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Commit 9ed1fe77 authored by Geremy Condra's avatar Geremy Condra
Browse files

init: make chmod/mkdir/chown not follow symlinks 

This change brings init's do_chmod, mkdir, and do_chown into line
with open's O_NOFOLLOW semantics, causing them to fail when the
last element of their target path is a symlink.

Change-Id: If00e1a25cfe17ef6f738af4bf0541abd0c1b084b
parent e8886740

init/builtins.c

+51 −5
Original line number Diff line number Diff line
@@ -75,6 +75,52 @@ static int write_file(const char *path, const char *value) 
    }

}



static int _chown(const char *path, unsigned int uid, unsigned int gid)

{

    int fd;

    int ret;



    fd = open(path, O_RDONLY | O_NOFOLLOW);

    if (fd < 0) {

        return -1;

    }



    ret = fchown(fd, uid, gid);

    if (ret < 0) {

        int errno_copy = errno;

        close(fd);

        errno = errno_copy;

        return -1;

    }



    close(fd);



    return 0;

}



static int _chmod(const char *path, mode_t mode)

{

    int fd;

    int ret;



    fd = open(path, O_RDONLY | O_NOFOLLOW);

    if (fd < 0) {

        return -1;

    }



    ret = fchmod(fd, mode);

    if (ret < 0) {

        int errno_copy = errno;

        close(fd);

        errno = errno_copy;

        return -1;

    }



    close(fd);



    return 0;

}



static int insmod(const char *filename, char *options)

{

    void *module;
@@ -246,7 +292,7 @@ int do_mkdir(int nargs, char **args) 
    ret = mkdir(args[1], mode);

    /* chmod in case the directory already exists */

    if (ret == -1 && errno == EEXIST) {

        ret = chmod(args[1], mode);

        ret = _chmod(args[1], mode);

    }

    if (ret == -1) {

        return -errno;
@@ -260,7 +306,7 @@ int do_mkdir(int nargs, char **args) 
            gid = decode_uid(args[4]);

        }



        if (chown(args[1], uid, gid)) {

        if (_chown(args[1], uid, gid) < 0) {

            return -errno;

        }

    }
@@ -644,10 +690,10 @@ out: 
int do_chown(int nargs, char **args) {

    /* GID is optional. */

    if (nargs == 3) {

        if (chown(args[2], decode_uid(args[1]), -1) < 0)

        if (_chown(args[2], decode_uid(args[1]), -1) < 0)

            return -errno;

    } else if (nargs == 4) {

        if (chown(args[3], decode_uid(args[1]), decode_uid(args[2])))

        if (_chown(args[3], decode_uid(args[1]), decode_uid(args[2])) < 0)

            return -errno;

    } else {

        return -1;
@@ -670,7 +716,7 @@ static mode_t get_mode(const char *s) { 


int do_chmod(int nargs, char **args) {

    mode_t mode = get_mode(args[1]);

    if (chmod(args[2], mode) < 0) {

    if (_chmod(args[2], mode) < 0) {

        return -errno;

    }

    return 0;