                                   ` Pavel Machek
2020-07-02 16:41                                                 ` [PATCH v3 11/16] bpfilter: Move bpfilter_umh back into init data Eric W. Biederman
2020-07-02 16:41                                                 ` [PATCH v3 12/16] umd: Track user space drivers with struct pid Eric W. Biederman
2020-07-02 16:41                                                 ` [PATCH v3 13/16] exit: Factor thread_group_exited out of pidfd_poll Eric W. Biederman
2020-07-03 20:30                                                   ` Alexei Starovoitov
2020-07-03 21:37                                                     ` Eric W. Biederman
2020-07-04  0:03                                                       ` Alexei Starovoitov
2020-07-04 15:50                                                       ` Christian Brauner
2020-07-07 17:09                                                         ` Eric W. Biederman
2020-07-08  0:05                                                           ` Daniel Borkmann
2020-07-08  3:50                                                             ` Eric W. Biederman
2020-07-04 16:00                                                   ` Christian Brauner
2020-07-02 16:41                                                 ` [PATCH v3 14/16] bpfilter: Take advantage of the facilities of struct pid Eric W. Biederman
2020-07-02 16:41                                                 ` [PATCH v3 15/16] umd: Remove exit_umh Eric W. Biederman
2020-07-02 16:41                                                 ` [PATCH v3 16/16] umd: Stop using split_argv Eric W. Biederman
2020-07-02 23:51                                                 ` [PATCH v3 00/16] Make the user mode driver code a better citizen Tetsuo Handa
2020-07-09 22:05                                                 ` [merged][PATCH " Eric W. Biederman
2020-07-14 19:42                                                   ` Alexei Starovoitov
2020-07-08  5:20                                               ` [PATCH v2 00/15] " Luis Chamberlain
2020-06-26 14:10                                           ` [PATCH 00/14] " Greg Kroah-Hartman
2020-06-26 16:40                                           ` Alexei Starovoitov
2020-06-26 17:17                                             ` Eric W. Biederman
2020-06-26 18:22                                               ` Alexei Starovoitov
2020-06-27 11:38                                           ` Tetsuo Handa
2020-06-27 12:59                                             ` Eric W. Biederman
2020-06-27 13:57                                               ` Tetsuo Handa
2020-06-28 19:44                                                 ` Alexei Starovoitov
2020-06-29  2:20                                                   ` Tetsuo Handa
2020-06-29 20:19                                                     ` Eric W. Biederman
2020-06-30  6:28                                                       ` Tetsuo Handa
2020-06-30 12:32                                                         ` Eric W. Biederman
2020-06-30 16:48                                                         ` Alexei Starovoitov
2020-06-30 21:54                                                           ` Tetsuo Handa
2020-06-30 21:57                                                             ` Alexei Starovoitov
2020-06-30 22:58                                                               ` Tetsuo Handa
2020-06-25 12:56                           ` [RFC][PATCH] net/bpfilter: Remove this broken and apparently unmantained Stephen Smalley
2020-06-25 13:25                             ` Greg Kroah-Hartman
2020-06-25 14:26                               ` Stephen Smalley
2020-06-25 14:36                                 ` Stephen Smalley
2020-06-25 15:21                                 ` Tetsuo Handa
2020-06-25 16:03                                   ` Stephen Smalley
2020-06-25 16:06                                   ` Casey Schaufler

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