passwd: add UPN validation support by ikerexxe · Pull Request #1633 · shadow-maint/shadow

ikerexxe · 2026-06-03T14:30:56Z

Add User Principal Name (UPN) validation to allow passwd command to accept usernames in user@domain.com format. This addresses rejection of valid UPN usernames by implementing proper RFC-compliant domain validation.

Changes include:

Add is_valid_upn(), is_valid_domain_name(), and is_valid_domain_label() functions to lib/chkname.c with RFC 1035/1123 compliant validation
Update passwd.c to accept both traditional usernames and UPN format
Add comprehensive unit tests covering UPN validation edge cases
Domain names limited to 253 chars total and 63 chars per label
Maintains backward compatibility with existing username validation

Fixes: 326889c (2024-10-22; "Fix coverity unbound buffer issues")
Closes: #1626
Reported-by: @nooreldeenmansour
Supersedes: #1627

ikerexxe · 2026-06-03T14:37:54Z

This is what I’ve managed to put in place with the time I had available...

ikerexxe · 2026-06-03T14:38:46Z

@MarcinDigitic do you mind testing?

alejandro-colomar · 2026-06-06T18:35:36Z

I've fixed several issues for you.

v2:

Use strspn(3) and strcspn(3) instead of manual byte operations.
Use strndup(3) instead of its pattern.
Allow trailing dot.
Allow non-FQDN.
Remove dead code.
Simplify documentation.
Other minor improvements.

range-diff

$ git range-diff --creation-factor=99 HEAD^^^ origin/passwd-upn passwd-upn -w
1:  a3d59004 ! 1:  8943055e lib: add UPN validation support
    @@ Metadata
     Author: Iker Pedrosa <ipedrosa@redhat.com>
     
      ## Commit message ##
    -    lib: add UPN validation support
    +    lib/chkname.*: Add UPN validation support
     
         Add is_valid_upn() function to validate User Principal Name format. UPN
         validation splits on @ and validates the prefix using existing username
         rules and suffix part using RFC 1035/1123 compliant domain name
         validation.
     
    +    Co-authored-by: Iker Pedrosa <ipedrosa@redhat.com>
         Signed-off-by: Iker Pedrosa <ipedrosa@redhat.com>
    +    Co-authored-by: Alejandro Colomar <alx@kernel.org>
    +    Signed-off-by: Alejandro Colomar <alx@kernel.org>
     
      ## lib/chkname.c ##
    +@@
    + 
    + 
    + /*
    +- * is_valid_user_name(), is_valid_group_name() - check the new user/group
    +- * name for validity;
    ++ * check user/group names for valid syntax
    +  * return values:
    +  *   true  - OK
    +  *   false - bad name
    +@@
    +  *   EINVAL       Invalid name
    +  *   EILSEQ       Invalid name character sequence (acceptable with --badname)
    +  *   EOVERFLOW    Name longer than maximum size
    ++ *   ENOMEM     Cannot allocate memory
    +  */
    + 
    + 
     @@
      #include "sysconf.h"
      
    @@ lib/chkname.c: is_valid_group_name(const char *name)
     +
     +
     +/*
    -+ * SYNOPSIS
    -+ *        static bool is_valid_domain_label(const char *label, size_t len);
    -+ *
    -+ * ARGUMENTS
    -+ *        label   Domain label string to validate.
    -+ *        len     Length of the label string.
    -+ *
    -+ * DESCRIPTION
     + * Validate a single DNS domain label according to RFC 1035/1123.
     + * Domain labels are components separated by dots in a domain name.
     + * For example, in "example.com", both "example" and "com" are labels.
    -+ *
    -+ * RETURN VALUE
    -+ *        true    Valid domain label.
    -+ *        false   Invalid domain label.
    -+ *
    -+ * ERRORS
    -+ *        This function does not set errno.
     + */
     +static bool
    -+is_valid_domain_label(const char *label, size_t len)
    ++is_valid_domain_label(const char *label)
     +{
    -+  size_t i;
    ++  size_t  len;
     +
    -+  /* Empty label is invalid */
    -+  if (len == 0 || len > LABEL_MAXLEN) {
    ++  if (strlen(label) > LABEL_MAXLEN) {
    ++          errno = EOVERFLOW;
     +          return false;
     +  }
    -+
    -+  /* Must start and end with alphanumeric */
    -+  if (!((label[0] >= 'a' && label[0] <= 'z') ||
    -+        (label[0] >= 'A' && label[0] <= 'Z') ||
    -+        (label[0] >= '0' && label[0] <= '9'))) {
    ++  if (!strcspn(label, "-")) {
    ++          errno = EINVAL;
     +          return false;
     +  }
    -+
    -+  if (len > 1) {
    ++  len = strlen(label);
     +  if (!((label[len-1] >= 'a' && label[len-1] <= 'z') ||
     +        (label[len-1] >= 'A' && label[len-1] <= 'Z') ||
    -+                (label[len-1] >= '0' && label[len-1] <= '9'))) {
    ++        (label[len-1] >= '0' && label[len-1] <= '9')))
    ++  {
    ++          errno = EINVAL;
     +          return false;
     +  }
    -+  }
     +
    -+  /* Check middle characters (can include hyphen) */
    -+  for (i = 1; i < len - 1; i++) {
    ++  for (size_t i = 0; i < len; i++) {
     +          if (!((label[i] >= 'a' && label[i] <= 'z') ||
     +                (label[i] >= 'A' && label[i] <= 'Z') ||
     +                (label[i] >= '0' && label[i] <= '9') ||
    -+                label[i] == '-')) {
    ++                label[i] == '-'))
    ++          {
    ++                  errno = EINVAL;
     +                  return false;
     +          }
     +  }
    @@ lib/chkname.c: is_valid_group_name(const char *name)
     +
     +
     +/*
    -+ * SYNOPSIS
    -+ *        static bool is_valid_domain_name(const char *domain);
    -+ *
    -+ * ARGUMENTS
    -+ *        domain  Domain name string to validate.
    -+ *
    -+ * DESCRIPTION
     + * Validate a domain name according to RFC 1035/1123 by splitting
     + * it into labels and validating each label individually.
    -+ *        Requires FQDN format (at least one dot).
    -+ *
    -+ * RETURN VALUE
    -+ *        true    Valid domain name.
    -+ *        false   Invalid domain name.
    -+ *
    -+ * ERRORS
    -+ *        EINVAL          Invalid domain structure (empty, leading/trailing dots, consecutive dots).
    -+ *        EILSEQ          Invalid domain label.
    -+ *        EOVERFLOW       Domain too long.
     + */
     +static bool
     +is_valid_domain_name(const char *domain)
     +{
    -+  const char *start, *end;
    -+  size_t domain_len, label_len;
    -+  bool has_dot = false;
    ++  char        *d;
    ++  const char  *l;
     +
    -+  if (streq(domain, "")) {
    -+          errno = EINVAL;
    -+          return false;
    -+  }
    -+
    -+  domain_len = strlen(domain);
    -+  if (domain_len > DOMAIN_MAXLEN) {
    ++  if (strlen(domain) > DOMAIN_MAXLEN) {
     +          errno = EOVERFLOW;
     +          return false;
     +  }
    -+
    -+  /* Check for leading or trailing dots */
    -+  if (domain[0] == '.' || domain[domain_len-1] == '.') {
    ++  if (!strcspn(domain, ".")) {
     +          errno = EINVAL;
     +          return false;
     +  }
     +
    -+  /* Parse and validate each label */
    -+  start = domain;
    -+  while ((end = strchr(start, '.')) != NULL) {
    -+          has_dot = true;
    -+          label_len = end - start;
    ++  d = strdupa(domain);
     +
    -+          /* Check for consecutive dots */
    -+          if (label_len == 0) {
    -+                  errno = EINVAL;
    -+                  return false;
    -+          }
    -+
    -+          if (!is_valid_domain_label(start, label_len)) {
    -+                  errno = EILSEQ;
    -+                  return false;
    -+          }
    -+
    -+          start = end + 1;
    -+  }
    -+
    -+  /* Validate final label */
    -+  label_len = strlen(start);
    -+  if (label_len == 0 || !is_valid_domain_label(start, label_len)) {
    -+          errno = EILSEQ;
    -+          return false;
    -+  }
    -+
    -+  /* Require FQDN (at least one dot) */
    -+  if (!has_dot) {
    -+          errno = EINVAL;
    ++  while (NULL != (l = strsep(&d, "."))) {
    ++          if (d == NULL && streq(l, ""))  // trailing root label
    ++                  break;
    ++          if (!is_valid_domain_label(l))
     +                  return false;
     +  }
     +
    @@ lib/chkname.c: is_valid_group_name(const char *name)
     +
     +
     +/*
    -+ * SYNOPSIS
    -+ *        bool is_valid_upn(const char *name);
    ++ * is_valid_upn - is valid User Principal Name
     + *
    -+ * ARGUMENTS
    -+ *        name    UPN (User Principal Name) string to validate.
    -+ *
    -+ * DESCRIPTION
    -+ *        Check UPN format (user@domain) for validity. A UPN consists of a
    -+ *        prefix (before @) and suffix (after @). The prefix must follow the
    -+ *        same rules as traditional usernames. The suffix part must be a
    ++ * Check UPN format (user@domain) for validity.  The user must follow
    ++ * the same rules as traditional usernames.  The domain part must be a
     + * valid domain name.
     + *
     + * This function only validates syntax, not whether the UPN exists
     + * in any authentication system.
    -+ *
    -+ * RETURN VALUE
    -+ *        true    Valid UPN format.
    -+ *        false   Invalid UPN format or not a UPN.
    -+ *
    -+ * ERRORS
    -+ *        EINVAL          Invalid UPN structure (empty parts, multiple @).
    -+ *        EILSEQ          Invalid character sequence.
    -+ *        EOVERFLOW       Name longer than maximum size.
    -+ *        ENOMEM          Memory allocation failure.
     + */
     +bool
    -+is_valid_upn(const char *name)
    ++is_valid_upn(const char *upn)
     +{
    ++  bool        ret;
    ++  char        *u;
     +  const char  *at_pos;
    -+  char *local_part, *domain_part;
    -+  size_t local_len;
    -+  bool result = false;
     +
    -+  /* Find exactly one @ symbol */
    -+  at_pos = strchr(name, '@');
    -+  if (at_pos == NULL) {
    -+          return false; /* Not a UPN */
    -+  }
    -+
    -+  /* Check for multiple @ symbols */
    -+  if (strchr(at_pos + 1, '@') != NULL) {
    -+          errno = EINVAL;
    ++  at_pos = strchr(upn, '@');
    ++  if (at_pos == NULL)
     +          return false;
    -+  }
     +
    -+  /* Extract prefix */
    -+  local_len = at_pos - name;
    -+  if (local_len == 0) {
    -+          errno = EINVAL;
    ++  u = strndup(upn, at_pos - upn);
    ++  if (u == NULL)
     +          return false;
    -+  }
     +
    -+  local_part = malloc(local_len + 1);
    -+  if (local_part == NULL) {
    -+          errno = ENOMEM;
    -+          return false;
    -+  }
    ++  ret = false;
     +
    -+  strncpy(local_part, name, local_len);
    -+  local_part[local_len] = '\0';
    -+
    -+  /* Extract suffix */
    -+  domain_part = strdup(at_pos + 1);
    -+  if (domain_part == NULL) {
    -+          errno = ENOMEM;
    -+          free(local_part);
    -+          return false;
    -+  }
    -+
    -+  if (streq(domain_part, "")) {
    -+          errno = EINVAL;
    ++  if (!is_valid_user_name(u))
     +          goto cleanup;
    -+  }
    -+
    -+  /* Validate local part using existing username rules */
    -+  if (!is_valid_user_name(local_part)) {
    ++  if (!is_valid_domain_name(at_pos + 1))
     +          goto cleanup;
    -+  }
    -+
    -+  /* Validate domain part using RFC-compliant domain name rules */
    -+  if (!is_valid_domain_name(domain_part)) {
    -+          goto cleanup;
    -+  }
    -+
    -+  result = true;
     +
    ++  ret = true;
     +cleanup:
    -+  free(local_part);
    -+  free(domain_part);
    -+  return result;
    ++  free(u);
    ++  return ret;
     +}
     
      ## lib/chkname.h ##
2:  5aa78162 = 2:  d9f3bc29 tests: add unit tests for UPN validation
3:  4ea29c1b = 3:  97b1a5c0 passwd: add UPN validation support

alejandro-colomar · 2026-06-06T22:08:39Z

 #include "sysconf.h"


+#define DOMAIN_MAXLEN	253


This seems to already account for the trailing root label, but if explicitly present, the limit is 254, AFAIK.

alejandro-colomar · 2026-06-06T22:23:10Z

+	if (strlen(domain) > DOMAIN_MAXLEN) {
+		errno = EOVERFLOW;
+		return false;
+	}


For accounting for the trailing root label correctly, regardless of whether it's implicit or explicit, this could be:

#define DOMAIN_MAXLEN 254 if (strlen(domain) + !!strrcspn(domain, ".") > DOMAIN_MAXLEN)

alejandro-colomar · 2026-06-06T23:22:36Z

I've fixed a few more issues for you.

v3:

The first check is now a length check. I test against compile-time constants, which provides guarantees that the maximum string is quite short, and thus fits in the stack.
The above allows me to drop the malloc(3) call (called through strndup(3)). Now that the string is really short, we can strdupa(3). This avoids ENOMEM entirely, and a vulnerability with it: the user can't force a crash with a huge UPN.
Use stpsep() to simplify.
Set errno in all false cases.
Further reduce documentation.

range-diff

$ git range-diff HEAD^^^ origin/passwd-upn passwd-upn 
1:  8943055e ! 1:  6020aa6c lib/chkname.*: Add UPN validation support
    @@ lib/chkname.c
       *   true  - OK
       *   false - bad name
     @@
    -  *   EINVAL       Invalid name
    -  *   EILSEQ       Invalid name character sequence (acceptable with --badname)
    -  *   EOVERFLOW    Name longer than maximum size
    -+ *   ENOMEM     Cannot allocate memory
    -  */
      
    - 
    -@@
    + #include "defines.h"
    + #include "chkname.h"
    ++#include "sizeof.h"
    + #include "string/ctype/strchrisascii/strchriscntrl.h"
    + #include "string/ctype/strisascii/strisdigit.h"
    + #include "string/strcmp/streq.h"
    + #include "string/strcmp/strcaseeq.h"
    ++#include "string/strtok/stpsep.h"
      #include "sysconf.h"
      
      
    @@ lib/chkname.c: is_valid_group_name(const char *name)
     +/*
     + * is_valid_upn - is valid User Principal Name
     + *
    -+ * Check UPN format (user@domain) for validity.  The user must follow
    -+ * the same rules as traditional usernames.  The domain part must be a
    -+ * valid domain name.
    ++ * Check UPN format (user@domain) for validity.
     + *
     + * This function only validates syntax, not whether the UPN exists
     + * in any authentication system.
    @@ lib/chkname.c: is_valid_group_name(const char *name)
     +bool
     +is_valid_upn(const char *upn)
     +{
    -+  bool        ret;
    -+  char        *u;
    -+  const char  *at_pos;
    ++  char  *u, *d;
     +
    -+  at_pos = strchr(upn, '@');
    -+  if (at_pos == NULL)
    ++  if (strlen(upn) >= LOGIN_NAME_MAX + STRLEN("@") + DOMAIN_MAXLEN) {
    ++          errno = EOVERFLOW;
     +          return false;
    ++  }
     +
    -+  u = strndup(upn, at_pos - upn);
    -+  if (u == NULL)
    ++  u = strdupa(upn);
    ++  d = stpsep(u, "@");
    ++  if (d == NULL) {
    ++          errno = EINVAL;
     +          return false;
    ++  }
     +
    -+  ret = false;
    -+
    -+  if (!is_valid_user_name(u))
    -+          goto cleanup;
    -+  if (!is_valid_domain_name(at_pos + 1))
    -+          goto cleanup;
    -+
    -+  ret = true;
    -+cleanup:
    -+  free(u);
    -+  return ret;
    ++  return is_valid_user_name(u) && is_valid_domain_name(d);
     +}
     
      ## lib/chkname.h ##
2:  d9f3bc29 = 2:  01d04883 tests: add unit tests for UPN validation
3:  97b1a5c0 = 3:  0428deec passwd: add UPN validation support

v3b:

Move the length checks closer to the corresponding strdupa(3) calls, to make it easier to verify that strdupa(3) calls are safe.

range-diff

$ git range-diff HEAD^^^ origin/passwd-upn passwd-upn 
1:  6020aa6c ! 1:  cf710e51 lib/chkname.*: Add UPN validation support
    @@ lib/chkname.c: is_valid_group_name(const char *name)
     +  char        *d;
     +  const char  *l;
     +
    -+  if (strlen(domain) > DOMAIN_MAXLEN) {
    -+          errno = EOVERFLOW;
    -+          return false;
    -+  }
     +  if (!strcspn(domain, ".")) {
     +          errno = EINVAL;
     +          return false;
     +  }
     +
    ++  if (strlen(domain) > DOMAIN_MAXLEN) {
    ++          errno = EOVERFLOW;
    ++          return false;
    ++  }
     +  d = strdupa(domain);
     +
     +  while (NULL != (l = strsep(&d, "."))) {
    @@ lib/chkname.c: is_valid_group_name(const char *name)
     +          errno = EOVERFLOW;
     +          return false;
     +  }
    -+
     +  u = strdupa(upn);
    ++
     +  d = stpsep(u, "@");
     +  if (d == NULL) {
     +          errno = EINVAL;
2:  01d04883 = 2:  9635aa1b tests: add unit tests for UPN validation
3:  0428deec = 3:  d2f556b7 passwd: add UPN validation support

alejandro-colomar · 2026-06-06T23:31:50Z

 	if (optind < argc) {
-		if (!is_valid_user_name (argv[optind])) {
+		if (!is_valid_user_name (argv[optind]) && !is_valid_upn (argv[optind])) {
 			fprintf (stderr, _("%s: Provided user name is not a valid name\n"), Prog);
 			fail_exit (E_NOPERM, process_selinux);
 		}


Hmmmm, now I've realized another issue that was introduced when we added syntax checking of the user names. There's no way to relax the syntax checking, since passwd(1) has no --badname option. Thus, we've effectively removed --badname support.

We should probably also fix that.

Maybe we should set badname to true in these programs that didn't check syntax before.

ikerexxe · 2026-06-09T08:46:41Z

I realize that one of the unit tests is failing, I'll fix it when related PRs are merged and I can base my work on stable APIs

alejandro-colomar · 2026-06-09T12:09:48Z

I realize that one of the unit tests is failing, I'll fix it when related PRs are merged and I can base my work on stable APIs

I think the reason for the failing tests is that I changed the code to accept user@domain.com. with a trailing root label, and also user@domain with a non-fully-qualified domain.

alejandro-colomar · 2026-06-14T00:27:44Z

I've fixed a few more things for you.

v4:

Rebase

range-diff

$ git range-diff origin/passwd-upn^^^..origin/passwd-upn upstream/master..passwd-upn 
1:  adc23074fe38 ! 1:  052644053b3d lib/chkname.*: Add UPN validation support
    @@ lib/chkname.c
      #include "defines.h"
      #include "chkname.h"
     +#include "sizeof.h"
    - #include "string/ctype/strchrisascii/strchriscntrl.h"
    - #include "string/ctype/strisascii/strisdigit.h"
    + #include "string/ctype/isascii.h"
      #include "string/strcmp/streq.h"
      #include "string/strcmp/strcaseeq.h"
     +#include "string/strtok/stpsep.h"
2:  f1f9f623dadd = 2:  522faa7a5861 tests: add unit tests for UPN validation
3:  d71db363028d = 3:  c3625ee0efcb passwd: add UPN validation support

v5:

Test the last character against '-' to simplify.
Use streq(stpspn(s, CTYPE_ALNUM_C "-"), "") to simplify.

range-diff

$ git range-diff origin/passwd-upn^^^..origin/passwd-upn upstream/master..passwd-upn 
1:  052644053b3d ! 1:  5e50c4a34637 lib/chkname.*: Add UPN validation support
    @@ lib/chkname.c: is_valid_group_name(const char *name)
     +static bool
     +is_valid_domain_label(const char *label)
     +{
    -+  size_t  len;
    -+
     +  if (strlen(label) > LABEL_MAXLEN) {
     +          errno = EOVERFLOW;
     +          return false;
     +  }
    -+  if (!strcspn(label, "-")) {
    ++  if (!strcspn(label, "-") || label[strlen(label)-1] == '-') {
     +          errno = EINVAL;
     +          return false;
     +  }
    -+  len = strlen(label);
    -+  if (!((label[len-1] >= 'a' && label[len-1] <= 'z') ||
    -+        (label[len-1] >= 'A' && label[len-1] <= 'Z') ||
    -+        (label[len-1] >= '0' && label[len-1] <= '9')))
    -+  {
    ++  if (!streq(stpspn(s, CTYPE_ALNUM_C "-"), "")) {
     +          errno = EINVAL;
     +          return false;
     +  }
     +
    -+  for (size_t i = 0; i < len; i++) {
    -+          if (!((label[i] >= 'a' && label[i] <= 'z') ||
    -+                (label[i] >= 'A' && label[i] <= 'Z') ||
    -+                (label[i] >= '0' && label[i] <= '9') ||
    -+                label[i] == '-'))
    -+          {
    -+                  errno = EINVAL;
    -+                  return false;
    -+          }
    -+  }
    -+
     +  return true;
     +}
     +
2:  522faa7a5861 = 2:  f0b23874316b tests: add unit tests for UPN validation
3:  c3625ee0efcb = 3:  48d9c38e8f0e passwd: add UPN validation support

Details

alejandro-colomar · 2026-06-14T00:40:13Z

+		errno = EOVERFLOW;
+		return false;
+	}
+	if (!strcspn(label, "-") || label[strlen(label)-1] == '-') {


We still need strrcspn_() to replace the second test.

alejandro-colomar · 2026-06-14T00:57:13Z

I've fixed a bug for you.

v6:

The first character in a label must be a letter. The comment correctly said this, but the code didn't do it. Fix the code, and remove the comment. Add a link to the specification in the commit message.
Use 2 spaces as inter-sentence spacing in commit message.

range-diff

$ git range-diff origin/passwd-upn^^^..origin/passwd-upn upstream/master..passwd-upn 
1:  5e50c4a34637 ! 1:  b1822d4782a6 lib/chkname.*: Add UPN validation support
    @@ Metadata
      ## Commit message ##
         lib/chkname.*: Add UPN validation support
     
    -    Add is_valid_upn() function to validate User Principal Name format. UPN
    +    Add is_valid_upn() function to validate User Principal Name format.  UPN
         validation splits on @ and validates the prefix using existing username
         rules and suffix part using RFC 1035/1123 compliant domain name
         validation.
     
    +    Link: <https://datatracker.ietf.org/doc/html/rfc1035#section-2.3.1>
         Co-authored-by: Iker Pedrosa <ipedrosa@redhat.com>
         Signed-off-by: Iker Pedrosa <ipedrosa@redhat.com>
         Co-authored-by: Alejandro Colomar <alx@kernel.org>
    @@ lib/chkname.c: is_valid_group_name(const char *name)
      }
     +
     +
    -+/*
    -+ * Validate a single DNS domain label according to RFC 1035/1123.
    -+ * Domain labels are components separated by dots in a domain name.
    -+ * For example, in "example.com", both "example" and "com" are labels.
    -+ *
    -+ * According to RFC 1035 2.3.1 labels must start with a letter, end with
    -+ * a letter or digit, and have as interior characters only letters, digits,
    -+ * and hyphen. Labels must be 63 characters or less.
    -+ */
    ++// Validate a single DNS domain label according to RFC 1035 2.3.1.
     +static bool
     +is_valid_domain_label(const char *label)
     +{
    @@ lib/chkname.c: is_valid_group_name(const char *name)
     +          errno = EOVERFLOW;
     +          return false;
     +  }
    -+  if (!strcspn(label, "-") || label[strlen(label)-1] == '-') {
    ++  if (!strspn(label, CTYPE_ALPHA_C) || label[strlen(label)-1] == '-') {
     +          errno = EINVAL;
     +          return false;
     +  }
2:  f0b23874316b = 2:  339dde667336 tests: add unit tests for UPN validation
3:  48d9c38e8f0e = 3:  23c7a5328623 passwd: add UPN validation support

ikerexxe · 2026-06-18T08:50:46Z

I'm actively looking into this PR now that the dependencies are merged. Please do not push

Add is_valid_upn() function to validate User Principal Name format. UPN validation splits on @ and validates the prefix using existing username rules and suffix part using RFC 1035/1123 compliant domain name validation. Link: <https://datatracker.ietf.org/doc/html/rfc1035#section-2.3.1> Co-authored-by: Iker Pedrosa <ipedrosa@redhat.com> Signed-off-by: Iker Pedrosa <ipedrosa@redhat.com> Co-authored-by: Alejandro Colomar <alx@kernel.org> Signed-off-by: Alejandro Colomar <alx@kernel.org>

Add comprehensive unit tests for is_valid_upn() function in `tests/unit/test_chkname.c` covering: - Valid UPN formats (user@domain.com) - Invalid structures (missing @, multiple @) - Domain validation (RFC compliance) - Boundary limits (253/254 char domains, 63+ char labels) Signed-off-by: Iker Pedrosa <ipedrosa@redhat.com>

@nooreldeenmansour

Add User Principal Name (UPN) validation to allow passwd command to accept usernames in user@domain.com format. Currently, passwd will accept both traditional usernames and UPN format. Fixes: 326889c (2024-10-22; "Fix coverity unbound buffer issues") Closes: <shadow-maint#1626> Reported-by: @nooreldeenmansour Signed-off-by: Iker Pedrosa <ipedrosa@redhat.com>

alejandro-colomar reviewed Jun 3, 2026

View reviewed changes

Comment thread lib/chkname.c Outdated

alejandro-colomar reviewed Jun 3, 2026

View reviewed changes

Comment thread lib/chkname.c Outdated

alejandro-colomar reviewed Jun 3, 2026

View reviewed changes

Comment thread lib/chkname.c Outdated

alejandro-colomar reviewed Jun 3, 2026

View reviewed changes

Comment thread lib/chkname.c Outdated

alejandro-colomar reviewed Jun 3, 2026

View reviewed changes

Comment thread lib/chkname.c Outdated

alejandro-colomar reviewed Jun 3, 2026

View reviewed changes

Comment thread lib/chkname.c Outdated

alejandro-colomar reviewed Jun 3, 2026

View reviewed changes

Comment thread lib/chkname.c Outdated

alejandro-colomar reviewed Jun 3, 2026

View reviewed changes

Comment thread lib/chkname.c Outdated

alejandro-colomar reviewed Jun 3, 2026

View reviewed changes

Comment thread lib/chkname.c Outdated

alejandro-colomar reviewed Jun 3, 2026

View reviewed changes

Comment thread lib/chkname.c Outdated

alejandro-colomar reviewed Jun 3, 2026

View reviewed changes

Comment thread lib/chkname.c Outdated

alejandro-colomar reviewed Jun 3, 2026

View reviewed changes

Comment thread lib/chkname.c Outdated

alejandro-colomar reviewed Jun 3, 2026

View reviewed changes

Comment thread lib/chkname.c Outdated

alejandro-colomar reviewed Jun 3, 2026

View reviewed changes

Comment thread lib/chkname.c Outdated

alejandro-colomar reviewed Jun 3, 2026

View reviewed changes

Comment thread lib/chkname.c Outdated

alejandro-colomar reviewed Jun 3, 2026

View reviewed changes

Comment thread lib/chkname.c Outdated

alejandro-colomar reviewed Jun 3, 2026

View reviewed changes

Comment thread lib/chkname.c Outdated

alejandro-colomar reviewed Jun 3, 2026

View reviewed changes

Comment thread lib/chkname.c Outdated

alejandro-colomar force-pushed the passwd-upn branch from 4ea29c1 to 97b1a5c Compare June 6, 2026 18:35

alejandro-colomar reviewed Jun 6, 2026

View reviewed changes

Comment thread lib/chkname.c Outdated

alejandro-colomar reviewed Jun 6, 2026

View reviewed changes

Comment thread lib/chkname.c Outdated

alejandro-colomar reviewed Jun 6, 2026

View reviewed changes

Comment thread lib/chkname.c

alejandro-colomar reviewed Jun 6, 2026

View reviewed changes

Comment thread lib/chkname.c Outdated

alejandro-colomar force-pushed the passwd-upn branch from 97b1a5c to 0428dee Compare June 6, 2026 23:20

alejandro-colomar reviewed Jun 6, 2026

View reviewed changes

alejandro-colomar force-pushed the passwd-upn branch from 0428dee to d2f556b Compare June 7, 2026 09:06

alejandro-colomar reviewed Jun 8, 2026

View reviewed changes

Comment thread tests/unit/test_chkname.c Outdated

ikerexxe force-pushed the passwd-upn branch from d2f556b to d71db36 Compare June 9, 2026 08:41

alejandro-colomar added the bug label Jun 11, 2026

alejandro-colomar assigned ikerexxe and alejandro-colomar Jun 11, 2026

alejandro-colomar force-pushed the passwd-upn branch from d71db36 to c3625ee Compare June 14, 2026 00:26

alejandro-colomar force-pushed the passwd-upn branch from c3625ee to 48d9c38 Compare June 14, 2026 00:36

alejandro-colomar reviewed Jun 14, 2026

View reviewed changes

Comment thread lib/chkname.c Outdated

alejandro-colomar force-pushed the passwd-upn branch from 48d9c38 to 23c7a53 Compare June 14, 2026 00:55

ikerexxe force-pushed the passwd-upn branch from 23c7a53 to d971d4d Compare June 18, 2026 09:56

ikerexxe and others added 3 commits June 18, 2026 12:15

ikerexxe force-pushed the passwd-upn branch from d971d4d to b12037f Compare June 18, 2026 10:16

Conversation

ikerexxe commented Jun 3, 2026

Uh oh!

ikerexxe commented Jun 3, 2026

Uh oh!

ikerexxe commented Jun 3, 2026

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

alejandro-colomar commented Jun 6, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

alejandro-colomar Jun 6, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

alejandro-colomar Jun 6, 2026

Choose a reason for hiding this comment

Uh oh!

Uh oh!

alejandro-colomar commented Jun 6, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

alejandro-colomar Jun 6, 2026

Choose a reason for hiding this comment

Uh oh!

alejandro-colomar Jun 6, 2026

Choose a reason for hiding this comment

Uh oh!

Uh oh!

ikerexxe commented Jun 9, 2026

Uh oh!

alejandro-colomar commented Jun 9, 2026

Uh oh!

alejandro-colomar commented Jun 14, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

alejandro-colomar Jun 14, 2026

Choose a reason for hiding this comment

Uh oh!

Uh oh!

alejandro-colomar commented Jun 14, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

ikerexxe commented Jun 18, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

alejandro-colomar commented Jun 6, 2026 •

edited

Loading

alejandro-colomar Jun 6, 2026 •

edited

Loading

alejandro-colomar commented Jun 6, 2026 •

edited

Loading

alejandro-colomar commented Jun 14, 2026 •

edited

Loading

alejandro-colomar commented Jun 14, 2026 •

edited

Loading