Sync from SUSE:SLFO:1.1 oath-toolkit revision fbae423f4e983fb7dbc93623cb9f60b9
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From 4302b149a186ba8ca155ea7e211c25fac112a3ef Mon Sep 17 00:00:00 2001
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From 345ae06e0f698bdb1e9b4529e5a882f12df04426 Mon Sep 17 00:00:00 2001
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From: Matthias Gerstner <matthias.gerstner@suse.de>
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Date: Wed, 11 Sep 2024 14:09:25 +0200
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Date: Wed, 16 Oct 2024 09:58:35 +0200
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Subject: [PATCH] usersfile: fix potential security issues in PAM module
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context (CVE-2024-47191)
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With the addition of the possibility to place a usersfile also into
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a user's home directory via variable expansion of ${HOME} and ${USER} in
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@ -68,11 +67,28 @@ for this is that locks obtained with F_SETLK cannot be inherited to
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child processes, which we need to do now. flock() would also have been
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an alternative, but it has unfortunate properties if the lockfile should
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be located on a network file system.
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This is a follow-up version of the patch that addresses a few
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shortcomings of the originally shared patch:
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- setgroups() is invoked to drop supplementary group membership. Without
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this the forked process wrongly retains the root group membership.
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Since the privilege drop is only an additional hardening measure, the
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original patch should still prove safe.
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- the usersfile is checked for additional hard-links; if the link count
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is not zero, then the file is rejected. This prevents possible hard
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link attacks on the end of the unprivileged user. With the Linux
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kernel sysctl protected_hardlinks set to 1 (the usual default on most
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distributions), this attack will not work either way.
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- O_NOCTTY has been added to the open() call of the usersfile. This
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makes this aspect explicit, although the code already checks that the
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file is a regular file, so the situation shouldn't arise in the first
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place.
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---
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liboath/errors.c | 7 +-
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liboath/oath.h.in | 7 +-
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liboath/usersfile.c | 694 ++++++++++++++++++++++++++++++++++++--------
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3 files changed, 580 insertions(+), 128 deletions(-)
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liboath/oath.h.in | 8 +-
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liboath/usersfile.c | 706 ++++++++++++++++++++++++++++++++++++--------
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3 files changed, 593 insertions(+), 128 deletions(-)
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diff --git a/liboath/errors.c b/liboath/errors.c
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index c1725f9..67ed008 100644
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@ -93,10 +109,10 @@ index c1725f9..67ed008 100644
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/**
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diff --git a/liboath/oath.h.in b/liboath/oath.h.in
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index b8b4fbd..dc3e973 100644
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index b8b4fbd..5ad7045 100644
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--- a/liboath/oath.h.in
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+++ b/liboath/oath.h.in
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@@ -152,9 +152,14 @@ extern "C"
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@@ -152,9 +152,15 @@ extern "C"
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OATH_FILE_CLOSE_ERROR = -25,
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OATH_FILE_CHOWN_ERROR = -26,
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OATH_FILE_STAT_ERROR = -27,
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@ -105,18 +121,19 @@ index b8b4fbd..dc3e973 100644
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+ OATH_WAIT_ERROR = -30,
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+ OATH_SETUID_ERROR = -31,
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+ OATH_SETGID_ERROR = -32,
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+ OATH_SETGROUPS_ERROR = -33,
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/* When adding anything here, update OATH_LAST_ERROR, errors.c
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and tests/tst_errors.c. */
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- OATH_LAST_ERROR = -27
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+ OATH_LAST_ERROR = -33
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+ OATH_LAST_ERROR = -34
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} oath_rc;
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/* Global */
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diff --git a/liboath/usersfile.c b/liboath/usersfile.c
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index 3b139d1..5bd3700 100644
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index 3b139d1..c9625f4 100644
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--- a/liboath/usersfile.c
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+++ b/liboath/usersfile.c
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@@ -29,10 +29,229 @@
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@@ -29,10 +29,239 @@
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#include <unistd.h> /* For ssize_t. */
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#include <fcntl.h> /* For fcntl. */
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#include <errno.h> /* For errno. */
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@ -124,6 +141,7 @@ index 3b139d1..5bd3700 100644
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#include <sys/stat.h> /* For S_IRUSR, S_IWUSR. */
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+#include <sys/wait.h> /* For wait */
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+#include <sys/stat.h> /* For stat */
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+#include <grp.h> /* For setgroups */
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#ifndef _WIN32
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@ -264,7 +282,7 @@ index 3b139d1..5bd3700 100644
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+ * recovery mechanism if we obtain a lock on the file, but the file has
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+ * already been replaced by a new version. This situation is detected by
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+ * opening the file again after the lock has been placed and comparing the
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+ * inode numbers. If the no longer match, then the new file has to be locked
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+ * inode numbers. If they no longer match, then the new file has to be locked
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+ * instead.
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+ *
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+ * On successful return ctx->fd will be valid and locked and ctx->st will
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@ -282,6 +300,15 @@ index 3b139d1..5bd3700 100644
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+ if (fstat(ctx->fd, &ctx->st) != 0)
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+ return OATH_FILE_STAT_ERROR;
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+
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+ /* don't allow hard-linked files, which would allow to fool our logic -
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+ * this can only happen if protected_hardlinks is disabled in the kernel,
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+ * though */
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+ if (ctx->st.st_nlink > 1)
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+ {
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+ close(ctx->fd);
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+ return OATH_FILE_OPEN_ERROR;
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+ }
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+
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+ /* lock and retry opening until all is consistent, abort after a couple of
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+ * times, it's unlikely that we race all the time (could be a DoS attempt) */
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+ for (int i = 0; i < 5; i++)
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@ -293,7 +320,7 @@ index 3b139d1..5bd3700 100644
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+ /* we need to open it read-write for write-locking it via fcntl(),
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+ * otherwise we wouldn't need write access for the file, since we'll
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+ * atomically replace it with a new one. */
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+ int err = reopen_path_fd(&ctx->fd, O_RDWR|O_CLOEXEC);
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+ int err = reopen_path_fd(&ctx->fd, O_RDWR|O_CLOEXEC|O_NOCTTY);
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+ if (err != OATH_OK)
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+ return err;
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+
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@ -346,7 +373,7 @@ index 3b139d1..5bd3700 100644
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static int
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parse_type (const char *str, unsigned *digits, unsigned *totpstepsize)
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{
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@@ -298,8 +517,92 @@ update_usersfile2 (const char *username,
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@@ -298,8 +527,92 @@ update_usersfile2 (const char *username,
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return OATH_OK;
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}
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@ -440,7 +467,7 @@ index 3b139d1..5bd3700 100644
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const char *username,
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const char *otp,
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FILE *infh,
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@@ -307,9 +610,7 @@ update_usersfile (const char *usersfile,
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@@ -307,9 +620,7 @@ update_usersfile (const char *usersfile,
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size_t *n, char *timestamp, uint64_t new_moving_factor,
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size_t skipped_users)
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{
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@ -450,7 +477,7 @@ index 3b139d1..5bd3700 100644
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/* Rewind input file. */
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{
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@@ -321,112 +622,236 @@ update_usersfile (const char *usersfile,
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@@ -321,112 +632,236 @@ update_usersfile (const char *usersfile,
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clearerr (infh);
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}
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@ -564,7 +591,9 @@ index 3b139d1..5bd3700 100644
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+ rc = OATH_FILE_SYNC_ERROR;
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+ goto out;
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+ }
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+
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- if (rc == OATH_OK && fstat (fileno (infh), &insb) == -1)
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- rc = OATH_FILE_STAT_ERROR;
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+out:
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+ if (outfd >= 0)
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+ close(outfd);
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@ -575,8 +604,10 @@ index 3b139d1..5bd3700 100644
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+ return rc;
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+}
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- if (rc == OATH_OK && fstat (fileno (infh), &insb) == -1)
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- rc = OATH_FILE_STAT_ERROR;
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- if (rc == OATH_OK
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- && fchown (fileno (outfh), insb.st_uid, insb.st_gid) != 0)
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- rc = OATH_FILE_CHOWN_ERROR;
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- }
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+static int
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+oath_process_usersfile (struct usersfile_ctx *ctx,
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+ const char *username,
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@ -591,29 +622,28 @@ index 3b139d1..5bd3700 100644
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+ int rc;
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+ size_t skipped_users;
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- if (rc == OATH_OK
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- && fchown (fileno (outfh), insb.st_uid, insb.st_gid) != 0)
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- rc = OATH_FILE_CHOWN_ERROR;
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- }
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- /* On success, flush the buffers. */
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- if (rc == OATH_OK && fflush (outfh) != 0)
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- rc = OATH_FILE_FLUSH_ERROR;
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+ infh = fdopen (ctx->fd, "r");
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+ if (infh == NULL)
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+ return OATH_FILE_OPEN_ERROR;
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- /* On success, flush the buffers. */
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- if (rc == OATH_OK && fflush (outfh) != 0)
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- rc = OATH_FILE_FLUSH_ERROR;
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+ /* ownership has been transferred to the FILE stream now */
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+ ctx->fd = -1;
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- /* On success, sync the disks. */
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- if (rc == OATH_OK && fsync (fileno (outfh)) != 0)
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- rc = OATH_FILE_SYNC_ERROR;
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+ rc = parse_usersfile (username, otp, window, passwd, last_otp,
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+ infh, &line, &n, &new_moving_factor, &skipped_users);
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+ /* ownership has been transferred to the FILE stream now */
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+ ctx->fd = -1;
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- /* Close the file regardless of success. */
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- if (fclose (outfh) != 0)
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- rc = OATH_FILE_CLOSE_ERROR;
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+ rc = parse_usersfile (username, otp, window, passwd, last_otp,
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+ infh, &line, &n, &new_moving_factor, &skipped_users);
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- /* On success, overwrite the usersfile with the new copy. */
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- if (rc == OATH_OK && rename (newfilename, usersfile) != 0)
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- rc = OATH_FILE_RENAME_ERROR;
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+ if (rc == OATH_OK)
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+ {
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+ char timestamp[30];
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@ -622,15 +652,12 @@ index 3b139d1..5bd3700 100644
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+ time_t t;
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+ size_t l;
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- /* On success, overwrite the usersfile with the new copy. */
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- if (rc == OATH_OK && rename (newfilename, usersfile) != 0)
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- rc = OATH_FILE_RENAME_ERROR;
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+ if (time (&t) == (time_t) - 1)
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+ return OATH_TIME_ERROR;
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- /* Something has failed, don't leave garbage lying around. */
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- if (rc != OATH_OK)
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- unlink (newfilename);
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+ if (time (&t) == (time_t) - 1)
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+ return OATH_TIME_ERROR;
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+
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+ if (localtime_r (&t, &now) == NULL)
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+ return OATH_TIME_ERROR;
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@ -638,6 +665,11 @@ index 3b139d1..5bd3700 100644
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+ l = strftime (timestamp, max, TIME_FORMAT_STRING, &now);
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+ if (l != 20)
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+ return OATH_TIME_ERROR;
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+
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+ rc = update_usersfile (ctx, username, otp, infh,
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+ &line, &n, timestamp, new_moving_factor,
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+ skipped_users);
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+ }
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- /* Complete, close the lockfile */
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- if (fclose (lockfh) != 0)
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@ -645,11 +677,6 @@ index 3b139d1..5bd3700 100644
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- if (unlink (lockfile) != 0)
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- rc = OATH_FILE_UNLINK_ERROR;
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- free (lockfile);
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+ rc = update_usersfile (ctx, username, otp, infh,
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+ &line, &n, timestamp, new_moving_factor,
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+ skipped_users);
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+ }
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+
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+ free (line);
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+ fclose (infh);
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@ -769,7 +796,7 @@ index 3b139d1..5bd3700 100644
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/**
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* oath_authenticate_usersfile:
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* @usersfile: string with user credential filename, in UsersFile format
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@@ -460,52 +885,69 @@ oath_authenticate_usersfile (const char *usersfile,
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@@ -460,52 +895,71 @@ oath_authenticate_usersfile (const char *usersfile,
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size_t window,
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const char *passwd, time_t *last_otp)
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{
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@ -846,6 +873,8 @@ index 3b139d1..5bd3700 100644
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+ if (cpid == 0)
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+ {
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+ /* child */
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+ if (setgroups(0, NULL) != 0)
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+ exit (abs(OATH_SETGROUPS_ERROR));
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+ if (setgid (ctx.st.st_gid) != 0)
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+ exit (abs(OATH_SETGID_ERROR));
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+ if (setuid (ctx.st.st_uid) != 0)
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@ -881,5 +910,5 @@ index 3b139d1..5bd3700 100644
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#else /* _WIN32 */
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--
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2.44.2
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2.45.2
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@ -1,3 +1,9 @@
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-------------------------------------------------------------------
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Wed Oct 16 14:24:27 UTC 2024 - Jan Zerebecki <jan.suse@zerebecki.de>
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- Update 0001-usersfile-fix-potential-security-issues-in-PAM-modul.patch
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with bsc#1231699 improvements for security fix CVE-2024-47191
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-------------------------------------------------------------------
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Fri Sep 13 15:10:22 UTC 2024 - Jan Zerebecki <jan.suse@zerebecki.de>
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