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Revert "libselinux: restorecon: pin file to avoid TOCTOU issues"

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This reverts commit 7e979b56fd.

The reverted commit broke `setfiles` when it's run from a chroot
without /proc mounted, e.g.

    # chroot /mnt/sysimage

    chroot# setfiles -e /proc -e /sys /sys /etc/selinux/targeted/contexts/files/file_contexts /
    [strace]
    openat(AT_FDCWD, "/", O_RDONLY|O_EXCL|O_NOFOLLOW|O_PATH) = 3
    newfstatat(3, "", {st_mode=S_IFDIR|0555, st_size=4096, ...}, AT_EMPTY_PATH) = 0
    mmap(NULL, 2101248, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f1697c91000
    fgetxattr(3, "security.selinux", 0x55be8881d3f0, 255) = -1 EBADF (Bad file descriptor)
    fcntl(3, F_GETFL)                       = 0x220000 (flags O_RDONLY|O_NOFOLLOW|O_PATH)
    getxattr("/proc/self/fd/3", "security.selinux", 0x55be8881d3f0, 255) = -1 ENOENT (No such file or directory)
    [/strace]
    setfiles: Could not set context for /:  No such file or directory

Signed-off-by: Petr Lautrbach <plautrba@redhat.com>
Acked-by: James Carter <jwcart2@gmail.com>
This commit is contained in:
Petr Lautrbach 2022-05-31 14:57:51 +02:00 committed by James Carter
parent 6d02b2fa29
commit de285252a1
1 changed files with 18 additions and 25 deletions
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43
libselinux/src/selinux_restorecon.c
View file

@ -623,13 +623,13 @@ out:
return rc;
}
static int restorecon_sb(const char *pathname, struct rest_flags *flags, bool first)
static int restorecon_sb(const char *pathname, const struct stat *sb,
struct rest_flags *flags, bool first)
{
char *newcon = NULL;
char *curcon = NULL;
char *newtypecon = NULL;
int fd = -1, rc;
struct stat stat_buf;
int rc;
bool updated = false;
const char *lookup_path = pathname;
float pc;
@ -644,21 +644,13 @@ static int restorecon_sb(const char *pathname, struct rest_flags *flags, bool fi
lookup_path += rootpathlen;
}
fd = open(pathname, O_PATH | O_NOFOLLOW | O_EXCL);
if (fd < 0)
goto err;
rc = fstat(fd, &stat_buf);
if (rc < 0)
goto err;
if (rootpath != NULL && lookup_path[0] == '\0')
/* this is actually the root dir of the alt root. */
rc = selabel_lookup_raw(fc_sehandle, &newcon, "/",
stat_buf.st_mode);
sb->st_mode);
else
rc = selabel_lookup_raw(fc_sehandle, &newcon, lookup_path,
stat_buf.st_mode);
sb->st_mode);
if (rc < 0) {
if (errno == ENOENT) {
@ -667,10 +659,10 @@ static int restorecon_sb(const char *pathname, struct rest_flags *flags, bool fi
"Warning no default label for %s\n",
lookup_path);
goto out; /* no match, but not an error */
return 0; /* no match, but not an error */
}
goto err;
return -1;
}
if (flags->progress) {
@ -690,17 +682,19 @@ static int restorecon_sb(const char *pathname, struct rest_flags *flags, bool fi
}
if (flags->add_assoc) {
rc = filespec_add(stat_buf.st_ino, newcon, pathname, flags);
rc = filespec_add(sb->st_ino, newcon, pathname, flags);
if (rc < 0) {
selinux_log(SELINUX_ERROR,
"filespec_add error: %s\n", pathname);
goto out1;
freecon(newcon);
return -1;
}
if (rc > 0) {
/* Already an association and it took precedence. */
goto out;
freecon(newcon);
return 0;
}
}
@ -708,7 +702,7 @@ static int restorecon_sb(const char *pathname, struct rest_flags *flags, bool fi
selinux_log(SELINUX_INFO, "%s matched by %s\n",
pathname, newcon);
if (fgetfilecon_raw(fd, &curcon) < 0) {
if (lgetfilecon_raw(pathname, &curcon) < 0) {
if (errno != ENODATA)
goto err;
@ -741,7 +735,7 @@ static int restorecon_sb(const char *pathname, struct rest_flags *flags, bool fi
}
if (!flags->nochange) {
if (fsetfilecon(fd, newcon) < 0)
if (lsetfilecon(pathname, newcon) < 0)
goto err;
updated = true;
}
@ -766,8 +760,6 @@ static int restorecon_sb(const char *pathname, struct rest_flags *flags, bool fi
out:
rc = 0;
out1:
if (fd >= 0)
close(fd);
freecon(curcon);
freecon(newcon);
return rc;
@ -865,6 +857,7 @@ static void *selinux_restorecon_thread(void *arg)
FTSENT *ftsent;
int error;
char ent_path[PATH_MAX];
struct stat ent_st;
bool first = false;
if (state->parallel)
@ -962,11 +955,11 @@ loop_body:
/* fall through */
default:
strcpy(ent_path, ftsent->fts_path);
ent_st = *ftsent->fts_statp;
if (state->parallel)
pthread_mutex_unlock(&state->mutex);
error = restorecon_sb(ent_path, &state->flags,
error = restorecon_sb(ent_path, &ent_st, &state->flags,
first);
if (state->parallel) {
@ -1162,7 +1155,7 @@ static int selinux_restorecon_common(const char *pathname_orig,
goto cleanup;
}
error = restorecon_sb(pathname, &state.flags, true);
error = restorecon_sb(pathname, &sb, &state.flags, true);
goto cleanup;
}