So far the kernel allowed passing an empty argv. Given that there's now a push to restrict the kernel in that regard make sure we pass at least one argument with argv. Cc: Ariadne Conill <ariadne@xxxxxxxxxxxxxxxx> Cc: Kees Cook <keescook@xxxxxxxxxxxx> Cc: Rich Felker <dalias@xxxxxxxx> Cc: Eryu Guan <guaneryu@xxxxxxxxx> Cc: Michael Kerrisk <mtk.manpages@xxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx> Cc: fstests@xxxxxxxxxxxxxxx Cc: linux-fsdevel@xxxxxxxxxxxxxxx Cc: linux-kernel@xxxxxxxxxxxxxxx Link: https://lore.kernel.org/lkml/20220127000724.15106-1-ariadne@xxxxxxxxxxxxxxxx Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx> --- /* v2 */ - Make sure argv array is NULL terminated. I fired the first patch too quickly. - Take the chance and remove the repeated argv open-coding and move it directly into the execveat helper and rename it to reflect the fact that it's not just a simple syscall wrapper anymore. --- src/idmapped-mounts/idmapped-mounts.c | 65 +++++++++------------------ 1 file changed, 22 insertions(+), 43 deletions(-) diff --git a/src/idmapped-mounts/idmapped-mounts.c b/src/idmapped-mounts/idmapped-mounts.c index 4cf6c3bb..5bab19a9 100644 --- a/src/idmapped-mounts/idmapped-mounts.c +++ b/src/idmapped-mounts/idmapped-mounts.c @@ -695,11 +695,14 @@ static int fd_to_fd(int from, int to) return 0; } -static int sys_execveat(int fd, const char *path, char **argv, char **envp, - int flags) +static int do_execveat(int fd, const char *path, char **envp) { #ifdef __NR_execveat - return syscall(__NR_execveat, fd, path, argv, envp, flags); + static char *argv_empty[] = { + "", + NULL, + }; + return syscall(__NR_execveat, fd, path, argv_empty, envp, 0); #else errno = ENOSYS; return -1; @@ -3597,15 +3600,12 @@ static int setid_binaries(void) "EXPECTED_EGID=5000", NULL, }; - static char *argv[] = { - NULL, - }; if (!expected_uid_gid(t_dir1_fd, FILE1, 0, 5000, 5000)) die("failure: expected_uid_gid"); - sys_execveat(t_dir1_fd, FILE1, argv, envp, 0); - die("failure: sys_execveat"); + do_execveat(t_dir1_fd, FILE1, envp); + die("failure: do_execveat"); exit(EXIT_FAILURE); } @@ -3725,15 +3725,12 @@ static int setid_binaries_idmapped_mounts(void) "EXPECTED_EGID=15000", NULL, }; - static char *argv[] = { - NULL, - }; if (!expected_uid_gid(open_tree_fd, FILE1, 0, 15000, 15000)) die("failure: expected_uid_gid"); - sys_execveat(open_tree_fd, FILE1, argv, envp, 0); - die("failure: sys_execveat"); + do_execveat(open_tree_fd, FILE1, envp); + die("failure: do_execveat"); exit(EXIT_FAILURE); } @@ -3864,9 +3861,6 @@ static int setid_binaries_idmapped_mounts_in_userns(void) "EXPECTED_EGID=5000", NULL, }; - static char *argv[] = { - NULL, - }; if (!switch_userns(attr.userns_fd, 0, 0, false)) die("failure: switch_userns"); @@ -3874,8 +3868,8 @@ static int setid_binaries_idmapped_mounts_in_userns(void) if (!expected_uid_gid(open_tree_fd, FILE1, 0, 5000, 5000)) die("failure: expected_uid_gid"); - sys_execveat(open_tree_fd, FILE1, argv, envp, 0); - die("failure: sys_execveat"); + do_execveat(open_tree_fd, FILE1, envp); + die("failure: do_execveat"); exit(EXIT_FAILURE); } @@ -3923,9 +3917,6 @@ static int setid_binaries_idmapped_mounts_in_userns(void) "EXPECTED_EGID=0", NULL, }; - static char *argv[] = { - NULL, - }; if (!caps_supported()) { log_debug("skip: capability library not installed"); @@ -3938,8 +3929,8 @@ static int setid_binaries_idmapped_mounts_in_userns(void) if (!expected_uid_gid(open_tree_fd, FILE1, 0, 0, 0)) die("failure: expected_uid_gid"); - sys_execveat(open_tree_fd, FILE1, argv, envp, 0); - die("failure: sys_execveat"); + do_execveat(open_tree_fd, FILE1, envp); + die("failure: do_execveat"); exit(EXIT_FAILURE); } @@ -3991,9 +3982,6 @@ static int setid_binaries_idmapped_mounts_in_userns(void) NULL, NULL, }; - static char *argv[] = { - NULL, - }; if (!switch_userns(attr.userns_fd, 0, 0, false)) die("failure: switch_userns"); @@ -4007,8 +3995,8 @@ static int setid_binaries_idmapped_mounts_in_userns(void) if (!expected_uid_gid(open_tree_fd, FILE1, 0, t_overflowuid, t_overflowgid)) die("failure: expected_uid_gid"); - sys_execveat(open_tree_fd, FILE1, argv, envp, 0); - die("failure: sys_execveat"); + do_execveat(open_tree_fd, FILE1, envp); + die("failure: do_execveat"); exit(EXIT_FAILURE); } @@ -4149,9 +4137,6 @@ static int setid_binaries_idmapped_mounts_in_userns_separate_userns(void) "EXPECTED_EGID=5000", NULL, }; - static char *argv[] = { - NULL, - }; userns_fd = get_userns_fd(0, 10000, 10000); if (userns_fd < 0) @@ -4163,8 +4148,8 @@ static int setid_binaries_idmapped_mounts_in_userns_separate_userns(void) if (!expected_uid_gid(open_tree_fd, FILE1, 0, 5000, 5000)) die("failure: expected_uid_gid"); - sys_execveat(open_tree_fd, FILE1, argv, envp, 0); - die("failure: sys_execveat"); + do_execveat(open_tree_fd, FILE1, envp); + die("failure: do_execveat"); exit(EXIT_FAILURE); } @@ -4213,9 +4198,6 @@ static int setid_binaries_idmapped_mounts_in_userns_separate_userns(void) "EXPECTED_EGID=0", NULL, }; - static char *argv[] = { - NULL, - }; userns_fd = get_userns_fd(0, 10000, 10000); if (userns_fd < 0) @@ -4232,8 +4214,8 @@ static int setid_binaries_idmapped_mounts_in_userns_separate_userns(void) if (!expected_uid_gid(open_tree_fd, FILE1, 0, 0, 0)) die("failure: expected_uid_gid"); - sys_execveat(open_tree_fd, FILE1, argv, envp, 0); - die("failure: sys_execveat"); + do_execveat(open_tree_fd, FILE1, envp); + die("failure: do_execveat"); exit(EXIT_FAILURE); } @@ -4285,9 +4267,6 @@ static int setid_binaries_idmapped_mounts_in_userns_separate_userns(void) NULL, NULL, }; - static char *argv[] = { - NULL, - }; userns_fd = get_userns_fd(0, 10000, 10000); if (userns_fd < 0) @@ -4305,8 +4284,8 @@ static int setid_binaries_idmapped_mounts_in_userns_separate_userns(void) if (!expected_uid_gid(open_tree_fd, FILE1, 0, t_overflowuid, t_overflowgid)) die("failure: expected_uid_gid"); - sys_execveat(open_tree_fd, FILE1, argv, envp, 0); - die("failure: sys_execveat"); + do_execveat(open_tree_fd, FILE1, envp); + die("failure: do_execveat"); exit(EXIT_FAILURE); } base-commit: d8dee1222ecdfa1cff1386a61248e587eb3b275d -- 2.32.0
