216 lines
6.5 KiB
Diff
216 lines
6.5 KiB
Diff
From 1e6cdb256c06b084501f5016d10bb5c8465c8287 Mon Sep 17 00:00:00 2001
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From: Panu Matilainen <pmatilai@redhat.com>
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Date: Mon, 19 Aug 2024 11:03:10 +0300
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Subject: [PATCH 4/5] Report unsafe symlinks during installation as a specific
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case
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RPM refuses to follow non root owned symlinks pointing to files owned by
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another user for security reasons. This case was lumped in with
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O_DIRECTORY behavior, leading to confusing error message as the symlink
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often indeed points at a directory. Emit a more meaningful error message
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when encountering unsafe symlinks.
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We already detect the error condition in the main if block here, might
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as well set the error code right there and then so we don't need to
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redetect later. We previously only tested for the unsafe link condition
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when our O_DIRECTORY equivalent was set, but that seems wrong. Probably
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doesn't matter with the existing callers, but we really must not
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follow those unsafe symlinks no matter what.
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Co-authored-by: Florian Festi <ffesti@redhat.com>
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Backported from commits:
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14516542c113560dc0070df2f9102568a7a71b58
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535eacc96ae6fe5289a2917bb0af43e491b0f4f4
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Tests are excluded from this backport since they would need significant
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rework, the use case will be covered by Beaker.
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Fixes: RHEL-39897
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---
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lib/fsm.c | 70 +++++++++++++++++++++++++++--------------------------
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lib/rpmfi.c | 1 +
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2 files changed, 37 insertions(+), 34 deletions(-)
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diff --git a/lib/fsm.c b/lib/fsm.c
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index 9dd50b784..720d4a2ec 100644
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--- a/lib/fsm.c
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+++ b/lib/fsm.c
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@@ -65,7 +65,7 @@ struct filedata_s {
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* things around needlessly
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*/
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static const char * fileActionString(rpmFileAction a);
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-static int fsmOpenat(int dirfd, const char *path, int flags, int dir);
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+static int fsmOpenat(int *fdp, int dirfd, const char *path, int flags, int dir);
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static int fsmClose(int *wfdp);
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/** \ingroup payload
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@@ -98,9 +98,9 @@ static int fsmLink(int odirfd, const char *opath, int dirfd, const char *path)
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#ifdef WITH_CAP
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static int cap_set_fileat(int dirfd, const char *path, cap_t fcaps)
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{
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- int rc = -1;
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- int fd = fsmOpenat(dirfd, path, O_RDONLY|O_NOFOLLOW, 0);
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- if (fd >= 0) {
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+ int fd = -1;
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+ int rc = fsmOpenat(&fd, dirfd, path, O_RDONLY|O_NOFOLLOW, 0);
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+ if (!rc) {
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rc = cap_set_fd(fd, fcaps);
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fsmClose(&fd);
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}
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@@ -299,12 +299,12 @@ static int fsmMkdir(int dirfd, const char *path, mode_t mode)
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return rc;
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}
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-static int fsmOpenat(int dirfd, const char *path, int flags, int dir)
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+static int fsmOpenat(int *wfdp, int dirfd, const char *path, int flags, int dir)
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{
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struct stat lsb, sb;
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int sflags = flags | O_NOFOLLOW;
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int fd = openat(dirfd, path, sflags);
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- int ffd = fd;
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+ int rc = 0;
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/*
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* Only ever follow symlinks by root or target owner. Since we can't
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@@ -313,7 +313,7 @@ static int fsmOpenat(int dirfd, const char *path, int flags, int dir)
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* it could've only been the link owner or root.
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*/
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if (fd < 0 && errno == ELOOP && flags != sflags) {
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- ffd = openat(dirfd, path, flags);
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+ int ffd = openat(dirfd, path, flags);
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if (ffd >= 0) {
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if (fstatat(dirfd, path, &lsb, AT_SYMLINK_NOFOLLOW) == 0) {
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if (fstat(ffd, &sb) == 0) {
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@@ -322,17 +322,26 @@ static int fsmOpenat(int dirfd, const char *path, int flags, int dir)
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}
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}
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}
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- if (ffd != fd)
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+ /* Symlink with non-matching owners */
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+ if (ffd != fd) {
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close(ffd);
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+ rc = RPMERR_INVALID_SYMLINK;
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+ }
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}
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}
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/* O_DIRECTORY equivalent */
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- if (dir && ((fd != ffd) || (fd >= 0 && fstat(fd, &sb) == 0 && !S_ISDIR(sb.st_mode)))) {
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- errno = ENOTDIR;
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+ if (!rc && dir && fd >= 0 && fstat(fd, &sb) == 0 && !S_ISDIR(sb.st_mode))
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+ rc = RPMERR_ENOTDIR;
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+
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+ if (!rc && fd < 0)
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+ rc = RPMERR_OPEN_FAILED;
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+
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+ if (rc)
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fsmClose(&fd);
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- }
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- return fd;
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+
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+ *wfdp = fd;
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+ return rc;
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}
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static int fsmDoMkDir(rpmPlugins plugins, int dirfd, const char *dn,
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@@ -351,9 +360,7 @@ static int fsmDoMkDir(rpmPlugins plugins, int dirfd, const char *dn,
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rc = fsmMkdir(dirfd, dn, mode);
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if (!rc) {
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- *fdp = fsmOpenat(dirfd, dn, O_RDONLY|O_NOFOLLOW, 1);
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- if (*fdp == -1)
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- rc = RPMERR_ENOTDIR;
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+ rc = fsmOpenat(fdp, dirfd, dn, O_RDONLY|O_NOFOLLOW, 1);
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}
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if (!rc) {
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@@ -378,47 +385,44 @@ static int ensureDir(rpmPlugins plugins, const char *p, int owned, int create,
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char *sp = NULL, *bn;
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char *apath = NULL;
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int oflags = O_RDONLY;
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- int rc = 0;
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if (*dirfdp >= 0)
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- return rc;
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+ return 0;
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- int dirfd = fsmOpenat(-1, "/", oflags, 1);
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+ int dirfd = -1;
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+ int rc = fsmOpenat(&dirfd, -1, "/", oflags, 1);
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int fd = dirfd; /* special case of "/" */
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char *path = xstrdup(p);
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char *dp = path;
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while ((bn = strtok_r(dp, "/", &sp)) != NULL) {
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- fd = fsmOpenat(dirfd, bn, oflags, 1);
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+ rc = fsmOpenat(&fd, dirfd, bn, oflags, 1);
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/* assemble absolute path for plugins benefit, sigh */
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apath = rstrscat(&apath, "/", bn, NULL);
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- if (fd < 0 && errno == ENOENT && create) {
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+ if (rc && errno == ENOENT && create) {
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mode_t mode = S_IFDIR | (_dirPerms & 07777);
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rc = fsmDoMkDir(plugins, dirfd, bn, apath, owned, mode, &fd);
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}
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fsmClose(&dirfd);
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- if (fd >= 0) {
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- dirfd = fd;
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- } else {
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- if (!quiet) {
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- rpmlog(RPMLOG_ERR, _("failed to open dir %s of %s: %s\n"),
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- bn, p, strerror(errno));
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- }
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- rc = RPMERR_OPEN_FAILED;
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+ if (rc)
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break;
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- }
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+ dirfd = fd;
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dp = NULL;
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}
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if (rc) {
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+ if (!quiet) {
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+ char *msg = rpmfileStrerror(rc);
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+ rpmlog(RPMLOG_ERR, _("failed to open dir %s of %s: %s\n"),
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+ bn, p, msg);
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+ free(msg);
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+ }
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fsmClose(&fd);
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fsmClose(&dirfd);
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- } else {
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- rc = 0;
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}
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*dirfdp = dirfd;
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@@ -1025,10 +1029,8 @@ setmeta:
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/* Only follow safe symlinks, and never on temporary files */
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if (fp->suffix)
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flags |= AT_SYMLINK_NOFOLLOW;
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- fd = fsmOpenat(di.dirfd, fp->fpath, flags,
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+ rc = fsmOpenat(&fd, di.dirfd, fp->fpath, flags,
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S_ISDIR(fp->sb.st_mode));
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- if (fd < 0)
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- rc = RPMERR_OPEN_FAILED;
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}
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if (!rc && fp->setmeta) {
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diff --git a/lib/rpmfi.c b/lib/rpmfi.c
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index 0aacd9f85..821bae875 100644
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--- a/lib/rpmfi.c
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+++ b/lib/rpmfi.c
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@@ -2432,6 +2432,7 @@ char * rpmfileStrerror(int rc)
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case RPMERR_DIGEST_MISMATCH: s = _("Digest mismatch"); break;
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case RPMERR_INTERNAL: s = _("Internal error"); break;
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case RPMERR_UNMAPPED_FILE: s = _("Archive file not in header"); break;
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+ case RPMERR_INVALID_SYMLINK: s = _("Unsafe symlink"); break;
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case RPMERR_ENOENT: s = strerror(ENOENT); break;
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case RPMERR_ENOTEMPTY: s = strerror(ENOTEMPTY); break;
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case RPMERR_EXIST_AS_DIR:
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--
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2.47.0
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