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scripts/mkusers: allow users with no password value set

PATCH Superseded James Knight 3 participants 5 messages May 22, 2015 – May 23, 2015

v1 of 2 Superseded Latest is v2 →

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#0 lore raw

PATCH 1/1 scripts/mkusers: allow users with no password value set

The following allows a user definition to specify that a created user entry should not have a password value set. Original implementation allowed a user definition to provide a password value of "-" (no quotes) to generate a crypt-encoded empty string value. In some cases, it may be desired to have no value specified for a user's password. By using a value "-" for a password, no value will be set in the shadow value.

---
 docs/manual/makeusers-syntax.txt | 3 ++-
 support/scripts/mkusers          | 3 +++
 2 files changed, 5 insertions(+), 1 deletion(-)
docs/manual/makeusers-syntax.txt +2 -1
index ffdb961..467e596 100644
@@ -31,7 +31,8 @@ Where:
   then login is disabled. If prefixed with +=+, then it is interpreted
   as clear-text, and will be crypt-encoded (using MD5). If prefixed with
   +!=+, then the password will be crypt-encoded (using MD5) and login
-  will be disabled. If set to +*+, then login is not allowed.
+  will be disabled. If set to +*+, then login is not allowed. If set to 
+  +-+, then no password value will be set.
 - +home+ is the desired home directory for the user. If set to '-', no
   home directory will be created, and the user's home will be +/+.
   Explicitly setting +home+ to +/+ is not allowed.
support/scripts/mkusers +3 -0
index 026519e..9c5c4dc 100755
@@ -318,6 +318,9 @@ add_one_user() {
         *)  fail "home must be an absolute path\n";;
     esac
     case "${passwd}" in
+        -)
+            _passwd=""
+            ;;
         !=*)
             _passwd='!'"$( encode_password "${passwd#!=}" )"
             ;;
Signature · 1 line
1.9.5.msysgit.1
#1 lore raw

PATCH 1/1 scripts/mkusers: allow users with no password value set

James, All,

On 2015-05-22 11:36 -0400, James Knight spake thusly:

Quoted 6 lines

The following allows a user definition to specify that a created user entry should not have a password value set. Original implementation allowed a user definition to provide a password value of "-" (no quotes) to generate a crypt-encoded empty string value. In some cases, it may be desired to have no value specified for a user's password. By using a value "-" for a password, no value will be set in the shadow value.

I fail to see how that is different from using an empty password as (without quotes): "="

From man 5 passwd:

The encrypted password field may be blank, in which case no password is required to authenticate as the specified login name. However, some applications which read the /etc/passwd file may decide not to permit any access at all if the password field is blank.

Thus, I believe it is safest to store an encoded empty password rather than set the password field empty.

Did I miss something?

Of course, the manual could be updated to reflect that a password-less account should use "=" in the password field.

Regards,
Yann E. MORIN.

Quoted 41 lines
---
 docs/manual/makeusers-syntax.txt | 3 ++-
 support/scripts/mkusers          | 3 +++
 2 files changed, 5 insertions(+), 1 deletion(-)
docs/manual/makeusers-syntax.txt +2 -1
index ffdb961..467e596 100644
@@ -31,7 +31,8 @@ Where:
   then login is disabled. If prefixed with +=+, then it is interpreted
   as clear-text, and will be crypt-encoded (using MD5). If prefixed with
   +!=+, then the password will be crypt-encoded (using MD5) and login
-  will be disabled. If set to +*+, then login is not allowed.
+  will be disabled. If set to +*+, then login is not allowed. If set to 
+  +-+, then no password value will be set.
 - +home+ is the desired home directory for the user. If set to '-', no
   home directory will be created, and the user's home will be +/+.
   Explicitly setting +home+ to +/+ is not allowed.
support/scripts/mkusers +3 -0
index 026519e..9c5c4dc 100755
@@ -318,6 +318,9 @@ add_one_user() {
         *)  fail "home must be an absolute path\n";;
     esac
     case "${passwd}" in
+        -)
+            _passwd=""
+            ;;
         !=*)
             _passwd='!'"$( encode_password "${passwd#!=}" )"
             ;;
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| +33 662 376 056 | Software  Designer | \ / CAMPAIGN     |  ___               |
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#2 lore raw

PATCH 1/1 scripts/mkusers: allow users with no password value set

Yann,

Quoted 2 lines

On 2015-05-22 11:36 -0400, James Knight spake thusly:

Quoted 1 line

The following allows a user definition to specify that a created

user

Quoted 2 lines
Quoted 2 lines

entry should not have a password value set. Original implementation allowed a user definition to provide a password value of "-" (no

quotes)

Quoted 1 line
Quoted 1 line

to generate a crypt-encoded empty string value. In some cases, it

may be

Quoted 9 lines
Quoted 2 lines

desired to have no value specified for a user's password. By using a value "-" for a password, no value will be set in the shadow value.

I fail to see how that is different from using an empty password as (without quotes): "="

From man 5 passwd:

The encrypted password field may be blank, in which case no

password

Quoted 2 lines

is required to authenticate as the specified login name. However, some applications which read the /etc/passwd file may decide not

to

Quoted 5 lines

permit any access at all if the password field is blank.

Thus, I believe it is safest to store an encoded empty password rather than set the password field empty.

Quoted 7 lines

Did I miss something?

Of course, the manual could be updated to reflect that a password-less account should use "=" in the password field.

Regards,
Yann E. MORIN.

Logging into a session with an encoded empty password will prompt me to enter a password since it doesn't know the password is empty. In this case, I would simply just hit enter to supply an empty password and it would authenticate.

If I alternatively set the password field blank, my login session will not prompt a password and will just login (since it knows there is no password set). This is what I'm hoping to achieve for the current target I'm developing.

#3 lore raw

PATCH 1/1 scripts/mkusers: allow users with no password value set

James, All,

On 2015-05-23 06:11 +0000, James Knight spake thusly:

Quoted 39 lines
Quoted 2 lines

On 2015-05-22 11:36 -0400, James Knight spake thusly:

Quoted 1 line

The following allows a user definition to specify that a created

user

Quoted 2 lines
Quoted 2 lines

entry should not have a password value set. Original implementation allowed a user definition to provide a password value of "-" (no

quotes)

Quoted 1 line
Quoted 1 line

to generate a crypt-encoded empty string value. In some cases, it

may be

Quoted 9 lines
Quoted 2 lines

desired to have no value specified for a user's password. By using a value "-" for a password, no value will be set in the shadow value.

I fail to see how that is different from using an empty password as (without quotes): "="

From man 5 passwd:

The encrypted password field may be blank, in which case no

password

Quoted 2 lines

is required to authenticate as the specified login name. However, some applications which read the /etc/passwd file may decide not

to

Quoted 5 lines

permit any access at all if the password field is blank.

Thus, I believe it is safest to store an encoded empty password rather than set the password field empty.

Quoted 7 lines

Did I miss something?

Of course, the manual could be updated to reflect that a password-less account should use "=" in the password field.

Regards,
Yann E. MORIN.

Logging into a session with an encoded empty password will prompt me to enter a password since it doesn't know the password is empty. In this case, I would simply just hit enter to supply an empty password and it would authenticate.

Quoted 4 lines

If I alternatively set the password field blank, my login session will not prompt a password and will just login (since it knows there is no password set). This is what I'm hoping to achieve for the current target I'm developing.

Ah, right, that's what I missed. OK.

Regards,
Yann E. MORIN.

Signature · 6 lines
.-----------------.--------------------.------------------.--------------------.
|  Yann E. MORIN  | Real-Time Embedded | /"\ ASCII RIBBON | Erics' conspiracy: |
| +33 662 376 056 | Software  Designer | \ / CAMPAIGN     |  ___               |
| +33 223 225 172 `------------.-------:  X  AGAINST      |  \e/  There is no  |
| http://ymorin.is-a-geek.org/ | _/*\_ | / \ HTML MAIL    |   v   conspiracy.  |
'------------------------------^-------^------------------^--------------------'
#4 lore raw

PATCH 1/1 scripts/mkusers: allow users with no password value set

In reply to James Knight

James, All,

On 2015-05-22 11:36 -0400, James Knight spake thusly:

Quoted 6 lines

The following allows a user definition to specify that a created user entry should not have a password value set. Original implementation allowed a user definition to provide a password value of "-" (no quotes) to generate a crypt-encoded empty string value. In some cases, it may be desired to have no value specified for a user's password. By using a value "-" for a password, no value will be set in the shadow value.

Well, that commit log was not completely explicit about what the goal was. What about something like:

Currently, it is not possible to create a password-less user, i.e. a user that can log without providing a password. All we can do is create a user with an empty password, but a pasword nonetheless.

Accept '-' as the password field, meaning that no password is set, which allows a user to log in by just providing is login, and no password will even be asked.

If you have yet a better explanation, go for it! ;-)

Quoted 1 line

With the commit log more explicit, you can add:

Thanks! :-)

Regards,
Yann E. MORIN.

Quoted 40 lines
---
 docs/manual/makeusers-syntax.txt | 3 ++-
 support/scripts/mkusers          | 3 +++
 2 files changed, 5 insertions(+), 1 deletion(-)
docs/manual/makeusers-syntax.txt +2 -1
index ffdb961..467e596 100644
@@ -31,7 +31,8 @@ Where:
   then login is disabled. If prefixed with +=+, then it is interpreted
   as clear-text, and will be crypt-encoded (using MD5). If prefixed with
   +!=+, then the password will be crypt-encoded (using MD5) and login
-  will be disabled. If set to +*+, then login is not allowed.
+  will be disabled. If set to +*+, then login is not allowed. If set to 
+  +-+, then no password value will be set.
 - +home+ is the desired home directory for the user. If set to '-', no
   home directory will be created, and the user's home will be +/+.
   Explicitly setting +home+ to +/+ is not allowed.
support/scripts/mkusers +3 -0
index 026519e..9c5c4dc 100755
@@ -318,6 +318,9 @@ add_one_user() {
         *)  fail "home must be an absolute path\n";;
     esac
     case "${passwd}" in
+        -)
+            _passwd=""
+            ;;
         !=*)
             _passwd='!'"$( encode_password "${passwd#!=}" )"
             ;;
Signature · 6 lines
1.9.5.msysgit.1

_______________________________________________
buildroot mailing list
buildroot at busybox.net
http://lists.busybox.net/mailman/listinfo/buildroot
Signature · 6 lines
.-----------------.--------------------.------------------.--------------------.
|  Yann E. MORIN  | Real-Time Embedded | /"\ ASCII RIBBON | Erics' conspiracy: |
| +33 662 376 056 | Software  Designer | \ / CAMPAIGN     |  ___               |
| +33 223 225 172 `------------.-------:  X  AGAINST      |  \e/  There is no  |
| http://ymorin.is-a-geek.org/ | _/*\_ | / \ HTML MAIL    |   v   conspiracy.  |
'------------------------------^-------^------------------^--------------------'